Long-term storage and shelf life of STR’s EVA-based encapsulants have been studied and characterized. The most significant impact of long-term storage can be observed with the encapsulant’s adhesive strength. Generally, encapsulant adhesion decreases with storage time (Figure 1).

This decrease in adhesion is due to moisture penetration and absorption by the primer component (prior to module lamination) blended in the encapsulant, which is responsible for the adhesion. Unlike adhesion, gel content is not affected by storage time (Figure 2).

When storing EVA-based encapsulant product, it is recommended to keep the product at the lowest humidity as possible in order to minimize moisture exposure. However, product usage rate and product packaging will influence storage conditions.

If product usage rate is high and stock turnover frequent, then an air-conditioned area may be sufficient. If the storage facility is in a humid location and/or usage rates are low, then refrigerated storage may be best.

Storage conditions will also be dependent on product packaging. Product in STR’s standard packaging should follow our general recommendation by minimizing humidity as much as possible during storage. Premium packaging is a much more robust packaging configuration and is not easily influenced by environmental conditions. STR recommends premium-packed products are kept indoors and away from physical damage. Premium packaging is also recommended for product that is shipped overseas via ocean freight