Moisture barriers used in firefighters' protective clothing: Effect of accelerated ultraviolet radiation aging on their mechanical and barrier performance

Firefighters rely on their protective clothing as a second skin to perform their job. In the middle of this multilayered protective garment, the moisture barrier plays a vital role in preventing liquids to enter while allowing perspiration to escape. This research delves into the impact of accelerated ultraviolet (UV) aging on the performance of firefighter protective clothing moisture barriers, focusing on tear force retention, water vapor transmission rate (WVTR), and wetting via apparent contact angle. Changes in the tearing behavior and reductions in the tear force and tearing distance were observed after aging. Additionally, a reduction in WVTR was found for all the moisture barriers, due to pore closure in the ePTFE/FR PU membrane. In terms of water repellency, the base fabric side of one moisture barrier experienced a transition from hydrophobic to superhydrophilic potentially due to the degradation of the water-repellent finish. The investigation also revealed that, due to the screening effect by the outer shell fabric, only a low percentage of UV radiation received by the turnout gear, less than 2% in the UVA range, may reach the moisture barrier. These results indicate the need to consider realistic exposure scenarios when assessing moisture barrier service life.