Modeling liquid diffusion in highly cross-linked polymer resins

Description

Highly crosslinked polymers play a key role in protecting sensitive electronic components in medical devices by serving as encapsulation materials that shield the interior against liquids or steam during sterilization. However, these resins are also capable of absorbing liquids, which can cause short circuits in the electronics.
We are currently investigating the swelling behavior of epoxy and phenolic resins, as well as silicon, in water, heptane, and isopropanol.[1] To measure the change in weight during swelling, we are conducting experiments in liquids or steam. Additionally, we are simulating the swelling behavior using the PC-SAFT theory[2], which considers the stretching of polymer chains due to liquid uptake and the repelling forces that this causes against further uptake. This elastic contribution is combined with the network term of Miao et al[3]. The model parameters are fitted to the total liquid uptake and polymer density, as we have previously described in our publications.[4] Thus, the diffusion with multiple solvents is described using only one parameter set for the polymer.
Diffusion is modeled using the Maxwell-Stefan equation, where the driving force is the chemical potential, which is calculated using PC-SAFT. For linear diffusion behavior, we supplement the Maxwell-Stefan model with the viscoelastic Kelvin-Voigt model, which combines a viscous damper and elastic spring in parallel.
At this conference, we are presenting and discussing our latest experimental and simulation results, including a comparison of predicted and experimental total uptake. We are also comparing the measured time-dependent solvent uptake with simulation results in 1D, 2D, and 3D dimensional space to examine the diffusion behavior. Our approach introduces a method for predicting diffusion behavior within electronic encapsulation.

Period	8 Nov 2023
Event title	AIChE Annual Meeting 2023
Event type	Conference
Location	United States, FloridaShow on map
Degree of Recognition	International