Solubility parameters of polymers from swelling measurements at 60°C

The swelling behavior of the networks of natural rubber, an epoxidized natural rubber, low-density polyethylene, polystyrene, and poly(methyl methacrylate) are studied in six classes of solvents at 60°C. The data of the swelling coefficient are successfully treated by a modified version of the empirical equation proposed by Gee, as to determine the solubility parameter of a polymer, δ₂. It is found that increasing the temperature would decrease the δ₂'s of these polymers with a common rate of 0.02 (J/mL)^1/2/K. A semiempirical model is proposed to rationalize the present finding satisfactorily. © 1995 John Wiley & Sons, Inc.