Aerogel nonwoven as reinforcement and batting material for firefighter’s protective clothing: a comparative study

Abstracts

Aerogel, the most insulated solid known to modern science, is gradually expanding its field of application from space shuttle to normal clothing. So far, apparel use of aerogel nonwoven has been successfully commercialized in case of cold weather clothing. Use of aerogel in high heat protective clothing is much complex as it requires to balance comfort with protection. This paper studied the protective performance of aerogel nonwoven in a high heat protective apparel, firefighter’s protective clothing (FPC). An investigation was carried out to justify its use as reinforcement material and/or batting in thermal liner or moisture barrier of FPC. Impressive results were observed in case of reducing the risk of burn injury, increasing comfort and enhancing protection. It was observed that aerogel nonwoven can provide eight times more thermal resistance than existing commercial reinforcement material and existing thermal batting material. When the aerogel nonwoven layer was used as thermal liner, it offered five times more resistance to heat than existing thermal liner and three times more resistance than combined performance of existing thermal liner and moisture barrier. The possible burn injury under 49 N compressive load was predicted on a 200 °C heated surface. It was found that the temperature behind the commercial reinforcement material quickly raised above 70 °C within 30 s of contact, while it took more than 4 min to reach the same temperature for proposed aerogel reinforcement material. This indicates that a firefighter will receive instant burn on contact in 30 s if only the commercial reinforcement material is used. It was measured that, without any reinforcement material even when only the aerogel nonwoven is used instead of current batting material, a firefighter will have 86 s before feeling any pain, 107 s before receiving first-degree burn and will have 2 and half minutes before theoretically receiving second-degree burn at the same condition. Thus, a firefighter will gain more than 1 min of escape time to withdraw from a danger situation, where it is only 5 s for existing thermal liner and reinforcement material. Performance was also evaluated against fabric thickness and weight, air permeability, resistance to one-way liquid transfer, moisture management, moisture vapour transfer and degree of evaporative cooling. The advantages and disadvantages of proposed combination have been discussed and it was concluded that the use of aerogel reinforcement can significantly increase the protective performance of FPC.

Highlights

Aerogel nonwoven (A) showed superior performance over existing reinforcement material (Rinf) and thermal liner (F+B1) for firefighter’s protective clothing. In particular, aerogel nonwoven has

• Over eight times more thermal resistance than ‘Rinf’;

• Excellent compressive heat resistance before receiving burn (A = more than 2.5 min, Rinf = 19 s);

• Better air permeability (A = 12.4 mL/cm²/s@50 Pa, