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Individual Highlight

Termite Resistance of Wood–Plastic Composites

Photo of Laboratory subterranean termite test (Coptotermes curvignathus Holmgren) with five wood-plastic composites blends and untreated pine wood.Laboratory subterranean termite test (Coptotermes curvignathus Holmgren) with five wood-plastic composites blends and untreated pine wood.Snapshot : Wood–plastic composite (WPC) specimens were exposed to termites both in the laboratory and the field in Bogor, Indonesia. On a scale of 0 (complete failure) to 10 (sound), after 30 months field exposure, the WPC made with acetylated wood flour had no attack (10), followed by one with 1% zinc borate blend (9), one with a coupling agent (8), and the unmodified WPC control (7), compared to untreated solid wood (0).

Principal Investigators(s) :
Ibach, Rebecca E. 
Research Location : USDA Forest Service Forest Products Laboratory, One Gifford Pinchot Drive, Madison, WI 53726 and Bogor, Indonesia
Research Station : Forest Products Laboratory (FPL)
Year : 2018
Highlight ID : 1507

Summary

Researchers investigated the termite resistance (both laboratory and field) of five different extruded WPC blends of 50% western pine wood flour (WF) and high-density polyethylene (HDPE). Untreated pine solid wood control boards were also included to verify termite activity and as a useful benchmark for comparison. All WPC blends tested performed well in the 10- week dry-wood laboratory termite test compared to the untreated solid wood. The WPCs were not presoaked to adjust for their lower water uptake rate in comparison to just wood. Dryness may significantly limit the amount of termite attack until the moisture is absorbed in the laboratory testing. Field exposure ratings are on a scale from 0 (complete failure) to 10 (sound, one to two small nibbles should be permitted.) After 30 months field exposure to Macrotermes gilvus Hagen in Bogor, Indonesia, the acetylated WPCs performed the best with ratings of all 10s and only 0.8% weight loss, followed by the 1% zinc borate blend with ratings of all 9s and 3.9% weight loss. The coupling agent blend had ratings of all 8s and 13.6% weight loss, while the unmodified WPC controls had ratings of 7 and from 11.3% to 22.6% weight loss. The solid wood was completely destroyed with 100% weight loss and 0 rating. This research is a first step in understanding the role that different mechanisms (e.g., moisture, toxicity) play in the termite resistance of WPC by comparing chemically modifying wood by acetylation with a toxicity approach by adding zinc borate.

Forest Service Partners

External Partners

  • Craig M Clemons, Engineered Composite Science, FPL
  • Sulaeman Yusuf, Indonesian Institute of Sciences, Bogor, Indonesia
  • Yusuf Sudo Hadi, Bogor Agricultural University, Indonesia