Many aspects of polymer materials performance and reliability depend on molecular mobility, interactions of the polymer with small molecules, and hence the nature of diffusion processes. These range from sorption and desorption behavior all the way to mass transfer under reactive competitive conditions or through barrier materials, with the fundamentals and mathematics of such processes having been sufficiently described in the literature. Materials may degrade due to ingress of oxygen or water, or may act as the source of off-gassing volatiles and impurities resulting in concerns for materials compatibility in assemblies and overall reliability. Similarly, accelerated aging by nature will involve permeation processes. Unfortunately, diffusion in polymers in not always easy to measure and its temperature behavior is not clearly understood, with free volume and Tg often regarded as key drivers for diffusivity, but comprehensive data sets not being available. We will present a brief overview of recent approaches towards quantification methods for oxygen and water diffusion in glassy thermosets and other polymers, as well as avenues to expand such studies towards spectroscopic monitoring of small molecule diffusion in polymer films, all as a function of temperature. Data will be discussed in the context of free volume and Tg, and our current understanding of diffusivity. All of these efforts are geared towards quantification of sorption/desorption phenomena and diffusion kinetics for predictive aging of these materials, off-gassing behavior and improved models towards long-term materials reliability.

H2O and O2 sorption and diffusion behavior in thermoset polymers with temperature

2019 Spring National Meeting

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