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  Subjects -> ENGINEERING (Total: 1962 journals)
    - CHEMICAL ENGINEERING (151 journals)
    - CIVIL ENGINEERING (149 journals)
    - ELECTRICAL ENGINEERING (82 journals)
    - ENGINEERING (1119 journals)
    - ENGINEERING MECHANICS AND MATERIALS (290 journals)
    - HYDRAULIC ENGINEERING (45 journals)
    - INDUSTRIAL ENGINEERING (52 journals)
    - MECHANICAL ENGINEERING (74 journals)

CHEMICAL ENGINEERING (151 journals)                  1 2     

ACS Combinatorial Science     Full-text available via subscription   (Followers: 7)
Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials     Hybrid Journal   (Followers: 3)
Acta Polymerica     Hybrid Journal   (Followers: 6)
Additives for Polymers     Full-text available via subscription   (Followers: 18)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 4)
Advanced Chemical Engineering Research     Open Access   (Followers: 7)
Advances in Applied Ceramics     Partially Free   (Followers: 2)
Advances in Chemical Engineering     Full-text available via subscription   (Followers: 15)
Advances in Chemical Engineering and Science     Open Access   (Followers: 21)
Advances in Polymer Technology     Hybrid Journal   (Followers: 10)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 1)
Annual Review of Analytical Chemistry     Full-text available via subscription   (Followers: 9)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 9)
Anti-Corrosion Methods and Materials     Hybrid Journal   (Followers: 4)
Applied Petrochemical Research     Open Access   (Followers: 3)
Asia-Pacific Journal of Chemical Engineering     Hybrid Journal   (Followers: 6)
Biochemical Engineering Journal     Hybrid Journal   (Followers: 8)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 5)
BMC Chemical Biology     Open Access   (Followers: 4)
Brazilian Journal of Chemical Engineering     Open Access   (Followers: 2)
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 1)
Carbohydrate Polymers     Hybrid Journal   (Followers: 8)
Catalysts     Open Access   (Followers: 6)
Chemical and Petroleum Engineering     Hybrid Journal   (Followers: 7)
Chemical and Process Engineering     Open Access   (Followers: 3)
Chemical and Process Engineering Research     Open Access   (Followers: 5)
Chemical Communications     Full-text available via subscription   (Followers: 27)
Chemical Engineering & Technology     Hybrid Journal   (Followers: 24)
Chemical Engineering and Processing: Process Intensification     Hybrid Journal   (Followers: 9)
Chemical Engineering and Science     Open Access   (Followers: 2)
Chemical Engineering Communications     Hybrid Journal   (Followers: 10)
Chemical Engineering Journal     Hybrid Journal   (Followers: 16)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 15)
Chemical Engineering Science     Hybrid Journal   (Followers: 9)
Chemical Geology     Hybrid Journal   (Followers: 9)
Chemical Papers     Hybrid Journal   (Followers: 3)
Chemical Product and Process Modeling     Full-text available via subscription   (Followers: 3)
Chemical Reviews     Full-text available via subscription   (Followers: 251)
Chemical Society Reviews     Full-text available via subscription   (Followers: 26)
Chemical Technology     Open Access   (Followers: 4)
ChemInform     Hybrid Journal   (Followers: 3)
Chemistry & Industry     Hybrid Journal   (Followers: 2)
Chemistry Central Journal     Open Access   (Followers: 5)
Chemistry of Materials     Full-text available via subscription   (Followers: 162)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 6)
ChemSusChem     Hybrid Journal   (Followers: 7)
Chinese Chemical Letters     Full-text available via subscription   (Followers: 1)
Chinese Journal of Chemical Engineering     Full-text available via subscription   (Followers: 3)
