Firefighters’ clothing could soon be made safer to wear, maintain and manufacture, findings from a couple of new studies from the University of Alberta in Canada have revealed.
- The first found that some fibres used in the protective gear break down when exposed to warm water, showing what can happen to the garments over time, during real-life firefighting scenarios and laundering.
- The second analysed the water used in the manufacture of fibres, identifying a handful of harmful dye compounds leaching from the fabrics that could weaken their protective qualities.
WEAR AND CARE: Using accelerated ageing treatments reflecting firefighting and laundering conditions, one of the studies investigated the effects of heat and water on 15 different yarns in eight fabrics typically used to manufacture protective clothing.
- The fibres were immersed in both purified neutral pH and acidic water ranging from 40 C to 90 C for up to 1,200 hours at a time, then checked for physical, chemical and other types of deterioration. The results of the hydrothermal aging showed that fabric blends containing a particular type of fibre, called para-aramid/polybenzimidazole, or PBI, degraded in strength 68 per cent more quickly when exposed to moisture, as opposed to similar fire-protective fabrics that didn’t contain PBI.
- High-performance fibre blends containing PBI are typically used to make firefighters’ outer jackets and trousers, due to the fibre’s flexibility and ability to withstand extreme temperatures.
- But because PBI fibres are manufactured using sulfuric acid, traces of the chemical remain behind, shows an earlier study led by Hoque. That residual sulphur increases a fabric’s sensitivity to moisture, and could lead to premature degradation of protective garments.
- The findings can help manufacturers of high-performance fibres and protective fabrics improve their processes.
- Laundering of firefighting gear also needs to be changed, by washing clothing with PBI fibres separately. This prevents the risk of damage to neighbouring fabrics that don’t contain PBI fibres and wouldn’t otherwise experience degradation in warm water.
HEAT AND WATER STRESS: The same study also established, for the first time, that meta-aramid fibres, another type commonly used in protective clothing, showed “remarkable resistance” to heat and water stress, even when exposed to acidic water.
- For example, one fabric sample comprising 93% meta-aramid fibres lost only 4% of its tensile strength after being immersed in water for 1,200 hours at 90 C.
- That discovery fills a knowledge gap about the effectiveness of high-performance fibres to resist heat and water, allowing manufacturers “more informed decisions in the selection and design of materials for more durable gear for firefighters.”
- It also opens up possibilities for using meta-aramid fibres in other products frequently exposed to water, such as marine safety equipment, he adds.
- The overall exploration of the various yarns and their fibres provides a fuller understanding of their durability. Suggestions can now be made to manufacturers on optimum fibre blends and fabric configurations that strike a better balance between long-term protection and comfort.
RESPONSIBLE MANUFACTURING: The second study developed a method of analysing the water used in the experiments, which can be used by fabric manufacturers to make their production processes more environmentally sustainable.
- The analysis identified three dye-related compounds known to pose some risk to the environment, “particularly when they leach into water systems.”
- Though not recommended for use, “it’s possible that some manufacturers still employ these compounds, so this information can help them prevent environmental pollution and adopt more sustainable practices.”
THE STUDIES: Both studies were conducted by PhD candidate Saiful Hoque from the Faculty of Agricultural, Life & Environmental Sciences (ALES).
- His various co-authors on the pair of studies were ALES associate professor Patricia Dolez, professor Hyun-Joong Chung and master’s student Ankit Saha in the Faculty of Engineering, and professor James Harynuk, research associate Paulina de la Mata and PhD candidate Trevor Johnson in the Faculty of Science.
- The two projects received funding from the Natural Sciences and Engineering Research Council of Canada, Mitacs, Davey Textile Solutions Inc. In-kind support was provided by Innotex and DuPont. The research was also supported by the U of A Protective Clothing and Equipment Research Facility, the U of A nanoFAB and the U of A Department of Chemistry.
