Dynamic Viscoelastic Properties of Wood Treated by three Drying Methods Measured at High-Temperature Range
Keywords:
Chinese fir, dynamic viscoelastic properties, different drying methods, micro-Brownian motion, apparent activation energyAbstract
The heartwood of Chinese fir was dried by high-temperature drying (HTD), low-temperature drying (LTD), and freeze-vacuum drying (FVD), respectively. The dynamic viscoelastic properties were investigated at a temperature range from 30 to 280°C at frequencies of 0.5-10 Hz using the technique of Dynamic Mechanical Analysis (DMA). The results showed that two relaxations labeled as α and β were detected in the order of the decreasing temperatures at which they occurred, attributed to the micro-Brownian motion of the amorphous cell-wall polymers and the molecular motion of lignin, respectively. The loss peak temperature in β relaxation of HTD wood was the lowest, probably because of the degradation of hemicellulose in the amorphous region. The highest apparent activation energy (ΔE) of HTD wood suggested that more bonds among molecular chains were broken in its segmental motion.References
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