Nanoscale hygromechanical behavior of lignin
Nanoscale hygromechanical behavior of lignin
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DOI：
10.1007/s10570-018-2045-3
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发表时间：
2018-11-01
期刊：
影响因子：
5.7
通讯作者：
Srubar, Wil V., III
中科院分区：
文献类型：
--
作者：
Hess, Kristen M.;Killgore, Jason P.;Srubar, Wil V., III
本文介绍了木质素的纳米尺度水力学行为。采用三种原子力显微镜实验方法，研究了木质素的吸湿性与其力学性能之间的关系。首先，采用悬臂式质量传感建立了吸附等温线，随后使用Guggenheim-Anderson-de Boer模型进行了预测。木质素颗粒的吸附等温线遵循可重复的循环趋势，在相对湿度（RH）约79%时，最大含水率约为17%。其次，利用接触共振力显微镜（CR-FM）获得三维纳米力学对比图像，观察木质素在三个RH循环中的水力学响应。最后，利用力体积映射和Hertz模型计算木质素弹性模量随含水率的变化规律。随着相对湿度的增加，CR-FM测量显示出初始的地形不均匀性，以及明显的表面软化，特别是在初始光滑的区域。随着含水率从0.024增加到9.1 ~ 17.3%，光滑区平均弹性模量从9.0 ~ 4.3 ~ 2.4 GPa下降。循环测量证实木质素的弹性模量在水分解吸后反弹。
The nanoscale hygromechanical behavior of lignin is presented in this work. Three atomic force microscopy experimental methods were used to correlate moisture sorption of lignin to its mechanical behavior. First, sorption isotherms were established using cantilever mass sensing and subsequently predicted using the Guggenheim-Anderson-de Boer model. The sorption isotherms of lignin particles followed a repeatable and cyclic trend reaching a maximum moisture content of approximate to 17% at approximate to 79% relative humidity (RH). Second, 3D nanomechanical contrast images were obtained using contact resonance force microscopy (CR-FM) to observe the hygromechanical response of lignin over three RH cycles. Finally, force volume mapping and the Hertz model were used to compute the elastic modulus of lignin as a function of moisture content. As RH increased, CR-FM measurements revealed initial topographical heterogeneity, as well as notable surface softening, especially in initially smooth domains. The average elastic modulus of the smooth domain decreased from 9.0 to 4.3 to 2.4 GPa as the moisture content increased from 0.024 to 9.1 to 17.3%, respectively. Cyclic measurements confirm that the elastic modulus of lignin rebounds upon moisture desorption.