Fracture behavior of recyclable all-polypropylene composites composed of alfa and beta modifications

ARIEL STOCCHI; ANDRAS IZER; TAMAS BARANY; CELINA BERNAL; TIBOR CZIGANY; VALERIA PETTARIN

Budapest

Conferencia; 14th European Conference on Composite Materials (ECCM-14); 2010

The fracture behavior of all-PP composites was studied under quasi-static loading conditions. Fracture toughness was evaluated by means of different Fracture Mechanics approaches depending on materials¡¯ behavior. Composites consolidated at low temperature exhibited pop-in features, the failure occurs typically by delamination and tape pullout and overall behavior seems to be stable. With increasing consolidation quality (with increasing processing temperature), the delamination becomes less pronounced before the specimens break. In composites consolidated at the highest temperature investigated (190¨¬C), the laminate-like structure typical of self-reinforced composites produced according to film-stacking method is lost. Accordingly, composites behave as if they were only ¥á-PP and ¥â-PP matrixes: ¥ár-PP exhibited typical brittle fracture of ¥á-PP, while ¥âr-PP exhibited the stable behavior with fully yielded ligament before crack propagation commonly observed for ¥â-PP. In general, stress-strain behavior changed from stable to unstable and fracture toughness strongly decreased as consolidation degree increased. Based on these results and previous findings, it can be concluded that the properties of self-reinforced PP composites can be tailored for a given application through the degree of consolidation. ¥á-PP and ¥â-PP matrixes: ¥ár-PP exhibited typical brittle fracture of ¥á-PP, while ¥âr-PP exhibited the stable behavior with fully yielded ligament before crack propagation commonly observed for ¥â-PP. In general, stress-strain behavior changed from stable to unstable and fracture toughness strongly decreased as consolidation degree increased. Based on these results and previous findings, it can be concluded that the properties of self-reinforced PP composites can be tailored for a given application through the degree of consolidation.