High-Resolution Setup for Measuring Photoyellowing of Transparent Materials

摘要

Polystyrene and many other materials turn yellow when exposed to ultraviolet (UV) radiation. The photoyellowing can be quantified with a yellowness index derived from transmittance or reflectance spectrum of the material [1]. In this research, we have constructed a laser-based setup for scanning transmittances spatially from samples. First, eight polystyrene samples were exposed to UV radiation of 276 - 421 nm for different time periods using a spectrograph [2]. Then, the transmittance spectrum of each sample was spatially scanned. Based on the results, the lower exposure wavelengths of 276 - 340 nm caused significant yellowing. In addition, the absorption is higher at the lower measurement wavelengths, as can be expected with yellowing. Using the results, an action spectrum of polystyrene photoyellowing will be derived.