Thermal behaviour and dynamic mechanical analysis of Pennisetum purpureum/glass-reinforced epoxy hybrid composites

Abstract The thermal behaviour and dynamic mechanical analysis of Pennisetum purpureum/glass-reinforced hybrid composites were investigated. Hybrid composite laminates were fabricated using untreated, 5%, or 10% alkali-treated P. purpureum fibres with woven E-glass fibres and epoxy resin. The composites were manufactured using a vacuum infusion process; the volume fractions of the P. purpureum, glass fibre, and epoxy resin were 24%, 6%, and 70%, respectively. Thermogravimetric analysis (TGA) demonstrated that the amount of residue of the hybrid composites decreased as the concentration of the alkali used to treat the P. purpureum fibres increased. The glass transition temperature values of the neat epoxy, and hybrid composites with the untreated, 5%, and 10% alkali-treated P. purpureum fibres were 64, 64, 67, and 63 °C, respectively as determined by dynamic mechanical analysis (DMA). When tested at room temperature (RT), the maximum tensile and flexural strengths were recorded for the hybrid composites with the 5% alkali-treated P. purpureum fibres. At >60 °C, as the temperature approached Tg, debonding of the fibre and matrix occurred, which resulted in a reduction of the tensile and flexural strengths. The fractured surface morphologies of the samples indicated that improved fibre–matrix interfacial bonding was achieved for the 5% alkali-treated P. purpureum/glass hybrid composites.