An experimental investigation and optimization on the impact strength of kenaf fiber biocomposite: application of response surface methodology

A big scientific challenge of biocomposites is in improving impact strength. Thus, the key aspect of the present study is in investigating an in-depth statistical approach on influence of processing parameters on the impact strength of the biocomposite. Natural fiber biocomposites, consisting of polypropylene (PP) and kenaf as natural fiber, were produced using melt blending. The simultaneous effects of different parameters including kenaf fiber loading, fiber length and polypropylene-grafted maleic anhydride (PP-g-MA) compatibilizer content on the impact strength have been evaluated. Response surface methodology (RSM) based on Box-Behnken design (BBD) was used to design the experiments. The optimum impact strength of 30.76 j/m was obtained with kenaf fiber loading of 26.77 wt%, fiber length of 6.09 mm and PP-g-MA content of 5 wt%. The biocomposites prepared with optimum levels of fabrication process parameters that were obtained using the response surface graph and models, had a 19% increase in impact strength than pure PP. Among the selected processing parameters, fiber loading has a most significant effect on the impact strength of the biocomposites. The thermal behavior of the kenaf fiber was evaluated from TGA/DTG thermograms. The fiber-matrix morphology in the treated biocomposites with PP-g-MA was confirmed by SEM analysis of the fractured specimens. FTIR spectra of the biocomposite with and without PP-g-MA were also studied to ascertain the existence of type of interfacial bonds. Finally, the crystallinity of PP and the biocomposites were also studied through DSC measurements.