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Journal Cover Journal of Applied Polymer Science
  [SJR: 0.578]   [H-I: 127]   [133 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0021-8995 - ISSN (Online) 1097-4628
   Published by John Wiley and Sons Homepage  [1579 journals]
  • EPDM–chlorobutyl rubber blends in γ-radiation and hydrocarbon
           environment: Mechanical, transport, and ageing behavior
    • Authors: Neelesh Ashok; Meera Balachandran, Falix Lawrence, Neethu Sebastian
      Abstract: In nuclear applications, ethylene propylene diene monomer (EPDM) rubber is the material of choice as gaskets and O-rings due to its radiations resistance. In nuclear fuel reprocessing, in addition to radiation, the elastomeric components have to withstand paraffinic hydrocarbons as well. But, EPDM has poor resistance to hydrocarbons. To enhance the durability of EPDM in such environments, EPDM–chlorobutyl rubber (CIIR) blends of varying compositions were developed and characterized for mechanical, thermal, dielectric, and solvent sorption behavior. Spectroscopic and morphological analysis was used to evaluate the compatibility of blends. Due to synergistic effect, the optimal composition of blends with superior mechanical properties and solvent resistance were found to be 60 to 80% EPDM and 20 to 40% CIIR. The optimized blends were irradiated with gamma rays at cumulative doses up to 2 MGy. Based on spectroscopic, morphological, mechanical, thermogravimetric, and sorption properties, blend containing 80% EPDM was found to have superior retention of properties after irradiation. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45195.
      PubDate: 2017-04-29T00:26:03.441511-05:
      DOI: 10.1002/app.45195
       
  • Ultraviolet protection of recycled polyethylene terephthalate
    • Authors: Greg W. Curtzwiler; Eric B. Williams, Austin L. Maples, Nathan W. Davis, Ted L. Bahns, J. Eliseo De León, Keith L. Vorst
      Abstract: Polyethylene terephthalate (PET) is commonly used for food packaging due to its high clarity, high resistance to water vapor, oxygen and carbon dioxide permeation, and good mechanical properties. However, its high transmittance in the ultraviolet-A (UVA) region leaves food susceptible to UV-induced degradation reactions. Incorporating post-consumer recycled (PCR) PET into virgin PET increased UVA absorption 100% when utilizing 100% PCR-PET, thus, increasing the protection potential of food packaging by reducing UVA-induced degradation reactions. Comparison of the current data with previous work demonstrated the reproducibility of UVA protection independent of the PC flake source. The thickness-normalized absorbance at 350 nm was a reliable predictor of the UVA protection potential regardless of composition and manufacture date. Raman, fluorescence, and attenuated total reflectance-Fourier transform infrared spectroscopy analyses provided support that the UVA absorbing moiety was a quinone derivative formed during degradation reactions that are known to occur during melt processing/re-processing. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45181.
      PubDate: 2017-04-29T00:25:54.874779-05:
      DOI: 10.1002/app.45181
       
  • Editorial Board, Aims & Scope, Table of Contents
    • PubDate: 2017-04-27T17:41:01.780051-05:
      DOI: 10.1002/app.44292
       
  • Cover Image, Volume 134, Issue 29
    • Abstract: Poly(N-isopropylacrylamide-co-monoalkyl itaconate)s crosslinked with tetraallylammonium bromide has structures including both hydrophobic and ionizable groups. In this research, Candan Erbil and colleagues discuss the effects of side chains on the compressive strengths of hydrogels in terms of physical crosslinks created by intermolecular interactions between octyl, cetyl and cyclohexyl groups. These POM images under bright field and between cross-polarizers also support the presence of ordered structures. Anisotropic phase of these hydrophobic side chains aligned perpendicularly to the main chain due to the possible rod-like, face-to-face and extended-coil conformations. These materials are excellent candidates for antimicrobial studies–due to improved mechanical properties and cationically modified-hydrophobic structures–and for the controlled release of hydrophilic and/or hydrophobic drugs because of improved mechanical properties and dual-responsive phase transitions. (
      DOI : 10.1002/app.45039)
      PubDate: 2017-04-27T17:40:59.526813-05:
       
  • Thermal behavior of extruded and injection-molded poly(lactic acid)–talc
           engineered biocomposites: Effects of material design, thermal history, and
           shear stresses during melt processing
    • Authors: M. Barletta; E. Pizzi, M. Puopolo, S. Vesco, F. Daneshvar-Fatah
      Abstract: Reinforced biocomposites were compounded by the reactive extrusion of poly(lactic acid) (PLA) and chemically modified microlamellar talcs. Talc was functionalized by the hydrolysis and condensation reaction of its surface hydroxyl groups with different kinds of organosilanes, namely, 3-aminopropyl triethoxysilane and (3-glycidoxypropyl)trimethoxysilane, and commercially available tri-isocyanates, namely, Bayhydur 3100 and Desmodur 3900, which feature hydrophilic and hydrophobic behaviors, respectively. PLA–talc biocomposites were also compounded by the addition of two types of reactive biodegradable compatibilizing agents, namely, maleic anhydride and glycidyl methacrylate modified PLA. The resulting compounds were melt-processed by injection molding to get flat substrates with different formulations. The thermal responses of the extruded compounds and injection-molded items, specifically the first and second thermal transitions, were analyzed by differential scanning calorimetry. In particular, the influence of the different material formulations, their thermal history, and/or shear stress in single- or multiple-stage heating and/or melt processing on the glass transition, crystallinity, and melting behavior of the biocomposites was investigated. The experimental findings revealed that the macroscopic thermal response of the compounds (i.e., extruded pellets) and substrates (i.e., injection-molded flat slabs) manufactured by the melt processing of the available formulations, was controlled and significantly improved by the fine-tuning of the chemical (i.e., reaction mechanisms, chemical bonds) and physical interactions (i.e., steric hindrances, physical bonds) among the modified talc, PLA, and compatibilizing agents. These results are of great practical importance and open up broader scenarios for the industrial application of biopolymers and biocomposites, specifically in all of those consumer goods where thermal stability and the preservation of mechanical performance at moderate and high temperatures of the materials are pivotal. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2017
      PubDate: 2017-04-26T23:35:42.884706-05:
      DOI: 10.1002/app.45179
       
  • Improved processability and performance of biomedical devices with
           poly(lactic acid)/poly(ethylene glycol) blends
    • Authors: Jianming Zhang; Shiwei Wang, Dongzhe Zhao, Yankun Zhang, Wenbo Pang, Binbin Zhang, Qian Li
      Abstract: To improve the processability of micropolymer-based devices used for biomedical applications, poly(lactic acid) (PLA) was melt-blended with poly(ethylene glycol)s (PEGs) of different molecular weights (MWs; weight-average molecular weights = 200, 800, 2000, and 4000; these PEGS are referred to as PEG200, PEG800, PEG2000, and PEG4000, respectively, in this article). The thermal properties, mechanical properties, and rheological properties of the PLA and the PLA–PEG blends were investigated. The tensile samples' morphologies showed that the low-MW PEGs filled molds well. The rheological properties confirmed that the low-MW PEGs decreased the complex viscosity, and improved the processability. With decreasing PEG MW, the PLA glass-transition temperature decreased. The nanoindenter data show that the addition of PEG decreased the modulus and hardness of PLA. The morphologies of the tensile samples showed that with increasing PEG MW, the thicknesses of the core layers increased gradually. The elongation at break was improved by approximately 247% with the addition of PEG200. Such methods can produce easily processed biological materials for producing biomedical products. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45194.
      PubDate: 2017-04-26T04:32:16.36701-05:0
      DOI: 10.1002/app.45194
       
  • One-step synthesis of corn starch urea based acrylate superabsorbents
    • Authors: Ting Guo Liu; Yun Tao Wang, Jun Guo, Tian Bao Liu, Xin Wang, Bin Li
      Abstract: A one-step synthesis procedure for starch-based acrylate superabsorbent polymers was proposed. The reaction conditions that may affect the water absorption capacity were discussed. A transparent gel-like polymer containing urea (USAP) was successfully obtained by dissolving starch in a NaOH solution without further gelatinizing processing and using acrylic acid directly without prior neutralization. Urea was used as the nitrogen source and pore-forming agent to improve the performance of the USAP. The optimum reaction conditions of the swelling ratio were also studied. A corn starch USAP was synthesized under the optimum conditions, and the water absorbency was 2704 ± 22, 561 ± 39, 100 ± 5, and 96 ± 4 g/g, respectively, in distilled water, running water, physiological saline, and artificial urine. Five kinds of starch-based USAPs were also successfully prepared under the same conditions with excellent water absorption capacities, revealing that the one-step method was a more convenient method for a potential industrial application pathway. The polymers were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis. The results indicated that the PAA chains were successfully grafted onto the starch backbone. However, the starch molecular structure was not completely destroyed during the graft polymerization. The thermal analysis and nitrogen content results proved that urea was also involved in the graft copolymerization. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2017
      PubDate: 2017-04-25T23:47:48.535896-05:
      DOI: 10.1002/app.45175
       
  • Synergistic effect of multiwalled carbon nanotubes and an intumescent
           flame retardant: Toward an ideal electromagnetic interference shielding
           material with excellent flame retardancy
    • Authors: Yuying Ma; Pengfei Ma, Yujiao Ma, Dong Xu, Peifeng Wang, Rui Yang
      Abstract: To shield undesirable electromagnetic waves caused by electronic devices and simultaneously resolve the flame safety of the electronic components, an electromagnetic interference (EMI) shielding material with excellent flame-retardant properties is urgently needed. The synergistic effect of the intumescent flame retardant (IFR) and multiwalled carbon nanotubes (MWCNTs) for polystyrene (PS) nanocomposites prepared by melt blending was investigated. The results show that addition of certain amounts of IFRs facilitated the dispersion of MWCNTs in the PS matrix, and the percolation threshold of the MWCNTs in the PS matrix also decreased from 1.67 ± 0.05 to 1.29 ± 0.04 wt %. Moreover, the EMI shielding efficiencies (SEs) of the PS–MWCNT–IFR composites were consistently higher than those of the PS–MWCNT composites without the addition of the IFRs at the same MWCNT content; this indicated that the synergistic effect of the MWCNTs and IFRs effectively improved the EMI SE of the PS–MWCNT–IFR composites. Furthermore, the limiting oxygen index (LOI) testing results show that the LOI values of the PS–MWCNT composites were consistently higher than 27%; this indicated that the PS–MWCNT composites effectively met the needs of flame safety; this indicated that the PS–MWCNT–IFR composite is a novel and promising candidate for an ideal EMI shielding material with excellent flame-retardant properties for today's electronic devices. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45088.
      PubDate: 2017-04-25T09:06:58.885301-05:
      DOI: 10.1002/app.45088
       
  • Antistatic effects and mechanism of ionic liquids for methyl vinyl
           silicone rubber
    • Authors: Xiwang Ye; Jianhua Guo, Xingrong Zeng
      Abstract: The effect of two ionic liquids (ILs), namely, 1-allyl-3-methyl imidazolium chloride ([AMIM]Cl) and 1-ethyl-3-methyl imidazolium tetrafluoroborate ([EMIM]BF4), on the surface and volume resistivities, mechanical properties, transparency, and water contact angle of methyl vinyl silicone rubber (MVQ) were investigated. The chemical structures of the two ILs before and after heat treatment were characterized by Fourier transform infrared spectroscopy. The morphology and fluorine and chlorine elemental dispersion were characterized by field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy mapping, respectively. The antistatic mechanism was revealed. The results show that the MVQ–[EMIM]BF4 composites had lower surface and volume resistivities than the MVQ–[AMIM]Cl composites. The mechanical properties of the MVQ–[EMIM]BF4 and MVQ–[AMIM]Cl composites were slightly lower than those of the pristine MVQ. With increasing [EMIM]BF4 content, the surface and volume resistivities and water contact angle of the MVQ–[EMIM]BF4 composites decreased. When the content of [EMIM]BF4 was 2.0 phr, the MVQ–[EMIM]BF4 composites showed better antistatic performance with lower surface and volume resistivities of 9.6 × 109 Ω and 1.2 × 1011 Ω cm, respectively. The antistatic mechanism of the MVQ–IL composites was ascribed to the synergistic effect of ionic migration and moisture absorption. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2017
      PubDate: 2017-04-24T23:46:02.826457-05:
      DOI: 10.1002/app.45180
       
  • Mechanical properties of biaxially strained poly(l-lactide) tubes: Strain
           rate and temperature dependence
    • Authors: Alexandra Liv Vest Løvdal; Jens W. Andreasen, Lars P. Mikkelsen, Karsten Agersted, Kristoffer Almdal
      Abstract: Poly(l-lactide) (PLLA) is a bioabsorbable polymer with high stiffness and strength compared to the other commercially available bioabsorbable polymers. The properties of PLLA can be improved by straining, causing deformation-mediated molecular orientation. PLLA tubes were biaxially strained above their Tg for improvement of their strength, in a two-step process (sequential straining). Mechanical properties and crystal morphology were investigated as a function of processing strain rate and temperature. DSC revealed that a low processing strain rate allows molecular chain relaxation in the direction of strain and the crystallization is suppressed. Faster strain rates on the other hand suppress chain relaxation, and results in crystalline tubes. The mechanical properties are influenced by both processing strain rate and temperature. Low strain rates allow chain relaxation resulting in the lowest strength and stiffness, whereas a larger stiffness and strength is achieved by increasing strain rate and temperature. Isotropic mechanical properties are only observed at high processing strain rates. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45192.
      PubDate: 2017-04-24T23:45:55.860179-05:
      DOI: 10.1002/app.45192
       
  • Synergistic effect of expandable graphite and α-type zirconium phosphate
           on flame retardancy of polyurethane elastomer
    • Authors: Wen-Zong Xu; Bao-Ling Xu, Gui-Song Wang, Xiao-Ling Wang, Liang Liu
      Abstract: Organically modified zirconium phosphate (OZrP) was prepared by cation exchange of natural counterions with hexadecyltri-n-butylphosphonium bromide. Subsequently, OZrP and expandable graphite (EG) were incorporated into polyurethane elastomer (PUE), and the thermal stability and flame retardancy of PUE composites were investigated. The thermogravimetric analysis indicated that partial substitution of EG with OZrP could improve both the thermal stability and char yield of PUE composites. The cone calorimetry and limiting oxygen index test showed that partial substitution of EG with OZrP could further enhance the flame retardancy of PUE composites and presented an excellent synergistic effect. Moreover, the char residue of PUE composites was analyzed by X-ray photoelectron spectroscopy and laser Raman spectroscopy. Their results indicated that the synergistic effect of the physical barrier to prevent transmission of heat and mass between condensed and gas phases. Therefore, the further combustion of the nether material could be inhibited, which created better flame retardancy. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45188.
      PubDate: 2017-04-21T00:22:24.84851-05:0
      DOI: 10.1002/app.45188
       
