2. A gas containment limit was observed for neat HDPE foams whereas the average cell size achieved in the HDPE/wood-flour composite foams remained insensitive to the CFA contents, irrespective of the foaming agent types.
3. The use of a coupling agent in the formulation was required to achieve HDPE/wood-flour composite foams with high void fraction.
4. The optimum active CFA content (to maximize the void fraction) seemed to lie at around 1% for neatHDPEand0.5%forHDPE/wood-flourcomposites, independent of the CFA type.