THERMOGRAVIMETRIC CHARACTERIZATION OF GLOVEBOX GLOVES

Abstract

An experimental project was initiated to characterize mass loss when heating different polymer glovebox glove material samples to three elevated temperatures, 90, 120, and 150 C. Samples from ten different polymeric gloves that are being considered for use in the tritium gloveboxes were tested. The intent of the study was to determine the amount of material lost. These data will be used in a subsequent study to characterize the composition of the material lost. One goal of the study was to determine which glove composition would least affect the glovebox atmosphere stripper system. Samples lost most of the mass in the initial 60 minutes of thermal exposure and as expected increasing the temperature increased the mass loss and shortened the time to achieve a steady state loss. The most mass loss was experienced by Jung butyl-Hypalon{reg_sign} at 146 C with 12.9% mass loss followed by Piercan Hypalon{reg_sign} at 144 C with 11.4 % mass loss and Jung butyl-Viton{reg_sign} at 140 C with 5.2% mass loss. The least mass loss was experienced by the Jung Viton{reg_sign} and the Piercan polyurethane. Unlike the permeation testing (1) the vendor and fabrication route influences the amount of gaseous species that is evolved. Additional testing to characterize these products is recommended. Savannah River Site (SRS) has many gloveboxes deployed in the Tritium Facility. These gloveboxes are used to protect the workers and to ensure a suitable environment in which to handle tritium gas products. The gas atmosphere in the gloveboxes is purified using a stripper system. The process gas strippers collect molecules that may have hydrogen or its isotopes attached, e.g., waters of hydration, acids, etc. Recently, sulfur containing compounds were detected in the stripper system and the presence of these compounds accelerates the stripper system's aging process. This accelerated aging requires the strippers to be replaced more often which can impact the facility's schedule and operational cost. It was posited that sulfur bearing and other volatile compounds were derived from glove off-gassing. Due to the large number of gloves in the facility, small mass loss from each glove could result in a significant total mass of undesirable material entering the glovebox atmosphere and subsequently the stripper system. A thermogravimetric analysis (TGA) study was conducted to determine the amount of low temperature volatiles that may be expected to offgas from the gloves. The data were taken on relatively small samples but are normalized with respect to the sample's surface area. Additional testing is needed to determine the composition of the off-gassing species. The TGA study was conducted to ascertain the magnitude of the issue and to determine if further experimentation is warranted or necessary.