Reinforcing potential of wood pulp-derived microfibres in a PVA matrix

In this study, the reinforcing potential of cellulose "microfibres'' obtained from bleached softwood kraft pulp was demonstrated in a matrix of polyvinyl alcohol (PVA). Microfibres are defined as fibres of cellulose of 0.1-1 mm in diameter, with a corresponding minimum length of 5-50 mm. Films cast with these microfibres in PVA showed a doubling of tensile strength and a 2.5-fold increase in stiffness with 5% microfibre loading. The theoretical stiffness of a microfibre was calculated as 69 GPa. The study also demonstrated that the strength of the composite was greater at 5% microfibre loading compared to 10% loading. Comparative studies with microcrystalline cellulose showed that the minimum aspect ratio of the reinforcing agent is more critical than its crystallinity in providing reinforcement in the composite.