Fungal and moisture durability of wood–plastic composites: summarizing 20 years of Forest Products Laboratory research

Abstract

After wood–plastic composites (WPCs) began to be used in exterior applications, early failures were noticed, which created considerable uncertainty about how resistant these materials were to environmental factors such as fungal attack. To address these concerns, we began a research program to develop a knowledge base on the fungal durability of WPCs. This report summarizes approximately 20 years of Forest Products Laboratory research on this subject. Improved evaluation protocols along with the application of new instrumental techniques were used to better understand and assess the fungal degradation of WPCs and identify key contributing factors. It appears that after an initial period of outdoor exposure, stresses resulting from moisture-induced expansion of wood particles create microcracks in the plastic matrix, ultimately providing decay fungi access to the wood component of WPCs. Approaches for improving fungal durability of WPCs using antimicrobials, additives, chemical treatments, and chemical modification of the wood component were explored during this research program.

Citation

Ibach, R.E.; Clemons, C.M. 2024. Fungal and moisture durability of wood–plastic composites: summarizing 20 years of Forest Products Laboratory research. General Technical Report FPL-GTR-303. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. 13 p. https://doi.org/10.2737/FPL-GTR-303