The Role of Silica in Improving the Properties of Kenaf/Silica/Epoxy Hybrid Composites

Abstract

Kenaf/silica/epoxy hybrid composites with differences in silica types have triggered research interest worldwide due to the role of silica in influencing the composite properties. This study aims to determine the effect of silica adding on the flexural and impact properties and water absorption of the kenaf/silica/epoxy hybrid composites. Alkali treated kenaf fibers 5 mm in length combined with silica fume microparticle 400 mesh (a37 Pm) in size were used to strengthen the epoxy resin of 70 vol.% for manufacturing the hybrid composites by a hand lay-up in the cold press mold for around 40 minutes. The silica loadings were varied by 0, 2, 3, and 5 (vol.%). The results showed that at 2 vol.% silica, the flexural and impact strengths increased by 16% and 18%, respectively, but decreased at higher than 2 vol.%. The lowest water absorption of 13.3% for 216 hours water immersion was also exhibited by 2 vol.% silica. The higher the loading of silica microparticles, the more particles occupied the matrix areas, making kenaf fibers harder to embed in the matrix, as verified by scanning electron microscopy (SEM). This work concluded that the addition of 2 vol.% of silica microparticles (37 Pm) into the kenaf/epoxy composite was an optimum value.