Synchrotron X-ray measurements of cellulose in wood cell wall layers of Pinus densiflora in the transmission and reflectance modes. Part 1: results without loading

Abstract

Abstract Synchrotron radiation X-ray diffraction (XRD) was applied to determine the cellulose content in 5-mm-thick sections of the annual rings of Japanese red pine (Pinus densiflora). Recent samples (air-dried in the last few years) and aged samples (250 years old) were investigated; the cellulose content in the S2 layer was measured by the transmission (Trs) method and that in the S1 and S3 layers by the reflection (Ref) method. Measurements were performed in the cellulose (004) Ref plane. The two XRD methods resulted in very different two-dimensional (2D) diffraction patterns, indicating differences in the cellulose characteristics. Azimuthal angle profiles showed cellulose chains measured by the Trs and the Ref methods oriented at about 9° and 75°, respectively, in terms of the longitudinal axis of the specimens. Moreover, 2θ profiles obtained by the Ref method had full-width-at-half-maximum (FWHM) values ≈3.5 times greater than the corresponding Trs profiles, indicating large variations in the cellulose lattice spacing d004. The 250 years of aging had no effect on the cellulose contents.