Dynamic viscoelastic properties of wood acetylated with acetic anhydride solution of glucose pentaacetate
Dynamic viscoelastic properties of wood acetylated with acetic anhydride solution of glucose pentaacetate
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DOI：
10.1007/s100860300024
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发表时间：
2003-01-01
影响因子：
2.9
通讯作者：
Gril, J
中科院分区：
文献类型：
--
作者：
Obataya, E;Furuta, Y;Gril, J
用葡萄糖五乙酸酯（GPA）的乙酸酐（AA）溶液对云杉木材进行乙酰化处理，并在不同相对湿度和温度下，将其沿径向沿着的粘弹性能与未处理和正常乙酰化的试样进行比较。当GPA被引入木材细胞壁时，更高浓度的GPA/ AA溶液导致木材更大的溶胀。在室温下，乙酰化木材的动态杨氏模量（E）提高了10%，而其机械损耗角正切（tan δ）几乎保持不变。这些变化被解释为木材细胞壁中庞大的GPA分子的抗增塑作用。在没有水分的情况下加热时，GPA-乙酰化木材在150 ℃以上表现出明显的E'下降和明显的tan δ峰，而未处理木材的E'和tan δ在200 ℃以下相对稳定。GPA乙酰化木材的tan δ峰随着GPA含量的增加而向较低温度移动，并且由于GPA本身的熔融而没有tan δ峰。因此，显着的热软化的GPA-乙酰化木材归因于软化的木材组分与GPA增塑。
Spruce wood specimens were acetylated with acetic anhydride (AA) solutions of glucose pentaacetate (GPA), and their viscoelastic properties along the radial direction were compared to those of the untreated and the normally acetylated specimens at various relative humidities and temperatures. Higher concentrations of the GPA/ AA solution resulted in more swelling of wood when GPA was introducted into the wood cell wall. At room temperature the dynamic Young's modulus (E) of the acetylated wood was enhanced by 10% with the introduction of GPA, whereas its mechanical loss tangent (tan delta) remained almost unchanged. These changes were interpreted to be an antiplasticizing effect of the bulky GPA molecules in the wood cell wall. On heating in the absence of moisture, the GPA-acetylated wood exhibited a marked drop in E' and a clear tan delta peak above 150degreesC, whereas the E' and tan delta of the untreated wood were relatively stable up to 200degreesC. The tan delta peak of the GPA-acetylated wood shifted to lower temperatures with increasing GPA content, and there was no tan 6 peak due to the melting of GPA itself. Thus the marked thermal softening of the GPA-acetylated wood was attributed to the softening of wood components plasticized with GPA.