Effect of empty fruit bunch fibre loading on properties of plasticised polylactic acid biocomposites

Polylactic acid (PLA) is an environmentally friendly bioplastic that is derived from renewable resources; however, the inherent brittleness, poor mechanical properties and high material cost limited its usage in current market. Hence, the addition of plasticiser and natural fibre can reduce the cost and improve the properties of the PLA biocomposite. In this research, the alkaline treated and untreated empty fruit bunch (EFB) fibre at different loading, i.e., 5, 10, 20 and 30 wt. % were added into coconut oil (CO) plasticised PLA to produce biocomposites. The sample preparation was performed via melt blending method followed by compression molding to produce thin sheet for characterisation. The results showed treated fibre samples have better enhancement in terms of tensile properties, particularly in tensile modulus as compared to untreated fibre. The optimum loading of the fibre was identified as 5 wt.% and 10 wt.% depending on the focus of tensile strength or longer elongation. The 5 wt.% treated fibre biocomposite has a better elongation at break (>8%) while 10 wt.% treated fibre biocomposite has the highest tensile strength (23.8 MPa) as compared to other fibre content. It is observed that high fibre loading can result in deterioration of the tensile properties. The density of biocomposites decreased significantly with the addition of CO but increased with the addition of EFB fibre. The SEM images of the untreated fibre biocomposites showed more fibres pull out, empty cavities and voids, this explained the poor performance in the tensile properties of the untreated fibre biocomposites.