Chinese Journal of Chemical Physics     Hybrid Journal   (Followers: 1)
Coke and Chemistry     Hybrid Journal  
Coloration Technology     Hybrid Journal   (Followers: 1)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 8)
Computer Aided Chemical Engineering     Full-text available via subscription   (Followers: 2)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 6)
Corrosion Engineering, Science and Technology     Hybrid Journal   (Followers: 18)
Corrosion Reviews     Full-text available via subscription   (Followers: 4)
Crystal Research and Technology     Hybrid Journal   (Followers: 2)
Current Opinion in Chemical Engineering     Open Access   (Followers: 2)
Education for Chemical Engineers     Hybrid Journal   (Followers: 4)
European Polymer Journal     Hybrid Journal   (Followers: 41)
Fibers and Polymers     Full-text available via subscription   (Followers: 3)
Focusing on Modern Food Industry     Open Access   (Followers: 3)
Frontiers of Chemical Science and Engineering     Hybrid Journal   (Followers: 1)
Geochemistry International     Hybrid Journal  
High Performance Polymers     Hybrid Journal  
Indian Chemical Engineer     Hybrid Journal   (Followers: 3)
Indian Journal of Chemical Technology (IJCT)     Open Access   (Followers: 12)
Industrial & Engineering Chemistry     Full-text available via subscription   (Followers: 9)
Industrial & Engineering Chemistry Research     Full-text available via subscription   (Followers: 16)
Industrial Chemistry Library     Full-text available via subscription   (Followers: 4)
International Journal of Chemical and Petroleum Sciences     Open Access   (Followers: 1)
International Journal of Chemical Engineering     Open Access   (Followers: 6)
International Journal of Chemical Reactor Engineering     Full-text available via subscription   (Followers: 3)
International Journal of Chemical Technology     Open Access   (Followers: 3)
International Journal of Chemoinformatics and Chemical Engineering     Full-text available via subscription   (Followers: 2)
International Journal of Food Science     Open Access   (Followers: 2)
International Journal of Industrial Chemistry     Open Access  
International Journal of Polymeric Materials     Hybrid Journal   (Followers: 3)
International Journal of Science and Engineering     Open Access   (Followers: 7)
International Journal of Waste Resources     Open Access   (Followers: 3)
ISRN Chemical Engineering     Open Access   (Followers: 4)
ISRN Polymer Science     Open Access   (Followers: 11)
Journal of Applied Crystallography     Hybrid Journal   (Followers: 4)
Journal of Applied Electrochemistry     Hybrid Journal   (Followers: 6)
Journal of Applied Polymer Science     Hybrid Journal   (Followers: 152)
Journal of Biomaterials Science, Polymer Edition     Hybrid Journal   (Followers: 7)
Journal of Chemical & Engineering Data     Full-text available via subscription   (Followers: 6)
Journal of Chemical Ecology     Hybrid Journal   (Followers: 1)
Journal of Chemical Engineering     Open Access   (Followers: 3)
Journal of Chemical Engineering and Materials Science     Open Access  
Journal of Chemical Science and Technology     Open Access   (Followers: 1)
Journal of Chemical Sciences     Partially Free   (Followers: 13)
Journal of Chemical Technology & Biotechnology     Hybrid Journal   (Followers: 2)
Journal of Chemical Theory and Computation     Full-text available via subscription   (Followers: 9)
Journal of Coatings     Open Access   (Followers: 2)
Journal of Crystallization Process and Technology     Open Access   (Followers: 5)
Journal of Food Measurement and Characterization     Hybrid Journal  
Journal of Fuel Chemistry and Technology     Full-text available via subscription   (Followers: 5)
Journal of Fuels     Open Access  
Journal of Geochemical Exploration     Hybrid Journal  

