高聚物两相体系相行为的流变学研究Ⅰ．均聚物共混体系相行为的研究

RHEOLOGY STUDIES ON THE PHASE BEHAVIOR OF TWOPHASE POLYMER SYSTEMS Ⅰ. PHASE SEPARATION IN BLENDS OF HOMOPOLYMERS

本文从流变学角度研究了氯化聚乙烯（ＣＰＥ）／、乙烯－醋酸乙烯酯（ＥＶＡ）共聚物及聚苯乙烯（ＰＳ）／聚乙烯基甲基醚（ＰＶＭＥ）两共混物不稳相分离的动力学过程．发现在相分离早期，共混物的粘度和贮能模量增加，中期及后期，两者逐渐变小．从Ｄｏｉ－Ｅｄｗａｒｄｓ模型出发．考虑到剪切引起的分子形变伴随的流体力学相互作用的变化及其作用下，相互的增长、破裂、旋转等因素，引入Ｄｉｃｋｉｅ有效体积的概念，分析、解释了上述实验现象．但对ＰＳ／ｐｖｍｅ（９０／１０，Ｗｔ％）ＨＣＰＥ／ＥＶＡ（２５／７５，Ｗｔ％）两共混物在相分离后期，粘度有所增长的实验事实，还需深入细致的研究．

he dynamics of liquid-liquid phase separation of two polymer blends ofpolystyrene/poly (vinyl methe ether) (PS/PVME ) and chlorinatedpolyethylene/ ethylene - vinyl acetate co polymer (CPE / EVA ) was studied bytime-resolved rheometrics meChanical spherometer in spinodal decomposi non (SD) regions. It was found that in the early stage of SD, the dynamicmodulus (G' ) and the dynamic viscosity (n' ) increased with time after the initiation of the isothermal phase mparation; in the intermediate and later stage, G'and n' decreased as the phaseseparation proceed. This behavior was analyzedand explained in the context of Dot-- Edwards model by considering the faCtors ofphase-size increasing, phase bursting and rotating under the shear motion. At thesame time, the concept of Dickie's effeCtive volume was introduce to manifest thisphenomenon. However, blends of CPE/EVA (25/75, wt/wt) andPS/PVME (90/ 10, wt/wt), the dynamic viscosity increased slightly in the latersarge, it 'eds further more detailed studies.