High-Impact Rubber-Modified Polymers

Abstract

Rubber toughening generally means the modification of a hard, brittle polymer with soft, rubber particles. High toughness is a synergistic effect that arises due to a defined morphology with special toughening mechanisms. TEM micrographs taken from stained ultrathin sections contain a variety of information on the size, size distribution, arrangement and internal structure of the modifier particles and have therefore led to an understanding of the toughening effect. From the morphological perspective, two types of rubber-toughened polymers can be distinguished: “disperse systems” that contain homogeneous, heterogeneous or core–shell particles, and “inclusion systems” or “network systems” that present a network arrangement of the rubber phase. After these differences in morphology are illustrated, three main micromechanical deformation mechanisms are described: the multiple crazing mechanism, the multiple shear yielding mechanism and the network yielding mechanism. The chapter closes with a description of some additional toughening mechanisms.