STRUCTURE AND MICRODEFORMATION OF (IPP IPP-G-MA)-PA6 REACTION-BONDED INTERFACES/

Transmission electron microscopy has been used in conjunction with RuO 4 staining to investigate the structure of (iPP/iPP-g-MA)-PA6 reaction bonded interfaces and microdeformation at interfaces which had failed by crack propagation along the interface. In relatively weak interfac es, the crack tip was preceded by a single, well-defined crazelike fib rillar deformation zone on the iPP/iPP-g-MA side of the interface, wit h fibril diameters of between 10 and 15 nm. The crack tip itself also propagated along the interface, providing some justification for the e xtension of established models for interfacial failure in glassy polym ers to the present case of two semicrystalline polymers. In stronger i nterfaces, however, considerable diffuse deformation was observed to a ccompany crack propagation. This was accounted for by the deeper penet ration of the damage zone into the iPP/iPP-g-MA, into regions where th e microstructure was less well ordered than immediately adjacent to th e interface. This transition from a well-defined to a diffuse damage z one may modify the relationship between the local interfacial strength and the global fracture toughness.