Humidity-induced damage in polyvinyl toluene and polystyrene plastic scintillator

Polyvinyl toluene and polystyrene are materials commonly used in plastic scintillators. In recent years, cold weather related performance degradation has been identified in plastic scintillators that are exposed to the environment. Prior exposure to water vapor at high temperatures, in particular, has been identified as a likely culprit. This work subjected a selection of commercially produced polyvinyl toluene and polystyrene plastic scintillator to a controlled high-temperature, high-humidity environment for an extended period of time, followed by exposure to freezing temperatures consistent with performance degradation. Polymethyl methacrylate, which is used as a light guide in detectors, was also subjected to these conditions. Samples were evaluated visually, and weight measurements were taken at regular intervals during and after the environmental exposure.