TOUGHENING MECHANISM OF RUBBER-MODIFIED POLYAMIDES

Rubber-modified polyamides were probed using scanning electron microsc opy (SEM), transmission electron microscopy (TEM), small-angle X-ray s cattering and various mechanical tests. TEM studies showed that in tou gh samples the crystalline orientation in the interparticle region is of a distinctly different character. The lamellae are organized perpen dicular to the rubber-matrix interface, while the hydrogen-bonded plan es of low slip resistance are aligned parallel to these interfaces. Ba sed on this observation a model is proposed to elucidate the deformati on and toughening mechanisms of these materials. Further SEM studies i n the stress-whitened regions of both the tensile bars and Izod specim ens revealed the evolution of a cavitation process in the rubber parti cles. The shape and the size of the cavities in tough samples is relat ed to the initial morphology of the matrix.