Micromechanical deformation processes in toughened PP/PA/SEBS-g-MA blends prepared by reactive processing

Toughening mechanisms occurring in PP/PA6 (70 vol.-%/30 vol.-%) blends containing various amounts of SEBS-g-MA have been studied by in situ straining in a high voltage electron microscope (HVEM). Variation of volume fraction of compatibilizer (SEBS-g-MA) with constant PA6 content and reactive processing conditions give excellent control over morphology and toughness/stiffness balance. With increasing volume fraction of compatibilizer the blend morphology changes significantly from discrete to cluster to island-like (percolating) structures. Micromechanical deformation processes have been characterized as a function of blend morphologies. Based on experimental results, the major toughening mechanism is the fibrillized cavitation process, and the main energy dissipation during deformation is shear yielding of matrix material triggered by irreversible plastic growth of microvoids caused by the fibrillized cavitation process. Finally, schematic models for micromechanical deformation processes in the various blend morphologies are proposed