Radical concentration was monitored by electron spin resonance to determine the effect of bromine concentration on radical reduction. Because bromine is an electron scavenger, it should reduce the amount of radicals formed in subsequent reactions. Tables I and II illustrate the significant stabilizing effect of the bromine compounds, with the more highly brominated formulations exhibiting the strongest effect. In the course of our investigations, we have found a new class of materials that are nonhalogenated compounds capable of DEA, and therefore able to act as electron scavengers. The graph indicates that the synergistic effects of the different electron scavengers with PPG are very similar.
Radical scavengers react with radicals produced along the polymer chain after irradiation.
Combining the two can yield polycarbonate formulations that undergo virtually no yellowing after gamma or electron-beam radiation. Post them in our Members' Discussion Forums .