  • Combined soft lithographic transfer-printing and patterning method of
           highly fluorinated polymers as a facile surface treatment protocol
    • Authors: Da-Hyeok Lee; Seok-Heon Jung, O Jun Kwon, Myoung-Soo Kim, Jin-Seok Park, Eunhye Lee, Byung Jun Jung, Beom-Hoan O, Se-Geun Park, Jin-Kyun Lee
      Abstract: A combined soft lithographic transfer-printing and patterning method of highly fluorinated polymers was investigated aiming to establish a facile surface treatment protocol for various substrates. Spin-coated layers of poly(1H,1H,2H,2H-perfluorodecyl methacrylate) (PFDMA) on patterned polydimethylsiloxane (PDMS) molds were transfer-printed successfully on silicon, glass, aluminum substrates, resulting in the well-controlled production of nano to micrometer-scale periodic structures. With careful optimization of the dimension and density of the PFDMA patterns, it was possible to achieve a water contact angle as high as 175° on the transfer-printed highly fluorinated polymer film. One of the advantages of the transfer-patterning method is that highly fluorinated polymer films can be printed on curved surfaces while retaining their superhydrophobic and corrosion-prevention character. In addition, the transfer-printed PFDMA layers on the glass plates showed enhanced light transmission, which led to the extraction of 10% more light when they were applied to the emitting side of green organic light-emitting devices. The micro-patterned PFDMA surfaces also exhibited a significantly reduced level of bacterial adhesion when they were incubated in human bile juice. These results strongly suggest that the proposed facile transfer-patterning protocol of highly fluorinated polymer films can be a suitable surface-treatment technique for implantable electronic devices that exhibit improved device performance and anti-biofouling nature. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45184.
      PubDate: 2017-04-21T00:22:11.460515-05:
      DOI: 10.1002/app.45184
       
  • Mechanical enhancement of zirconia reinforced polyimine nanocomposites
    • Authors: Si Zhang; Yanting Lv, Jiayi Li, Song Liang, Zhenning Liu
      Abstract: Polymeric nanocomposites have demonstrated superior performance in recent decades, combining the advantages of polymer and nanoparticle fillers. However, nanocomposites of polyimine, a neoteric thermoset material, have been rarely investigated. Herein, a series of polyimine nanocomposites reinforced by zirconia (ZrO2) have been fabricated by heat-pressing under mild conditions. The resultant polyimine nanocomposites show significant enhancements on multiple mechanical properties including tensile strength, toughness, bending strength, and impact strength, whereas the optimal amount of ZrO2 particles for the best performance of a specific property varies. Interestingly, the tensile strength and toughness of the polyimine nanocomposites can be simultaneously increased by 40% and 85%, indicating that the nanocomposites exhibit excellent integration of tensile strength and toughness analogous to natural materials. Hence, a facile and cost-effective approach to enhance mechanical properties of polyimine has been realized for more applications. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45183.
      PubDate: 2017-04-21T00:22:09.318542-05:
      DOI: 10.1002/app.45183
       
  • Poly(4-vinylphenol)/tetra-n-butylammonium iodide: Efficient
           organocatalytic system for synthesis of cyclic carbonates from CO2 and
           epoxides
    • Authors: Xiangyong Wang; Yingying Zhao, Koichi Kodama, Takuji Hirose
      Abstract: An efficient polymer-based catalytic system of poly(4-vinylphenol) (PVP) and tetra-n-butylammonium iodide (TBAI) was developed for the synthesis of cyclic carbonates from epoxides and CO2. Owing to the synergistic effects of hydroxyl groups and iodide anions, this commercially available and metal-free system was highly active for the reaction of various terminal epoxides under environmentally benign conditions, at 25 to 60 °C and atmospheric pressure of CO2, without the use of any organic solvents. The catalyst system can be easily separated by adding ether, and its ability was recovered by treating it with 40% CH3CO2H aq. The recyclability was investigated in detail for three substrates, epichlorohydrin, 1,2-epoxyhexane, and styrene oxide, using 1H nuclear magnetic resonance (NMR) analysis. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45189.
      PubDate: 2017-04-21T00:22:02.615228-05:
      DOI: 10.1002/app.45189
       
  • Self-healing and interfacially toughened carbon fibre-epoxy composites
           based on electrospun core-shell nanofibres
    • Authors: Rasoul Esmaeely Neisiany; Jeremy Kong Yoong Lee, Saied Nouri Khorasani, Seeram Ramakrishna
      Abstract: Dual components of a self-healing epoxy system comprising a low viscosity epoxy resin, along with its amine based curing agent, were separately encapsulated in a polyacrylonitrile (PAN) shell via coaxial electrospinning. These nanofiber layers were then incorporated between sheets of carbon fiber fabric during the wet layup process followed by vacuum-assisted resin transfer molding (VARTM) to fabricate self-healing carbon fiber composites. Mechanical analysis of the nanofiber toughened composites demonstrated an 11% improvement in tensile strength, 19% increase in short beam shear strength, 14% greater flexural strength, and a 4% gain in impact energy absorption compared to the control composite without nanofibers. Three point bending tests affirmed the spontaneous, room temperature healing characteristics of the nanofiber containing composites, with a 96% recovery in flexural strength observed 24 h after the initial bending fracture, and a 102% recovery recorded 24 h after the successive bending fracture. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44956.
      PubDate: 2017-04-20T06:21:33.729654-05:
      DOI: 10.1002/app.44956
       
  • Structural, mechanical, and thermal properties of 3D printed
           L-CNC/acrylonitrile butadiene styrene nanocomposites
    • Authors: Xinhao Feng; Zhaozhe Yang, Sahar S. H. Rostom, Mark Dadmun, Yanjun Xie, Siqun Wang
      Abstract: 3D printing has been extensively applied in human-related activities, and therefore the 3D printed nanocomposites became more popular and important in end-use products. In the present study, we use lignin-coated cellulose nanocrystal (L-CNC) to reinforce 3D printed acrylonitrile butadiene styrene (ABS) and explore the effect of L-CNC on the structural, mechanical, and thermal properties of 3D printed L-CNC/ABS nanocomposites. The results indicate that the addition of L-CNC foams the ABS and decreases the density of 3D printed L-CNC/ABS nanocomposites. However, the tensile modulus and storage modulus increase by adding 4 % L-CNC. The thermal stability of 3D printed L-CNC/ABS nanocomposites is also significantly improved as indicated by an increase in the maximum degradation temperature. The morphology of the nanocomposites reveals good dispersion and interfacial adhesion between L-CNC and ABS. The finding indicates that the 3D printed nanocomposites become lighter and stiffer with addition of L-CNC, which will have great potential to be applied in end-use products. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45082.
      PubDate: 2017-04-20T06:21:12.248968-05:
      DOI: 10.1002/app.45082
       
  • Development of quaternarized poly(vinyl alcohol) anion-exchange membranes
           for applications in electrodialysis
    • Authors: Franciélli Müller; Rafaela Andretta, Lorenzo de Oliveira Meneguzzi, Carlos Arthur Ferreira
      Abstract: The main objective of this work is the development of anionic exchange membranes for the treatment of solutions containing metallic ions using the electrodialysis process. Anionic membranes were synthesized from poly(vinyl alcohol) (PVA), with the insertion of quaternary ammonium groups in the polymeric matrix and subsequent crosslinking with glutaraldehyde and maleic anhydride. Different membranes were synthesized in order to evaluate the combination of physical–chemical properties and ionic transport. The morphology and structure of the membranes were investigated by scanning electron microscopy (SEM) and infrared spectroscopy (FTIR). The thermal transitions and stability of all the membranes were characterized using calorimetric techniques: thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC), and compared with those of the individual polymers. The physical properties (ion-exchange capacity, water absorption, and dimensional stability) showed that the different crosslink agents used significantly affect the membrane properties. The electrodialysis performance of the membranes in the transport of chloride and nitrate ions showed that the membranes produced can be successfully used in this separation process. Selemion® AMV commercial membrane was used to compare the percentage extractions of the indicated ions with the produced membranes. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 133, 44946.
      PubDate: 2017-04-20T06:20:59.951093-05:
      DOI: 10.1002/app.44946
       
  • Polytriazoles based on alkyne terminated polybutadiene with and without
           urethane segments: Morphology and properties
    • Authors: Hui Li; Qianqian Yu, Fengqi Zhao, Bozhou Wang, Na Li
      Abstract: Alkyne terminated polybutadiene with urethane segments (PUPB), a well-controlled macromolecule, is synthesized with a two-step routine and characterized by 1H NMR, IR spectroscopy as well as gel permeation chromatograph. Alkyne terminated polybutadiene without urethane segments (PTPB) is also synthesized and characterized. The two alkyne terminated polybutadiene are cured to generate corresponding polytriazoles. It is found that the mechanical properties of PUPB based polytriazoles are superior to that of PTPB. The fractured surfaces of PTPB based polytriazoles exhibit smooth microstructures whereas PUPB based polytriazoles show the rough microstructures. The atomic force microscopy images reveal well-established microphase-separated morphology in polytriazoles with the promotion of urethane segments. Thus, the strong hydrogen bonding interaction existed in urethane has remarkable effect on the morphology and then the mechanical properties of the as-prepared polytriazoles. In addition, dioctyl sebacate can serve as an excellent plasticizer to PUPB based polytriazoles, lowering the glass transition temperature (Tg) and improving the ductility. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45178.
      PubDate: 2017-04-19T23:40:54.029745-05:
      DOI: 10.1002/app.45178
       
  • Effects of macromolecular configuration of thermally sensitive binder in
           lithium-ion battery
    • Authors: Anh V. Le; Meng Wang, Daniel J. Noelle, Yang Shi, Hyojung Yoon, Minghao Zhang, Y. Shirley Meng, Yu Qiao
      Abstract: In order to suppress heat generation of nail-penetrated lithium-ion battery (LIB) cell, thermally sensitive binders (TSB) based on poly(vinylidenefluoride) (PVDF) and poly(vinylidenefluoride-co-hexafluoropropylene) (PVDF-HFP) were investigated. The testing data showed that with appropriate treatment, TSB could efficiently reduce the peak temperature associated with internal shorting, and did not influence the cycling performance of LIB. The molecular weight of TSB was not a vital factor, while crosslinking was critical. This technology can be used to mitigate thermal runaway of LIB, enabling safe and robust large-scale energy storage. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45078.
      PubDate: 2017-04-19T23:40:51.844217-05:
      DOI: 10.1002/app.45078
       
  • Application of polyhedral oligomeric silsesquioxane to the stabilization
           and performance enhancement of poly(4-methyl-2-pentyne) nanocomposite
           membranes for natural gas conditioning
    • Authors: Arash Khosravi; Ali Vatani, Toraj Mohammadi
      Abstract: The application of octatrimethylsiloxy polyhedral oligomeric silsesquioxane (POSS) nanoparticles was investigated in the fabrication of novel reverse-selective poly(4-methyl-2-pentyne) (PMP) nanocomposite membranes for the separation of heavier hydrocarbons from methane. Generally, PMP and PMP–fumed silica (FS) nanocomposite membranes suffer severe physical aging with approximately 40% permeation flux reduction over 120 days. A straightforward strategy was introduced to suppress the physical aging of PMP and also to improve the thermal stability without compromising the selectivities and permeabilities through the incorporation of a functionalized POSS–FS binary filler system. Fourier transform infrared spectroscopy and scanning electron microscopy proved productive interactions between the fillers and polymer, with a fair compatibility between them. Thermogravimetric analysis confirmed that the thermal stability of the neat PMP was enhanced by the incorporation of the fillers into the nanocomposites. The addition of POSS and FS led to improved operational performance, such as in the permeability and selectivity, over the neat PMP. The permeation stabilities of the PMP–POSS and PMP–FS–POSS nanocomposite membranes were clearly improved over a long time (120 days). The permeation data indicated that the PMP–3 wt % POSS–20 wt % FS nanocomposite membrane is promising for C3H8/N2 and C3H8/CH4 separation. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45158.
      PubDate: 2017-04-19T02:11:12.125082-05:
      DOI: 10.1002/app.45158
       
  • Functionalization of styrene–butadiene rubber with meta-pentadecenyl
           phenol for better processing: A multifunctional additive and renewable
           resource
    • Authors: Denial Mahata; Onkar Prabhavale, Satyajit Samantarai, Himadri Maity, Ahindra Nag, Golok B. Nando
      Abstract: Meta-pentadecenyl phenol, a nonisoprenoid phenolic lipid, is a renewable agricultural resource and also a byproduct of the cashew industry; it is popularly known as cardanol. This study throws light on the grafting of cardanol, which has been established as a multifunctional additive for natural rubber, onto the main-chain backbone of styrene–butadiene rubber (SBR), a synthetic polymer used to imbibe the multifunctional properties of the former, such as those of a plasticizer, curing promoter, process aid, and antioxidant, into the latter. The grafting was carried out in the solution stage on a trial basis with a peroxide catalyst, and all of the grafting parameters were optimized with a Taguchi methodology. The grafting of cardanol onto the SBR backbone was successfully confirmed by UV–visible spectroscopy, Fourier transform infrared spectroscopy, and NMR analysis. Thermal analysis of the cardanol-grafted styrene–butadiene rubber (C-g-SBR) revealed a higher thermal stability and better plasticizing effect than that those found in the virgin SBR. The rheological properties of the grafted rubber indicated the improvement of the pseudo-plastic (shear-thinning) nature compared to that in gum SBR. The unfilled C-g-SBR vulcanizates exhibited physicomechanical properties comparable to 5-phr processing-oil-containing SBR [oil-plasticized styrene–butadiene rubber (OPSBR)] vulcanizates. The carbon-black-filled C-g-SBR vulcanizates exhibited improved plasticization, a faster curing rate, easy processability, and better physicomechanical properties compared to the 5-phr OPSBR vulcanizates. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45150.
      PubDate: 2017-04-19T02:11:09.185977-05:
      DOI: 10.1002/app.45150
       
