A structural–thermodynamic study of triphenylsilylcellulose

Abstract

AbstractThe purpose of this article is to report the characterization of a solution of triphenylsilylcellulose (TPSC) in terms of its rheologic properties by osmometry and viscometry to better understand processing parameters and conditions. This work is an extension of previous similar work on trimethylsilylcellulose (TMSC). TPSC was prepared in a medium of dimethylformamide (DMF) plus pyridine, under heterogeneous starting conditions and nitrogen atmosphere, by silylation of activated celluloses with triphenylchlorosilane at 115–120 °C. The isolated and purified ethers were characterized according to their polydispersities and their substitution degrees, by osmometry and viscometry in various solvents. The Mark–Houwink–Sakurada equation coefficients were evaluated in 1,1,1‐trichloroethane, chloroform, and o‐xylene at 30 °C and in o‐xylene over the 30–70 °C temperature range. The values of 2.12–2.18 obtained for exponent “a” correlated with the very low values of pre‐exponential factor (of 10−12 order), indicating a high stiffness of the macromolecular chains. The viscous flow parameters for dilute solutions of TPSC in o‐xylene were determined in the temperature range 30–70 °C. The temperature dependence of the dynamic viscosity of the solutions obeys an Arrhenius‐type equation in which the apparent activation energy is linearly dependent on both the concentration and molecular weight of the solution. No significant dependence on concentration and molecular weight was found for the pre‐exponential factor. This behavior was attributed to the great stiffness of the macromolecular chains. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2875–2884, 2002