Flexural analysis of hemp, kenaf and glass fibre-reinforced polyester resin

Natural fibres have a high potential to replace synthetic fibres such as glass in a variety of applications. However, natural fibre-reinforced composites still have some limitations with respect to the mechanical performance especially in high load bearing capabilities. The hybridization of natural fibres with synthetic fibres in the same matrix has proven to create a balancing effect and enhanced the composites performance. Besides that, fibre architectures that include fibres continuity, fibres orientation, fibres arrangement and fibres interlocking are also considered to enhance the overall performance of the composites. In this study, the hemp mat, kenaf mat and glass chopped strand mat were hybridised with woven glass fibres, respectively in polyester resin to form 12 systems of the composites. The hybridization effects of different fibre core material, fibre core thickness and fibre arrangement on flexural response were investigated according to ASTM D7264. The results indicated that hybrid CSM glass/woven glass composite showed the highest flexural strength and modulus compared to hemp/woven glass and kenaf/woven glass composites, with about 377.15 +/- 48.41 MPa and 16.74 +/- 7.15 GPa. Among natural fibres, kenaf fibre (2WG/K/2WG) composite showed better flexural properties compared to hemp fibre (2WG/H/2WG) composite. 2WG/2G/2WG composites with two plies of CSM glass showed maximum flexural properties. As for hemp/woven glass and kenaf/glass hybrid composites, the flexural properties reached a maximum value in system arrangement of (2:1:2) but it reduced in the system arrangement of (2:2:2) and (2:4:2). On the evaluation effect of fibre arrangement, hemp, kenaf and glass mat used as core (arrange in the middle; (2:2:2)) showed higher flexural properties as compared to the use as skin (arrange in outer; (1:4:1)). (2WG/2K/2WG) showed better flexural properties than (2WG/2H/2WG) as the core, while (H/4WG/H) showed better flexural properties than (K/4WG/K) as skin.