Effects of styrene butadiene rubber on physical and mechanical properties of kenaf core fiber reinforced polypropylene composites

In this research, the kenaf core fiber (KCF) reinforced polypropylene (PP) in the presence of styrene butadiene rubber (SBR) were melted blending with PP using Brabender internal mixer. The composites then fabricated using compression molding to form a sheet of PP and KCF reinforced PP (KCFPP) composites. Pure polypropylene (PP) matrix was used to serve as control whilst SBR was functionalized as impact modifier to improve the toughness properties of PP. Fourier transform infrared (FTIR) spectroscopy was used to identify the chemical compounds in pure PP and KCFPP composites. The mechanical properties were determined by tensile test using Universal Testing Machine (UTM) according to ASTM D5803. Then Field Emission Scanning Electron Microscopy (FESEM) was used to characterize the fracture surface of the composites after mechanical failure. Water absorption was also conducted in order to evaluate its resistance of KCFPP composites. The results show that the increment in SBR content has given an improvement in impact related properties (elongation at break) but at the expenses of strength and modulus properties. Besides, the water absorption increased with the increment of SBR content. The morphological studies proved that the presence of matrix fibrillation contributed for increasing of toughness properties of KCFPP composites, but the existence of fiber pull-out and void contributed to the low strength, modulus and water absorption properties.