Scaling analysis of cotton cellulose/LiCl·DMAc solution using light scattering and rheological measurements

Abstract

Semidilute solution of cotton lint (CC1) in 8 wt % LiCl/N,N- dimethylacetamide was investigated using static light scattering (SLS) and rheological measurements. The reduced osmotic modulus estimated by SLS measurements for CC1 solutions are proportional to c1.16 in the semidilute region. From the exponent of 1.16, de Gennes' scaling theory derives the relationship between radius of gyration, Rg, and molecular weight, Mw, of CC1 as Rg as Rg ∝ M 0.62 This corresponds to the Mark-Houwink-Sakurada exponent of 0.86. This exponent is very close to that estimated from scaling analysis of zero shear rate viscosity, that is 0.85. Apparent radius of gyration, R g,app, estimated by SLS measurements for CC1 solutions are proportional to c-0.5 in the semidilute region. Rg,app indicates the mesh size of polymer entanglement in the semidilute region. On the assumption of the Gaussian behavior of CC1 molecule in the semidilute region, the exponent of -0.5 gives the relationship between the molar mass between entanglements, Me, and c as following relationship: Me ∝ c-1. This agrees with the concentration dependence on plateau modulus estimated from the dynamic viscoelastic measurements. © 2006 Wiley Periodicals, Inc.