Introduction:

The use of wood-plastic composites (WPCs) has been limited due to their low impact strength and high density compared to natural wood.

Objective:

To characterize the cellular morphology and density of WPCs prepared with virgin and recycled polyethylene, and Pinus radiata wood.

Materials and methods:

The polymer and the foamed WPCs were manufactured by an extrusion process. The virgin and recycled high-density polyethylene was mixed separately with P. radiata wood. The plastic/wood ratios were 80/20 and 70/30, with an endothermic foaming agent (Hydrocerol 1700 at 1 and 3 %), a coupling agent (Licocene 4351), and a lubricating agent (Licolub H12) added.

Results and discussion:

The density of virgin polymer, with 1 and 3 % foaming agent, was reduced by 39 and 20 %, respectively, but in the recycled polymer the reduction was 18 and 23 %, respectively. In the foamed WPCs, the reduction was less than 10 %. The foamed composites had smaller bubble diameter and higher cell density. The void fraction was higher in the virgin polymer at 3 % foaming.

Conclusion:

The use of a foaming agent gave better physical properties to the composites.

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