Interaction parameter (χ); expansion factor (ε); steric hindrance factor (σ); and shielding function F(ξ); for the system PEA-organic solvents by intrinsic viscosity measurements

Abstract

In this work we present experimental data of the Flory binary interaction parameter, χ, of poly (ethylene adipate) PEA, a plasticizer material. We have used the viscometric method for measuring dilute PEA solutions in good solvents: benzene, chloroform and acetone. A procedure based on the Stockmayer-Fixman, (SF), hydrodynamic solutions theory, allows us to evaluate some thermodynamic parameters via the intrinsic viscosity [η], measured in several good solvents. This method also estimates the unperturbed parameter, k0, and the steric hindrance parameter, (σ), by viscosity measurements at constant temperature of 30°C. By correlation of the molecular weight (M) and intrinsic viscosity data, according to the Stockmayer-Fixman (SF) solution theory model, values of Flory binary interaction parameter χ, equal χ1,2 =0.1544 ± 0.01; χ1,2 =0.1631 ± 0.01; and χ1,2 =0.1922 ± 0.01, for PEA in benzene, chloroform and acetone, respectively, were obtained. In addition we applied the Debye-Bueche theory, in order to estimate values of: expansion factor (ε), shielding factor (ξ) and depth of shielding (L) for the system PEA-organic solvents, by [η] and (M) experimental data correlation. The results confirm that values obtained, correspond to "good solvents" for the PEA polymer. ©2005 Sociedade Brasileira de Química.