        1 2     

Journal Cover High Performance Polymers
   Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 0954-0083 - ISSN (Online) 1361-6412
     Published by Sage Publications Homepage  [737 journals]   [SJR: 0.344]   [H-I: 28]
  • Preparation and characterization of heat-resistant polyimide/titanium
           dioxide nanocomposite films containing triptycene side units by sol-gel
           processes
    • Authors: Rafiee, Z; Mallakpour, S, Hatamvand, R.
      Pages: 373 - 380
      Abstract: Thermally stable polyimide/titanium dioxide (PI/TiO2) hybrid nanocomposite films have been successfully synthesized through the in situ formation of TiO2 within a PI matrix via sol–gel process. Poly(amic acid) (PAA) solutions are prepared from bis(4-aminophenoxy)phenyl triptycene and 3,3',4,4'-benzophenone tetracarboxylic dianhydride in N-methyl-2-pyrrolidinone solvent. The different amounts of tetraethyl orthotitanate and actylacetone (acac) are incorporated into PAA matrix, and then thermally imidized to form PI/TiO2. The chelating agent, acac, was applied to reduce the gelation rate of titanium alkoxide. Thermal decomposition temperatures with a 10% weight loss are in excess of 510°C, and char yields at 800°C under nitrogen atmosphere are higher than 69%. The chemical and morphological structures of the hybrid nanocomposites were characterized using Fourier transform infrared spectroscopy, x-ray diffraction, and transmission electron microscopy. The results show that the TiO2 particles are well dispersed in the PI matrix with particle size between 10 and 30 nm in diameter.
      PubDate: 2014-05-18T22:45:06-07:00
      DOI: 10.1177/0954008313515285|hwp:master-id:sphip;0954008313515285
      Issue No: Vol. 26, No. 4 (2014)
       
  • Synthesis and properties of aligned all-aromatic liquid crystal networks
    • Authors: Iqbal, M; Picken, S. J, Dingemans, T. J.
      Pages: 381 - 391
      Abstract: A series all-aromatic main-chain liquid crystalline (LC) polymers based on 6-hydroxy-2-naphtoic acid (HNA), biphenyl-4,4'-dicarboxylic acid (BA), resorcinol (RS), and a cross-linkable ethynyl functionality, 4,4'-(1,2-ethynediyl)bisbenzoic acid (EBA) were synthesized using a one-pot melt condensation method. In contrast with reactive LC oligomers where reactive functionalities were placed at the chain terminus, the reactive ethynyl group is now used as a cross-linking functionality placed in the polymer main-chain. Differential scanning calorimetric analysis reveals that these polymers can be cured at temperatures above 350°C in the nematic melt and exhibit excellent thermal properties, that is, temperature at 5% weight loss> 465°C, and reaches a maximum after cure glass transition temperature (T g) of 167°C. When only 5 mol% of BA was replaced with EBA, a slightly cross-linked nematic network, HNA/BA/RS/EBA-5, was obtained and thin films thereof could be stretched by 400% strain above T g in four consecutive steps. A maximum order parameter $$$$ of 0.54 could be achieved, and this moderately aligned LC network displays a room temperature storage modulus (E') of 29 GPa, a tensile strength of 330 MPa, a tensile modulus of 7 GPa, and an elongation at break of 7%. Cross-linking also improved the transverse properties of the nematic films. E' of HNA/BA/RS/EBA-5 is 1.0 GPa at 150°C after being stretched by 400% versus 0.16 GPa for the non-cross-linked reference polymer. An affine deformation model was used to calculate E' using $$\overline{{P}_{2}}$$ , and the predicted values are in close agreement with the experimental results.
      PubDate: 2014-05-18T22:45:06-07:00
      DOI: 10.1177/0954008313516986|hwp:master-id:sphip;0954008313516986
      Issue No: Vol. 26, No. 4 (2014)
       
