Hemp Fibre as an Alternative to Glass Fibre in Sheet Moulding Compound: Part 1. Influence of Fibre Content and Surface Treatment on Mechanical Properties

Hemp fibre mat reinforced polyester composites were fabricated using a conventional sheet moulding compound (SMC) process. The influence of fibre and CaCO3 filler content on strength and stiffness of the HF-SMCs is reported and compared with data for chopped glass fibre reinforced sheet moulding compounds (GF-SMCs). In addition the influence of alkaline and silane treatments of the hemp fibres is evaluated. The experimental data is compared to modified versions of the Cox-Krenchel and Kelly-Tyson models, supplemented with parameters of composite porosity to improve the prediction of composite tensile properties. A good agreement was found between the modified models and experimental data for strength and stiffness. The results indicate that HF-SMCs are of interest for lowcost engineering applications that require high stiffness to weight ratios.