Morphology and mechanical properties of coconut shell powder-filled untreated cornhusk fibre-unsaturated polyester composites

Abstract

The development of the best properties of corn husk fibre (CHF) as a reinforcing material from coconut shell powder–polyester composite is an extremely interesting subject. This research focuses on characterising the mechanical properties and morphology of polyester/coconut shell powder composites filled with CHF. The variations of coconut shell powder (CSP) contents are 5% and 10%, and the corn husk fibre contents are 10%, 15%, 20% and 30% (vol%). The mixture is blended and poured into a composite mould using the hot press technique. The tensile and flexural strengths of the mixture were investigated, and the fracture surface of the composite was also analysed by scanning electron microscopy (SEM). The tensile strength of polyester/5 vol % CSP decreased dramatically from 22.459 MPa to 16.955 MPa. However, flexural strength increased from 24.233 MPa to 45.844 MPa when the corn husk fibre (CHF) content increased. Further, all polyester–10% of CSP composites have higher flexural strength values than the polyester–5% of CSP counterparts. Conversely, the tensile strength properties decrease at 10%–15% CHF content and then increase at 20%–30% CHF contents. This outcome is due to the tighter and stronger interfacial bonding between CHF–CSP–polyester and the decreasing number of fibres–pull-outs. Fractured morphology with SEM shows poor interfacial bonding between CHF–CSP–polyester and fibre pullout on composites.