The toughening behavior in propylene-ethylene block copolymer filled with carbon black and styrene-ethylene butylene-styrene triblock copolymer

This work examines the toughening behavior of propylene-ethylene block copolymer (Co-PP) filled with carbon black (CB) and styrene-ethylene butylene-styrene triblock copolymer (SEBS). Appropriate amounts of the two components are mixed through melt-blending in a twin-screw extruder. The blended pellets, following preparation in a series of specimens by injection molding, are studied and compared. A scanning electron microscope (SEM) morphology study of the impact-fractured surfaces verifies the changes in fracture mechanisms at various temperatures and SEBS contents. In addition, the flexural modulus, tensile strength, heat distortion temperature (HDT), and dynamic mechanical properties are also studied here. According to those results, the blending of CB in Co-PP not only improves the impact strength, but also enhances the flexural modulus and tensile strength. However, the HDT of the Co-PP/CB blends decreases with a greater filler content. Moreover, SEBS markedly upgrades the impact endurance in the lower temperature range when blended with Co-PP, due to the increased compatibility in the interface between SEBS particles and the Co-PP matrix. (C) 1998 Elsevier Science S.A. All rights reserved.