Dynamic analysis of crystal transformation of cellulose

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(1) A highly oriented film of microcrystalline Cladophora cellulose was heated in helium atmosphere, resulting in the transformation of cellulose Ia to cellulose Ib. This process was followed by a position-sensitive proportional counter (PSPC) and the change in the crystal lattice was successfully recorded. While the exact molecular mechanism of the transformation from cellulose Ia to Ib is not elucidated, our present results will give an important clue to determine whether it involves the rotation of molecular chain.(2) The use of PSPC allowed us to determine simultaneously the deformation of crystal lattice of ramie fiber in both lateral and longitudinal directions. A bundle of 100 ramie fibers was subjected to tensile stress by using the fiber-tensioning device, and a load elongation chart was obtained by recording the three major equatorial reflections with PSPC.Analysis of similarly obtained load-elongation data for the meridional reflection gave longitudinal elastic modulus and poisson ratio of cellulose crystal, 129Gpa and 0.34, respectively.(3) Swelling of ramie fiber by aq.Sodium hydroxice was studied by the use of PSPC and imaging plate (IP), resulting in new information. When aq.NaOH was added in 50 uL aliquots of to a bundle of 400 remie fibers, the change in three major equatorial reflections could be followed simultaneously. Comparison of the change in integral intensity led to the conclusion that the change in crystal lattice does not proceed isotropically but the change in a-axis direction precedes those in other directions, i.e., the hydrogen-bonded molecular sheet in the ab plane appears to be peeled off from the crystallite.(4) cellulose-calcium thiocyanate complex was found to form cellulose I by regenerating in water. This complex was found to be a well-defined fibrous crystal, which is remarkably different from that of alkali cellulose.