Engineering and evaluation of hemp fibre reinforced polypropylene composites: Fibre treatment and matrix modification

Abstract

Hemp fibres were alkali treated to improve their suitability for use as reinforcements in composite materials. Improvements in tensile strength, Young’s modulus, fibre separation, crystallinity index, lignin reduction and thermal stability were observed for hemp fibres treated with a solution of 5 wt% NaOH/2 wt% Na₂SO₃. A range of hemp fibre reinforced polypropylene composites were produced by extrusion and injection moulding, and the effect of fibre treatments and MAPP content on the tensile strength and Young’s modulus of composites were investigated. The optimum composite, consisting of polypropylene, 40 wt% NaOH/Na₂SO₃ treated hemp fibre and 4 wt% MAPP, was found to have a tensile strength of 50.5 MPa and a Young’s modulus of 5.31 GPa.