Mechanical properties of single kenaf fibre with optimisation and indentation behaviour of kenaf fibre reinforced epoxy composite

Abstract

The development of eco-friendly materials has attracted a lot of researchers’ interest to avoid environmental imbalance and prevent depletion of the ozone layer. Hence, the reinforcement of polymer composite using natural fibre called composites is interesting to develop. Inconsistency of morphology structure of single kenaf fibres, an optimum of bonding parameters between fibres-epoxy matrices interaction and low resistance to localised loading during composites’ impact response is fascinating to discover. Therefore, this study aims to determine the kenaf fibre's monotonic tensile properties, optimising the blending composition and examining the indentation behaviour of kenaf fibre composites. Initially, the effect of chemical treatment and fibre length of single kenaf fibres were evaluated using a Weibull statistical approach. Next, the mixing parameter between the kenaf fibre and epoxy resin, including alkaline treatment, fibre loading and fibre length, was then elucidated using central composite design (CCD) of response surface methodology (RSM). The contact stiffness and indentation parameter of the kenaf epoxy composite were subsequently calculated using Mayer indentation law. The finding highlights that the Weibull modulus (m) of single kenaf fibre varied between two and four. Moreover, the highest absolute value of tensile strength for fibre length and chemical treatment were yielded at 30 mm and 6 wt.% of alkaline concentration, respectively. The surface morphology showed that the surface was rough and no impurities were obtained from the treated fibre. Furthermore, through the CCD analysis, the optimum configuration of the biocomposites (alkaline concentration, fibre loading and fibre length) were obtained at 6.03 wt.%, 26.02 wt.% and 7.39 mm. Lastly, the value of the indentation parameter laid between 1.4 and 1.8. It was also found that the contact stiffness increased with increasing density of composites, indenter diameter and velocity impact. This optimises kenaf reinforced epoxy composite which is suitable to be used for consumer product with short life cycles ranging between three and four years, where the mechanical properties of structures are of paramount importance.