Effect of bark fiber content and size on the mechanical properties of bark/HDPE composites

Black spruce and trembling aspen bark fibers and high density polyethylene were used to process bark–plastic composites by extrusion. Fibers of fine, medium, and coarse size and contents of 50% and 60% based on oven-dry weight were used. The effects of species, fiber content and size on the flexural and tensile properties of the composite were investigated and were found to be highly significant. Black spruce bark composites exhibited higher strength but showed more brittle behavior than aspen bark composites. The effect of content on mechanical properties was more important than size. Compared to wood flour composites, those from bark showed lower strength.