Structure development during flow of ternary blends of a polyamide (nylon 46), a thermotropic liquid crystalline polymer (poly(ester amide)), and a thermoplastic elastomer (EPDM)

Abstract

It was shown that a fine fibril structure of a thermotropic liquid crystalline polymer (TLCP)(poly(ester amide)) can be developed in a shear flow field of a thermoplastic matrix (polyamide, nylon 46) when the viscosity of the latter is lower than that of the former. Addition of a third component, a functionalized elastomer (maleic anhydride grafted ethylene-propylene-diene terpolymer, MA-EPDM) that interacts with the matrix polymer (nylon 46) and the thermotropic liquid crystalline polymer, facilitates the structural development of the TLCP by acting as a compatibilizer at the interface. Maleic anhydride grafted to EPDM reacts with TLCP and nylon 46. Morphological observation determined the significance of compatibilization in immiscible polymer blends. The compatibilizer brings about good adhesion at the interface, reduces the droplet size, and enables finely dispersed liquid crystalline polymer to be deformed in shear flow without strong elongation even though the viscosity of the matrix was much lower than that of the liquid crystalline polymer. Fibrous structural development was observed in the edge area of the extruding strand without elongation and also in the central region with weak elongation. Mechanical properties were significantly improved by good adhesion and fibril generation, which were ascribed to the produced compatibilizer. These results have important implications in that they provide a means to produce strong and tough in situ composites when the viscosity of the matrix polymer is lower than that of a dispersed liquid crystalline polymer that is immiscible with the matrix polymer.