  • Formulation of silver chloride/poly
           (3-hydroxybutyrate-co-3-hydroxyvalerate) (AgCl/PHBV) films for potential
           use in bone tissue engineering
    • Authors: Rotimi Bakare; Lauren Wells, Negene McLennon, Manisha Singh, Ayele Gugssa, John Stubbs, Berhanu Zewde, Dharmaraj Raghavan
      Abstract: Orthopedic implant failure due to bacterial infection has been a concern in bone tissue engineering. Here, we have formulated a composite made of biodegradable polymer, i.e., poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), and silver chloride. Ag+ ions released from the AgCl/PHBV film can promote an aseptic environment by promoting inhibition of bacterial growth while maintaining bone cell growth, depending on AgCl loading. The objective of this study is to formulate AgCl/PHBV film(s) of varying composition so as to evaluate the dependence of AgCl loading in the film on antimicrobial activity and cytotoxicity. The release kinetics of silver ions from AgCl/PHBV film in aqueous and DMEM medium showed similarity in the initial burst of ions during the first day of desorption followed by a gradual release of ions over extended time period. The antibacterial efficacy of AgCl/PHBV film against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa was evaluated by microbiological assay, while cytotoxicity of the film towards MC3T3-E1 cells was determined by MTT assay. For all compositions studied, a clear zone of inhibition around AgCl/PHBV film was noticed on a modified Kirby-Bauer disk diffusion assay. We established that MC3T3-E1 cell attachment on AgCl/PHBV film is strongly related to loading of AgCl in the film. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45162.
      PubDate: 2017-04-19T02:11:06.905643-05:
      DOI: 10.1002/app.45162
       
  • Amphiphilic ABA-type triblock copolymers for the development of
           high-performance poly(vinylidene fluoride)/poly(vinyl pyrrolidone) blend
           ultrafiltration membranes for oil separation
    • Authors: Tota Rajasekhar; Polisetti Veera Babu, Jonnalagadda Gopinath, Annadanam V. Sesha Sainath, A. V. R. Reddy
      Abstract: ABA-type amphiphilic triblock copolymers (TBCs) were synthesized by a reversible addition fragmentation chain transfer (RAFT) process with a telechelic polystyrene macro-RAFT agent and 4-[n-(acryloyloxy)alkyloxy]benzoic acid monomers. Ultrafiltration (UF) membranes were fabricated by a phase-inversion process with blends of the TBC, poly(vinylidene fluoride) (PVDF), and poly(vinyl pyrrolidone) (PVP) in dimethylformamide. The UF-fabricated membranes were characterized by scanning electron microscopy, atomic force microscopy, water contact angle measurement, thermogravimetric analysis, and differential scanning calorimetry. Pure water permeation, molecular weight cutoff values obtained by the permeation of different molecular weight polymers as probe solutes, bovine serum albumin (BSA) solution permeate flux, and oil–water emulsion filtration tests were used to evaluate the separation characteristics of the fabricated membranes. The tripolymer blend membranes exhibited a higher flux recovery ratio (FRR) after the membrane was washed with sodium lauryl sulfate (0.05 wt %) solution for a BSA solution (FRR = 88%) and oil–water emulsion (FRR = 95%) feeds when than the PVDF–PVP blend membrane (57 and 80% FRR values for the BSA solution and oil–water emulsion, respectively). The pendant carboxylic acid functional moieties in this ABA-type TBC have potential advantages in the fabrication of high-performance membranes. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45132.
      PubDate: 2017-04-19T02:11:01.631385-05:
      DOI: 10.1002/app.45132
       
  • Method for improving the mechanical performance and thermal stability of
           unsaturated polyester resin/waste-printed circuit board nonmetals
           composites via isocyanate chemistry
    • Authors: Dechao Hu; Zhixin Jia, Bangchao Zhong, Jing Lin, Maolin Liu, Yuanfang Luo, Demin Jia
      Abstract: To strengthen the interfacial interactions between waste-printed circuit board (WPCB) nonmetals and unsaturated polyester resin (UPE) and achieve a high performance in UPE composites, a novel type of polyurethane prepolymer (pre-PU) with dual functions was prepared by the reaction of isophorone diisocyanate with poly(ethylene glycol). We found that pre-PU was chemically bonded to the surface of the WPCB nonmetals, and a stronger interaction between the WPCB nonmetals and UPE matrix was formed. The mechanical properties and thermal stability of the UPE/pre-PU–WPCB nonmetal composites showed remarkable improvements compared with those of the UPE/WPCB nonmetals composites, in particular, the impact toughness, which increased threefold. We envision that this promising modification method will not only open up new opportunities for the preparation of high-performance plastic composites but also provide a guarantee for the practical industrial application of WPCB nonmetals. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45129.
      PubDate: 2017-04-19T02:10:58.82518-05:0
      DOI: 10.1002/app.45129
       
  • Compatibilized TPU-PDMS blends: Pros and cons of melt mixing and solution
           mixing techniques
    • Authors: M.P. Drupitha; Kinsuk Naskar, Golok B. Nando
      Abstract: The present work describes the influence of processing route on thermomechanical properties of thermoplastic polyurethane (TPU) and polydimethylsiloxane (PDMS) compatibilized blends. In this study, compatibilized blends of TPU and PDMS prepared by melt mixing and solution mixing techniques were compared. Ethylene methyl acrylate (EMA) at different doses of 1, 2, 3, and 4 phr was used as the compatibilizer in 90:10, 80:20, and 70:30 blend ratios of TPU and PDMS. Optimum percentage of compatibilizer was same in both the methods and which was increased with the percentage of PDMS. As compared to melt mixed blends, solution mixed blends showed improved mechanical properties. From the dynamical mechanical analysis it was observed that the glass transition temperature (Tg) obtained was higher for the solution mixed blends due to the stiffer chains. The enhanced physicomechanical properties of the solution mixed blends were attributed to the improved thermal stability of the blends. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45164.
      PubDate: 2017-04-19T02:10:48.409036-05:
      DOI: 10.1002/app.45164
       
  • Preparation and performance of a transparent poly(3,4-ethylene
           dioxythiophene)–poly(p-styrene sulfonate-co-acrylic acid sodium) film
           with a high stability and water resistance
    • Authors: Wanping Cai; Xiangyan Ma, Jiahong Guo, Xing Peng, Sai Zhang, Zhoutong Qiu, Jie Ying, Jikui Wang
      Abstract: Poly(p-styrene sulfonate-co-acrylic acid sodium) (PSA) from the copolymerization of acrylic acid sodium (AA) and p-styrene sulfonate (SS) monomers were used to dope poly(3,4-ethylene dioxythiophene) (PEDOT) to generate PEDOT–PSA antistatic dispersions. Compared to those of the PEDOT–poly(p-styrene sulfonate sodium) (PSS), the physical and electrical properties of the PEDOT–PSA conductive liquids were much better. The PEDOT–PSA films possessed a better water resistance without a decrease in the conductivity. The sheet resistance of the PEDOT–PSA–poly(ethylene terephthalate) (PET) films was about 1.5 × 104 Ω/sq with a 100 nm thickness, the same as the PEDOT–PSS–PET films. The transmittance of the PEDOT–PSA–PET films exceeded 88%. Furthermore, the environmental dispersity of the PEDOT–PSA antistatic dispersion was apparently improved by the dopant PSA so that the stability was extraordinarily promoted. Meanwhile, the water resistances of the PEDOT–PSA–PET and PEDOT–PSA films were also enhanced. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45163.
      PubDate: 2017-04-16T23:36:07.593643-05:
      DOI: 10.1002/app.45163
       
  • Replacing 100% of phenol in phenolic adhesive formulations with lignin
    • Authors: Somayyeh Kalami; Maryam Arefmanesh, Emma Master, Mojgan Nejad
      Abstract: Lignin, produced as a byproduct of pulp and paper and bioethanol industries, is a polyphenolic compound that has excellent potential to be used as phenol replacement in phenolic adhesive formulation. In this study, the phenol portion of phenol formaldehyde (PF) resin has been replaced by an agricultural-based lignin, which was produced as a byproduct of a cellulosic bioethanol process through dilute-acid pretreatment and enzymatic hydrolysis from corn stover. The PF resol resin was formulated using isolated lignin under alkaline condition. Chemical, physical, and thermal properties of the isolated lignin, PF resin and adhesive were measured using advanced analytical techniques such as: Fourier transformed infrared spectroscopy (FTIR), size exclusion chromatography (SEC), phosphorous nuclear magnetic resonance spectroscopy (31P NMR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The developed 100% lignin-based adhesive and a commercially formulated phenol resorcinol formaldehyde (PRF, as reference) were used to prepare single-lap-joint samples for mechanical testing. The plywood samples were pressed under exactly the same conditions (time, temperature, and pressure) as what recommended for the commercial PRF formulation. According to two-way ANOVA results, statistically there was no significant difference between the shear strengths of plywood samples made with 100% lignin-based adhesive and those made with the commercial PRF resin. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45124.
      PubDate: 2017-04-16T23:36:02.805911-05:
      DOI: 10.1002/app.45124
       
  • Graphene nanoribbons (GNRs) by unzipping MWCNTs for the improvement of
           PMMA microcellular foams
    • Authors: Meijuan Li; Ping Cheng, Guoqiang Luo, Qiang Shen, Lianmeng Zhang
      Abstract: This work presents the cellular microstructures and properties of PMMA/graphene nanoribbons (GNRs) microcellular foams. GNRs were obtained by oxidative unzipping multiwalled carbon nanotubes (MWCNTs) and solvent thermal reduction in dimethylformamide (DMF), then they were mixed with PMMA to fabricate PMMA/GNRs nanocomposites by solution blending. Subsequently, supercritical carbon dioxide (scCO2) as a friendly foaming agent was applied to fabricate PMMA/GNRs microcellular foam by a batch foaming in a special mold. The morphology of cell structure was analyzed by scanning electron microscopy (SEM) and image software, showing that the addition of a smaller content of GNRs caused a fine cellular structure with a higher cell density (∼3 × 1011 cells/cm3) and smaller cell sizes (∼1 μm) due to their remarkable heterogeneous nucleation effect. The mechanical testing of PMMA/GNRs microcellular foams demonstrated that the obtained GNRs also could be used as a reinforcing filler to increase the mechanical properties of PMMA foams. An improvement in the compressive strength of ∼80% (about 39% increase standardized by specific compressive strength) was achieved by 1.5 wt % GNRs addition, and the thermal stability of PMMA/GNRs foams was enhanced too. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45182.
      PubDate: 2017-04-16T23:35:59.44731-05:0
      DOI: 10.1002/app.45182
       
  • Novel phosphorus-based flame retardants containing
           4-tert-butylcalix[4]arene: Preparation and application for the fire safety
           of epoxy resins
    • Authors: Lingang Lu; Xiaodong Qian, Zejun Zeng, Shousheng Yang, Gaosong Shao, Huiya Wang, Jing Jin, Xiaonan Xu
      Abstract: A novel flame retardant (FR) containing phosphorus and 4-tert-butylcalix[4]arene was synthesized and characterized. The FR combined with ammonium polyphosphate (APP) was then incorporated into epoxy resins (EPs) at different ratios. The flame retardancy, thermal stability, and smoke-releasing properties were investigated. The limiting oxygen index was as high as 30.8% when the mass fraction ratio of the FR to APP was 1:2. The improved FR effect have been due to the combined FR effects between the FR and APP. The char residue content at 800 °C under a nitrogen atmosphere increased notably from 8.22 to 17.6% when the FR APP was incorporated into EP; this indicated an improvement in the thermooxidation resistance. From the cone test, we found that both the total heat-release and peak heat-release rate of the FR resins were reduced. Compared to the resins containing no FRs, the smoke-production rate and total smoke-production results indicate that the FR resins also exhibited good smoke-suppression properties. Generally, the stable char layer of the FR APP–EP not only effectively prevented the release of combustion gases but also hindered the propagation of oxygen and heat into the interior substrate. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2017
      PubDate: 2017-04-16T23:35:55.957007-05:
      DOI: 10.1002/app.45105
       
  • The effects of temperatures and volumetric expansion on the diffusion of
           fluids through solid polymers
    • Authors: Yiming Fan; Antonio Gomez, Serena Ferraro, Brian Pinto, Anastasia Muliana, Valeria La Saponara
      Abstract: This study examines moisture sorption behaviors of two glassy polymers, epoxy and vinylester, immersed in different fluids at two temperatures below the glass transition temperatures of the polymers. The main purpose of this study is to understand the effect of volume-dependent temperatures and deformations on the diffusion process of solid polymers. Diffusivity coefficients are first determined by assuming the diffusion to follow the classical Fickian diffusion. In some cases, moisture sorption led to quite significant changes of volume, and the diffusion process cannot be well described by the Fickian diffusion. In such situation, the coupled deformation-diffusion model for linear elastic isotropic materials presented by Gurtin is adopted, as a first approximation. This coupled deformation-diffusion model reduces to a Fickian diffusion model when the coupling parameters are absent and the volume changes in the solid polymers during diffusion are negligible. A finite difference method is used in order to solve for the coupled deformation-diffusion model. The model is used to predict the one-dimensional moisture diffusion in thin plates and the multiaxial three-dimensional moisture diffusion in dogbone specimens. The multiaxial diffusion in the dogbone specimens is used to validate the calibrated material parameters from the standard thin plate diffusion characterization. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45151.
      PubDate: 2017-04-16T23:35:53.206838-05:
      DOI: 10.1002/app.45151
       
  • High performance electrospun PVdF-HFP/SiO2 nanocomposite membrane
           electrolyte for Li-ion capacitors
    • Authors: Arun Kumar Solarajan; Vignesh Murugadoss, Subramania Angaiah
      Abstract: Electrospun poly[(vinylidene fluoride)-co-hexafluoropropylene]/silica (PVdF-HFP/SiO2) nanocomposite polymer membranes (esCPMs) were prepared by incorporating different weight percentages of SiO2 nanoparticles onto electrospun PVdF-HFP by electrospinning technique. The surface morphology of electrospun PVdF-HFP nanocomposite membranes was characterized by scanning electron microscopy. The effect of SiO2 nanoparticles incorporation onto electrospun PVdF-HFP polymer membranes (esPMs) has been studied by XRD, DSC, TGA, and tensile analysis. The electrospun PVdF-HFP/SiO2 based nanocomposite membrane electrolytes (esCPMEs) were prepared by soaking the corresponding esCPMs into 1 M LiPF6 in EC:DMC (1:1 vol/vol %). The ionic conductivity of the esCPMEs was studied by AC-impedance studies and it was found that the incorporation of SiO2 nanoparticles into PVdF-HFP membrane has improved the ionic conductivity from 1.320 × 10−3 S cm−1 to 2.259 × 10−3 S cm−1. The electrochemical stability of the esCPME was studied by linear sweep voltammetry studies and it was found to be 2.87 V. Finally, a prototype LiCo0.2Mn1.8O4//C Li-ion capacitor (LIC) cell was fabricated with esCPME, which delivered a discharge capacitance of 128 F g−1 at the current density of 1 A g−1 and retained 86% of its discharge capacitance even after 10,000 cycles. These results demonstrated that the esCPMEs could be used as promising polymer membrane electrolyte for LICs. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45177.
      PubDate: 2017-04-16T23:35:45.111237-05:
      DOI: 10.1002/app.45177
       
