PMMA glazing has long been used in military and commercial aircraft. Tinted acrylic sheet can be used to reduce solar heat gain through windows. Acrylic is being used increasingly in buildings for skylights, large area enclosures for shopping centres, restaurants and swimming pools. Because of its resistance to heat, relatively good weathering and transparency, PC is being used more and more in commercial and residential lighting applications. Examples of such uses include street light globes, airport lighting, highway diffusers, home light fixtures and patio lights.
Polycarbonate sheet used for outdoor applications is stabilized against the effects of sunlight.
Prolonged exposure to the outdoor environment, however, causes yellowing of the sheet and formation of surface microcracks on the front side. This results in considerable reduction in impact strength. The glass fibre reinforcement in the general purpose material used for light transmission applications is usually in the form of chopped strand mat. A special grade of GRP sheeting has been developed for use as glazing in flat-plate solar collectors. The deterioration results in discoloration, fibre pop out, surface microcracking, reduced light transmission, and increased brittleness.