Damage Mechanisms in Polymer Blends

The development of volume strain in the polymer blends was expected a priori since many authors previously observed the initiation of different kinds of voids in such materials at a microscopic scale. 

The decohesion of the particles from the matrix was frequently observed in blends with ductile matrix and poorly adherent particles. Typical cases for such a 

Cavitation was also identified as an active mechanism in systems where a mbberlike phase (particles or interphase) is susceptible to implode under the effect of the hydrostatic stress induced by the applied tension. Fond (36) has recently revisited the critical conditions under which this form of damage becomes energetically favorable. In the case of core-shell rubber-toughened PMMA, he ascribed the extensive whitening under tension at room temperature to the profuse formation of voids in the mbber shell of the toughening particles. 

The three mechanisms described above briefly contribute to the overall dilatation of the material under tension, and it is not easy to assign to each process its relative importance in the recorded damage rate A. However, some authors like Keskkula and Schwarz (37) for HIPS, showed from detailed morphological observation that the crazing in the PS matrix is not the only active source of damage, but that the decohesion at the PS/PB interface and cavitation in the PB nodules play a significant role as well. 

---