尼龙6/液晶聚合物共混体系中化学反应对体系热行为及形貌的影响

采用漫反射红外光谱法(DRIFT)和示差扫描量热法(DSC)研究了2种不同特性黏数的尼龙6与3种液晶聚合物(Vectra A950、Vectra B950和Rodrun LC5000)之间的酯-酰胺交换反应.DRIFT测试证实了尼龙6与LC5000之间存在化学反应.DSC分析表明,酯-酰胺交换反应使体系中尼龙6的熔点下降、结晶度降低.增加反应时间和增大共混体系中液晶聚合物的含量有利于酯-酰胺交换反应的发生.与Vectra A950和Vectra B950相比,分子链柔性较强的Rodrun LC5000与尼龙6之间的化学反应更容易进行.扫描电子显微镜(SEM)观察表明,随着共混时间的延长,分散相形貌由球状粒子发展为短棒状纤维,乃至最终形成直径更细的微纤结构.

EFFECT OF ESTER-AMIDE EXCHANGE REACTION ON THERMAL BEHAVIOUR AND MORPHOLOGY OF NYLON 6/THERMOTROPIC LIQUID CRYSTALLINE POLYMER BLENDS

Binary blends of two grades of nylon 6 and three kinds of commercialized thermotropic liquid crystal polymers (LCPs) (Vectra A950,Vectra B950 and Rodrun LC5000) were prepared by melting blending process,respectively.The ester-amide exchange reaction between nylon 6 and LCPs was analyzed by using diffuse reflectance FTIR spectroscopy (DRIFT) and differential scanning calorimetry (DSC).The blending time,composition and the type of LCPs exerted dramatic influence on the exchange reaction,resulting in the decrease of melting point and crystallinity of nylon 6 in the blends.The increase of blending time promoted the contact and the entanglement of macromolecular chains of the two phases,and therefore,promoted the exchange reaction.The increase of LCP content was another favorable parameter for the exchange reaction.When the content of Rodrun LC5000 was 80 wt%,the melting temperature of nylon 6 in the blend decreased from 219.1℃ to 185.5℃,and the crystallinity was decreased from 37.9% to 20.0%.Compared with Vectra A950 and Vectra B950,Rodrun LC5000 tends to react with nylon 6 more extensively,due to its more flexible molecular chain.The morphology of blends was characterized by using scanning electron microscopy (SEM).It is shown that,unlike other completely incompatible blending systems,the morphology of nylon 6/LCP blends was controlled by blending time as well as the exchange reaction.With the increase of blending time,the morphology of dispersed LCP was developed from droplets to deformed short bars,and finally,fine fibrils with diameter of about 1 μm.