Photoaging and stabilization of rigid PVC/wood-fiber composites

Ultraviolet (UV) weathering performance of unpigmented and rutile titanium dioxide pigmented rigid polyvinyl chloride (PVC)/wood-fiber composites has been studied. The composite samples were manufactured by dry-blending PVC, wood fibers, and other processing additives in a high-intensity mixer. The dry-blended compounds were extruded and compression molded into panel sampl es. The manufactured samples were artificially weathered using laboratory a ccelerated UV tests. Composite samples were exposed to 340-nm fluorescent U V lamps and assessed every 200 h, for a total of 1200 h of accelerated weat hering. Each assessment consisted of a visual examination of surface roughn ess or erosion, a contact angle measurement, a FTIR collection, and a color measurement. The experimental results indicated that wood fibers are effec tive sensitizers and that their incorporation into a rigid PVC matrix has a deleterious effect on the ability of the matrix to resist degradation caus ed ultraviolet irradiation. The light stability of these composites could b e improved quite efficiently with the addition of rutile titanium dioxide p hotoactive pigment during formulation. (C) 2001 John Wiley & Sons, Inc.