Effect of moisture and fungal exposure on the mechanical properties of hem-fir plywood

Abstract

Hem-fir plywood were exposed to two brown rot fungi,Gloeophyllum trabeum andPostia placenta, and one white rot fungus,Trametes versicolor, to investigate the effect of fungal decay on mechanical properties of plywood. Results showed that modulus of rupture (MOR) and modulus of elasticity (MOE) of hem-fir plywood declined significantly by inoculating fungi, and weight loss of sample had a modest decrease. The fungi also made a greater effect on MOR than on MOE. Of three fungi,Postia placenta caused a most significant weight loss, andGloeophyllum trabeum resulted in a largest flexural properties loss. Substantial declines in MOR and MOE of hem-fir plywood were also observed when the plywood samples were stored under wet conditions over 15 weeks, even in, the absence of fungal attack.

Keywords

Fungus decay / Weight loss / Flexural properties / Moist condition / Plywood / MOR / MOE / S781.2 / A

References

[1] Green F., Larsen M.J.J., Winandy E., Highley T.L. Role of oxalic acid in incipient brown-rot decay [J]. Mater. Org., 1991, 26(3): 193-213.

[2] Highley T. Biodeterioration of wood. Wood Handbook: Wood as an Engineering Material, [M], 1999 Wisconsin: USDA Forest Service Forest Products Laboratory 16-16.

[3] Imamura Y. Estimation of the fungal resistance of wood composites for structural use [J]. Current Japanese Materials Res., 1993, 11: 75-84.

[4] Kim G., Ra J. Reduction in mechanical properties of radiate pine-wood associated with incipient brown-rot decay [J]. Mokchae Konghak, 1996, 24(1): 81-86.

[5] Petersen R.C., Schwandt U.H. Wood sugar analysis by anion chromatography [J]. J. of Wood Chemistry and Technology, 1991, 11(4): 495-501.

[6] Schmidt E.L., French D.W., Gertjejansen R., Herman J., Hall H. Strength reduction in particleboard caused by fungi [J]. Forest Prod. J., 1978, 28(2): 26-31.

[7] Wilcox W.W. Review of literature on the effects of early stages of decay on wood strength [J]. Wood and Fiber Science, 1978, 9(4): 252-257.

[8] Winandy J.E., Morrell J.J. Relationship between incipient decay, strength, and chemical composition of Douglas-fir heartwood [J]. Wood and Fiber Science, 1993, 25(3): 278-288.