1. An empirical model for sorption by glassy polymers: An assessment of thermodynamic parameters
- Author
-
Ivan Argatov and Vitaly Kocherbitov
- Subjects
Flory-Huggins interaction parameter ,Materials science ,Sorption isotherms ,Polymers and Plastics ,Thermodynamic parameter ,Flory-Huggins parameter ,Thermodynamics ,Flory-Huggins ,02 engineering and technology ,Flory–Huggins solution theory ,010402 general chemistry ,Physical Chemistry ,01 natural sciences ,Glassy polymers ,Maximum variations ,Biopolymers ,Empirical model ,Position (vector) ,Polymers and polymer manufacture ,Fysikalisk kemi ,chemistry.chemical_classification ,Fitting model ,Huggins equation ,Adsorption isotherms ,Organic Chemistry ,Temperature ,Sorption ,Function (mathematics) ,Polymer ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Condensed Matter::Soft Condensed Matter ,Flory–Huggins interaction parameter ,TP1080-1185 ,chemistry ,Volume fraction ,Sorption isotherm ,Solvents ,Glass ,Linear approximation ,0210 nano-technology ,Glass transition - Abstract
A new fitting model for sorption by glassy polymers is suggested based on the Flory–Huggins (FH) equation with a composite formula for the FH interaction parameter, χ, which is applicable if sorption experimental data shows a single-maximum variation of the FH parameter. Namely, a power-like and a linear approximation is assumed for χ ( φ 1 ) , as a function of solvent volume fraction φ 1 , before and after the point of its maximum. After determining the maximum point from a direct inspection of the sorption data, the three fitting parameters are evaluated by solving two independent least-square minimization problems. Several sorption studies of biopolymers taken from the literature show that the endset of the glass transition region is correlated with the position of the maximum of the FH interaction parameter. Based on this hypothesis and the Vrentas–Vrentas model for sorption of glassy polymers, a theoretical framework for the glass transition analysis is developed. In particular, the solvent-induced glass transition temperature variation can be estimated from the sorption isotherm as a function of the solvent content corresponding to temperatures above the temperature of sorption.
- Published
- 2021