For improved polymer lifetime predictions it is necessary to establish relevant correlations between physical property changes and oxidative chemistry as well as to extrapolate relatively slow oxidative reactions to lower temperatures. Significant challenges in lifetime extrapolations to lower temperatures, such as in mechanical strength or bulk modulus, also exist because oxidative reactions are spatially variant, and thus lower temperature behavior may exhibit dissimilar thermal dependence in specific polymer property changes as a function of sample geometry and material transitions.Simple 1D localized oxidative degradation models have been available via kinetic or DLO models for many years. As an extension of this work, we have succeeded to predict spatially resolved degradation processes for layered materials in 2-dimensions, and 3D where symmetry is valid, using Galerkin FEM approaches to accommodate boundaries or material transitions, i. e. step changes in oxygen permeation and similar parameters. Elastic modulus can then be spatially predicted when oxidative correlations from non-DLO conditions exist. Oxidation rate pressure dependence also affects permeation experiments, which have been demonstrated as a method for deducing the rate-pressure dependence through spatially resolved simulation. Analytical treatment of the spatial differential equation is shown to yield a solution for the total O2 flux as a function of oxidation rate and oxygen permeation, which has not been previously demonstrated.

Modeling of spatially dependent oxidative degradation

248th National Meeting (2014)

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