Factors for Phyllostachys edulis timber glass transition temperatures
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摘要: 利用动态机械热分析仪（DMTA）研究毛竹Phyllostachys edulis材在不同初含水率、径向部位、竹龄和高度等条件下的玻璃化转变温度（Tg）并分析其变化规律，旨在为竹材的软化和展平提供理论依据。结果表明：①在温度50.0～250.0 ℃范围，随初含水率增加（0%，15%，30%，60%和饱水），毛竹材的玻璃化转变温度显著降低，从绝干材的217.3 ℃降低到饱水材的113.0 ℃，毛竹材在较低含水率（＜15%）范围内比高含水率（＞15%）范围内变化对毛竹材的玻璃化转变温度影响更明显，表明提高毛竹材初含水率对竹材软化有益。②在相同竹龄、初含水率和高度条件下的毛竹材沿竹壁径向的竹青、竹肉和竹黄的玻璃化转变温度有差别但不显著，两两之间最大和最小分别相差12.0 ℃和0.5 ℃。③在相同径向部位和含水率条件下，不同竹龄和不同高度的毛竹材玻璃化转变温度均无明显差异，相差在5.0 ℃以内。这有助于实际生产中最大化利用原材料。图4表2参22Abstract: 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.］
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https://zlxb.zafu.edu.cn/article/doi/10.11833/j.issn.2095-0756.2015.06.011
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