JournalTOCs

Chinese Journal of Polymer Science
Journal Prestige (SJR): 0.506

Citation Impact (citeScore): 2
Number of Followers: 9

Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0256-7679 - ISSN (Online) 1439-6203
Published by Springer-Verlag

[2469 journals]

The Effect of Substrate on the Properties of Non-volatile Ferroelectric
P(VDF-TrFE)/P3HT Memory Devices
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Ferroelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE))/semiconducting poly(3-hexyl thiophene) (P3HT) blend systems have drawn great attention with their potential use for electronic applications, particularly non-volatile memory devices. It is essential to grasp a full understanding of the crystallization habits of the two polymers on different substrates for purposeful control of the structures of the blend and therefore the properties of the devices. Here, the effects of structure and morphology of the blend films generated at different substrate surfaces on the ferroelectric and switching properties of related devices are reported. It is identified that P(VDF-TrFE)/P3HT blend films prepared on graphene substrate show not only an obvious optimization in the ferroelectric behavior of P(VDF-TrFE), but also an enhancement of the charge transport within P3HT domains. By employing sandwich structure constructed by silver electrode and P3HT/P(VDF-TrFE) blend film on graphene substrate, high-performance ferroelectric memory devices have been obtained, which exhibit a great electrical switching behavior with high ON/OFF ratio of about 1000 and low coercive voltage of approximately 5 V. These findings provide useful guidance for fabricating high-performance ferroelectric memory devices.
  PubDate: 2022-05-05
Experimental and Data Fitting Guidelines for the Determination of Polymer
Crystallization Kinetics
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: The crystallization kinetics of semicrystalline polymers is often studied with isothermal experiments and analyzed by fitting the data with analytical expressions of the Avrami and Lauritzen and Hoffman (LH) theories. To correctly carry out the analysis, precautions in both experiments and data fitting should be taken. Here, we systematically discussed the factors that influence the validity of the crystallization kinetics study. The basic concepts and fundamentals of the Avrami and LH theories were introduced at first. Then, experimental protocols were discussed in detail. To clarify the impact of various experimental parameters, selected common polymers, i.e., polypropylene and polylactide, were studied using various experimental techniques (i.e., differential scanning calorimetry and polarized light optical microscopy). Common mistakes were simulated under conditions when non-ideal experimental parameters were applied. Furthermore, from a practical point of view, we show how to fit the experimental data to the Avrami and the LH theories, using an Origin® App developed by us.
  PubDate: 2022-05-05
Facile and One-step Direct Synthesis of Poly(valine) as a Robust Drug
Nanocarrier for Enhanced Breast Cancer Therapy
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Synthetic poly(amino acid)s with good biodegradable and biocompatible properties have attracted increased attention as carriers in biomedical applications in recent years, their synthesis and purification procedures are usually complicated and some by-products would occur yet. Given this, polypeptide with good biodegradable and biocompatible properties is prepared and optimized by one-step and direct synthesis strategy and poly(valine) (PVal) is selected here as a model polypeptide in this study. This newly generated PVal can self-assemble into poly(valine) nanoparticles (PVal-NPs) with a high drug-loading capacity (>20 wt%) of doxorubicin (DOX) and shows strong cytotoxicity against 4T1 cells. Upon cellular internalization, the release of DOX could be accelerated by the endosomal acidic environment which leads to enhanced anticancer effects. The results in vivo show that DOX@PVal-NPs have a long blood circulation time, high cancer accumulation and penetration, and good therapeutic performance in 4T1 tumor-bearing mice without causing obvious adverse effect on main organs. With these combined advantages, these PVal-based nanoplatform would provide an effective drug delivery tool for clinical breast cancer therapy.
