Effects of physical treatment of wood fibres on fibre morphology and biocomposite properties

In the study, the effect of refining and fractionation of wood fibres on fibre morphology and biocomposite properties was determined. Kraft pine pulp and thermomechanical pulp were selected for the fibre treatments. Effects of physical treatment on fibre morphology were analysed with a fibre analyser and microscopy techniques. For the composites, polylactic acid was used as a polymer matrix. Composites were produced by melt processing to a fibre content of 30 wt‐%, and the mechanical properties of the injection moulded biocomposites were investigated. In general, thermomechanical pulp fibres improved the mechanical properties of polylactic acid more than pine pulp fibres did. Two different fibre fractions with distinct fibre properties were obtained by fractionation, and the use of a long fibre fraction provided improved mechanical properties for composites. The refining of pine pulp led to clear fibrillation of the fibre surface, but it had a negative effect on the mechanical properties of biocomposites