Modeling Solvent Absorption in Highly Cross-Linked Polymer Resins with PC-SAFT

In recent years, the swelling of polymer networks was intensively analyzed, especially in the case of hydrogels. But also in the case of highly cross-linked polymers, the knowledge absorption is essential, especially in the case of encapsulation of electronics and sensors as protection against liquids or vapor.

The absorption in highly cross-linked polymers such as epoxy-, polyphenolic resins and silicon will be investigated in this work. In all samples, the uptake of fluids such as water, heptane, isopropanol, and saturated water steam was experimentally analyzed. The resulting absorption equilibria were modeled applying PC-SAFT [1]. Due to the solvent uptake, the polymer chains are stretched, which causes forces acting against a further solvent uptake. These elastic forces are taken into account by combining PC-SAFT with the network term of Miao et al. [2]. According to our previous work [3], the PC-SAFT parameters of the epoxy resin were fitted to the solvent uptake in equilibrium and its density. The modelling of the phase equilibrium with PC-SAFT forms the basis for the modelling of the Maxwell-Stefan mass transfer modelling in the polymer matrix. Hereby also the stretching of the polymer chains was considered by a Kelvin-Voigt approach. So the diffusion of the different solvents could be modelled.

In this work, the modelling of the equilibrium as well as of the mass transfer will be shown and discussed.