  • Expandable graphite in polyurethane foams: The effect of expansion volume
           and intercalants on flame retardancy
    • Authors: A. Lorenzetti; B. Dittrich, B. Schartel, M. Roso, M. Modesti
      Abstract: Several expandable graphites (EGs), differing in expansion volume but with the same mean size, are compared as flame retardants in polyurethane (PUR) foams. Not only common sulfur-intercalated graphites are investigated, but also a new one intercalated with phosphorus. The main aim of this article is to understand which properties of EG are important for its flame retardancy effectiveness in PUR foams. Thermal stability, flammability, and fire behavior are analyzed through limiting oxygen index and cone calorimeter tests. Detailed characterization of the phosphorus-intercalated graphite is also provided as well as physical–mechanical characterization. The results show that the well-known sulfur-intercalated graphites and the one with phosphorus both enhance the residue yield, induce a protective layer, and thus efficiently flame-retard PUR foams. While the expansion volume of the EGs had a surprisingly limited influence on the performance of the foams, at least in the range tested, the most important feature controlling the effectiveness of EG in terms of flame retardant PUR foams was the type of intercalant. The presence of EG affected the physical–mechanical properties of the foams, however no significant effect of the expansion volume or intercalant type has been revealed on the physical–mechanical properties of the foams. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45173.
      PubDate: 2017-04-16T23:35:40.252853-05:
      DOI: 10.1002/app.45173
       
  • Solvent induced crystal formation in polymers—Experimental studies and
           
    • Authors: Narayan Ramesh; Mourad Hamedi, Ronald P. Danner, John M. Zielinski
      Abstract: A model has been developed to describe the simultaneous diffusion and solvent induced crystal formation in polymers based on the idea that crystal formation is governed by polymer chain mobility and a thermodynamic driving force. The polymer chain mobility is described based on solvent and polymer physical characteristics using the free-volume theory of transport. The semicrystalline polymer-solvent system is treated as a ternary system consisting of crystalline polymer, amorphous polymer, and solvent. The addition of solvent to the amorphous phase is assumed to increase the local free volume and facilitate movement of polymer chains, thereby enabling crystal formation. Diffusion of the solvent is assumed to occur solely in the amorphous polymer phase. The species continuity equations are formulated in volume-averaged coordinates and give rise to a convective term due to the density change accompanying transformation of the amorphous polymer to the crystalline polymer. Accurate modeling of this problem requires that a moving boundary be considered. The model was tested using gravimetric sorption data for the poly(vinyl alcohol)-water system. In the experimental studies the water was initially absorbed and then a high percentage of it was expelled. The proposed model accurately describes this behavior. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45171.
      PubDate: 2017-04-16T23:35:37.810532-05:
      DOI: 10.1002/app.45171
       
  • Corrigendum: Effect of different organic amino cations on SAPO-34 for
           PES/SAPO-34 mixed matrix membranes toward CO2/CH4 separation
    • Authors: N. N. R. Ahmad; H. Mukhtar, D. F. Mohshim, R. Nasir, Z. Man
      PubDate: 2017-04-16T23:35:35.778005-05:
      DOI: 10.1002/app.45130
       
  • Hydrophobic and Tribological Behaviors of a Poly(p-phenylene
           benzobisoxazole) Fabric Composite Reinforced with Nano-TiO2
    • Authors: Deke Li; Zhiguang Guo
      Abstract: 1H,1H,2H,2H-Perfluorooctyl trichlorosilane (PFTS) was used to modify TiO2 nanoparticles, and hydrophobic PFTS–TiO2 nanoparticles were obtained by an ultrasonic reaction method. The PFTS–TiO2 surface morphological and hydrophobic properties were analyzed with scanning electron microscopy (SEM), Fourier transform infrared spectrometry, and contact angle (CA) testing. Then, the poly(p-phenylene benzobisoxazole) fabric–phenolic composite filled with PFTS–TiO2 as a lubricant additive was fabricated by a dip-coating process. The tribological properties of the composite were investigated, and the wear surface morphology was observed by SEM. The experimental results show that the water CA of the composite filled with PFTS–TiO2 was 158°, and the composite containing 4 wt % PFTS–TiO2 exhibited excellent antifriction and abrasion resistance. The hydrophobic surface of the composite showed the excellent durable performance with a static water CA of 126.7° after abrasion. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45077.
      PubDate: 2017-04-13T01:14:44.506668-05:
      DOI: 10.1002/app.45077
       
  • Mechanics of surface cross-linked polydimethylsiloxane microstructure used
           for microcontact transfer printing
    • Authors: Chao Bao; Zhifan Wang, Yu Liu, Yanning Zhang, Heng-Yong Nie, Woon-Ming Lau, Jun Mei
      Abstract: In microcontact transfer printing, the mechanics of the microstructure on an elastomeric stamp are crucial for obtaining a printed image with high feature resolution and repeatability. In this article, we are dedicating research efforts to visit a methodology for surface crosslinking a polydimethylsiloxane (PDMS) microstructure, implemented by a hyperthermal hydrogen induced crosslinking (HHIC) technique. The significant enhancement of Young's modulus of elastomeric base after the surface crosslinking is confirmed by consequent ab initio calculation and numerical simulation. Experiments based on compression test and forced lateral scanning have been done for verifying the enhanced mechanic stability. This work provides a surface treatment way for fabricating a printing stamp with high robustness and transfer printing quality. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45166.
      PubDate: 2017-04-13T01:14:28.023433-05:
      DOI: 10.1002/app.45166
       
  • Maleic anhydride grafted linear low density polyethylene/waste paper
           powder composites with superior mechanical behavior
    • Authors: Arun Saini; Chandravati Yadav, Madhab Bera, Pragya Gupta, Pradip K. Maji
      Abstract: The present work aims to study the perspectives of an efficient utilization of waste products as fillers for the thermoplastic polymer. Maleic anhydride grafted linear low-density polyethylene (LLDPE-g-MA), without any compatibilizers, has been used as polymer matrix to prepare composites with different contents (0–50 phr) of waste paper powder (WPP). Mechanical properties assessment has shown up to 88% improvement in tensile strength and a huge increment of 409% in Young's modulus for the composites prepared at 30 phr WPP. The reinforcement effect of WPP in the polymer matrix was also assessed by Guth-Gold and modified Guth-Gold equations. Microstructural analysis of the fractured surfaces revealed good interfacial adhesion with fewer voids and fiber pull out up to 30 phr WPP loading. Interfacial interaction between maleic anhydride group of LLDPE-g-MA and OH groups present dominantly in the cellulosic component of WPP was established through Fourier transform infrared spectroscopy (FTIR). The thermal properties of prepared composites were analyzed by DSC (differential scanning calorimetry). © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45167.
      PubDate: 2017-04-13T01:14:26.103337-05:
      DOI: 10.1002/app.45167
       
  • Depolymerization of PET waste to potentially applicable aromatic amides:
           Their characterization and DFT study
    • Authors: Meenu Teotia; Nazia Tarannum, Rakesh Kumar Soni
      Abstract: Poly(ethylene terephthalate) waste has been depolymerized to a series of potentially applicable aromatic amides through aminolysis with different amines such as methylamine, ethylenediamine, ethanolamine, and butylamine at ambient conditions of temperature and pressure. The amides prepared were characterized by different techniques like FTIR, UV-Visible spectroscopy, NMR, elemental analysis, mass spectrometry, powdered XRD, Raman spectroscopy and thermal analysis. Further, an attempt is being made to insight the physical parameters of the aromatic amides using ab initio DFT (Density Functional Theory) study. DFT calculations were performed at Becke's three parameter functional and Lee–Yang–Parr functional (B3LYP) level of calculation with 321-G basis set. The atomic orbital energy (HOMO and LUMO) and energy gap is also represented. The vibrational frequencies optimized by DFT were in agreement with the experimental FTIR data. An efficient conversion of PET waste to amides was achieved without catalyst through environment friendly clean approach. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45153.
      PubDate: 2017-04-13T01:14:16.725108-05:
      DOI: 10.1002/app.45153
       
  • Relationship between bridged groups and antioxidant activity for aliphatic
           diamine bridged hindered phenol in polyolefins
    • Authors: Cuiqin Li; Peng Sun, Suyue Guo, Zhiqiu Zhang, Jun Wang
      Abstract: Four aliphatic diamine bridged hindered phenols were successfully synthesized with aliphatic diamine as the bridged group and 3-(3,5-di-tert-butyl-4-hydroxy-phenyl)-propionyl chloride as the material, and their structures were clarified by NMR, Fourier transform infrared spectroscopy, and mass spectrometry. Their performance as antioxidant for polypropylene (PP) and linear low-density polyethylene (LLDPE) were investigated through the melt flow rate and the oxidation induction time. The thermooxidative stabilities of PP and LLDPE with different aliphatic diamine bridged hindered phenols were assessed by the measurement of the oxidation induction temperature and with long-term aging testing. The results showed that aliphatic diamine bridged hindered phenols could protect two kinds of polyolefins from thermal oxidative degradation, and the mechanical properties and antioxidant activities of polyolefins stabilized with aliphatic diamine bridged hindered phenols were increased with increasing length of the bridged group for aliphatic diamine bridged hindered phenols at the same concentration of phenolic hydroxyl group. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45095.
      PubDate: 2017-04-13T01:14:06.106871-05:
      DOI: 10.1002/app.45095
       
  • The utilization of thermomechanical pulp fibers in WPC: A review
    • Authors: Oliver Mertens; Julius Gurr, Andreas Krause
      Abstract: Thermomechanical pulp, among other natural fibers, features characteristics that make it a promising candidate for the utilization in polymer composites. This review is providing an overview on the current state of research on TMP reinforced polymer composites. More than 50 references were reviewed. The cited literature is catalogued according to pretreatments, batch or continuous procedures, processing at laboratory or industrial scale, fiber contents, polymer types, coupling agents as well as wood species. The reinforcing potential of TMP utilized in composites is demonstrated. Tensile strength was found to be peaking at a fiber content of around 40 wt %. Fiber morphology is presumed to be an important determinator for composite properties. Specific mechanical energy [kWh/kg] (SME) is presented as an indicator suitable to compare the influence of various processes on fiber morphology. Furthermore, the feed-in and dosing issue that generally accompanies the utilization of cellulosic fibers is described and possible solutions are discussed. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45161.
      PubDate: 2017-04-13T01:14:03.809251-05:
      DOI: 10.1002/app.45161
       
  • High performance of hydrophilic polymers on the crosslinked polystyrene
           spheres for controlling contaminants in white water
    • Authors: He Xiao; Beihai He, Junrong Li, Lihui Chen, Liulian Huang
      Abstract: The accumulation of dissolved and colloidal substances (DCS) and inorganic salts in the white water of papermaking circulation system will result in the abnormal runnability of paper machine and low quality of products. Contaminant adsorption on a solid adsorbent in a fluidized bed reactor has been applied for white water treatment. In this study, three kinds of hydrophilic polymers [i.e., poly(methacryloxyethyltrimethyl ammonium chloride) (poly-MAC), polyacrylamide (poly-AM) and poly(acrylic acid) (poly-AA)] had been grafted on the surface of the polystyrene (PS) spheres through two-step reactions. Fourier transform infrared spectroscopy, scanning electron microscopy, elemental analysis, Zeta potential were evaluated the characteristics of modified PS spheres. The results showed that PS-poly(MAC) had good affinity to DCS. Cationic demand, TDCS, and turbidity of white water had been reduced by 79.5%, 40.0%, and 38.4%, respectively, when the amount of PS-poly(MAC) was 50 g/L. While PS-poly(AA) played an important role in removal of metal ions so as to cut down the conductivity of white water. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45169.
      PubDate: 2017-04-13T01:14:01.318494-05:
      DOI: 10.1002/app.45169
       
  • Structure and properties of microwave transparent crosslinked polystyrene
           prepared through 3D printing bulk polymerization
    • Authors: Yuanwu Chen; Jiale Mao, Yejun Zhu, Kai Zhang, Gangpeng Wu, Jingshen Wu, Haiyan Zhang
      Abstract: Polystyrene (PS) crosslinked with divinylbenzene (DVB) is one of the most promising microwave (MW) transparent polymers for structural application. However, preparation of it has been always inhibited by severe thermal runaway. Under this background, novel technology referred to as “3D printing bulk polymerization” is innovated with great advantages on heat release control. Comparing to the multi-stage batch polymerization as previously reported, the products obtained in present work are also superior on both the thermal-mechanical properties and dielectric properties at microwave band. The modulus is improved from 2.43 GPa to 3.06 GPa, and Tg is increased to over 120 °C after crosslinking, while the ultra-low dielectric loss feature of polystyrene is well maintained with the loss factor to the order of 10−4. In-depth investigation about the effects of crosslinking on main-chain segments has found it extend to secondary relaxation originates from pendent phenyl groups and resulted in a dispersion shift towards higher band. Based on the Raman study, a possible mechanism is also proposed that the torsional relaxation of side groups is governed by a potential barrier arises from constraint by main-chain of several adjacent atoms through interaction between them. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44865.
      PubDate: 2017-04-11T00:06:02.227007-05:
      DOI: 10.1002/app.44865
       
  • Erratum: Cover Image, Volume 134, Issue 23
    • PubDate: 2017-04-11T00:05:49.16623-05:0
      DOI: 10.1002/app.45160
       
