The Viscoelastic Properties of Chinese Fir During Water-Loss Process Under Hydrothermal Conditions

Abstract

In this article, the viscoelastic properties of water-swollen Chinese fir during a water-loss process under different hydrothermal conditions (30–90°C, 40–80% RH) were investigated. After the 300 min hydrothermal process at 70 or 90°C, the moisture contents (MCs) of the specimens were well below the MC value at the fiber saturation point. During the hydrothermal process, normalized E′ increased at first, and then leveled off at temperatures above 50°C. The wood specimens were softened due to the hydrothermal effect. The glass transition of hemicellulose appeared at 50°C. Lignin transition was observed at 70 and 90°C. Superposition of transitions of lignin and hemicellulose moved to low storage modulus E′ with increasing temperature and RH level.

Keywords:

• Chinese fir
• Cole-Cole diagrams
• Hydrothermal
• Viscoelastic properties
• Water-loss process