Moisture dynamics of WPC and the impact on fungal testing

Wood-plastic composites (WPCs) are increasingly used in decking applications, where exterior exposure can lead to sufficient moisture for fungal deterioration. Standard tests recommended to assess fungal durability of WPC, but initially developed for wood or wood-based panels, are not applied in this study because the similarity in moisture behaviour for wood (-based panels) and WPC is questioned. The moisture dynamics of commercialised WPC versus wood-based panels were studied employing different moistening methods. The moisture sorption differences between various WPCs were minimal despite different wood contents, particle sizes, and plastics employed, but given sufficient time WPC wood particles gained sufficient water for fungal decay. To assay fungal durability of WPCs, immersion of the specimens for at least 1 week in water at 70 °C seems to be the most effective pre-treatment.