  • Synthesis, characterization, and properties of thermosets based on the
           cocuring of an acetylene-terminated liquid-crystal and silicon-containing
           arylacetylene oligomer
    • Authors: Mengna Han; Kangkang Guo, Fan Wang, Yaping Zhu, Huimin Qi
      Abstract: A thermotropic acetylene-terminated liquid-crystal monomer, 2-methyl-1,4-phenylene bis(4-ethynylbenzoate) (MPBE), was prepared and used as a modification composition to react and cocure with a silicon-containing arylacetylene (PSA) oligomer for improving PSA resin. The curing behavior of the PSA–MPBE resins were characterized by differential scanning calorimetry and Fourier transform infrared spectroscopy. The microstructure and morphology of the PSA–MPBE resins were investigated by scanning electron microscopy (SEM) and transmission electron microscopy. Their dynamic mechanical properties and thermostability were measured by dynamic mechanical analysis (DMA) and thermogravimetric analysis. The results indicate that the thermotropic acetylene-terminated liquid-crystal monomer melted into a schlieren texture. MPBE and PSA could copolymerize to fix the mesogenic domain in the crosslinked network and form a homogeneous-phase sea-island structure, which improved the rigidity and toughness of the materials. DMA showed that the storage modulus of the PSA–MPBE resins increased by about 400 MPa compared to the those of the pure components. The SEM experiments showed a noticeable change in the morphology, from a typical brittle fracture for the pure PSA to microplastic deformation behavior for the PSA–MPBE resins. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45141.
      PubDate: 2017-04-10T08:13:02.998234-05:
      DOI: 10.1002/app.45141
       
  • Physical and tensile properties of epoxy laminated magnetic bacterial
           cellulose nanocomposite films
    • Authors: Mahdi Mashkour; Zahra Moradabadi, Abolghasem Khazaeian
      Abstract: Despite many potential applications, the adverse impacts of magnetic nanoparticles on the tensile properties of magnetic cellulose papers and films are well established. On the other hand, water absorption and thickness swelling of cellulose materials are important limiting factors in many engineering applications. These challenges caused limited applications of magnetic cellulose nanocomposites. The aim of this study is to examine the possibility of modifying the physical and mechanical behaviors of magnetic bacterial cellulose films by epoxy resin lamination. Results showed that the tensile modulus and strength of the magnetic bacterial cellulose film respectively increased about 280 and 240% after epoxy lamination while they maintained their desirable magnetic and flexibility properties. Furthermore, the water absorption and thickness swelling of the epoxy laminated magnetic nanocomposite films respectively improved about 43 and 42%. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45118.
      PubDate: 2017-04-10T08:12:46.490791-05:
      DOI: 10.1002/app.45118
       
  • Hydrophilic modification of a poly(ether sulfone) flat-sheet
           ultrafiltration membrane applied to coking sewage
    • Authors: Shu Guang Ouyang; Jun Yan Yao, Guang Heng Wei Zhu, Zhao Yue Liu, Chi Feng, Gang Wang
      Abstract: In this article, a new modified poly(ether sulfone) flat-sheet ultrafiltration membrane, which is expected to effectively handle coking sewage, was prepared by an immersion precipitation phase-inversion technique to settle the wastewater treatment problem in coking plants. Nanometer TiO2 particle–poly(ethylene glycol) (PEG) blends were used as additives to modify the membranes by a blending method. The effects of different PEG mass concentrations on the membrane structure and properties were studied. The pure water flux and chemical oxygen demand (COD) rejection rate were analyzed as aggregative indicators by the comprehensive evaluation method, and then, the optimal PEG mass concentration was determined. The results show that the best modified effect was obtained at a PEG mass concentration of 0.25%. When coking sewage in a secondary settling tank was filtered with such membranes, the COD rejection rate reached 90.68%, and the water flux was 127.21 L m−2 h−1. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45149.
      PubDate: 2017-04-10T08:12:41.346235-05:
      DOI: 10.1002/app.45149
       
  • Synthesis and characterization of a surface imprinting silica gel polymer
           functionalized with phosphonic acid groups for selective adsorption of
           Fe(III) from aqueous solution
    • Authors: Hongxing He; Qiang Gan, Changgen Feng
      Abstract: A Fe(III) ion-imprinted silica gel polymer functionalized with phosphonic acid groups (IIP-PA/SiO2) was prepared with surface imprinting technique by using Fe(III) ion as template ion, grafted silica gel as support and vinylphosphonic acid (VPA) as functional monomer. The polymer was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) and thermogravimetric analysis (TG). The synthesized imprinted silica gel polymer was used as a sorbent for Fe(III) adsorption. The adsorption properties, such as the effect of solution pH, adsorption kinetic, adsorption isotherm, adsorption selectivity as well as the regeneration of sorbent were studied. The results showd that the prepared sorbent (IIP-PA/SiO2) had a short adsorption equilibrium time (12 min) and high adsorption capacity (29.92 mg·g−1) for Fe(III) at the optimal pH of 2.0. The selectivity coefficients of the sorbent for Fe(III) in presence of Cr(III), Mn(II), Zn(II) were 51.76, 27.86 and 207. 76, respectively. Moreover, the adsorption capacity of the prepared sorbent did not decrease significantly after six repeated use. Thus, the prepared ion-imprinted silica gel polymer was a promising candidate sorbent for the selective adsorption of Fe(III) from aqueous solutions. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45165.
      PubDate: 2017-04-10T08:12:37.5199-05:00
      DOI: 10.1002/app.45165
       
  • Nonthermal gelation of whey proteins induced by organic acids
    • Authors: Ana S. Queirós; José A. Lopes-da-Silva
      Abstract: Gelation of native whey proteins induced by organic acids at ambient temperature was investigated by fundamental small-deformation oscillatory rheology. Gelling capability, gelation time, and final viscoelastic properties of the gel were dependent on type of acid, protein and acid concentrations, and on the pH value. Increasing organic acid concentration or increasing the pH (below pI) resulted in lower gelation times and higher gel modulus values. Differential scanning calorimetry demonstrated that the presence of acetic acid significantly reduced denaturation temperature and enthalpy implying a destabilization effect of the protein structure against thermal unfolding, contrarily to what was observed in the presence of HCl at similar pH values. The gelling ability and the denaturing effectiveness of the acids increase with increasing chain length of the alkyl chain, thus suggesting an important contribution of hydrophobic effects promoting denaturation and fostering the establishment of new interactions between the proteins leading to a nonthermal gelation process. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45134.
      PubDate: 2017-04-10T08:08:01.557717-05:
      DOI: 10.1002/app.45134
       
  • Influence of coalescing aids on the latex properties and film formation of
           waterborne coatings
    • Authors: Peter Berce; Saša Skale, Tina Razboršek, Mojca Slemnik
      Abstract: Coalescing aids are organic solvents that are widely used to accommodate the film formation of waterborne coatings. The influence of the volatility, hydrophilicity, and amount of coalescing aids on the properties of waterborne dispersions and the dynamics of film formation was investigated. The results show that coalescing aids increased the viscosity through particle swelling and solvation, with the effect being stronger with more hydrophilic solvents. The results obtained with electrochemical impedance spectroscopy (EIS) and indentation tests show that hydrophilic coalescing aids were more efficient because of the partitioning on the particle interfaces but they could temporarily decrease the water resistance. The ease of coalescence was countered by solvent retention, which complicated the dynamics of film formation. EIS was used to optimize a real-world coating formulation and identify the pitfalls arising from the complex dynamics of film formation. The best resistance to humidity was obtained with a combination of hydrophobic and hydrophilic coalescing aids. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45142.
      PubDate: 2017-04-10T08:07:52.107841-05:
      DOI: 10.1002/app.45142
       
  • Systemized organic functional group controls in polydiacetylenes and their
           effects on color changes
    • Authors: Narae Han; Hyeon Ji Woo, Se Eun Kim, Suyeon Jung, Min Jae Shin, Min Kim, Jae Sup Shin
      Abstract: A variety of organic functional groups have been successfully installed into polydiacetylenes (PDAs) and applied to the color change-controlled system of PDA sensors. Ten diacetylene compounds possessing different functionalities and lengths were systemically synthesized and fully characterized using spectroscopic methods. The polymerized vesicle solution with these compounds showed different temperatures required to induce a color change (from blue to red) depending on the functionalities installed on PCDA (10,12-pentacosadiynoic acid) molecules. In addition, the results reported here reveals that the intermolecular interactions of PCDA molecules and the intermolecular distance play a key role to the color of PDA system. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45011.
      PubDate: 2017-04-10T08:07:46.094988-05:
      DOI: 10.1002/app.45011
       
  • Preparation of functional reduced graphene oxide and its influence on the
           properties of polyimide composites
    • Authors: Lang Ma; Guojian Wang, Jinfeng Dai
      Abstract: Homogeneous dispersion and strong filler–matrix interfacial interactions were vital factors for graphene for enhancing the properties of polymer composites. To improve the dispersion of graphene in the polymer matrix and enhance the interfacial interactions, graphene oxide (GO), as an important precursor of graphene, was functionalized with amine-terminated poly(ethylene glycol) (PEG–NH2) to prepare GO–poly(ethylene glycol) (PEG). Then, GO–PEG was further reduced to prepare modified reduced graphene oxide (rGO)–PEG with N2H4·H2O. The success of the modification was confirmed by Fourier transform infrared spectroscopy, thermogravimetric analysis, and Raman spectroscopy. Different loadings of rGO–PEG were introduced into polyimide (PI) to produce composites via in situ polymerization and a thermal reduction process. The modification of PEG–NH2 on the surface of rGO inhibited its reaggregation and improved the filler–matrix interfacial interactions. The properties of the composites were enhanced by the incorporation of rGO–PEG. With the addition of 1.0 wt % rGO–PEG, the tensile strength of PI increased by 81.5%, and the electrical conductivity increased by eight orders of magnitude. This significant improvement was attributed to the homogeneous dispersion of rGO–PEG and its strong filler–matrix interfacial interactions. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45119.
      PubDate: 2017-04-10T08:07:38.713092-05:
      DOI: 10.1002/app.45119
       
  • Wettability of a microgrid-structured polymer film with microfabrication
           utilizing the stick–slip phenomenon
    • Authors: Keishi Naito; Taisei Yamada, Takafumi Tsutsumi, Kisaragi Yashiro
      Abstract: A microgrid structure was formed on the surface of a polyethylene terephthalate (PET) film with an original microfabrication method (termed SS processing) utilizing the stick–slip (SS) phenomenon, and the effect of this surface structure on wettability was evaluated. Microgrid-structured films could be fabricated by two-axis SS processing. Moreover, an arbitrary parallelogram microgrid structure could be formed by selecting the direction of the second SS processing with respect to that of the first SS processing. Both water contact angle and water sliding angle of the SS-processed film were larger than that of the PET film. Hence, the SS-processed film showed a petal-like effect. Furthermore, the water sliding angle of the microgrid-structured film showed anisotropy due to the pinning effect derived from the microgrid structure. As a result, it is revealed that a hydrophobic PET film with a petal-like effect and anisotropic wettability can be fabricated by SS processing. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2017
      PubDate: 2017-04-10T08:07:34.48785-05:0
      DOI: 10.1002/app.45140
       
  • Relationship between degree of polymerization and optical and thermal
           properties of fluorene in polycarbonate polymers
    • Authors: Noriyuki Kato; Shinya Ikeda, Manabu Hirakawa, Hiroshi Ito
      Abstract: The influences of average degree of polymerization (Dp) and terminal group on thermal- and optical-properties of high refractive indexed transparent polymers were investigated. In this study, 9,9-bis[4–(2-hydroxyethoxy) phenyl] fluorene (BPEF) homo polymer was selected because it has been used as a representative monomer in high refractive index polymers as well as its unique property. BPEF has stable amorphous phase and reacts like a polymer. Its unique reaction allows continuous investigation from monomer to polymer. For hydroxyl terminated polymer, the refractive index (nd) decreased with increasing Dp. On the other hand, for a phenolic terminated group, nd increased with increasing Dp, and both converged to same value in high Dp region. As for glass transition temperatures (Tg), both terminal group series were increased as Dp increased. Though Tg of hydroxyl terminated polymer was higher than that of phenolic terminated polymer in the low Dp region, both converged to the same value and the inverse number of Tg had linear correlation against the weight percentage of carbonyl groups (CO), which was calculated by Dp. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45042.
      PubDate: 2017-04-10T08:07:24.042274-05:
      DOI: 10.1002/app.45042
       
  • Fabricating and robust artificial neural network modeling nano-scale
           polyurethane fiber using electrospinning method
    • Authors: Ebrahim Hosaini-Alvand; Hamed Mirshekar, Mohammad Taghi Khorasani, Mahmoud Parvazinia, Alireza Joorabloo
      Abstract: With regard to the fact that currently there is no comprehensive method to predict diameter of polyurethane/solvent fiber from electrospinning, in this study, diameter prediction of polyurethane/solvent fiber was conducted using neural networks and an error of 166 nm was observed. This error shows that artificial neural networks can predict diameter of electrospinning polyurethane fibers well. Then, considering weak repeatability nature of electrospinning in fabricating fibers with desired diameter, Least Mean Square (LMS) is used to improve stability of neural network model that shows an error of 113 nm, which represented better results compared to common artificial neural network. To investigate the effect of each one of parameters affecting fiber diameter, sensitivity analysis was conducted. Along with this predicting model, sensitivity analysis can be used to reduce parameters space before conducting future studies. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45116.
      PubDate: 2017-04-08T01:46:32.237807-05:
      DOI: 10.1002/app.45116
       
  • Characterization and cell response of electrospun Rana chensinensis skin
           collagen/poly(L-lactide) scaffolds with different fiber orientations
    • Authors: Mei Zhang; Ziqi Li, Pan Jiang, Tong Lin, Xueqi Li, Dahui Sun
      Abstract: Collagen was extracted from Rana chensinensis skin supplied from byproducts via an acid enzymatic extraction method. The R. chensinensis skin collagen (RCSC) and poly(l-lactide) (PLLA) were blended at a 3:7 ratio in 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) at a concentration of 10% (g/mL) and electrospun to produce nanofibers in an aligned and random orientation. For comparison, pure PLLA nanofibrous membranes with aligned and random nanofiber orientation were also produced. The secondary structure of the RCSC nanofibers was investigated by circular dichroism to confirm that the extracted substance was collagen. The presence of collagen in the blend nanofiber was verified by LSCM. The blended nanofibers showed uniform, smooth, and bead-free morphologies and presented a smaller fiber diameter (278 nm and 259 nm) than the pure the ones of PLLA (559 nm and 439 nm) nanofibers. It was found that the addition of RCSC and the modification of the nanofiber's orientation affected the fiber's diameter and the crystallization of PLLA. The cell viability studies with human fibroblast cells demonstrated that the RCSC/PLLA nanofibrous membranes formed by electrospinning exhibited good biocompatibility and that the aligned scaffolds could regulate the cell morphology by inducing cell orientation. The empirical results in this study indicated that the aligned RCSC/PLLA nanofibrous membrane is a potential wound dressing candidate for skin regeneration. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45109.
      PubDate: 2017-04-06T23:46:48.659911-05:
      DOI: 10.1002/app.45109
       
