Kuribayashi Tomoko, Ogawa Yu, Rochas Cyrille, Matsumoto Yuji, Heux Laurent, Nishiyama Yoshiharu
Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-Ku, Tokyo 113-8657, Japan.
CNRS, CERMAV, F-38000 Grenoble, France.
ACS Macro Lett. 2016 Jun 21;5(6):730-734. doi: 10.1021/acsmacrolett.6b00273. Epub 2016 May 27.
The ultrastructural transformation of wood cellulose crystals by hydrothermal treatment was followed by synchrotron and standard X-ray scattering experiments. When treated at 200 °C for 2 h in the presence of an excess of water, a significant sharpening of the equatorial reflections of crystalline cellulose was observed, and the average crystallite size, estimated from the X-ray line broadening, was twice as large as that of untreated wood cellulose. During the treatment, the cellulose structure was converted from the native monoclinic form of cellulose I into a pseudo-orthorhombic system, coined as cellulose I', a transformation occurring only with an excess of water, above 180 °C and after more than half an hour. In situ experiments indicated that the increase of crystallite size was likely due to cocrystallization of individual crystallites rather than to the crystallization of the amorphous domains of cellulose.
通过同步加速器和标准X射线散射实验跟踪了水热处理对木材纤维素晶体的超微结构转变。当在过量水存在下于200℃处理2小时时，观察到结晶纤维素赤道反射显著锐化，根据X射线线宽估计的平均微晶尺寸是未处理木材纤维素的两倍。在处理过程中，纤维素结构从天然的单斜晶型纤维素I转变为伪正交晶系，称为纤维素I'，这种转变仅在过量水存在、温度高于180℃且经过半小时以上时发生。原位实验表明，微晶尺寸的增加可能是由于单个微晶的共结晶，而不是纤维素无定形区域的结晶。
