Mechanical Properties and Performance Evaluation of Polypropylene/Betel Nut Husk Composite

Composites existed because reinforcement helps to improve the properties of a matrix for various applications. Biocomposites are heavily studied as a greener alternative as natural fibers are used as reinforcement. Natural fibers are renewable, inexpensive, biodegradable and possess comparable strength to those of manmade fibers. Despite the ongoing studies on biocomposites, there are still many more unexplored alternatives of natural fibers that can be utilized as reinforcement especially those of which come from agricultural waste. In this project, betel nut husk fiber was used as the reinforcement for polypropylene matrix. It is a native fruit to Malaysia among few other tropical Asia countries. While studies were done to evaluate its husk fiber strength to be used as reinforcement, there were only very few studies done on betel nut husk fiber reinforced composite especially with thermoplastic matrix. Therefore, the objective of this project was to evaluate the effect of fiber-matrix composition on performance of the composites through the analysis of their mechanical properties which were tensile, flexural and impact properties. The compositions involved were 80/20 and 70/30 (Polypropylene/Betel nut husk fiber). Compounding of the materials were done using twin screw extruder and the test specimens were fabricated using injection moulding process. The results showed that tensile strength of the composite was slightly lower than the neat PP. However, improvement over 100% was evident in the tensile modulus. Fiber pull-outs were observed in the scanning electron microscopy (SEM) images suggesting poor adhesion between the fiber and matrix. Flexural properties, on the other hand, increase by 28% and 44% for the strength and modulus, respectively. The impact strength decreased due to the nature of the reinforcement which was short fiber and also the increase in discontinuity of the matrix as the fiber loading increased.