  • A green route for the synthesis of novel optically active
           poly(amide-imide) nanocomposites containing
           N-trimellitylimido-L-phenylalanine segments and modified alumina
           nanoparticles
    • Authors: Mallakpour, S; Khadem, E.
      Pages: 392 - 400
      Abstract: In the present study, novel optically active poly(amide–imide)/alumina nanocomposites (PAI/Al2O3 NCs) containing different amounts of modified α-Al2O3 nanoparticles (NPs) were synthesized using the ultrasonic-assisted technique. To improve NPs dispersion and increase the possible interaction between NPs and PAI matrix, the surface of α-Al2O3 NP was modified with bioactive diacid coupling agent. The PAI chains were formed from the polycondensation of N-trimellitylimido-l-phenylalanine diacid with 1,5-diamino naphthalene under green conditions. The obtained polymer and inorganic metal oxide NPs were used to prepare chiral PAI/Al2O3 NCs through the ultrasonic irradiation. PAI/Al2O3 NCs were characterized by Fourier transform infrared spectra, x-ray diffraction patterns, field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and ultraviolet–visible (UV-Vis). TGA results confirmed that the heat stability of the prepared NP-reinforced composites was improved compared with the pure polymer. In addition, TEM and FESEM images showed that NPs were dispersed into the polymer matrix at nanoscale.
      PubDate: 2014-05-18T22:45:06-07:00
      DOI: 10.1177/0954008313516820|hwp:master-id:sphip;0954008313516820
      Issue No: Vol. 26, No. 4 (2014)
       
  • Preparation of polyphenylsulfone containing imidazole group for gas
           separation membrane material
    • Authors: Yu, Y; Liu, B, Wang, Y, Liu, S, Li, X, Liu, Z, Jiang, Z.
      Pages: 401 - 407
      Abstract: In this work, a series of polyphenylsulfones containing imidazole group in the polymer chain (imPPSU) was successfully synthesized. The permeability of gases carbon dioxide (CO2), nitrogen (N2), oxygen (O2), and helium through a series of imPPSUs was determined at 25°C and an upstream pressure of 1 atm. The effects of nitrogen-containing heterocyclic groups on permeability coefficient and selectivity for the gas pairs CO2/O2, CO2/N2, and O2/N2 were discussed. The polymers containing imidazole group exhibited high permeability and surprisingly higher selectivity considering the interaction between CO2 and imidazole group. Imidazole groups were introduced into polymers by a simple synthetic scheme. In addition, we investigated the effect on the content of the imidazole group on the permeability of CO2.
      PubDate: 2014-05-18T22:45:06-07:00
      DOI: 10.1177/0954008313520021|hwp:master-id:sphip;0954008313520021
      Issue No: Vol. 26, No. 4 (2014)
       
  • Synthesis and properties of a novel poly(aryl ether sulfone)
           functionalized with pinacol phenylboronate pendants
    • Authors: Wang, Y; Zhang, H, Liu, M, Shang, Y, Lin, Y, Jiang, Z.
      Pages: 408 - 412
      Abstract: A novel poly(arylene ether sulfone) (PAES) with pinacol phenylboronate pendants (PAES-B) was prepared by the borylation of brominated PAES (PAES-Br). The reaction was carried out under mild conditions in the presence of cuprous iodide and tri-n-butylphosphine in tetrahydrofuran solution. After heat treatment at 150°C for 132 h, the PAES-B exhibited an interesting solvent resistance. Fourier transform infrared spectroscopy (FTIR) and thermal analysis were performed to investigate the reason. FTIR spectra showed that heat treatment could facilitate losing of pinacol groups and formation of phenylboronic acid in the polymer. Meanwhile, differential scanning calorimetric (DSC) curves demonstrated that the polymer had cross-linking behaviors during heat treatment. In addition, the thermal oxidative stability of PAES-B was researched by the thermogravimetric analysis (TGA).
      PubDate: 2014-05-18T22:45:06-07:00
      DOI: 10.1177/0954008313517251|hwp:master-id:sphip;0954008313517251
      Issue No: Vol. 26, No. 4 (2014)
       
