Crystalline Character of Native and Chemically Treated Saudi Arabian Cotton Fibers

Abstract

The crystalline character of Saudi Arabian cotton fibers was studied using a wide angle x-ray diffraction technique. The purified cotton fibers were examined in their native state and after treatment with urea or caustic soda (NaOH). Cellulosic phases in Saudi Arabian cotton were identified by measuring and indexing the reflections 101, 101, and 002. The x-ray diffractograms showed a cellulose I structure in native cotton fibers as well as those treated with urea. Cotton fibers treated with NaOH and with urea followed by NaOH showed a cellulose II structure. Computer data processing was used to determine the percent crystallinity, lattice spacings, disorder parameter, and crystallite sizes. The percent crystallinity of native cotton decreased from 64% to 47% with mercerization (NaOH). The lattice spacings calculated from the resolved peak positions indicated that d ₁₀₁ for each phase increased by 1 %, while both d₁₀₁ and d₀₀₂ decreased with treatment. The disorder parameter increased from 0.0094 to 0.0123 with mercerization. The crystallite sizes L ₁₀₁ and L₁₀₁ were 3.75 and 2.61 nm, respec tively, for native cotton, and changed to 3.39 and 2.64 nm with the urea treatment. With mercerization, L ₁₀₁ and L₁₀₁ were 4.35 and 3.15 nm, respectively, but with mercerization after the urea treatment, the crystallite sizes dropped to 1.27 and 2.85 nm, respectively. In the direction perpendicular to the c-axis, the crystallite sizes (L₀₀₂) were 4.32, 3.7, 3.07, and 2.94 nm for the untreated cotton, urea treated, mercerized, and mercerized after urea treatment, respectively.