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首页> 外文期刊>Wood Science and Technology >Effect of weight percent gain and experimental method on fiber saturation point of acetylated wood determined by differential scanning calorimetry
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Effect of weight percent gain and experimental method on fiber saturation point of acetylated wood determined by differential scanning calorimetry

机译：增重和实验方法对差示扫描量热法测定乙酰化木材纤维饱和点的影响

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摘要

This paper evaluates the effects of acetylation level and experimental method on the observed fiber saturation point (FSP) of loblolly pine (Pinus taeda) wood measured using differential scanning calorimetry. To achieve this goal, 1-mm-thick latewood samples were tested over a wide range of equilibrium moisture content (EMC). In this work, the FSP was defined as the non-freezable portion of water of the samples. Two experimental methods were used: the extrapolation of the melting enthalpy to zero and the direct calculation of the non-freezable water amount. For both methods, the FSP decreased with increasing acetylation, varying from about 27% reduced EMC (EMCR) for control to about 9% EMCR for the highest level of acetylation. For unmodified samples, the measured FSP was higher with faster scan rates. Moreover, under a specific range of EMCR, freezing curves revealed the occurrence of two water phase transitions for samples at the highest level of acetylation. Based on previous studies and in present findings, there is strong evidence that the lower temperature freezing peak may result from the homogenous nucleation of water, which is physically separated from water that freezes heterogeneously.
机译：本文评估了乙酰化水平和实验方法对差示扫描量热法测量的火炬松（Pinus taeda）木材的观察到的纤维饱和点（FSP）的影响。为了达到这个目标，在很宽的平衡水分含量（EMC）范围内测试了1毫米厚的胶木样品。在这项工作中，FSP被定义为样品中水的不可冻结部分。使用了两种实验方法：将熔融焓外推至零和直接计算不可冻结的水量。对于这两种方法，FSP随着乙酰化程度的增加而降低，从控制降低的EMC（EMCR）降低约27％，到乙酰化程度最高的EMCR降低约9％。对于未修饰的样品，以更快的扫描速率测得的FSP较高。此外，在EMCR的特定范围内，冰冻曲线显示出乙酰化程度最高的样品发生了两个水相转变。根据以前的研究和当前的发现，有充分的证据表明，较低的温度冻结峰可能是由于水的均相成核而引起的，而水的均质成核是从与异质冻结的水中物理分离出来的。

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  • 来源
    《Wood Science and Technology》 |2017年第6期|1291-1305|共15页
  • 作者

    Passarini Leandro; Zelinka Samuel L.; Glass Samuel V.; Hunt Christopher G.;

  • 作者单位

    US Forest Serv, Bldg & Fire Sci, Forest Prod Lab, 1 Gifford Pinchot Dr, Madison, WI 53726 USA;

    US Forest Serv, Bldg & Fire Sci, Forest Prod Lab, 1 Gifford Pinchot Dr, Madison, WI 53726 USA;

    US Forest Serv, Bldg & Fire Sci, Forest Prod Lab, 1 Gifford Pinchot Dr, Madison, WI 53726 USA;

    US Forest Serv, Forest Biopolymer Sci & Engn, Forest Prod Lab, 1 Gifford Pinchot Dr, Madison, WI 53726 USA;

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