Drop weight impact and work of fracture of short glass fiber reinforced polypropylene composites toughened with elastomer

Short glass fiber (SGF) reinforced polypropylene composites toughened with styrene-ethylene butylene-styrene (SEBS) or maleated SEBS (SEBS-g-MA) triblock copolymer were injection molded. Charpy drop-weight impact properties and the impact essential work of fracture (EWF) of the SGF/SEBS/PP and SGF/SEBS-g-MA/PP hybrids were investigated. Drop-weight impact results revealed that the SGF/SEBS/PP hybrid exhibits higher impact strength than the SGF/SEBS-g-MA/PP hybrid at low impact speeds. This was derived from the pull-out of fibers from the SGF/SEBS/PP hybrid. At high impact speeds, the impact strength of the SGF/SEBS-g-MA/PP hybrid was slightly higher than that of the SGF/SEBS/PP hybrid. Impact EWF measurements showed that the hybrids only exhibit specific essential work (W_e) at a high impact speed of 3 ms^-1. The non-essential work does not occur in the hybrids under high impact rate loading conditions. Moreover, SEBS or SEBS-g-MA addition was beneficial in enhancing the high-rate specific essential work of the SGF/SEBS/PP and SGF/SEBS-g-MA/PP hybrid composites.