Photochemical deterioration of poly(vinylbutyral) in the range of wavelengths from middle ultraviolet to the visible

Films of poly(vinylbutyral) (PVB) from two proprietary sources were tested for photochemical behavior upon exposure to UVB, UVA, BLB, and high-output “daylight” fluorescent (DLF) lamps. Discoloration and brittleness followed the buildup and subsequent decline of peroxide content. In the range of 60-89.9 °C, the onset of crosslinking and the loss of weight obeyed the Arrhenius relationship. At temperatures above the second-order-transition temperature, Tg, crosslinking predominated; at temperatures below Tg, chain breaking tended to prevail.