Relationship between mechanical absorption and birefringence of regenerated cellulose solid in solvent

This study correlates the temperature dependence of birefringence Delta n o f a regenerated cellulose solid in a solvent with thermal chain motion eval uated from mechanical loss tangent tan delta. Two regenerated cellulose hol low fibers composed of fine spherical particles (primary particles) from 10 to 20nm in size were used. Solvents as immersing media were methanol, etha nol, n-propanol, and ethylene glycol. The temperature dependence of Delta n in the solvent was measured by the freezing method and the equilibrium met hod proposed by us. [Bull. Fac. Human Environ. Sci., Fukuoka Women's Univ., 28, 37 (1997)] 1 do vs. temperature curves by the freezing method showed a few peaks at the temperature region where tan delta vs. temperature curve showed peaks or a shoulder. 2 Peak value varied with immersing media and fr eezing conditions. 3 For the sample having anisotropic orientation of the w orking direction of the intermolecular hydrogen bond, a few peaks were obse rved in the case of the freezing method at beta(a) absorption due to a loca l twisting motion of a main chain. 4 In the lower temperature region betwee n beta(a) absorption and alpha(a) absorption, due to a micro-Brownian motio n of a main chain, Delta n was reflected in molecular interactions between the medium and cellulose molecules. In the temperature region of alpha(a) a bsorption, a few peaks of Delta n appears in both methods. Delta n peaks th us correlate closely with the onsets of mechanical absorption.