  • Thermal expansion behavior of polyimide films containing benzoxazole unit
    • Authors: Song, G; Wang, D, Dang, G, Zhou, H, Chen, C, Zhao, X.
      Pages: 413 - 419
      Abstract: Thermal expansion behavior of polyimide (PI) films based on benzoxazole containing diamine, 5,4'-diamino-2-phenyl benzoxazole (DAPBO), was investigated systematically. Effects of preparation parameters on the values of in-plane coefficient of thermal expansion (in-plane CTE) were studied from the viewpoint of film thicknesses, curing rates, and substrates. It was found that the in-plane CTE values increased as a function of film thicknesses and curing rates, this pattern was also applicable to PI based on DAPBO and pyromellitic dianhydride (PMDA), which showed negative in-plane CTE value. The influence of preparation parameters on in-plane CTEs was interpreted by the effect of residual solvent. Thermogravimetric and dynamic mechanical analyses were used to study the curing process of poly(amic) acid films with various amounts of residual solvent and further to illustrate the effect of residual solvent on in-plane CTE values. In-plane and out-of-plane CTE of PI film based on DAPBO and 3,3',4,4'-oxydiphthalic dianhydride (ODPA) were directly measured using thermomechanical analysis instrument, and the values were 22.5 and 62.3 ppm K-1, respectively, indicating the orientation character of PI chains along the film plane direction.
      PubDate: 2014-05-18T22:45:06-07:00
      DOI: 10.1177/0954008313517250|hwp:master-id:sphip;0954008313517250
      Issue No: Vol. 26, No. 4 (2014)
       
  • Synthesis and characterisation of new sulphur-containing epoxy networks
    • Authors: Vogel, W; Dingemans, T. J, Varley, R. J, Tian, W, Dao, B, Tucker, S. J, Christensen, S.
      Pages: 420 - 435
      Abstract: The position of sulphur within a cured epoxy amine network and its impact upon the thermal, mechanical, chemical and physical properties has been investigated in this study. Sulphur-containing epoxy resins, diglycidyl thioether of bisphenol A (DGTEBA) and diglycidyl ether of dithio diphenyl (DGTED) have been synthesised, cured and characterised and then compared with the benchmark epoxy resin, diglycidyl ether of bisphenol A (DGEBA). DGTEBA has two sulphur atoms located terminally to the epoxide groups, whilst DGTED has a sulphur atom located centrally between two phenyl groups. Evaluation of the properties and cure mechanism using 4,4'-diamino diphenyl sulphone (4,4'-DDS) as the hardener showed that when the sulphur was terminally located, the glass transition temperature, cure conversion, thermal stability, yield strain and stress decrease substantially, whilst the rate of cure and methyl ethyl ketone (MEK) ingress was comparatively higher. Near-infrared spectroscopy revealed that a competing hydrogen abstraction reaction mechanism deactivated the epoxide ring to nucleophilic attack to produce a heterogeneous network and poorer properties. In contrast, the properties and network structure of the DGTED-cured network, which had sulphur placed centrally between the diphenyl groups were similar to DGEBA except that MEK fluid ingress was reduced. The DGTEBA epoxy was also cured with other amines of varying reactivity to reveal that the hydrogen abstraction mechanism was dependent upon the reactivity of the hardener. Less reactive hardeners were dominated by the hydrogen abstraction mechanism, whilst the more reactive amines displayed a step-growth mechanism more typically associated with epoxy amine cure.
      PubDate: 2014-05-18T22:45:06-07:00
      DOI: 10.1177/0954008313518083|hwp:master-id:sphip;0954008313518083
      Issue No: Vol. 26, No. 4 (2014)
       