  • Mechanically enhanced electrically conductive films from polymerization of
           3,4-ethylenedioxythiophene with wood microfibers
    • Authors: Islam Hafez; Han-Seung Yang, William Tai Yin Tze
      Abstract: This study was aimed at enhancing the mechanical properties of poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT:PSS) using wood microfibers. Ultra-fine friction grinding was conducted on wood particles to reduce their size to the micron scale and to induce fibrillation. Oxidative polymerization was performed on 3,4-ethylenedioxythiophene (EDOT) monomer at seven dosages based on the content of microfibers in the formulation. The presence of PEDOT:PSS in the prepared films was verified by infra-red (IR) spectroscopy and scanning electron microscopy (SEM). The composite films became stronger and stiffer as the fiber content increased. An EDOT:microfibers ratio of 33 wt % was considered the best among the seven tested levels, judging from their low sheet resistivity (340 Ω/sq.) and favorable tensile properties (38 MPa strength and 4.8 GPa stiffness). The selected films were also tested for their resistance to solvents to obtain information about their potential use in different environments. Among the tested solvents, sodium hydroxide greatly decreased the film conductivity. It also had the harshest effect on reducing the weight of the film. Findings from this study demonstrate the successful use of wood microfibers alternative to synthetic substrates and cellulose nanofiber as a supportive and reinforcing material for electrically conductive polymers. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45127.
      PubDate: 2017-04-06T23:46:14.955959-05:
      DOI: 10.1002/app.45127
       
  • Visualization of PVDF nanofibers coated on filter paper using fluorescein
           silica nanoparticles
    • Authors: Hirokazu Miyoshi; Akira Yumoto, Masayuki Shono, Tomoyuki Ueki, Yoshinori Itsuki
      Abstract: Fluorescein silica nanoparticles (NPs) were prepared using a silane compound bound between fluorescein-N-hydroxysuccinimide (NHS-Fluorescein) and 3-aminopropylorthosilicate (APS) by a sol–gel method. The fluorescein-silica NPs were mixed with a poly(vinylidene fluoride) (PVDF) solution, and the solution loaded with the NPs was electrospun on a filter paper. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images confirmed the encapsulation of the fluorescein silica NPs in the PVDF nanofibers. Laser scanning confocal microscopy (LSCM) images showed fluorescein silica NPs as dots, and photoluminescence (PL) images obtained using a fluoroanalyzer indicated the emission of uniform PL from filter papers coated with fluorescein-silica-NP-encapsulated PVDF nanofibers. It was demonstrated that the fluorescein silica NPs enabled PVDF nanofibers coated on a filter paper to be easily visualized. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45125.
      PubDate: 2017-04-06T00:15:54.4837-05:00
      DOI: 10.1002/app.45125
       
  • Phenolic antioxidants based on calixarene: Synthesis, structural
           characterization, and antioxidative properties in natural rubber
    • Authors: Hongqiang Li; Yong Zhong, Wenjian Wu, Lin Zhang, Xuejun Lai, Xingrong Zeng
      Abstract: C-methylcalix[4]resorcinarene (CMCR) was first synthesized by condensation reaction between resorcinol and acetaldehyde, and then used as functional monomer to prepare two CMCR derivatives including C-methylcalix[4]resorcinarene-1 (CMCR-1) and C-methylcalix[4]resorcinarene-2 (CMCR-2) with four ethoxymethyl chains and four hexylthiolmethyl chains, respectively. The structures of CMCR and its derivatives were confirmed by Fourier transform infrared (FT-IR) spectroscopy and high-resolution mass spectrometry (HRMS). Thermogravimetric analysis (TGA) revealed CMCR, CMCR-1, and CMCR-2 had superior thermal stability than commercial antioxidant 2,6-Di-tert-butyl-4-methylphenol (BHT). Oxidation induction time and accelerated thermal aging tests indicated that CMCR-2 exhibited excellent antioxidative property in natural rubber (NR), which was due to multiphenol groups, big steric hindrance, and synergistic effect between thiother and hindered phenol. Importantly, CMCR-2 also possessed outstanding extraction resistance. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45144.
      PubDate: 2017-04-06T00:15:25.931031-05:
      DOI: 10.1002/app.45144
       
  • Inhibiting the concentration polarization of FO membranes based on the
           wettable microporous supporting layer and the enhanced dense skin layer
    • Authors: Xinzhen Zhao; Changkun Liu
      Abstract: A novel thin film composite (TFC) type forward osmosis (FO) membrane with inhibited concentration polarization phenomenon and expectant separation performance was prepared by continuous interfacial polymerization method. The nylon-6,6 microfiltration membrane with the average pore size of 5 μm and the self-wetting property was for the first time used as the supporting layer of the FO membranes, which decreased the mass transfer resistance in the porous supporting layer. The skin layer was prepared via the continuous interfacial polymerization of polyamide (PA) as a relatively dense layer, with the reverse salt flux of less than 1 g/m2h. The mass transfer resistance and the reverse salt flux of the prepared FO membranes were remarkably reduced due to the functional design of the double-layer structure, which effectively enhanced the separation selectivity and restrain the concentration polarization of the FO membranes. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45133.
      PubDate: 2017-04-06T00:12:37.111586-05:
      DOI: 10.1002/app.45133
       
  • Synergistic flame-retardant effect of phosphaphenanthrene derivative and
           aluminum diethylphosphinate in glass fiber reinforced polyamide 66
    • Authors: Yanfang Cao; Lijun Qian, Yajun Chen, Ze Wang
      Abstract: The synergistic flame-retardant effect of 1,1′-bis(4-hydroxyphenyl)-metheylene-bis(9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide-2-hydroxypropan-1-yl) (DPOH) and aluminum diethylphosphinate (AlPi) composites on glass fiber reinforced polyamide 66 (PA) was investigated by limiting oxygen index (LOI) tests, vertical burning (UL94) tests, and cone calorimeter tests. DPOH/AlPi system with 1:1 mass ratio increased UL94 ratings, suppressed heat release rate and increased residue yields of PA composites, and DPOH/AlPi system also imposed high LOI values and lower total heat release values to PA composites. All these results verified excellent synergistic flame-retardant effect between DPOH and AlPi. The reason of DPOH/AlPi system with higher flame-retardant efficiency was caused by the quenching effect as good as that of DPOH and also by the higher charring effect than that of AlPi. DPOH/AlPi system possesses good flame retardancy in gas phase and also the strengthened flame-retardant effect in condensed phase compared with DPOH and AlPi alone, which led to excellent synergistic flame-retardant effect between the two components DPOH and AlPi. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45126.
      PubDate: 2017-04-06T00:08:31.118639-05:
      DOI: 10.1002/app.45126
       
  • Isoprene (co)polymers with glycidyl methacrylate via bimolecular and
           unimolecular nitroxide mediated radical polymerization
    • Authors: David Contreras-López; Martha Albores-Velasco, Enrique Saldívar-Guerra
      Abstract: Homo and copolymerization of isoprene (IP) with small amounts (1–10 wt %) of glycidyl methacrylate (GMA) are conducted using controlled-living radical polymerization (CRP) mediated by nitroxides (NMP) at 120 °C and 1170 kPa in solution with toluene (30 wt % solids). N-tert-butyl-N-(2-methyl-1-phenylpropyl)-O-(1-phenylethyl) hydroxylamine (TIPAL) is successfully used as a control agent (unimolecular process) although other controllers are also tested (TIPNO and OH-TEMPO in a bimolecular process using BPO as initiator). Chain extension experiments demonstrate the livingness of the synthesized materials. Several additives (acetic anhydride, camphorsulfonic acid and glucose) prove effective in accelerating the reactions. All the successful polymerizations result in first-order kinetics with respect to the monomer, yielding average molecular weights (Mn) of about 75% compared to the theoretical Mn (Mn, theo) with dispersities (Ð) ranging from 1.2 to 1.7 depending on the agent used for control. Controlled grafts of poly (isoprene-co-GMA) are also attached to polyisoprene via nitroxide chemistry. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45108.
      PubDate: 2017-04-06T00:05:59.271489-05:
      DOI: 10.1002/app.45108
       
  • Thermal and mechanical behavior evaluation of dental composites filled
           with irradiated montmorillonite
    • Authors: L. M. P. Campos; T. Zaharescu, L. C. Boaro, L. K. G. Santos, T. M. R. Santos, H. P. Ferreira, D. F. Parra
      Abstract: The effects of pre-irradiation treatment (dose ranged from 25 to 50 kGy) of MMT (Montmorillonite) nanoclay added as filler (50 wt %) in experimental dental composites was studied; composites containing similar amounts of non-irradiated MMT were also tested. The thermal stability of the resulting material was tested by thermogravimetric analysis (TGA) ranging from 50 to 800 °C. Elastic modulus and flexural strength were determined by the three point bending test (n = 10). Data for elastic modulus was analyzed using two way ANOVA/Tukey's test. Data for flexural strength was analyzed using Kruskal–Wallis/Tukey's test. For all tests, the global significance level was 5%. The modifications in elastic modulus and flexural strength with applied dose were characterized. X-ray diffraction analysis (XRD) allows the depicting of intercalation phenomenon between base-polymer and nanophase. The polymeric system modified with MMT nanoparticles showed higher thermal stability by delaying the thermal degradation, compared to the control group, and the radiation dose influenced this thermal behavior directly. However, the applied dose was not sufficient to improve the mechanical properties significantly, which is related to the interaction between MMT and polymeric matrix. The pre-irradiation treatment of MMT nanoclay phase was useful for attaining efficient interaction between the two constitutive phases of the polymeric systems based bis-GMA/TEGDMA [bisphenol A bis(2-hydroxy-3-methacryloxypropyl)ether/triethyleneglycol dimethacrylate], modified with MMT nanoparticles, because the polymer component was not affected. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45063.
      PubDate: 2017-04-06T00:05:15.925865-05:
      DOI: 10.1002/app.45063
       
  • Surface-confined electropolymerization of pyronin Y in the graphene
           composite paper structure for the amperometric determination of dopamine
    • Authors: Kader Dağcı Kıranşan; Ezgi Topçu, Murat Alanyalıoğlu
      Abstract: Surface-confined electropolymerization allowed us to easily prepare homogeneous polymer composite paper structures. The fabrication of freestanding graphene (Gr)-based composite electrodes is very important for many modular approaches in electrochemical applications, such as fuel cells, supercapacitors, and sensors. A Gr composite paper electrode doped with polymeric films of pyronin Y was fabricated by two repetitive simple applications: vacuum filtration and surface-confined electropolymerization. The characterization of this composite paper was done with scanning tunneling microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, powder X-ray diffraction spectroscopy, Raman spectroscopy, UV–visible absorption spectroscopy, four-point probe conductivity measurement, cyclic voltammetry, and electrochemical impedance spectroscopy. The freestanding composite paper demonstrated good electrocatalytic activity for the electrooxidation of dopamine; this indicated that this composite paper could be used for the amperometric quantification of dopamine in real samples. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45139.
      PubDate: 2017-04-04T23:40:40.630476-05:
      DOI: 10.1002/app.45139
       
  • Plasticized thermoplastic polyurethanes for dielectric elastomers with
           improved electromechanical actuation
    • Authors: Christophe Renard; Dongrui Wang, Yu Yang, Silai Xiong, Chang-Yong Shi, Zhi-Min Dang
      Abstract: In this article, four different plasticizers are blended in thermoplastic polyurethane (PU) to improve its electromechanical actuation performance. The selected plasticizers include dibutyl phthalate, triphenyl phosphate, polyethylene glycol (PEG), and an unsaturated polyester PMG. The plasticization effect of various plasticizers on the mechanical properties, dielectric properties, and the electromechanical actuation of PU films is carefully characterized and compared. Results demonstrate that the actuated strain under low electric fields and the electromechanical coupling efficiency of PU can be substantially improved by blending with appropriate type and amount of plasticizers. The oligomer-type plasticizers, PEG and PMG, act more efficiently in the improvement of actuation. An actuated strain in thickness of 1.54%, 140 times higher than that of pure PU, along with an electromechanical coupling efficiency of 0.60 under a low electric field of 5 V/μm was achieved for the PU plasticized with PMG suggesting an attractive approach toward advanced dielectric elastomer actuators. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45123.
      PubDate: 2017-04-04T23:40:33.762057-05:
      DOI: 10.1002/app.45123
       
  • Influence of shear thinning and material flow on robotic dispensing of
           poly(ethylene glycol) diacrylate/poloxamer 407 hydrogels
    • Authors: Gabriele Kraut; Laura Yenchesky, Fermin Prieto, Günter E. M. Tovar, Alexander Southan
      Abstract: Robotic dispensing of hydrogels offers a direct way for generating complex hydrogel shapes. For this, there is a general need for hydrogel formulations with suitable rheological properties. In this contribution, hydrogel formulations containing poly(ethylene glycol) diacrylate and Poloxamer 407 are characterized regarding their flow behavior during robotic dispensing. Formulations contain between 15% and 20% PEG-DA and 22.5% and 25% Poloxamer 407. All formulations show shear thinning which can be described using a power law with a power law index between 0.10 and 0.11 and calculated shear rates at the wall of the dispensing needle of 379 s−1 with a dispensing speed of 8 mm s−1 and a dispensing needle inner diameter of 0.51 mm. Thus facilitating the generation of smooth hydrogel strands, three-dimensional hydrogel objects can be prepared without flow after robotic dispensing and can be cured afterwards to elastic hydrogels, retaining the shape of the dispensed object. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45083.
      PubDate: 2017-04-02T23:57:06.656401-05:
      DOI: 10.1002/app.45083
       
  • Mechanical properties of carbon fiber reinforced bisphenol A dicyanate
           ester composites modified with multiwalled carbon nanotubes
    • Authors: Hui Mei; Junchao Xia, Ding Zhang, Haiqing Li, Qianglai Bai, Laifei Cheng
      Abstract: A novel electrophoretic deposition (EPD) method was employed for grafting multiwalled carbon nanotubes (MWCNTs) on carbon fibers, which, after impregnation with bisphenol A dicyanate ester (BADCy), synergistically reinforced BADCy matrix composites (CNT-C/BADCy). The effect of MWCNT presence on the mechanical properties of the composites was investigated. Composite tensile strength increased by 45.2% for an EPD duration of 2 min, while flexural strength exhibited a decreasing trend with EPD duration. Optical microscopy revealed that the existence of MWCNTs enhanced the fiber-matrix interface while a large number of CNTs were observed to have pulled-out from the matrix, a finding which explained the observed tensile strength increase in terms of energy dissipation by the specific toughening mechanism. The flexural strength decrease of the composites with CNTs as compared to specimens without nanotubes was found linked to the increased stress concentration in the BADCy matrix due to tube presence which weakens the adhesion between carbon fabrics. In a word, carbon nanotubes will enhance the micro interface and weaken the macro interface of the composites. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45100.
      PubDate: 2017-04-02T23:57:01.187224-05:
      DOI: 10.1002/app.45100
       
