SYNTHESIS OF HIGH-PERFORMANCE COMPOSITES BY IN-SITU POLYCONDENSATION AND THEIR MECHANICAL-PROPERTIES

High-performance composites of vinylpyridine-styrene copolymers and po lyamic acid (PAA) were prepared by the so-called 'in situ polymerizati on method'. Poly(4-vinylpyridine-co-styrene) (P4VPy-St) and poly(2-vin ylpyridine-co-styrene) (P2VPy-St) were used as flexible matrix polymer s. A molecular composite could be obtained from a polymer pair having an attractive interaction such as a coulombic interaction. Their morph ologies were observed by scanning electron microscopy (SEM); mechanica l properties of these composites were studied by tensile tests. The PA A content dependence of tensile strength for the composite films obtai ned by the in situ polymerization method was investigated. The tensile strength of the resulting composite was about 1.5 times higher than t hat of PAA film. The coulombic interaction between the pyridine moiety in the matrix copolymer and resulting PAA enhanced both the miscibili ty and mechanical properties of the composites. Furthermore, a polyimi de (PI) structure was formed by stepwise heat-treatment and greatly en hanced the tensile strength of the composite films.