  • Synthesis and characterization of para- and meta-polybenzimidazoles for
           high-temperature proton exchange membrane fuel cells
    • Authors: Malinowski, M; Iwan, A, Paściak, G, Parafiniuk, K, Gorecki, L.
      Pages: 436 - 444
      Abstract: In this article, two polybenzimidazoles (PBIs) were synthesized by the polycondensation reaction of 3,3'-diaminobenzidine with terephthalic acid (p-PBI) or isophthalic acid (m-PBI) for application in high-temperature proton exchange membrane fuel cells. Two kinds of purification (P1, P2) were applied to clean the polymers. The chemical structure of PBI polymers was confirmed using Fourier transform infrared (FTIR) spectroscopy. Polymers after P1 can be soluble and cast into film only from hot sulfuric acid solution (H2SO4), whereas both polymers after P2 were soluble in dimethylacetamide solution. Polymer films cast from H2SO4 were investigated using FTIR. The thermal stabilities of PBIs and PBI films were studied using the thermogravimetric analysis and the first derivative of the TG method. The temperature of 5% weight loss (T 5%) for both PBIs ranges from 136 to 312°C under nitrogen atmosphere, depending on the dicarboxylic acid used and the kind of purification. The PBI films exhibited T 5% at 55°C because of the protonation of nitrogen atom in PBI by hydrogen atom of hydroxyl group in H2SO4. Electrical behavior of the two polymers was tested using electrochemical impedance spectroscopy for gold (Au)/PBI/Au architecture. For both measured polymers, Nyquist plots are presented with fittings based on circuit models.
      PubDate: 2014-05-18T22:45:06-07:00
      DOI: 10.1177/0954008313517909|hwp:master-id:sphip;0954008313517909
      Issue No: Vol. 26, No. 4 (2014)
       
  • Thermal stability and combustion behavior of flame-retardant polypropylene
           with thermoplastic polyurethane-microencapsulated ammonium polyphosphate
    • Authors: Chen, M; Xu, Y, Chen, X, Ma, Y, He, W, Yu, J, Zhang, Z.
      Pages: 445 - 454
      Abstract: In this article, thermoplastic polyurethane-microencapsulated ammonium polyphosphate (MTAPP) is prepared and well characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis (TGA). MTAPP and APP are added onto polypropylene (PP) as a novel intumescent flame-retardant system to improve the flame retardancy of PP. The flammability, thermal stability, and mechanical properties of the flame-retardant PP composites are investigated by limiting oxygen index (LOI), UL-94 vertical burning test, cone calorimeter test (CCT), TGA, and mechanical properties tests. The results show that MTAPP exhibits better flame retardancy and thermal stability than that of the APP in the flame-retardant PP composites. The LOI value of the PP/MTAPP composite at the same loading level is higher than that of PP/APP composite. The dripping of MTAPP system disappears compared with APP system from UL-94 test. The results of the CCT also indicate that MTAPP is an effective flame retardant in PP. The improvement may be attributed to the better charring capacity of MTAPP from TGA. Additionally, the mechanical properties of MTAPP are better than those of APP in PP.
      PubDate: 2014-05-18T22:45:06-07:00
      DOI: 10.1177/0954008313517910|hwp:master-id:sphip;0954008313517910
      Issue No: Vol. 26, No. 4 (2014)
       
  • Synthesis and characterization of novel polyimides derived from
           3,6-bis(4-aminophenoxy)pyridazine
    • Authors: Guan, Y; Wang, D, Song, G, Zhang, X, Chen, C, Zhou, H, Dang, G, Zhao, X.
      Pages: 455 - 462
      Abstract: Pyridazine-containing aromatic diamine monomer, 3,6-bis(4-aminophenoxy)pyridazine (APPD), was successfully synthesized by a nucleophilic substitution reaction of 3,6-dichloropyridazine with para-aminophenol. The aromatic heterocyclic diamine was employed to synthesize a series of polyimides (PIs) by polycondensation with various commercially available aromatic dianhydrides in N,N-dimethylacetamide via the conventional two-step method and further thermal imidization forming polyimides. The inherent viscosities of the resulting poly (amic acid)s were in the range of 0.47–1.51 dL g–1. Meanwhile, strong and flexible PI films were obtained, which had good thermal resistance, with the glass transition temperatures of 214–305°C and the temperature at 5% weight loss of 421–463°C under nitrogen atmosphere, as well as outstanding mechanical properties with tensile strengths of 61–102 MPa and elongations at break of 2.8–64.7%. The cutoff wavelength of the PI films were ranged in 357–413 nm.
      PubDate: 2014-05-18T22:45:07-07:00
      DOI: 10.1177/0954008313518566|hwp:master-id:sphip;0954008313518566
      Issue No: Vol. 26, No. 4 (2014)
       
