木材动态黏弹性的湿热耦合效应

doi:10.11707/j.1001-7488.20141214

Abstract

Abstract:

The hydrothermal effects of time and temperature on dynamic viscoelastic properties of Chinese fir (Cunninghamia lanceolata) were investigated using dynamic mechanical analysis (DMA Q800) in this study. The tests were applied to specimens at a series of constant temperature and humidity fields (25- 90 ℃, 0-93%) for 550 min. Changes in storage modulus and loss tangent with heating time were examined. The results indicated that the impacts of hydrothermal processes mainly resulted in the decreasing of glass transition temperature of hemicellulose and lignin. For absolutely dried wood, there was no softening occurred in this study. At the temperature range of 40 ℃ to 60 ℃, a relaxation phenomenon was observed for wood with 5.88% -13.36% MC, which could be attributed to the glass transition of hemicellulose. At the temperatures above 50 ℃, an increasing trend of loss factor with heating time due to the hydrothermal softening of lignin was observed for wood with 9.08% -19.39% MC. It is suggested that the hemicellulose and lignin softening occur at higher temperatures or higher moisture content with shorter heating times.

Key words: Chinese fir, moisture content, hydrothermal, relative storage modulus, loss factor

CLC Number:

S781

Jiang Jiali, Lü Jianxiong. Hydrothermal Effects on Dynamic Viscoelastic Properties of Wood[J]. Scientia Silvae Sinicae, 2014, 50(12): 101-108.

References

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Hydrothermal Effects on Dynamic Viscoelastic Properties of Wood

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