Factors for Phyllostachys edulis timber glass transition temperatures

Abstract

To provide a theoretical basis for bamboo softening and flattening, a dynamic mechanical analyzer （DMTA） was used at various initial moisture contents （MC） （0%, 15%, 30%, 60%, and water saturation）, radial positions （outer, median, and inner layers）, ages （3, 5, and 7 years old）, and heights （2.5 m, 4.0 m, 5.5 m） to study the glass transition temperature （Tg） of Phyllostachys edulis bamboo. The test were performed between 30.0－260.0 ℃ with heating rate 5 ℃min－1, and amplitude 5 m and a frequency of 3 Hz. Results showed: that （1） with an increase of MC at 50.0－250.0 ℃, Tg decreased from 217.3 ℃ to 113.0 ℃. Initial MC changes at lower levels （＜15% MC） had a greater effect on Tg than moisture content changes ＞15% MC. （2） The Tg for the outer, median, and inner layers of bamboo along the radial direction showed little differences under the same age, initial MC, and height; maximum difference in Tg was 12.0 ℃ and minimum was 0.5 ℃. （3） With identical radial positions and initial MC, different ages and the heights did not affect bamboo Tg which had differences of less than 5.0 ℃. This study showed that an increased initial MC was good for bamboo softening and will, thus, help make full use of materials in the production process. ［Ch, 4 fig. 2 tab. 22 ref.］