  • Synthesis and properties of cross-linkable polysiloxane via incorporating
           benzocyclobutene
    • Authors: Yang, L; Cao, K, Huang, Y, Chang, G, Zhu, F, Yang, J.
      Pages: 463 - 469
      Abstract: Benzocyclobutene (BCB), as a reactive group, was incorporated into the side chains of polysiloxane via platinum/carbon hydrosilylation reaction. The hydrosilylation reaction showed good tunability for the incorporation ratio of BCB pendant groups. Differential scanning calorimetry results revealed that upon heating the BCB-containing polysiloxanes, great exothermic reaction occurred via [4+2] cycloaddtion reaction involving vinyl and BCB. The onset decomposition temperature (T donset) of the BCB-siloxane resins reaches 518°C. This high T d demonstrates an excellent thermal resistance. The high-temperature performance of the resulting polymers illustrates the power of benzocyclobutene pendant groups in the design and preparation of potential high-performance silicon resins.
      PubDate: 2014-05-18T22:45:07-07:00
      DOI: 10.1177/0954008313518567|hwp:master-id:sphip;0954008313518567
      Issue No: Vol. 26, No. 4 (2014)
       
  • Chain microstructure of soluble copolyimides containing moieties of
           aliphatic and aromatic diamines and aromatic dianhydrides prepared in
           molten benzoic acid
    • Authors: Batuashvili, M. R; Tsegelskya, A. Y, Perov, N. S, Semenova, G. K, Abramov, I. G, Kuznetsov, A. A.
      Pages: 470 - 476
      Abstract: Two series of high-molecular-weight copolyimides CPI-1 and CPI-2 containing five-membered imide cycles have been prepared by high-temperature polycondensation in molten benzoic acid (BA) at 140°C from a pair of aromatic/aliphatic diamines (9,9-bis(4-amino)fluorene (AFL) and 1,12-dodecamethylene diamine (DDA)) and one dianhydride (4,4'-oxydiphthalic anhydride (in CPI-1 series) or (1,3-phenylene)-bis(4-oxyphtalic anhydride) (in CPI-2 series)) using different order of the components loading. The diamines moiety distribution in chain was analyzed by means of high resolution carbon nuclear magnetic resonance. It is found that CPI-1 and CPI-2 samples prepared using one-shot comonomers/intermonomer loading have random moieties distribution, whereas the samples prepared using stepwise addition of dianhydride to the mixture of two diamines have multiblock (MB) chain microstructure. Thus, despite complicated scheme of CPIs synthesis in molten BA including several reactions, the process as a whole displays a feature typical for ideal one-stage interbipolycondensation of symmetrical components with independent groups. The average block length increases when DDA and dianhydride are added together slowly to AFL solution in molten BA. The phase morphology of CPI-2 was studied by means of differential scanning calorimeter. The data obtained demonstrate symptoms of microphase separation in nascent powders of MB CPI-2.
      PubDate: 2014-05-18T22:45:07-07:00
      DOI: 10.1177/0954008313518950|hwp:master-id:sphip;0954008313518950
      Issue No: Vol. 26, No. 4 (2014)
       