  • Fabrication of a sulfonated aramid-graphene nanoplatelet composite paper
           and its performance as a supercapacitor electrode
    • Authors: Saswata Bose; Sankhadeep Basu, Arit Das, Mehabub Rahman, Lawrence T. Drzal
      Abstract: Sulfonated aramid fiber (SA) modified Graphene nanoplatelet (GnP) paper was fabricated employing simple vacuum filtration technique. The SA macromolecules were noncovalently attached on the surface of GnP through π−π interactions. Robustness of the film was characterized via DMA study. X-ray photoelectron spectroscopy was employed to investigate the extent of surface functionalization. The specific capacitance of 166 F/g was obtained for the sulfonated graphene nanoplatelet (SGNP) composite paper with 97% of specific capacitance retained after 1000 cycles establishing the cyclic stability of the said composite paper. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45099.
      PubDate: 2017-04-02T23:56:58.435276-05:
      DOI: 10.1002/app.45099
       
  • HDPE composites strengthened–toughened synergistically by l-aspartic
           acid functionalized graphene/carbon nanotubes hybrid nanomaterials
    • Authors: J. Bian; G. Wang, H. L. Lin, X. Zhou, Z. J. Wang, W. Q. Xiao, X. W. Zhao
      Abstract: Ethylenediamine (EDA) covalently functionalized graphene sheets (GS-EDA) and acidized carbon nanotubes (MWNTs-COOH) were first prepared, followed by synthesizing l-aspartic acid functionalized GS-EDA/MWNTs-COOH (LGC) hybrid nanomaterials by using l-aspartic acid as a bridging agent. Then nanocomposites of high density polyethylene-g-maleic anhydride (HDPE-g-MAH) synergistic strengthening–toughening using LGC hybrids were prepared via melt compounding method. The surface structure of filler was characterized by using infrared (FTIR) and Raman spectrum. The synergistic strengthening–toughening effects of LGC hybrids on the HDPE-g-MAH were investigated by scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), thermal gravimetric analysis (TGA), tensile, and impact tests. FTIR showed that EDA has been grafted on the graphene sheets, and COOH group has been introduced into MWNTs. The l-aspartic acid connected GS-EDA and MWNTs-COOH through chemical bonds. SEM observations showed that LGC hybrids were homogeneously dispersed in HDPE-g-MAH nanocomposites. Tensile and impact tests indicated that the mechanical properties of nanocomposites were improved obviously when LGC hybrid nanomaterials were incorporated simultaneously. DMA analysis indicated that the storage modulus of composites was higher than that of pure HDPE-g-MAH matrix. TGA results revealed that the maximum decomposition temperature of HDPE-g-MAH composites containing 0.75 wt % of LGC showed 11.5 °C higher than that of HDPE-g-MAH matrix. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45055.
      PubDate: 2017-04-02T23:56:48.736645-05:
      DOI: 10.1002/app.45055
       
  • Surface modification of lignin for applications in polypropylene blends
    • Authors: Siham Atifi; Chuanwei Miao, Wadood Y. Hamad
      Abstract: The surface modification of wet-milled softwood lignin produced with the LignoForce System was successfully carried out in a one-step aqueous process. Different hydrophobic molecules, including cetyl trimethyl ammonium bromide, poly(ethylene oxide), polyethylene-block-poly(ethylene glycol), dodecenyl succinic anhydride, and alkyl ketene dimer (AKD), were investigated to design the hydrophobicity of lignin with the objective of improving the adhesion and compatibility in polymer blends composed of polar lignin particles and, for example, nonpolar polypropylene (PP). AKD, among all of the investigated approaches, proved to be the simplest and most effective for significantly increasing the contact angle of lignin while preserving the original micrometer size of wet-milled, spray-dried lignin particles. This treatment led to a noticeable improvement in the stiffness of lignin–PP composite blends, with an increase of approximately 15% in Young's modulus. The compatibility of the AKD-treated lignin with PP was assessed through tensile strength measurements and blend morphology observation, whereas the mechanism of AKD interaction with lignin was investigated with contact angle measurement, differential scanning calorimetry, Fourier transform infrared spectroscopy, and 1H-NMR spectroscopy measurements. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45103.
      PubDate: 2017-03-31T07:50:49.695765-05:
      DOI: 10.1002/app.45103
       
  • Selectively enhanced oil retention of porous polyimide bearing materials
           by direct chemical modification
    • Authors: Di Zhang; Tingmei Wang, Qihua Wang, Chao Wang
      Abstract: Porous polyimide (PI) materials containing lubricating oil have been widely used as bearing retainers in aerospace industry. High oil content and retention of porous bearing materials play an important role in assuring a successful mission of the spacecraft. Keeping both oil content and retention of bearing retainer materials high, however, is one of the bottlenecks to fulfill long lifetime missions. Chemical modification is expected to break this limitation by changing the surface properties. Inspired by this, here for the first time, the authors design a chemical method to improve silicon oil retention of porous PI samples. The results indicated that this modification could not only change the wettability of PI from hydrophilicity to hydrophobicity but also enhance the silicon oil retention from 52% to 87%. This strategy provides a novel approach to improve the oil retention of porous PI materials, which has the potential application in preparing bearing retainers with reliable, long-term performance. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45106.
      PubDate: 2017-03-30T05:15:34.701777-05:
      DOI: 10.1002/app.45106
       
  • Influences of diallyl phthalate as chain extender on the properties of
           high molecular weight poly(vinyl chloride) resin
    • Authors: Jianning Wu; Baoxun Sui, Lei Li, Guihua Meng, Xuhong Guo, Zhiyong Liu
      Abstract: A higher porosity with better thermostability is desirable for poly(vinyl chloride) (PVC) resin. In this study, high molecular weight PVC resins are prepared by vinyl chloride monomer (VCM)-diallyl phthalate (DAP) suspension copolymerization in a 20-L reactor at 50 °C using DAP as chain extender. SEM, BET, and analyses of plasticizer absorption results show the high molecular weight poly(vinyl chloride) (HPVC) by DAP-VCM copolymerization is loose and porous. With increasing DAP content when the mass ratio of DAP/VCM (ω) is below the gel point, the porosity and the degree of polymerization increase. Nevertheless, the bulk density and particle size decrease. When more than the gel point, these relationships are reversed. Thermogravimetric analysis revealed that the HPVC had better thermostability than that of commercial PVC, and its thermostability increases with increasing ω before it reaches the gel point. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45093.
      PubDate: 2017-03-28T23:35:35.516477-05:
      DOI: 10.1002/app.45093
       
  • Detailed examination of nitrile stretching vibrations relevant for
           understanding the behavior of thermally treated polyacrylonitrile
    • Authors: Klaus Ruhland; Nino Haase, Andreas Fischer
      Abstract: The influence of electronic and environmental effects on the wave number of nitrile stretching vibrations was examined with respect to moieties relevant for the polyacrylonitrile homopolymer and its assumed transformation products on thermal treatment in the course of carbon fiber production on the basis of four sources of information. Literature values were collected. Fourier transform infrared (FTIR) measurements on relevant commercially available compounds were performed. For the first time, model compounds were synthesized and examined, and for the first time, density functional theory calculations for unavailable important compounds were performed. The results place the interpretation of the FTIR data on much safer scientific ground than any other study before; in particular, they unequivocally disprove suggestions given in the previous literature and provide quantitative relative oscillation strengths for important peaks necessary for the quantitative kinetic evaluation of the changes, which will enable the systematic fine-tuning of new proposals. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44936.
      PubDate: 2017-03-28T07:05:36.352341-05:
      DOI: 10.1002/app.44936
       
  • Facile synthesis of graphene/polypyrrole 3D composite for a
           high-sensitivity non-enzymatic dopamine detection
    • Authors: Zhou Rui; Wei Huang, Yong Chen, Kexi Zhang, Yang Cao, Jinchun Tu
      Abstract: One kind of nanocomposite consisting of graphene and polypyrrole was synthesized via a facile and mild way with the assistant of microwave irradiation. The synthesis route was embedding the polypyrrole into the graphene flakes to form a 3D structure, to achieve larger active surface and higher electro-catalysis property. Structures and components of the composite were measured by X-ray diffraction, field emission scanning electron microscopy, and Fourier transform infrared spectroscopy. A stronger electrochemical response of electrode with modified resultant was observed in the electrochemical test. Dopamine sensor based on the composite showed a sensitivity of 363 μA mM−1 cm−2, a linear range of 1 × 10−4 M to 1 × 10−3 M, and a detection limit of 2.3 × 10−6 M (S/N = 3). © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44840.
      PubDate: 2017-03-27T23:40:27.324303-05:
      DOI: 10.1002/app.44840
       
  • Single crystals of crystalline block copolymers formed in n-hexanol and
           methanol/DMF solutions: A comparative study
    • Authors: Wangqian Zhuo; Yanming Li, Runke Zhang, Runsheng Huang, Jie Zhou, Zaizai Tong, Guohua Jiang
      Abstract: Lamellar single crystals of poly(ɛ-caprolactone) (PCL)-based crystalline/liquid-crystalline block copolymer (BCP) were prepared from two methods: solution crystallization in n-hexanol as well as addition of methanol dropwise to BCP/DMF solution. The crystalline morphologies of PCL single crystals prepared at different temperatures were investigated. It was observed that well-developed single crystals were formed in n-hexanol at high crystallization temperatures, while low crystallization temperatures favored to fabricate well-developed nanosheets in methanol/DMF. Annealing at the melting temperature of single crystals yielded the crystalline seeds and unimers in n-hexanol, while it formed spherical micelles in methanol/DMF system. As a result, the size of single crystals in n-hexanol could be tuned by addition of different ratios of unimer/seed. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45089.
      PubDate: 2017-03-27T05:02:24.102942-05:
      DOI: 10.1002/app.45089
       
  • Fabrication of highly monodisperse CeO2@poly(methyl silsesquioxane)
           microspheres and their application in UV-shielding films
    • Authors: Jinfang Yuan; Wenshi Ma, Jinpeng Mo
      Abstract: Highly monodisperse CeO2@poly(methyl silsesquioxane) (PMSQ) microspheres were successfully prepared by a facile chemical precipitation technique. The structures and properties of CeO2@PMSQ were analyzed by Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy techniques. We confirmed that the PMSQ microspheres were uniformly coated by CeO2 nanoparticles, with about an 8 nm crystallite diameter. Then, CeO2@PMSQ was incorporated into a poly(vinyl alcohol) (PVA) matrix to fabricate PVA/CeO2@PMSQ composite films by the casting of homogeneous solutions. The thermal and optical properties of the composite films were investigated by thermogravimetric analysis and UV–visible spectroscopy. The results show the high UV-shielding efficiency of the composites: for a film containing 2.5 wt % CeO2@PMSQ microspheres, about 80% UV light at wavelengths between 200 and 360 nm was absorbed, whereas the optical transparency in the visible region still remained very high. The addition of CeO2@PMSQ microspheres improved the thermal stability of the PVA films. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45065.
      PubDate: 2017-03-27T05:01:59.091918-05:
      DOI: 10.1002/app.45065
       
  • Surface modification of polyamide TFC membranes via redox-initiated graft
           polymerization of acrylic acid
    • Authors: Thu Hong Anh Ngo; Khai Dinh Do, Dung Thi Tran
      Abstract: In this work, the redox-initiated graft polymerization of acrylic acid (AA) onto the surface of polyamide thin film composite membranes has been carried out to enhance membrane separation and antifouling properties. The membrane surface characteristics were determined through the attenuated total reflection Fourier transform infrared spectra, scanning electron microscopy, atomic force microscopy, and water contact angles. The membrane separation performance was evaluated through membrane flux and rejection of some organic compounds such as reactive red dye (RR261), humic acid, and bovine serum albumin in aqueous feed solutions. The experimental results indicated that the membrane surfaces became more hydrophilic and smoother after grafting of AA. The modified membranes have a better separation performance with a significant enhancement of flux at a great retention. The fouling resistance of the modified membranes is also clearly improved with the higher maintained flux ratio and the lower irreversible fouling factor compared to the unmodified one. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45110.
      PubDate: 2017-03-27T05:01:18.028342-05:
      DOI: 10.1002/app.45110
       
  • Preparation of chitosan–graphene nanosheet composites with enhanced
           electrochemical and mechanical properties
    • Authors: Guangyu Wu; Jianguo Huang, Weidong Li
      Abstract: In this study, we proposed an alternative way to produce graphene nanosheet (GNS)/chitosan (CS) composites. Graphite-intercalating compounds (GICs) were prepared by graphite and m-chloroperbenzion acid (M-CPBA) as starting materials. The GNS–CS composites were produced through the mixing of the GICs into CS and the removal of impurities in the final step. X-ray diffraction, atomic force microscopy, and transmission and scanning electron microscopy analyses showed that graphite could be effectively exfoliated by an intercalating agent (M-CPBA) and the GNSs were homogeneously dispersed into the CS matrix. Furthermore, we demonstrated that the electrochemical behavior and mechanical properties of the GNS–CS composites were significantly improved with a low level of GNSs in CS. The redox peak current increased 509%, and the modulus and hardness of the GNS–CS composites increased by 2.7 and 0.15 GPa, respectively, when the GNSs addition was 0.6 wt %. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45104.
      PubDate: 2017-03-27T00:43:09.257053-05:
      DOI: 10.1002/app.45104
       
