Kinetics of swollen surface layer formation in the diffusion process of polymer dissolution

Abstract

The diffusion process of polymer dissolution in liquid solvents and the kinetics of the surface swollen layer formation have been studied. The following fundamental kinetic paraeters of the dissolution and swelling processes have been presented: the rate of dissolution u _OC and its relevant thermodynamic and kinetic parameters (ΔH ^≠_d and ΔH ^≠_D,d ); the induction period of dissolution t _Q and its apparent activation energy values in the swelling process (ΔH ^≠_s ); and, in the diffusion process connected with swelling (ΔH ^≠_D,s ). Both the kinetic and thermodynamic activity of individual solvents for given polymers (carboxymethylcellulose (CMC), hydroxyethylcellulose (HEC) and polyvinyl chloride (PVC)) have been expressed through the internal quantities RA _δ,s and RA _δ,d, i.e., expansion work of the polymeric coil accomplished by action of the internal pressure P _i.