Effects of Radon Chamber Exposure on the Mechanical and Structural Properties of Protective Glove Materials

Protective gloves used by firefighters and other first responders may be stored for long periods in environments where radon and its decay products can accumulate. However, despite extensive research on the radiation ageing of elastomers, directly comparable data on the long-term response of finished nitrile rubber (NBR) and chloroprene rubber (CR) used as protective glove materials under radon chamber conditions remain limited. Accordingly, this study evaluated time-dependent changes in these two glove materials during up to six months of conditioning. The specimens were conditioned at an approximately constant 222Rn activity concentration of 540 kBq/m3, corresponding to a cumulative exposure of up to 2.35×106 kBq/m3. Changes were evaluated using microhardness measurements, mechanical testing, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and atomic force microscopy (AFM). NBR exhibited a non-monotonic microhardness response, with an initial increase followed by a gradual decrease during further conditioning; after six months, the microhardness remained higher than that of the reference material. Isolated microcracks became visible after six months. In contrast, CR showed a general decrease in microhardness and earlier surface changes, including increased roughness and micropore formation. Its tensile strength decreased from approximately 1.2 MPa to 0.8 MPa after six months, corresponding to a reduction of about 33%, although force at break partially recovered during the later conditioning period. FTIR analysis revealed only limited chemical changes. Overall, the two materials exhibited distinct time-dependent responses, with NBR retaining greater mechanical and morphological stability than CR under the investigated conditions. Although barrier performance was not assessed directly, the observed defects may increase susceptibility to damage during use, highlighting the importance of appropriate storage, stock rotation, and pre-use inspection.