Radiation induced degradation of polymers ‐an approach by using liquid paraffins as a model system

Abstract

Paraffins, n-hexadecane and squalane, were employ_ed as a model of polymers and radiation induced reactions in the polymers have been simulated. After vacuum irradiation, products were identified and their yields were determined by a variety of techniques. In the presence of the aromatic additives, the reduction of the degradation, so called protection effect, was clearly observed. Both energy and charge transfer play important roles in the protection effect. The same system was adapted to the irradiation under aerated condition in order to clan'fy the radiation induced oxidation. Furthermore, corresponding experiments using polypropylene were also performed and validity of the model system and phase effect were discussed. On the basis of the above results, it was revealed that the model experiment is valuable to understand the radiation induced reactions in polymers, especially amorphous phase of the polymers.Recently, the same model system has been extended to the thermal degradation at the temperamre ranges of 300 -400'C. When radiation was introduced, both a significant acceleration of the degradation and an enhancement of H? evolution were clearly observed. This is suggesting a potential application of radiations to the degradation of polymers at elevated temperatures.induced reactions in polymers were simulated. The protection effect was also investigated. Ln order to confirm the experimental findings observed in the model system, similar experiment was done in polypropylene. It was revealed that this approach is very useful and powerful to understand the radiation induced degradation processes in polymers [ 1-51.Similar system was extended to the experiment on radiation thermal cracking in order to evaluate whether radiation would be helpful to the thermal cracking and, further, applicable to the general thcrmal degradation processes. It was found that, under a certain condition, irradiation accelerates the thermal degradation an order of 100 times [6-61.i n the present experiment, liquid paraffins were chosen as a polymer model, in whichPaper presented at