Investigation on crystallization behavior and hydrophilicity of poly(vinylidene fluoride)/poly(methyl methacrylate)/poly(vinyl pyrrolidone) ternary blends by solution casting

Ternary blends composed of matrix polymer poly(vinylidene fluoride) (PVDF) with different proportions of poly(methyl methacrylate) (PMMA)/poly(vinyl pyrrolidone) (PVP) blends were prepared by solution casting. The crystallization behavior and hydrophilicity of ternary blends were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), wide angle X‐ray diffraction (WAXD), differential scanning calorimetry (DSC), and contact angle test. According to morphological analysis, the surface was full of typical spherulitic structure of PVDF and the average diameter was in the order of 3 μm. The samples presented predominantly β phase of PVDF by solution casting. It indicated that the size of surface spherulites and crystalline phase had little change with the PMMA or PVP addition. Moreover, FTIR demonstrated special interactions among the ternary polymers, which led to the shift of the carbonyl stretching absorption band of PVP. On the other hand, the melting, crystallization temperature, and crystallinity of the blends had a little change compared with the neat PVDF in the first heating process. Except for the content of PVP containing 30 wt %, the crystallinity of PVDF decreased remarkably from 64% to 33% and the value of t_1/2 was not obtained. Besides, the hydrophilicity of PVDF was remarkably improved by blending with PMMA/PVP, especially when the content of PVP reached 30 wt %, the water contact angle displayed the lowest value which decreased from 98.8° to 51.0°. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis and reactive features of a terpolymer: Poly(N‐vinyl‐2‐pyrrolidone‐co‐vinyl acetate‐co‐glycidyl methacrylate)

A polyvinyl pyrrolidone terpolymer system is described that can be chemically cross‐linked at moderate, 70–100°C, temperatures. The system has significant potential for development of durable long‐lasting pyrrolidone coatings in a wide range of applications, particularly in water filtration membrane construction where leaching is an unresolved, serious problem. The synthesis of the terpolymer, poly(N‐vinyl‐2‐pyrrolidone‐co‐vinyl acetate‐co‐glycidyl methacrylate), by free radical polymerization is described. The reactive features of this terpolymer are presented in the context of acidic anhydride curing. In a polar aprotic solvent, the terpolymer is reacted with poly(methyl vinyl ether‐co‐maleic acid) and cured thermally. Key aspects of the terpolymer synthesis and the acid anhydride cross‐linking reaction using DSC, rheology, FTIR, and a small molecule model system to study the cross‐linking chemistry are presented. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

煤制乙炔裂解气提浓工艺简介

介绍了高温等离子体裂解煤制乙炔裂解气提浓的工艺流程和运行情况,并根据工艺特性制定了安全预防措施。提浓装置经多次调试后运行稳定,当裂解气中乙炔体积分数为10％时,提浓后的乙炔体积分数可达99％。     

Influence of the Polyvinyl Pyrrolidone Concentration on Particle Size and Dispersion of ZnS Nanoparticles Synthesized by Microwave Irradiation

Zinc sulfide semiconductor nanoparticles were synthesized in an aqueous solution of polyvinyl pyrrolidone via a simple microwave irradiation method. The effect of the polymer concentration and the type of sulfur source on the particle size and dispersion of the final ZnS nanoparticle product was carefully examined. Microwave heating generally occurs by two main mechanisms: dipolar polarization of water and ionic conduction of precursors. The introduction of the polymer affects the heating rate by restriction of the rotational motion of dipole molecules and immobilization of ions. Consequently, our results show that the presence of the polymer strongly affects the nucleation and growth rates of the ZnS nanoparticles and therefore determines the average particle size and the dispersion. Moreover, we found that PVP adsorbed on the surface of the ZnS nanoparticles by interaction of the C–N and C=O with the nanoparticle’s surface, thereby affording protection from agglomeration by steric hindrance. Generally, with increasing PVP concentration, mono-dispersed colloidal solutions were obtained and at the optimal PVP concentration (5%), sufficiently small size and narrow size distributions were obtained from both sodium sulfide and thioacetamide sulfur sources. Finally, the sulfur source directly influences the reaction mechanism and the final particle morphology, as well as the average size.     

ELECTROINDUCED DISPERSIVE POLYMERIZATION OF METHYL METHACRYLATE IN AQUEOUS MEDIA

The electroinduced and chemical dispersion polymerization of methyl methacrylate was performed in aqueous methanol solution (water/methyl alcohol ratio 50/50 by wt%) in the presence of poly(vinyl pyrrolidone) as a stabilizer with ceric sulfate as an initiator. The effects of various polymerization parameters, for example concentrations of recipe ingredients, temperature, potential, and duration, on polymerization yield were examined. In all cases higher yield was obtained with the electrochemical polymerization procedure. Initiation rates of polymerization processes, thermal properties of polymers, interaction of initiator with monomer and stabilizer were investigated in detail. Possible structure of polymer is proposed, and a tentative polymerization mechanism is suggested.     

