POLYETHYLENE TOUGHENED BY CACO3 PARTICLE ASTERISK - BRITTLE-DUCTILE TRANSITION OF CACO3-TOUGHENED HDPE

The dependencies of the notched Izod impact toughness of HDPE/CaCO3 blends on CaCO3 particle concentration and particle size are analyzed. It was found that the notched Izod impact strength (S) of HDPE/CaCO3 blends depends discontinuously on CaCO3 particle concentration. A brittle-ductile transition occurs when the CaCO3 volume fraction (V(f)) increases to a critical value (V(f)'). Furthermore, a brittle-ductile transition master curve can be constructed by taking the matrix ligament thickness (L) into account as a parameter instead of V(f). The results show that the critical matrix ligament thickness (L(c)) is a single parameter for the transition and L(c) = 5.2 mum for HDPE/CaCO3 blends. The impact strength, however, varies considerably with CaCO3 particle size, which shows that CaCO3 particle size is another dominating parameter for the toughness of HDPE/CaCO3 blends.