Strategies for processing wood plastic composites with chemical blowing agents

The production of a cellular structure in wood-flour/plastic composites (WPC) is overwhelmingly dominated by the gaseous emissions/volatiles released by the wood-flour (WF), which prevents the formation of a uniform and fine-celled structure. By adopting effective processing strategies, the adverse effects of these volatile emissions on the foam morphology of WPC can be largely suppressed. This study discusses these strategies, and presents the results obtained from extrusion processing in cases where the chemical blowing agent (CBA) predominantly controls the density reduction. The effects of CBAs on extrusion processing of WPC are discussed. All the CBAs used, produced uniform and reasonably fine-celled structures.