SPLTRAK Abstract Submission
The Natural and Accelerated Evolution of EVA Adhesion through Intermediate Exposures
Patrick Thornton1, Nick Bosco2, Reinhold H Dauskardt1
1Stanford University, Stanford, CA, United States
/2National Renewable Energy Laboratory, Golden, CO, United States

Ethylene vinyl acetate (EVA) encapsulants comprise the majority of the encapsulants currently in use; much work has been done to understand and model the adhesive characteristics of EVA-encapsulated modules, but limited work has provided reliable insight into adhesion during the intermediate stages of exposure, limiting the ability to validate model predictions in this range. Here we provide the critical adhesion energy measurements for EVA adhesion after up to 4 years of field aging in 3 different US locations and 10,000 hours of accelerated aging. Both field and accelerated aging reveal a distinct plateau that emerges during the intermediate exposure periods (after 1 year in the field and after 1,000 hours in a chamber). After 10,000 hours, adhesion strength within accelerated aged mini-modules falls by an order of magnitude and the failure path transitions to the glass/EVA interface – trends generally seen after long-term field exposures (>15 years). Previous adhesive modeling predicted that adhesion would continuously decrease over the lifetime of a module, but these current results uncover an intermediate plateauing trend that is critical to accurately modeling the evolution of adhesion and predicting potential adhesive failure.