Durability of Polymeric Glazing and Absorber Materials

Candidate polycarbonate (PC) glazings have been subjected to accelerated exposure testing at a light intensity level of up to 50 UV suns for an equivalent 20 years outdoor exposure in Miami, FL. The most promising construction uses a UV-screening film, Korad®, which is laminated to a PC sheet. With the addition of a UV-screening film, significant loss in hemispherical transmittance does not begin for samples exposed at 70°C until between 10-15 years equivalent outdoor exposure. Samples exposed at 40°C exhibit greater durability. The mechanical properties of two candidate absorber materials, namely metallocene-based multi-density polyethylene (MBMDPE) and polypropylene (PP), were measured as a function of wet and dry thermal exposure. Little loss in tensile properties was found for samples exposed wet. However, materials were observed to become suffer and less ductile after exposure to elevated temperatures in both water and air. Absorber materials were also tested for UV resistance, and appear adequate for unglazed absorbers.