  PubDate: 2022-05-05
Biodegradable Polymers, History Tells Polymer Science’s Fortune
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  PubDate: 2022-05-01
Based on the Second Virial Coefficient (A2) to Study Effect of the
Synergistic Action of Solvent and External Electric Field on the Solution
Behavior and Film’s Condensed State Structure
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: The solventnatures are crucial to deeply reveal solution behavior of macromolecular chains, physical essence of condensed state structures formation of the film as well as the photoelectronic devices performance. Based on the second virial coefficient (A2), effect of the synergistic action of solvents and external electric field on both solution behavior and the film’s condensed state structure for the semi-rigid conjugated polymer, poly[2-methoxy-5-(2′-ethylhexoxy)-1,4-phenylvinylene] (MEH-PPV) was investigated by dynamic/static light scattering, photoluminescence spectroscopy and transmission electron microscopy, etc. It was found that although the MEH-PPV solutions with different solvents (toluene, chlorobenzene, chloroform and tetrahydrofuran) all could generate a response to the external electric field, the degree of response varied significantly with the change of solvent nature. Furthermore, ordered degree of the film from the solutions was also obviously different. The essential reason for this responsive difference was firstly revealed in the research, which actually depended on the degree of interaction between the solute and solvent, and this degree of interaction could be quantitatively described by the second virial coefficient (A2). The bigger the A2, the stronger the interaction between solvent and solute in the solution, and the stronger the response to the external electric field. Further, under the induction of external electric field, chains aggregations with different sizes were formed accompanied by large-scale chains ordered structure in the solution. This ordered structure not only can effectively transfer to film prepared by the precursor solution but also is beneficial to enhance the carrier mobility and device efficiency of the photoelectronic film.
  PubDate: 2022-05-01
Fiber Bending Flexibility Evaluation by Worm-like Chain Model
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: A new method for characterizing fiber bending flexibility was developed by worm-like chain model proposed by Kratky-Porod,[1] which was first introduced to the pulp and paper field in this study. For the three types of pulps, the experimental results were compared with the KP chain model, and the resulting determination coefficients were all above 0.95, which proved that the model was feasible to be applied to these three fibers. The relation between fiber bending rigidity and that of cellulosic chains inside was discussed to deduce the fiber bending flexibility. The flexibility of an individual fiber can be approximated as the contribution of that of all the cellulose chains inside. By this method, the fiber flexibility values were determined to be in the range of 0.6×1011−3.5×1011 N−1·m−2, which was comparable to that of the conventional methods recorded in the literature.
  PubDate: 2022-05-01
Fully Chemical Recyclable Poly(γ-butyrolactone)-based Copolymers with
Tunable Structures and Properties
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: The emerging chemical recyclable polymers, such as poly(γ-butyrolactone) (PGBL) and poly((R)-3,4-trans six-membered ring-fused GBL) (P((R)-M)), provide a good solution to the plastic pollution. However, these homopolymers suffer from limited structures and properties. Herein, we reported a fully chemical recyclable copolymer P(GBL-co-((R)-M)) through ring-opening copolymerization (ROCOP) of GBL and (R)-M. By employing organomagnesium as the catalyst and regulating the reaction conditions, the chemical structures of copolymers were well-controlled (GBL content=13%–78%, Mn=6560–15600 g/mol, ÐM=1.08–1.59). The resultant P(GBL-co-((R)-M)) exhibited fully chemical recyclability, which rapidly and quantitatively depolymerized into initial GBL and (R)-M monomer through chemolysis. By varying GBL content, tunable thermal properties were achieved for P(GBL-co-((R)-M)). The onset decomposition temperatures of copolymers varied from 193 °C to 234 °C. A linear evolution of glass transition temperature (Tg) of P(GBL-co-((R)-M)) versus GBL content was obtained as following equation of Tg = −1.06 × GBL mol% × 100 + 39.6. We hope that the reported fully chemical recyclable copolymers with tunable structures and properties would serve as the candidate material for sustainable applications.
