An integrating sphere-based ultraviolet exposure chamber design for the photodegradation of polymeric materials

The primary method for obtaining laboratory weathering data for a wide rang e of commercial polymer products including coatings, textiles, elastomers, plastics and polymeric composites is through the use of ultraviolet radiati on exposure chambers (UV-chambers). Although numerous improvements have bee n made in the design of W-chambers over the last 80 years, the repeatabilit y and reproducibility of the exposure results from these chambers have rema ined elusive. This lack of reproducibility and repeatability is attributed to systematic errors in their design, operation, and control which, in turn , has prevented comparisons of the performance of competing construction ma terials exposed in the same environment, comparisons of the performance of the same material exposed in different laboratories, and the comparison of field and laboratory results. The paper re-examines current UV-chamber desi gns, discusses possible sources of systematic error associated with these c hambers, and describes an innovative UV-chamber design having a basis in in tegrating sphere technology which greatly reduces the magnitude of these er rors. (C) 1999 Elsevier Science Ltd. All rights reserved.