The cross-linking chemical reaction of EVA (Ethylene Vinyl Acetate) film in laminated glass offers several advantages. It improves the mechanical properties of the material, enhances durability under harsh conditions, and offers excellent adhesive bonding.
EVA is a key material used for traditional solar panel lamination. Once laminated, EVA sheets play an essential role in preventing humidity and dirt from penetrating the solar panels. It also helps the solar cells ‘float’ between the glass and backsheet, absorbing shocks and vibrations, thus protecting the solar cells and their circuits. Quality EVA film is known for its excellent durability, even in challenging weather circumstances such as high temperature and high humidity. Cross-linking is the general term for forming covalent bonds or short sequences of chemical bonds to join two polymer chains together. It usually refers to the use of cross-links to promote a change in the polymers’ physical properties. When the entire bulk of the polymer has been exposed to the cross-linking method, the resulting modification of mechanical properties depends strongly on the cross-link density. Low cross-link densities increase the viscosities of polymer melts. Intermediate cross-link densities transform gummy polymers into materials that have elastomeric properties and potentially high strengths. Very high cross-link densities can cause materials to become very rigid or glassy. Cross-linking can also be induced in materials that are normally thermoplastic through exposure to a radiation source. For example, electron beam processing is used to cross-link the C type of cross-linked polyethylene. Cross-linking can improve the mechanical properties of the polymeric material and also can improve the adhesion between two interfaces of the coating. In a study investigating the relationship between the cross-linking level of copolymer of ethylene and vinyl acetate (EVA) as the encapsulant and the degree of degradation due to potential induced degradation (PID) phenomenon, it was found that PV modules encapsulated by EVA with a higher cross-linking level showed a lower degradation degree due to the PID phenomenon. EVA with a higher cross-linking level also tended to have higher volume resistivity. The study concluded that PV modules encapsulated by EVA with a higher cross-linking level, higher volume resistivity, and increased thickness would be more tolerant of the PID phenomenon.
In conclusion, the cross-linking chemical reaction of EVA film in laminated glass has several benefits, such as improving the mechanical properties of the material, enhancing its durability, and providing excellent adhesive bonding. It also makes the material more resistant to potential induced degradation, which is critical in applications like solar panels.