Molecular Transport Behavior of Substituted Aromatic Solvents through Biobased Chain Extended Polyurethane

Abstract

The biobased chain extended polyurethane (PU) was obtained by reacting castor oil based polyol with toluene-2,4-diisocyanate (TDI) and chain extender such as glutaric acid. The effect of incorporation of chain extender into PU on the molecular transport of substituted aromatic solvent penetrants (benzene, chlorobenzene and nitrobenzene) was studied in comparison with a neat PU. Sorption (S) studies were carried out at different temperatures viz., 25, 40 and 60°C. From the sorption results, the diffusion (D) and permeation (P) coefficients of penetrants have been calculated. A significant increase in the diffusion and permeation coefficients were observed with an increase in the temperature of the sorption experiments. Higher values of diffusion and permeation coefficients were noticed for chain extended PUs as compared to PU. Attempts were made to estimate the empirical parameters like n, which suggests the mode of transport and K is a constant depends on the structural characteristics of the composite in addition to its interaction with penetrants. The temperature dependence of the transport coefficients has been used to estimate the activation energy parameters for diffusion (ED) and permeation (Ep) processes from Arrhenius plots.