Determination of the cross-linking degree of commercial ethylene-vinyl-acetate polymer by luminescence spectroscopy

Ethylene-Vinyl-Acetate is the most common encapsulation polymer in photovoltaic modules. Its degree of crosslinking is a critical parameter of the production process, greatly influencing the durability of the product. The luminescence of Ethylene-Vinyl-Acetate with UV excitation is presented here as a non-destructive method to determine the degree of crosslinking. The luminescence intensity increases with the degree of crosslinking. Supposing a linear correlation the method allows determining the degree of crosslinking with a relative precision of 12 %. This optical method it is suitable and comparatively easy to apply for an industrial in-line measurement.