Investigation on the interpenetrating polymer networks (ipns) of polyvinyl alcohol and poly(N-vinyl pyrrolidone) hydrogel and its in vitro bioassessment

Poly(vinyl alcohol) (PVA) and poly(N-vinyl pyrrolidone) (PVP) composite hydrogel with interpenetrating polymer networks (IPNs) was prepared by in situ polymerization and compared with pure PVA hydrogel. The prepared IPN hydrogel was characterized by infrared spectroscopy (IR), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy. The mechanical property and cell culture were also tested. The results show that PVP can chemically bond with PVA and form uniform blend hydrogel. The content of PVP can affect the structure, crystallinity, glass transition temperature (T_g), and mechanical property of the hydrogel. The T_g of the PVA hydrogel is 2.7°C while the T_g of the IPN hydrogel is −37°C. The IPN hydrogel has lower glass transition temperature, corresponding to better elastic properties, and has better mechanical performance on stretch and compression than PVA hydrogel. The crystallinity (X_c) of PVA hydrogel and IPN hydrogel is 65.3 and 26.3%, respectively. The DMA curves and XPS analysis suggest that PVA and PVP are well miscible on a molecular level in the IPN hydrogel. The cell proliferation trend demonstrates that the addition of PVP has a positive influence on the cell growth and the IPN hydrogel may be used as a promising biomaterial for artificial cartilage substitute. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

交联PVP对茶多酚的吸附作用

采用自制交联PVP处理铁观音茶叶水 ,在交联度为 0 .5 %、用量为 7g/L、30℃下处理 30min时 ,茶多酚的吸附率为 66 83%。分析吸附机理认为 ,交联PVP上的活性吸附中心与茶多酚形成氢键吸附。     

Effect of tacticity of poly(methyl methacrylate) on the miscibility with poly(vinyl pyrrolidone)

Isotactic, atactic, and syndiotactic poly(methyl methacrylates) (PMMA) (designated iPMMA, aPMMA, and sPMMA) with approximately the same molecular weight were mixed separately with poly(vinyl pyrrolidone) (PVP) primarily in chloroform to make three polymer blend systems. Differential scanning calorimetry (DSC) was used to study the miscibility of these blends. The results showed that the tacticity of PMMA has a definite impact on its miscibility with PVP. The aPMMA/PVP and sPMMA/PVP blends were found to be miscible because all the prepared films showed composition-dependent glass-transition temperatures (T_g). The glass-transition temperatures of the aPMMA/PVP blends are equal to or lower than weight average and can be qualitatively described by the Gordon–Taylor equation. The glass-transition temperatures of the other miscible blends (i.e., sPMMA/PVP blends) are mostly higher than weight average and can be approximately fitted by the simplified Kwei equation. The iPMMA/PVP blends were found to be immiscible or partially miscible based on the observation of two glass-transition temperatures. The immiscibility is probably attributable to a stronger interaction among isotactic MMA segments because its ordination and molecular packing contribute to form a rigid domain. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3190–3197, 2001     

环保增塑剂的研究进展

综述了新型环保增塑剂的分类,重点介绍了环己烷二羧酸酯系列、改性植物油系列、多元醇系列等环保增塑剂的合成工艺以及应用性能,最后建议我国环保增塑剂发展方向。     

Fibrous membranes of cellulose acetate and poly(vinyl pyrrolidone) by electrospinning method: Preparation and characterization

Fibrous membranes of cellulose acetate (CA), poly(vinyl pyrrolidone) (PVP) and composite membranes of these polymers, were obtained by the electrospinning method. Using systematic method, the optimal conditions for preparation of fibrous membranes were found. Both CA and PVP a concentration of 8% weight was found. The CA was dissolved in a acetone:water solution, volume ratio 80 : 20 and the PVP is dissolved in ethanol:water solution, ratio volume 85 : 15. The flow rate for both polymers was 1.5 mL h^?1. The same applied voltage value and the distance between the needle and collection plate were for polymer both, 15 kV and 15 cm respectively. The morphology of fibrous membranes and composite membranes were evaluated by scanning electron microscopy (SEM). The CA fibers showed ribon morphology, while the PVP fibers were cilindric, in both cases with diameters in the micrometer range. Thermogravimetric analysis showed that CA had a complete degradation to 445°C, while the fibrous membranes PVP required a value of temperature for degradation of up to 571°C. Fibrous composite membrane PVP/CA/PVP shows a higher value of strain at break (%), and a lower value of tensile strength (MPa) compared to CA/PVP/CA. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010