  PubDate: 2022-05-01
Detection of the Destruction Mechanism of Perfluorinated Elastomer (FFKM)
Network under Thermo-oxidative Aging Conditions
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: The changes of crosslinking network of perfluorinated elastomer (FFKM) cured by TAIC and DBPH under thermo-oxidative aging conditions were investigated. Two competitive processes including post-curing and network destruction occur simultaneously, which directly affect the storage modulus and crosslinking density. With the increase of aging temperature, the network destruction becomes dominant. FTIR and XPS characterizations further reveal that the network destruction happens preferentially on the crosslink points of TAIC structure, and the post-curing is mainly caused by the decomposition of residual curing agent DBPH. Unlike the easier breaking of TAIC structure in the crosslinking network, both the backbone and the pendent groups of FFKM itself are much more stable. To further figure out the destruction mechanism, TGA-FTIR-GC-MS test was also conducted and a schematic degradation process of TAIC structure was proposed. It is found that the destruction of TAIC crosslinking points happens first on the unstable exocyclic C-N bonds and the intermediate ring radicals could eventually decompose into volatile hydrogen isocyanate (HCNO) under extreme condition.
  PubDate: 2022-05-01
Helical Nonfouling Polypeptides for Biomedical Applications
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Synthetic polypeptides, also known as poly(α-amino acid)s (PαAAs), are biomimetic and biodegradable polymers holding great potential for a variety of biomedical applications. Possessing the same peptide bonds as natural proteins, polypeptides can also adopt typical well-defined secondary structures including α-helix, which have been shown to significantly impact the physicochemical properties and biological outcomes of materials. In this feature article, we review the state-of-the-art progresses of α-helical polypeptides for biomedical applications, with a special emphasis on the manipulation of helix-to-coil dynamic transition, conformation-associated anti-biofouling coatings, cellular uptake regulation, and reducing immunogenicity of polypeptide-protein conjugates. Finally, perspectives on outstanding challenges remained in this field and some important future directions are discussed.
  PubDate: 2022-05-01
Implantable Polyurethane Scaffolds Loading with PEG-Paclitaxel Conjugates
for the Treatment of Glioblastoma Multiforme
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Improvement of the treatment for Glioblastoma multiforme (GBM) especially the development of in situ controllable drug release is still a major concern. In this study, we developed waterborne biodegradable polyurethane (WBPU) scaffolds incorporated with redox-sensitive and RGD-decorated paclitaxel (PTX) polymer-drug conjugates (PDCs) for targeted GBM therapy in situ. The drug scaffolds could be implanted at residual GBM site post-operation. Dual-targeting PTX-PDCs were obtained through step-by-step conjugation of disulfide linked PTX, poly(ethylene glycol) (PEG), and arginine-glycine-aspartic acid (RGD). The RGD-modified PTX-PDCs were spherical nanoparticles (NPs) that would be released from scaffolds and identified GBM cells actively. Internalized redox-sensitive PTX-PDCs would be decomposed and release PTX inside GBM cells under the circumstances of glutathione (GSH). The release profiles of PTX from the scaffolds with/without GSH were investigated. In vitro cytotoxicity assay revealed that the dual-targeting PTX-PDCs from scaffolds could specifically kill GBM cells and protect normal cells, suggesting that dual-targeting PTX-PDC-loaded scaffolds may have the potential to repair tumor-induced brain injury. In vivo anti-recurrence assay indicated that the PTX-PDC-scaffolds could deliver PTX-PDCs to the GBM cells followed by inhibiting tumor growth and inducing apoptosis. In general, the PTX prodrug-loaded devices exhibited significant anti-GBM effects and normal tissue protection simultaneously, indicating that the WBPU scaffolds incorporated with dual-targeting PTX-PDCs may be a promising strategy for local therapy of GBM.