  • Effect of nano-TiO2 surface modification on polarization characteristics
           and corona aging performance of polyimide nano-composites
    • Authors: Haowei Lu; Jiaqi Lin, Wenlong Yang, Lizhu Liu, Yu Wang, Gaoru Chen, Wei Huang
      Abstract: Using coupling agent isocyanatopropyltriethoxysilane (ICTOS) to modified nano-TiO2, the polyimide (PI) with different titanium dioxide (TiO2) contents (0, 1, 2, 3, 4, and 5 wt %) doped nano-composites were prepared by sol–gel method (PI/TiO2 ICTOS composites). The effect of ICTOS modification on polarization and time-to-breakdown properties of composites were investigated by thermally stimulated depolarization current (TSDC) method, dielectric, and Corona aging measurements. The TSDC spectra show that ICTOS modification enhanced α-peak intensity and make β-peak disappear in composites. Relevant trap parameters were calculated by an approximate model, and the results indicate that introduction of ICTOS is effective for the charge carrier traps, activation energy distribution in composites. Corona aging measurement show corona resistance was also sufficient improved in PI/TiO2 ICTOS composites. The changes of activation energy and intensity of traps in composites may be responsible for the corona resistance. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45101.
      PubDate: 2017-03-24T23:46:24.184508-05:
      DOI: 10.1002/app.45101
       
  • A quantitative evaluation method of the barrier property of the residue
           for flame retardant polymers
    • Authors: Wenhua Chen; Xin Ma, Yuansen Liu, Pengju Liu, Yuan Liu, Qi Wang
      Abstract: To investigate the flame retardant properties and mechanisms of those fire retardant polymer systems that mainly depend on the produced protective char shields, quantitative analysis for the barrier quality of the char layer is important but still a challenge. In the present article, a novel and simple characterization method based on atmosphere permeability is proposed to quantitatively evaluate the barrier property: an incombustible fabric carrier coated with the flame retardant polymer solution, is carbonized at high temperature to make the produced char residue adhered to the fabric. As the interfibrous gaps are filled and closed by the chars, the atmosphere permeability of the heated fabric decreases compared with that of original one. Their difference value can really reflect the contribution of the charring residue to the barrier property. This method combined with other characterizations including residue morphology observation, vertical burning test, limiting oxygen index, and calorimetric analysis, is very helpful to reveal the correlation between the flame retardance and barrier property of the char residue, evaluate the flame retardant efficiency in the condense phase, and estimate the corresponding flame retardant mechanisms. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45102.
      PubDate: 2017-03-24T23:46:08.76265-05:0
      DOI: 10.1002/app.45102
       
  • Effect of amphoteric dispersant on the dispersion properties of nano-SiO2
           particles
    • Authors: Rui-Jun Gao; Yan Yao, Hao Wu, Ling Wang
      Abstract: An amphoteric polycarboxylate dispersant (APC) was synthesized by copolymerization of acrylic acid (AA), methacryloxyethyltrimethyl ammonium chloride (DMC), and isopentenol polyoxyethylene ether (IPEG). The molecular structure of APC was characterized by FT-IR, 1H-NMR, and GPC. Effect of the dosage of APC on the rheological performance of nano-SiO2 suspension was investigated by measurements of the plastic viscosity. The results indicated that the best dispersion effect of APC was obtained when the dosage of APC was about 10 wt % (by the weight percent of nano-SiO2), which can maintain the dispersion of nano-SiO2 suspension uniformly for 4 h without settlement. Meanwhile, the zeta potential value on the surface of nano-SiO2 particles shows that the better dispersion performance of APC was attributed to the solvation water film formed by the polyoxyethylene side chains and the electrostatic repulsion formed by positively groups (CN+) on the APC structure combined with -SiO– groups on the surface of nano-SiO2 particles. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45075.
      PubDate: 2017-03-24T23:45:56.074898-05:
      DOI: 10.1002/app.45075
       
  • Bacterial exopolysaccharides for corrosion resistance on low carbon steel
    • Authors: Victoria L. Finkenstadt; Claudiu B. Bucur, Gregory L. Côté, Kervin O. Evans
      Abstract: Corrosion is a global issue that affects safety and economics. There is an increasing demand for bio-based polymers for industrial applications and production of polymers by micro-organisms is especially attractive. This work reports on the electrochemical and physical properties of exopolysaccharides produced from lactic acid bacteria and their suitability as anti-corrosive coatings. Bacterial exopolysaccharide coatings protected low carbon steel from corrosion by reducing ionic diffusion rates and maintaining a relatively passive metal-coating interface. The data suggest the kinetics of film deposition are fast (
      PubDate: 2017-03-24T23:45:49.681538-05:
      DOI: 10.1002/app.45032
       
  • Direct solid state polycondensation of tetra- and hexa-methylenediammonium
           terephthalate: Scaling up from the TGA micro-reactor to a laboratory
           autoclave
    • Authors: Athanasios D. Porfyris; Constantine D. Papaspyrides, Ruud Rulkens, Eric Grolman
      Abstract: The direct solid state polycondensation (DSSP) reaction of tetramethylenediammonium and hexamethylenediammonium terephthalate (4 T and 6 T salts) in a laboratory scale autoclave reactor was investigated. The autoclave reactor is 3 orders of magnitude larger than the TGA micro-reactor we used previously. The larger scale reactor allows more extensive analyses such as analysis of the formed condensate by titration and allows investigation of operating conditions that are important on industrial scale, such as batch (closed system) versus semibatch (open system) operation and flow of nitrogen used. Comparing the two scales has given important insight into the parameters that are important in scaling-up direct solid-state polycondensation. Furthermore, the effect of scaling up on the quality of the final semiaromatic polyamide products was determined, by comparing the obtained thermal properties, the solution viscosity and the end-group concentrations obtained by 1H-NMR spectroscopy. When operating the open reactor with a gentle nitrogen stream, the results show that products of similar properties were obtained from the micro and the laboratory scale reactors if critical parameters like temperature and pressure time profile were kept the same. The solid character of the reacting mass was retained only when maintaining the reactor at atmospheric pressure, allowing the condensation water to be removed. When keeping the autoclave reactor closed, both polyamide (PA) products (i.e., PA4T and PA6T) were agglomerated as a result of a solid melt transition during the direct solid state polycondensation. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45080.
      PubDate: 2017-03-24T23:45:43.480593-05:
      DOI: 10.1002/app.45080
       
  • Synthesis and properties of sulfonated biphenyl poly(ether sulfone) and
           
    • Authors: Nan Zhao; Tao Liu, Zhongzhu Liu, Yu Su, Hongyang Yu, Jingjing Ma, Yanhua Yang, Zhenhua Jiang
      Abstract: We prepared mixed-matrix membranes (MMMs) composed of carboxylated single-walled carbon nanotubes (f-SWCNTs) and a sulfonated biphenyl poly(ether sulfone) (S-PPSU) polymer matrix. The thermal stability and properties of the pores of the S-PPSU and f-SWCNTs were characterized by thermogravimetric analysis and sorption isotherm curves, respectively; these showed that the surface and pore diameter decreased after the introduction of carboxyl groups to the single-walled carbon nanotubes (SWCNTs), and the pore properties did not restore original values even when the f-SWCNTs were preheated to 350 °C to remove carboxyl groups. The gas-separation measurement showed that the MMMs comprised of the S-PPSU and f-SWCNTs possessed better gas-separation properties than the ones composed of biphenyl poly(ether sulfone) and SWCNTs. The permeability for N2, O2, He, and CO2 and the selectivity for O2/N2 and O2/CO2 were enhanced simultaneously because of the good dispersion of f-SWCNTs and the improved interaction between the two phases. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44995.
      PubDate: 2017-03-24T23:45:39.04959-05:0
      DOI: 10.1002/app.44995
       
  • Surface modification of textile material through deposition of regenerated
           silk fibroin
    • Authors: Ha-Thanh Ngo; Thomas Bechtold
      Abstract: Regeneration of silk fibroin from calcium chloride/ethanol/water solution is of high interest to shape biomaterial based products for medical and technical application. In this study a continuous process for surface modification of cellulose or polyamide fibers by regenerated fibroin deposits has been investigated. The decomposition of the fibroin-calcium complex was initiated by addition of K2CO3 followed by a methanol rinse. Reactive Blue 19 labeled fibroin was used to monitor the deposition of fibroin on the substrates by colour measurement. The fibroin deposits on the fabric were characterized by microscopy, N-content, calcium, and protein content. Stiffness and surface resistivity of modified fabrics were determined as representative physical parameters. The reduced mobility of fibers increased fabric stiffness. Surface resistivity of treated samples was reduced by a factor of 10 to 100, which gives an example for the potential of the technique as coating for man-made fiber textiles. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45098.
      PubDate: 2017-03-24T07:40:39.220798-05:
      DOI: 10.1002/app.45098
       
  • Influence of foaming and carbon nanotubes on sound transmission loss of
           wood fiber-low density polyethylene composites
    • Authors: Behrouz Neyciyani; Saeed Kazemi Najafi, Ismaeel Ghasemi
      Abstract: The aim of this study was to investigate the effect of carbon nanotubes (CNTs) and foaming on sound transmission loss (STL) of wood fiber-low density polyethylene composite. For this purpose, low density polyethylene, wood fiber, foaming agent, coupling agent and modified CNTs were mixed in an internal mixer to produce test samples. The standard circular samples were produced by using compression molding method in a hot press machine. Sound transmission loss was measured by an impedance tube. Results showed that the use of CNTs improved the foam morphology in the composites. Foaming and the use of CNTs improve the STL of composites (especially at medium and higher frequencies) and the highest STL was obtained for wood fiber/LDPE foamed composites containing 1% CNT. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45096.
      PubDate: 2017-03-24T07:40:33.353512-05:
      DOI: 10.1002/app.45096
       
  • Industrial polyethylene melt index prediction using ensemble manifold
           learning–based local model
    • Authors: Yi Liu; Yu Liang, Zengliang Gao
      Abstract: For online melt index prediction in multiple-grade polyethylene polymerization processes, using only a fixed model is insufficient. Additionally, without enough process knowledge, it is difficult to select suitable input variables to accurately construct prediction models. A novel manifold learning based local probabilistic modeling method named ensemble just-in-time Gaussian process regression (EJGPR) is developed. By utilizing output variables, an optimization framework is proposed to preserve the local structure of both input and output variables. Then the output information is integrated into construction of a JGPR-based local model. Additionally, some new extracted variables in the projection space can be obtained. Moreover, using the probabilistic prediction information, the uncertainty of each JGPR-based local candidate model can be simply described. Consequently, using an efficient ensemble strategy, a more accurate EJGPR prediction model can be constructed online. The melt index prediction results in an industrial polyethylene process show it has better performance than conventional methods. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45094.
      PubDate: 2017-03-24T07:40:30.670604-05:
      DOI: 10.1002/app.45094
       
  • Poly(hydroxybutyrate-co-hydroxyvalerate) and bovine serum albumin blend
           prepared by electrospinning
    • Authors: Elizaveta R. Pavlova; Dmitry V. Bagrov, Maria N. Kopitsyna, Dmitry A. Shchelokov, Anton P. Bonartsev, Irina I. Zharkova, Tatiana K. Mahina, Vera L. Myshkina, Galina A. Bonartseva, Konstantin V. Shaitan, Dmitry V. Klinov
      Abstract: Electrospinning is a method for the preparation of nanosized polymer fibers. Here, electrospinning is used to prepare a blend of a polyester, poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV), and a globular protein, bovine serum albumin (BSA). The electrospun blend film is compared with a solution-cast blend film and with single-component electrospun films made of PHBV and BSA. In the electrospun blend films, BSA manifests itself as flat ribbons and a fine network formed from fibers less than 50 nm in diameter. The dissolution rate of BSA from the electrospun blended film is lower than from the solution-cast one. The films are characterized using scanning electron microscopy, differential scanning calorimetry, and contact-angle measurements. The obtained PHBV+BSA blend films have several emergent properties: a slow BSA dissolution rate, a fine BSA network, and unusual thermal behavior. Thus, the PHBV+BSA blend films introduce a new class of polymer–protein blends. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45090.
      PubDate: 2017-03-20T05:16:06.93625-05:0
      DOI: 10.1002/app.45090
       
  • Exploration on polypropylene carbonate polymer for gel polymer electrolyte
           preparation and dye-sensitized solar cell application
    • Authors: N. K. Farhana; Mohammad H. Khanmirzaei, S. Ramesh, K. Ramesh
      Abstract: Gel polymer electrolytes (GPEs) with incorporation of polypropylene carbonate (PPC) polymer and different weight percentages of sodium iodide (NaI) salt are prepared. Ethylene carbonate and propylene carbonate are used as plasticizers. The maximum ionic conductivity of 2.01 mS cm−1 is achieved at room temperature. Temperature-dependent ionic conductivity study is performed. The GPEs are studied for structural properties using Fourier transform infrared (FTIR). The FTIR analysis confirms that complexation between PPC and NaI has occurred. By using GPEs, dye-sensitized solar cells (DSSC) are fabricated under the one Sun light intensity. The highest energy conversion efficiency of 6.38% is achieved with incorporation of 60 wt % of NaI. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45091.
      PubDate: 2017-03-20T05:15:34.706772-05:
      DOI: 10.1002/app.45091
       
  • Compressive moduli and network parameters of N-isopropylacrylamide
           hydrogels copolymerized by monoesters of itaconic acid and crosslinked
           with tetraallylammonium bromide
    • Authors: Cansu Kozbekçi; B. Filiz Şenkal, Candan Erbil
      Abstract: The present study focuses on the mechanical properties of hydrophilically or hydrophobically modified poly(N-isopropylacrylamide) (PNIPAAm) hydrogels, and all discussions on their improved mechanical strengths are based on the conformational effects of hydrophobic side chains attached to the comonomers and the structural differences between the crosslinkers. Three different types of monoalkyl itaconates, bearing octyl (Oc), cetyl (Ce), and cyclohexyl (CH) groups as comonomers, were used to prepare the copolymeric PNIPAAm hydrogels crosslinked with N,N′-methylenebisacrylamide (BIS) and tetraallylammonium bromide (TAB) as neutral tetrafunctional and ionic octafunctional crosslinkers, respectively. The most striking result is the compressive E modulus of TAB-crosslinked PNIPAAm hydrogel containing 10 mol % of mOcI. It reaches nearly 1.0 MPa and is independent of the temperature and pH of the swelling/shrinking medium. The result was discussed in terms of the inter/intramolecular interactions between hydrophobic octyl groups adopting a rod-like conformation in the case of 25 °C/distilled deionized water (DDW) and 37 °C/DDW combinations. Further, it was observed that the electrostatic repulsive forces between the carboxylate groups on mOcI units could be suppressed even at 37 °C and pH 9 due to the rod-like conformations of C8H17 groups. Its micrographs under bright-field and polarized light supported the presence of an ordered anisotropic phase and multiple associations of extended, hydrophobic side chains. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45039.
      PubDate: 2017-03-13T23:35:45.892646-05:
      DOI: 10.1002/app.45039
       
 
 
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