【摘要】 用差示扫描量热仪与扭辨分析检出了四氟乙烯-六氟丙烯共聚物熔体中的转变。为了阐明转变的性质,用毛细管流变仪和微型平板粘度计研究了其熔体粘度的温度依赖性。发现,当温度上升到转变温度附近,熔体粘度先升高,然后下降,其粘度行为与热致型小分子液晶相似。但用偏光显微镜观察FEP共聚物熔体,未发现双折射现象。根据实验结果对转变的机制提出了解释。更多还原

【Abstract】 The transition in the melt of FEP copolymer was detected by differential scanning calorimeter and torsional braid analysis techniques. In order to clarify the nature of the transition, the changes of melt viscosity with temperature and shear rate were investigated by capillary rheometer and micro-parallel type rheometer. The result obtained shows that, the plot of In η vs. 1/T of FEP copolymer at constant shear rate or sheading stress does not show a linear relationship as usually observed in the conventional polymer melt but an anomalous increase of 17 , when the temperature increases above the transition temperature. This rheological behavior is similar to that of low molecular liquid crystal. But no birefringence in the melt can be perceived under crossed polarizing microscope. Based on these experimental facts, a model was presented to explain this transition.更多还原