  PubDate: 2022-05-01
Architecting Branch Structure in Terpolymer of CO2, Propylene Oxide and
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Poly(propylene carbonate phthalate) (PPC-P) is a chemically modified poly(propylene carbonate) (PPC) biodegradable thermoplastic by introducing phthalic anhydride (PA) as the third monomer into the copolymerization of propylene oxide (PO) and CO2. To enhance the thermal and mechanical properties of PPC-P, a branching agent pyromellitic anhydride (PMDA) was introduced into the terpolymerization of PO, PA and CO2. The resulting copolymers with branched structure, named branched PPC-P, can be obtained using metal-free Lewis pair consisting of triethyl borane (TEB) and bis(triphenylphosphine)iminium chloride (PPNCl) as catalyst. The products obtained were analyzed by NMR spectroscopy and their thermal, mechanical properties and melt processability were evaluated by DSC, TGA, tensile test and melt flow index (MFI) measurement. The obtained branched PPC-P has a high molecular weight up to 156.0 kg·mol−1. It shows an increased glass transition temperature (Tg) higher than 50 °C and an enhanced tensile strength as high as 38.9 MPa. Noteworthily, the MFI value decreases obviously, indicative of an improved melt strength arising from the branched structure and high molecular weight. What is more, the branched PPC-P exhibits reasonable biodegradability, which demonstrates the great potential as a new green thermoplastic for the family of biodegradable plastics.
  PubDate: 2022-05-01
Simultaneously Improved Dielectric Constant and Breakdown Strength of
PVDF-based Composites with Polypyrrole Nanowire Encapsuled Molybdenum
Disulfide Nanosheets
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: High-performance dielectric polymer composites have received increasing attention due to their important applications in the field of energy storage. The rational structural design of hybrid fillers can lead to a balance between high dielectric constant and insulation in composites. In this work, novel hybrid fillers were fabricated by in situ synthesizing one-dimensional polypyrrole nanowires (PPynws) on the two-dimensional molybdenum disulfide (MoS2), which integrated the good ion polarization ability of PPynws and the high insulation and adjustable band gap of MoS2. Compared with the binary poly(vinylidene fluoride) (PVDF)/MoS2 composites, the PVDF/MoS2-PPynws composites exhibited remarkably improved dielectric constant and breakdown strength, while the dielectric loss was still maintained at a low level. An optimal ternary composite with 1 wt% MoS2-PPynws showed a high dielectric constant (15@1kHz), suppressed dielectric loss (0.027@1kHz), and high breakdown strength (422.1 MV/m). PPynws inducing strong interfacial polarization and the highly insulated MoS2 nanosheets extending the breakdown path mainly contributed to the synchronously enhanced dielectric constant and breakdown strength. This intriguing synthesis method of PVDF/MoS2-PPynws nanocomposite will open up new opportunities for fabricating nanostructured polymer composites to produce high dielectric materials.
  PubDate: 2022-05-01
Precise Pentamers with Diverse Monomer Sequences and Their Thermal
Properties
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Sequenced-defined oligomer has been emerged as one of the hot topics in polymer chemistry due to its capability of precisely controlling both chain length and monomer sequence. Recent efforts have focused on development of synthetic methodologies using state-of-the-art chemistry tools. However, investigating the impact of minor changes in monomer sequence on physical properties of these materials is still underdeveloped. Herein, four sequenced pentamers are synthesized by a reversible addition-fragmentation chain transfer (RAFT) single unit monomer insertion technique, in which a base pentamer possesses a relatively rigid backbone comprising of five cyclic monomer units. One of the cyclic units in this base pentamer is replaced by an acyclic monomer at different locations (the 1st, 3rd and 5th unit) to produce three modified pentamers, which leads to a significant decrease of glass transition temperature (Tg) compared to the base pentamer. Meanwhile, the modified pentamers with identical primary structures but distinct monomer sequences also present different Tg values depending on the position of the acyclic monomer unit. The middle (3rd) position of the acyclic unit causes profound decrease of Tg due to its increased molecular flexibility. These synthetic pentamers have been demonstrated to be excellent oligomeric plasticizers to modulate thermal transitions of bulk polymer materials.
