Seventh-year durability evaluation of zinc borate incorporated wood-plastic composites and particleboard

WOS: 000428487200012 Several formulations of wood-plastic composites and a particleboard were fabricated with combining zinc borate biocide at different retention levels during the manufacturing process. The treated specimens were exposed to a field test under protected above ground conditions for 7 years in southern Japan. During biannual inspections, the specimens were visually inspected and graded for decay and Formosan subterranean termite damage. While zinc borate retention levels tested were able to protect the particleboards from decay activity for 7 years, their efficacy was lower against termite attack. The retention levels tested up to 2% (w/w) helped to reduce termite damage noticeably but failed from full protection (e.g. rating 10) indicating higher zinc borate loadings are required in particleboards if they will be utilized in southern Japan climatic conditions. Wood-plastic composites were also more durable against fungal damage during the 7 years exposure period but this condition seems changed last 18 months since some lower decay ratings were recorded even for zinc borate embedded formulations. While termite destruction diminished significantly with zinc borate integrated formulations, higher retentions might be recommended as threshold for full protection in wood-polypropylene composites.