Mechanical behavior and fracture toughness evaluation of maleic anhydride compatibilized short glass fiber/SEBS/polypropylene hybrid composites

Short glass fiber (SGF) reinforced polypropylene composites toughened with styrene-ethylene-butylene-styrene (SEBS) triblock copolymer were injection molded. The effect of maleic anhydride (MA) functional group on the mechanical performance of the hybrid composites was investigated. In this study, MA was either grafted to PP (PP-g-MA) or SEBS copolymer (SEBS-g-MA). The mPP blend was prepared by compounding 95% PP with 5% PP-g-MA. The matrix of hybrid composites consists of either SEBS/mPP or SEBS-g-MA/mPP. Tensile tests showed that SGF exhibits a beneficial effect for restoring the stiffness of the SEBS/mPP blend. Impact measurements on SEBS/mPP exhibited superior impact strength. However, the incorporation of SGF into SEBS/mPP and SEBS-g-MA/mPP blends reduced the impact strength considerably. SEM observations revealed that the SGF surfaces of both SGF/SEBS/mPP and SGF/SEBS-g-MA/mPP hybrids are coated with a thin layer of matrix material. This implied that the MA functional group of mPP improves the adhesion between SGF and PP, and between SGF and SEBS. The essential work of fracture (EWF) method revealed that a strong interfacial bonding between SGF and PP is detrimental to the fracture toughness of ternary SGF/SEBS/mPP and SGF/SEBS-g-MA/mPP hybrid composites. Finally, dynamic mechanical analysis showed that SGF increases the storage modulus but decreases the intensity of damping factor for the hybrids.