Thermodynamic and Hydrodynamic Properties of Cellulose Diacetate–Dimethylacetamide Solutions

Abstract

Viscometric and light scattering investigations were carried out on cellulose diacetate (degree of substitution, DS=2.46) in dimethylacetamide (DMAc) at 25°C. The following molecular weight dependence of limiting viscosity number [η], radius of gyration ‹S2›z1/2 and Flory’s viscosity parameter Φ were obtained: [η]=1.34×10−2 Mw0.82 (cm3 g−1), ‹S2›z1/2=0.68×10−8 Mw0.53 (cm), and Φ=5.15×1021 Mw0.23. Draining effect was not negligible for this system. The unperturbed chain dimension A was determined by methods 2B, 2C, 2E, 2F, and 2G proposed previously [K. Kamide and Y. Miyazaki, Polym. J., 10, 409 (1978)]. The A values obtained by methods 2B, 2C, and 2G were in good agreement with each other and the most probable A value was found to be 1.98×10−8 (cm). The variation in [η], ‹S2›z1/2, and A with solvent is discussed in terms of the dielectric constant of the solvent and also the chemical shifts of the O-acetyl methyl and hydroxyl groups.