Test Methods


Some important EVA characteristics for solar module manufacture are EVA adhesion to glass and/or substrate, cured EVA gel content and unrestricted EVA shrinkage.




Adhesion of EVA to substrates is key to the longevity of a module throughout it's operational lifetime. With PHOTOCAP® EVA you can be assured your modules are STR PROTECTED™. Our adhesion control agents promote seals with glass and backsheets to provide a moisture barrier that protects the module during extreme weather. Flucutations in temperature and moisture are no issue.


Evaluating EVA/glass adhesion is a good test to determine if the encapsulant material has been overexposed to moisture during storage or shipping as well as its fitness for use. A 180° peel test can be utilized to measure encapsulant adhesive strength to glass. This simple test involves laminating EVA coupled to a backsheet such as TPE or TPT to glass. The backsheet serves as a pulling substrate during the test.


STR considers EVA glass strength 53 N/10 mm (30 lb/in) or greater satisfactory. Typical glass adhesion values are between 70 and 86 N/10 mm (40-50 lb/in).


 Download Adhesion Test Sheet


Gel Content


Gel content of EVA is a measure of crosslinking of the polymer. Gel content levels of 70% and higher are desired to provide the modules with the mechanical integrity needed to withstand harsh out door environments.


 Download Gel Content Sheet

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