Morphologies and mechanical properties of polyarylate/liquid crystalline polymer blends compatibilized by a multifunctional epoxy resin

Abstract

The tetrafunctional epoxy resin, tetraglycidyl-4′,4′-diaminodiphenyl methane (TGDDM), has been investigated as an efficient reactive compatibilizer for the blends of polyarylate (PAr) with a liquid crystalline polymer (LCP). TGDDM can react with PAr and LCP at the interface simultaneously to produce the PAr-co-TGDDM-co-LCP mixed copolymers during melt blending. These copolymers tend to anchor along the interface as the result of the interfacial reaction and thus serve as effective compatibilizers to reduce the interfacial tension and to enhance the interfacial adhesion in the solid state. The morphologies of the PAr/LCP blends were inspected by means of scanning electron microscopy (SEM). It is observed that the dispersed LCP phase domains reduce obviously after compatibilization. Furthermore, it is also found that the reduced interfacial tension caused by the addition of TGDDM plays a vital role in affecting the deformation of the LCP phase domains in the compatibilized PAr/LCP blends. The LCP phase tends to deform into greater numbers and finer fibrils with high aspect ratio after the addition of TGDDM in those blends containing adequate LCP content (> 10 %). In the blend containing low amount of LCP (Par / LCP = 95/5) with high TGDDM content (0.3 phr or higher), however, the LCP phase can only exist as fine but short fibrils or even ellipsoids. The overall mechanical properties of the PAr/LCP blends are substantially improved after compatibilization by this coupling-type reactive compatibilizer. The generation of LCP fibrils with high aspect ratio and improved interfacial adhesion are the two hinges to enhance the performance of the compatibilized PAr/LCP blends.