INTERFACIAL THICKNESS AND WELD STRENGTH BETWEEN POLYCARBONATE AND POLY(STYRENE-CO-ACRYLONITRILE)

The interfacial fracture toughness, G(c), and the equilibrium interfac ial thickness, lambda, between polycarbonate and poly(styrene-co-acryl onitrile), SAN, were measured by the double cantilever beam method and ellipsometry, respectively. Acrylonitrile, AN, content in SAN was cha nged in a range of 0-50 wt%. The Flory interaction parameter chi(AB) w as estimated from lambda. When AN content was 25 wt%, G(c) and lambda showed maxima, while chi(AB) showed a minimum. G(c) was found to incre ase with lambda (G(c) similar to lambda(2)). Atomic force microscopy s howed an interfacial failure for weak interface (AN=O.11 and 50 wt%) a nd a crazing failure for strong interface (AN=19 and 25 wt%).