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

Abstract

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.