Long-Time Exudation of Plasticizer from Swollen Rubber Vulcanizates: (II) Diffusivity during Exudation

Abstract

In the first paper in this series, two mutually consistent kinetic models were put forth to evaluate concentration-dependent diffusion coefficients of plasticizer during the extensive swelling and exudation processes of several typical rubber vulcanizates containing it. According to the model for swelling, the diffusivities were estimated using experimental data taken from the literature. In this paper the counterpart for exudation is applied to the exudation data of the same systems and diffusivities and exudation times taken to reach equilibrium are both estimated. The predicted results are compared with those of the swelling case. The results of both cases are used to account for the remarkable difference between the swelling/exudation behaviors and the lengthy exudation time as compared with the corresponding swelling time.

Keywords:

• diffusion coefficient
• exudation kinetics
• Fickian approach
• plasticizer
• vulcanized rubber