CO2 absorption into a polymer within a multilayer structure: The case of poly(ethylene-co-vinyl acetate) in photovoltaic modules

The delamination of photovoltaic modules with supercritical CO2 is an interesting approach to integrate photovoltaics into a circular economy. This article describes the first phase of this process: the absorption of CO2 into poly(ethylene-co-vinyl acetate) (EVA-28), one of the layers in a photovoltaic module. The swelling of the polymer, determined by an on-line coupling between high pressure cell and an optical method using digital camera, under 60-200 bar at 60, 75 and 90 degrees C, was well reproduced by a modified Sanchez-Lacombe equation of state. The diffusion coefficient of CO2 into EVA-28 was determined using the same approach and was found to range, at 130 bar, from 1.1 x 10(-9) m(2).s(-1) at 60 degrees C to 1.8 x 10(-9) m(2).s(-1) at 90 degrees C. A preferential CO2 diffusion at the rear side of the cell, due to a high porosity, and at the "backsheet" interface was highlighted.