Poly(lactic acid) composites reinforced with kraft pulp fibres: Production by a papermaking process and characterisation

Four different pulp fibres, representing short and long cellulose fibres and chemically modified fibres, were tested as reinforcements for poly(lactic acid) composites. A simple papermaking method was used to form the composite sheets, which were further compression moulded. The effects of morphological, chemical, and mechanical characteristics of kraft pulp fibres and their contents on the PLA composite characteristics were investigated. The incorporation of kraft pulp fibres provided composites with 16-24% and 36-39% higher tensile strength and Young's modulus values, respectively, than those of neat PLA. Unbleached pulp fibres, which had higher intrinsic strength than that of the corresponding bleached pulp, provided composites with higher tensile properties. In the tested range, the effect of the cellulose fibre length was not significant. Compared to those of neat PLA, barrier properties for water vapour and oxygen were slightly superior for composites incorporating up to 30% (wt) of kraft pulp.