Silicone elastomers have industrial relevance as adhesives, sealants, and engineered parts in a myriad of commercial applications. Commercial silicones can be subject to a variety of curing conditions and harsh aging conditions, such as complex strain fields, that complicate predictions of component lifetime and performance. Non-destructive methods that can quantify changes in silicone chemistry are needed to further our understanding of how environmental stressors contribute to material curing and degradation. Residual proton dipolar couplings present due to topological constraints that prevent complete motional averaging are quite sensitive to morphological changes throughout elastomers. Magnetic resonance imaging (MRI) provides an opportunity to spatially resolve fluctuations in dipolar couplings within a sample via changes in transverse relaxation times (T2). Here, we report the application of T2-weighted MRI not only to quantify the curing kinetics of a silicone sealant but also to visualize areas of material degradation in silicone elastomers as a function of compressive strain and material aging. The results presented here are part of an ongoing effort to develop non-destructive methodologies that can be used to monitor subtle changes in network chemistry as a function of curing, stress, and material lifetime.
This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344. LLNL-ABS-774088.