Stochastic 3D modeling of non-woven materials with wet-proofing agent

A novel, realistic 3D model is developed describing the microstructure of non-woven GDL in PEMFC which consists of strongly curved and non-overlapping fibers. The model is constructed by a two-stage procedure. First we introduce a system of random fibers, where the locations of their midpoints are modeled by a 3D Poisson point process and the fibers themselves by random 3D polygonal tracks which represent single fibers in terms of multivariate time series. Secondly, we transform the random fiber system into a system of non-overlapping fibers using an iterative method leaned on the so-called force-biased algorithm. The model is validated by comparing transport-relevant characteristics computed for experimental 3D synchrotron data, and for realizations sampled from the stochastic microstructure model. Finally, we suggest a model for the spatial distribution of PTFE, a wet-proofing agent often used in non-woven GDL, and combine this PTFE model with our new microstructure model for non-woven GDL.