The Use of Pulp Fibres for the Production of Wood/Plastic Composites

Natural fibres can enhance the performance of a plastic component in a manner similar to glass fibre. Compared with glass fibres natural fibres have the advantage that the whole composite material remains carbon based which brings benefits in terms of (energy-) recycling, machine abrasion and a 'green' image. They are also usually cheaper than their synthetically produced counterparts. The disadvantage of natural fibres is a propensity to take up water, variable quality and uncertainty of supply. Quality and supply issues of natural fibres arise as the currently used natural fibres are predominately agricultural fibres such as hemp or sisal which are harvested on a seasonal basis. The pulping of wood on the other hand creates fibres with very consistent quality and supply can be guaranteed for many years ahead. This makes wood fibres an ideal candidate for composite products. Scion is undertaking research that looks at the suitability of various types of pulp fibres for composite production. Composites made from polypropylene and incorporating several common pulp types were prepared. The composites show substantially increased performance similar and in some cases superior to agricultural fibres. High-yield pulps such as TMP or MDF show good reinforcement potential. This paper gives an introduction to pulp based wood/plastic composites, describes some composite forming techniques using pulp fibres and compares the performance of several pulps when used for composite manufacture.