The Study On The Aging Properties Of Crosslinking POE Used As Encapsulation Film

In today’s world, with the continuous development of society, environment pollution and energy shortage become the biggest challenge which mankind has to face. One of the most effective ways to solve these problems is to transform clean and renewable solar energy into electricity by use of solar cells. The core component of PV modules is Si solar cells, which posses as long service life as30years. However, transparent polymeric encapsulation that act as fixing, sealing and protecting Si solar cells will discolor or even craze in the process of weathering, seriously affect the efficiency of PV modules, thus leading to a decrease in the service life of PV modules. Thus, it is a key to prepare transparent polymeric encapsulation possessing stable properties and long service life for modules and reducing the cost of PV modules.Polyethylene elastomer (POE) was used as the basic raw materials to prepare weather-resisting POE films for encapsulating PV modules. The additives including curing agent, ultraviolet absorbent, antioxidants were added to POE by melt extrusion to obtain POE films. The effects of curing agents on the gel content of POE films and the adhesion properties with glass and polyethylene terephthalate (PET) films were studied under different curing conditions. Under different curing time and curing temperature, through the orthogonal experiment, the POE film was prepareded and its mechanical properties and curing degree were tested. Then the best curing system of POE films was established. Namely, the curing agent content of dicumyl peroxide (DCP) and triallyl isocyanurate (TAIC) were0.6%and0.5%respectively, curing temperature for135℃, curing time was14minutes. Thus the gel content of the prepared POE film was87.23%, and the peel strength between glass and PET film were126.7N/cm and68.4N/cm, respectively. The tensile strength was20MPa.The thermal oxidation of POE films was run at90℃. The changes in mechanical properties, transmittance and yellow index (YI) of POE films with different compositior were studied, and the structural transformation and aging mechanism of POE films in the process of thermal oxidation were analyzed by means of thermogravimetry(TG) FTIR-ATR and differential scanning calorimetry(DSC). The results showed that under the above curing condition, and antioxidant content of1010:168=3:1, the decline of the properties of POE films through the aging process is least. Namely, the tensile strength reduced from19.4MPa to17.9MPa. which reduced1.SMPa; transmittance from81.46%to72.65%,only reduced by8.81%.As to POE UV aging property, a0-800h UV aging test was used. The changes in mechanical properties, transmittance and yellow index (YI) of POE films with different ultraviolet absorber were studied, and the structural transformation and aging mechanism of POE films in the process of ultraviolet aging were analyzed by means of TG, FTIR-ATR, DSC and scanning electron microscope(SEM). The results showed that under the above curing condition, and ultraviolet absorber(totle0.5%) UV-940:UV-770: UV-531=5:3:5. The decline of the properties of POE film after UV aging800hours was least. Namely, the tensile strength reduced from21.85MPa to19.85MPa. which fell by2MPa; transmittance from80.57%to60.19%, which decreased by20.41%.