Comprehensive analysis of factors influencing the peel strength of EVA film

Ethylene-vinyl acetate copolymer (EVA) can be used as a core adhesive in the manufacturing process of CIGS flexible thin film solar modules. To assess the adhesion properties of EVA, peel strength is often measured using a peel test. However, the peel strength test results are affected by various parameters of the peel test system, so the conditions under which the experiment was run must be fully described and properly analyzed to correctly assess the test results. We conducted a peel test of a composite film layer with EVA as the adhesive, considering the effects of peel angle, peel rate, and peel specimen width on the peel force. The experimental results indicate that under the same test conditions, the ratio of peel forces is approximately equal to the ratio of the widths of the peel specimens. The peel rate primarily affects the peel strength by influencing the viscoelastic response of EVA during the peel process, leading to a change in failure mode. Different peel angles result in different peel forces required to achieve the same interfacial toughness because the tensile stress component dominates at smaller angles, while the shear stress component dominates at larger angles.