Specific interactions in blends of poly(ethylene oxide) and poly(bisphenol A-co-epichlorohydrin): FTIR and thermal study

Blends of poly(ethylene oxide) (PEO) of high molecular weight with poly(bisphenol A-co-epichlorohydrin) (PBE) with high epoxy equivalent were studied spectroscopically, thermally and morphologically. As similar systems of low molecular weight, a single T_g was observed for all blends, indicating miscibility. A progressive decrease in the degree of crystallinity and in the size of the PEO spherulites as the PBE is added is also observed. Quantitative analysis from FTIR spectra provided determination of specific interactions between the constituents and their variation with PEO content. Simulations were performed utilising the spectra of the pure polymers to confirm that the observed changes in the experimental spectra of the blends were due to interaction between the polymers.     

微量PEO-PS-PEO/PEO共混体系结晶过程中共聚物胶束的成核作用

本工作将Leibler等近期关于含非晶两嵌段共聚物“稀固体溶液”的胶束理论推广并应用到含结晶三嵌段共聚物的“稀固体溶液”.对微量聚氧化乙烯-聚苯乙烯-聚氧化乙烯三嵌段共聚物/聚氧化乙烯均聚物共混体系的结晶行为进行了研究.结果表明,共聚物胶束在共混体系的结晶过程中可以起到成核剂的作用.这对改善结晶均聚物的性能具有一定的应用价值.     

Crystallization and melting behavior of poly(ethylene oxide)/poly(n-butyl methacrylate) blends

The phase diagram, crystallization and melting behavior of poly(ethylene oxide) (PEO)/poly(n-butyl methacrylate) (PnBMA) blends have been investigated using differential scanning calorimetry and optical microscopy. The results show that the blends are miscible up to 85 °C and show an lower critical solution temperature-type demixing at a higher temperature. The isothermal crystallization studies of the blends indicate a reduction in the overall rate of crystallization. Analysis of isothermal crystallization data by means of Avrami equation leads to average values of the Avrami index of 2.5 for pure PEO and 3.0 for the different blend compositions. The melting behavior of the blends reveals double endotherms, which is ascribed to both secondary crystallization and recrystallization. The melting point depression study yielded χ₁₂=0, indicating a relatively low interaction strength.     

COMPATIBILITY AND PHASE BEHAVIOR OF PS/SBR BLENDS H. TORSIONAL BRAID ANALYSIS

The compatibility and phase behavior of PS/SBR blends was studied with torsional braid analysis technique. The technique used in this study for preparation of braids was first developed by one of the authors, which gives more precise phase diagram as compared to other conventional methods. The results obtained are in good agreement with those obtained in our previous work.     

CROSSLINKING AND COMPATIBILIZATION IN BLENDS OF POLYSTYRENE AND POLYETHYLENE

This paper investigated the influences of butadiene rubber (BR) and dicumylperoxide (DCP) on thermal and rheological behaviour, morphology and mechanical proper-ties of PS/LLDPE/SBS blend. Addition of DCP alone was found to decrease the mechanicalproperties of PS/LLDPE/SBS blend due to the decomposition of PS. When BR was addedtogether with DCP, it is found that the co-crosslinking of BR, SBS and PE takes place,and the decomposition of PS is reduced simultaneously because of the consumption of thefree radicals in the crosslinking process. Synergism was thus realised which resulted in theimprovement of the ductility of blend.     

Novolac/乙烯-醋酸乙烯酯共聚物共混体系中的反应诱导Spinodal相分离

Ｎｏｖｏｌａｃ／乙烯 醋酸乙烯酯共聚物共混体系中的反应诱导Ｓｐｉｎｏｄａｌ相分离陈文杰吴坚江明（复旦大学高分子科学系和国家教委聚合物分子工程实验室上海２００４３３）关键词Ｓｐｉｎｏｄａｌ相分离，共混物，光散射，酚醛树脂，固化反应在高分子多相体系中，...     

Morphology and mechanical properties of poly(ether-imide)-modified polycyanurates

A high temperature thermosetting bisphenol A dicyanate (BADCy) was modified with a novel thermoplastic poly(ether-imide) (PEI) at various compositions. Fourier transform infrared spectroscopy was used to measure the conversion of BADCy. Curing kinetics of the BADCy/PEI blend were studied by the dynamic differential scanning calorimeter method. Morphologies of PEI-modified polycyanurates were investigated by scanning electron microscopy (SEM). It was found that the phase structures of the blends changed dramatically with the PEI content and molecular weight. The tensile results showed that the mechanical properties could be correlated with the morphologies. The blend with cocontinuous morphology had the highest tensile strength and elongation at break while the blend with ribbon-like morphology had the lowest one despite PEI molecular weight.     

Dielectric method for detection of phase separation and its kinetics in TMPC/PS blends

A new method for the detection of phase separation and its kinetics through real-time measurements is presented using the dielectric technique. The kinetics of phase separation were determined for a blend of tetramethyl bisphenol-A polycarbonate TMPC and polystyrene PS at different temperatures. The temperature dependence of the rate constant of phase separation was determined. The activation energy of phase separation process is found to be equal to 46 kcal/mole. In addition, it was possible to determine the variation in the composition of the TMPC-rich phase with time. The results obtained were compared with the literature data and were found to be in good agreement.     

高密度聚乙烯／天然橡胶共混体系的流变性能研究

高密度聚乙烯／天然橡胶共混体系的流变性能研究方征平，许承威（杭州大学化学系杭州３１００２８）关键词高密度聚乙烯，天然橡胶，共混物，流变，改性用橡胶与聚乙烯共混是提高后者的物理机械性能，尤其是耐环境应力开裂性能（ＥＳＣＲ）的主要方法之一“－“．然而，由...     

Studies of the structure of blends containing two liquid crystal polymers

Blends in which both of the component materials are capable of forming liquid crystalline phases are considered in the present work. Solid-state characterization data are presented that suggest that chemical reaction is not a dominant event when two such materials are blended in the melt. Also, ideas of small-molecule liquid crystal mixing are shown to be not applicable to describe the behavior of this system. A formalism for describing blends of liquid crystal polymers, based on Windle's sequence matching arguments, is proposed.