Photodegradation Behavior of High-Impact Polystyrene Studied by Pyrolysis-Gas Chromatography

Thermograms and MS of Pyrolyzates [Notes] In the pyrogram of high - impact polystyrene ( HIPS ) , peaks of butadiene monomer and dimer were clearly observed along with major peaks of styrene monomer, dimer and trimer from the polystyrene main chain. On the other hand, in the case of ultraviolet - irradiated HIPS, the peaks of butadiene monomer and dimer almost disappeared in the pyrogram while the styrene - related peaks were still observed similarly to those for the original HIPS. This fact suggests that the photodegradation of HIPS is mainly caused by the decomposition of polybutadiene components, accompanied by the deterioration, especially of the impact properties. Furthermore, as for the market - recovered HIPS for cover materials, the degree of yellowing ( color di ff erence ¦ E ) of the materials was well correlated with the decrease in the relative peak intensities of butadiene monomer and dimer observed in their pyrograms. This result demonstrates that the degree of photodeterioration of HIPS can be roughly evaluated by Py - GC.