  PubDate: 2022-05-01
Effect of Solvent Viscosity on the Driven Translocation of Charged
Polymers through Nanopores
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: The effect of viscosity of non-translocated (cis) side, ηcis, on the driven translocation of charged polymers through nanopores is investigated using Langevin dynamics simulation. Results show that the translocation of polymer chains can be regulated by changing ηcis. As ηcis decreases, the translocation time τ decreases, and the exponent δ in the scaling relation with driving force f, τ⋃f−δ, increases whereas α in the scaling relation with chain length N, τ⋃Nα, decreases. Simultaneously, the conformation of the polymer chain at the cis side gravitates towards an equilibrium state. The results imply a relationship between the translocation and the conformation of polymer chains. To verify this hypothesis, we change the conformation of polymer by artificially relaxing the translocating polymer via adding an additional relaxation time in the simulation. A sufficient large additional relaxation time for the translocating polymer chain at the cis side only or at both cis and trans sides results in exponents α and δ both close to 1, in contrast to α=1.36 and δ=0.8 for the translocation without the additional relaxation. The additional relaxation for the polymer chain at the cis side accelerates the translocation and plays a more important role than that for polymer chain at the trans side.
  PubDate: 2022-05-01
Influence of Backbone and Axial Substituent of Catalyst on α-Imino-ketone
Nickel Mediated Ethylene (Co)Polymerization
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: The α-imino-ketone nickel catalyst is an emerging versatile platform that is easy to prepare and allows for the production of branched high molecular weight functionalized polyethylenes. However, study on this catalyst system is rare thus far. In this contribution, by introducing different backbones, flexible and rigid axial substituents into the α-imino-ketone framework, a family of cationic nickel catalysts were synthesized and fully characterized. Without the addition of any activator, systematic studies on ethylene polymerization and copolymerization with polar monomers were performed to explore the influence of both backbone and axial substituent on catalytic activity, polymer molecular weight, branching density and incorporation. In particular, owing to the unique semi-opening feature of the α-imino-ketone framework, the preferred nickel catalyst exhibited high activity of 175 kg·mol−1·h−1 to produce functionalized polyethylene with molecular weight of 13.4 kg·mol−1 and comonomer incorporation of 2.9 mol%.
  PubDate: 2022-05-01
Polymer Features in Crystallization
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: This review firstly gives an overview on the importance of crystallization in natural and synthetic polymers/macromolecules. Then it introduces the typical features that have been raised by chain-like macromolecules in crystallization, including anisotropic interactions in the thermodynamic driving forces, chain folding in the crystal morphologies, chemical confinement in the copolymer crystallization, and mechanical enhancement in the stretching processes. Four features separately cover the thermodynamics and the kinetics of polymer crystallization, as well as the crystallinity and the mechanical properties of semicrystalline polymers. The review ends up with how these features enhance specific functions of crystalline polymers, which demonstrates polymer crystallization as a challenging yet promising field in the future.
  PubDate: 2022-04-29
Halogen-free Polymer Donors Based on 3,4-Dicyanothiophene for
High-performance Polymer Solar Cells
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Abstract Polymer solar cells (PSCs) consisting of a polymer donor and a small molecular acceptor is a promising photovoltaic technology, whose device performance is determined by both polymer donor and small molecular acceptor. Halogen atoms such as fluorine or chlorine atoms were usually introduced onto the polymer donors to downshift the highest occupied molecular orbital (HOMO) energy levels and improve the open-circuit voltage (VOC) of the PSCs. However, the introduction of the halogen atoms especially fluorine atoms greatly complicates the polymer synthesis. Herein, we report the use of a structural simple and easily synthesized building block, 3,4-dicyanothiophene (DCT), to construct a set of halogen-free polymer donors PBCNTx (x=25, 50, 75) via ternary random copolymerization. The introduction of DCT units not only simplified the synthesis, but also downshifted the HOMO energy levels of the polymers and improved the VOC of PSCs effectively. Encouragingly, the PBCNT75 afforded a power conversion efficiency up to 15.7% with a VOC of 0.83 V, which are among the top values for halogen-free polymer donors. This work shows that the introduction of DCT units is a simple yet effective strategy to construct halogen-free and low-cost polymer donors for high-performance PSCs.
