Susceptibility of high-density polyethylene/wood-flour composite to mold discoloration

MICHIGAN STATE UNIVERSITY 

Dawson-Andoh, B., Matuana, L. M., & Harrison, J. (2005). Susceptibility of high-density polyethylene/wood-flour composite to mold discoloration. Journal of the Institute of Wood Science, 17(2), 114-119.

B. Dawson-Andoh ; L. M. Matuana ; J. Harrison

Abstract

High density polyethylene (HDPE)/wood-flour composites containing either pine or maple flour were evaluated for susceptibility to mold colonization and discoloration using two different ASTM standards: ASTM standards D4445 and G21. Some test specimens were pre-exposed to accelerated ultraviolet weathering and freeze-thaw cycles and these were air-dried before exposure to molds in either ASTM D4445 or G21. Mold colonization on the surface of exposed samples was visually rated. Wood plastic composites containing either pine or hard maple exhibited greater fungal colonization and discoloration in the ASTM G21 test than the ASTM D4445. Consequently, the ASTM standard G21 was a more sensitive and better test protocol for evaluating the susceptibility of HDPE/wood-flour composite to mold discoloration. It is evident that constant or frequent moisture presence is necessary for the growth and support of mold colonization and discoloration of HDPE/wood-flour composite. Pre-conditioning of HDPE/wood-flour composites to accelerated UV weathering or freeze thaw cycles had no discernible effect on susceptibility to mold discoloration. Environmental scanning electron microscopic analysis of the surface of HDPE/wood-flour composite clearly indicated that wood flour is not completely encapsulated by the HDPE matrix and exposed wood flour may serve as points for moisture adsorption and fungal colonization.

Original language	English (US)
Pages (from-to)	114-119
Number of pages	6
Journal	Journal of the Institute of Wood Science
Volume	17
Issue number	2
State	Published - 2005

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