Synchrotron X-ray fiber diffraction study on the thermal expansion behavior of cellulose crystals in tension wood of Japanese poplar in the low-temperature region

Abstract

Abstract The thermal expansion behavior of tension wood cellulose obtained from Populus maximowiczii A. Henry was investigated by synchrotron X-ray fiber diffraction at temperatures ranging from 100 to 300 K. Three equatorial and one meridional d-spacings indexed as , 110, 200, and 004 showed a gradual linear increase with increasing temperature. Unit-cell parameters calculated from the changes in these d-spacings showed anisotropic thermal expansion behavior in the three axial directions related to the crystal structure and hydrogen-bonding system of cellulose Iβ. The linear thermal expansion coefficients (TECs) of the a-, b-, and c-axes were: α a=5.2×10-5 K-1, α b=2.1×10-5 K-1, and α c=0.4×10-5 K-1, respectively. The volume TEC was β=7.8×10-5 K-1, which was approximately 70% of previously reported values in the high-temperature region from room temperature to 250°C.