  PubDate: 2022-04-27
Dual Effects of Interfacial Interaction and Geometric Constraints on
Structural Formation of Poly(butylene terephthalate) Nanorods
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Abstract When the size of the material is smaller than the size of the molecular chain, new nanostructures can be formed by crystallizing polymers in nanoporous alumina. However, the effect of pore wall and geometric constraints on polymer nanostructures remains unclear. In this study, we demonstrate three new restricted nanostructures {upright-, flat- and tilting-ring} in polybutylene terephthalate (PBT) nanorods prepared from nanoporous alumina. The dual effects of geometrical constraints and interfacial interactions on the formation of PBT nanostructures were investigated for the first time by using X-ray diffraction and Cerius2 modeling packages. Under weak constraints, the interaction between pore wall and the PBT rings is dominant and the ring plane tends to be parallel to the pore wall and radiate outward to grow the upright-ring crystals. Surprisingly, in strong 2D confinement, a structural formation reversal occurs and geometrical constraints overpower the effect of pore wall. Rings tend to pile up vertically or obliquely along the long axis of the rod, so the flat- and tilting-ring crystals are predominate in the constrained system. In principle, our study of the nanostructure formation based on the geometrical constraints and the pore wall interfacial effects could provide a new route to manipulate the chain assembly at the nanoscale, further improving the performance of polymer nanomaterial.
  PubDate: 2022-04-27
A Novel Ternary Composite of Polyurethane/Polyaniline/Nanosilica with
Antistatic Property and Excellent Mechanical Strength: Preparation and
Mechanism
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Abstract Antistatic and strength properties are of vital importance for polyurethane rubber used in moving parts of many industrial instruments. Herein, polyurethane was composited with polyaniline and nanosilica based on in situ synthesis of polymer and physical mixing of these fillers to reach desired antistatic and mechanical properties. Chemical, morphological and thermal properties of the polyurethane/polyaniline/nanosilica composites were studied. The electrical resistivity of the composite decreased from 1.1×106 MΩ to 7.6×104 MΩ as a result of the addition of 4% polyaniline. The tensile strength and elongation at break of the polyurethane composites improved by nearly 300% and 100%, respectively, when compared with those of the neat polyurethane. The electronic resistance of PU/PANI/NS ternary is low enough for its antistatic property and decreases with the increase of the added nanosilica, which is unexpectedly and rather significant. Our results would shed light on the development of antistatic PU with excellent mechanical performance.
  PubDate: 2022-04-27
Shear-induced Precursors of Fibrillar Crystals of Poly(butene-1): A
Rheological Study
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Abstract Strong preshear flow stretches poly(butene-1) chains to form flow-induced precursors of fibrillar crystals. The formation leads to further growth of shear/normal stress after the stress reaches the steady state. In this study, stress relaxation measurements are performed after intervals of a strong flow during which the precursors form. The small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) measurements are conducted to characterize the crystalline structure formed after the preshear and relaxation processes, each of different periods. A combination of the stress relaxation and scattering results reveal that for the precursors formed within 5 s, the stress can fully relax and the orientation of the subsequent crystals (formed upon quenching the sample at different stress levels) decays gradually with the relaxation. In comparison, for those precursors formed after 5 s, the stress hardly relaxes during ∼104 s, and the orientation of the subsequent crystals hardly decays, suggesting that the precursors have been somehow stabilized during the shear. These features have been discussed with respect to the percolation of the precursors to form a reversible network.
  PubDate: 2022-04-25