  • Synthesis and characterization of high refractive epoxy prepolymers with
           different molecular structures
    • Authors: Luo, C; Zuo, J, Yuan, Y, Zhao, J.
      Pages: 477 - 482
      Abstract: Three kinds of epoxy prepolymers with high refractive index, diglycidyl ether of thiodibenzenethiol (DGETDBT), diglycidyl ether of thiobis-phenol (DGETP), and diglycidyl ether of oxydiphenol, were synthesized via a two-step method, and the relationship between the chemical structure and refractive index of epoxy prepolymer was discussed. Their chemical structures were characterized using Fourier transform infrared (FTIR) spectrometer and proton nuclear magnetic resonance spectrometer. The curing behavior of all the epoxy prepolymers cured with methylhexahydrophthalic anhydride (MHHPA) was studied using differential scanning calorimetry and was compared with that of diglycidyl ether of bisphenol A (DGEBA). Thermal and optical properties of these cured epoxy resins were investigated using thermogravimetric analyses, ultaviolet–visible scanning spectrophotometer, and Abbe refractometer, respectively. The results showed that three kinds of epoxy prepolymers had the similar thermal property and curing behavior. The sulfur atoms in DGETDBT and DGETP had contributed to an obvious increase in their refractive indexes, while the methyl group in DGEBA cut down its refractive index. The DGETDBT has the biggest refractive index (1.665), followed by the DGETP with 1.612. But the high cost and the lower thermal decomposition temperature of cured DGETDBT/MHHPA resin will limit its application. The refractive index of cured DGETP/MHHPA resin, with preferable thermal stability and acceptable price, is 1.595, which is higher than that of DGEBA/MHHPA resin (1.568). Therefore, DGETP resin can be expected to be a kind of the more effective encapsulant to light-emitting diode.
      PubDate: 2014-05-18T22:45:07-07:00
      DOI: 10.1177/0954008313519277|hwp:master-id:sphip;0954008313519277
      Issue No: Vol. 26, No. 4 (2014)
       
  • High-effective preparation of ultrafine
           poly-(L-lactide-co-isin-caprolactone-diOH) fibers containing silver
           nanoparticles
    • Authors: Liu, M; Song, L, Wang, Y, Cheng, Z, Li, J.
      Pages: 483 - 487
      Abstract: A novel method utilizing combination of N, N-dimethylformamide (DMF) and ultraviolet (UV) irradiation to reduce silver (Ag+) ions in situ in ultrafine poly-(l-lactide-co- -caprolactone-diOH) (PCLA) fibers was developed. Compared with traditional solvent reduction method, the new method exhibited much higher efficiency. UV–visible spectra indicated that the addition of UV irradiation could shorten the reaction time dramatically. Transmission electron microscope and x-ray photoelectron spectroscopy results demonstrated that the new method had produced a larger number of uniform Ag nanoparticles (AgNPs). After statistical analysis, their mean size was determined as 6.96 nm, which was smaller than that of traditional AgNPs. In addition, as a biodegradable polymer, PCLA was first used to carry AgNPs. It was found that PCLA can be a stabilizing agent of Ag+ ions. Therefore, the formation mechanism of AgNPs with larger number and smaller size can be determined.
      PubDate: 2014-05-18T22:45:07-07:00
      DOI: 10.1177/0954008313520333|hwp:master-id:sphip;0954008313520333
      Issue No: Vol. 26, No. 4 (2014)
       
  • Highly cross-linked poly(styrene sulfonic acid)-grafted
           poly(tetrafluoroethylene-co-perfluoropropyl vinyl ether) membranes with
           various thicknesses and their application to direct methanol fuel cell
    • Authors: Shin, J; Kang, S.-A, Choi, J, Sohn, J.-Y, Kim, C.-Y.
      Pages: 488 - 495
      Abstract: Highly cross-linked poly(styrene sulfonic acid)-grafted poly(tetrafluoroethylene-co-perfluoropropyl vinyl ether) (PFA-g-PSSA) membranes with various thicknesses have been successfully prepared through the simultaneous irradiation grafting of styrene/divinylbenzene (DVB) onto PFA films with thicknesses of 25, 50, and 100 μm followed by sulfonation to introduce sulfonic acid moiety. It was observed that a concentrated chlorosulfonic acid solution and a high reaction temperature are needed to provide sufficient sulfonic acid as the thickness of the PFA films and the content of DVB both increase. The physicochemical properties of the prepared membranes such as water uptake, proton conductivity, methanol permeability, and chemical stability, were also investigated in this study.
      PubDate: 2014-05-18T22:45:07-07:00
      DOI: 10.1177/0954008313520334|hwp:master-id:sphip;0954008313520334
      Issue No: Vol. 26, No. 4 (2014)
       
 
 
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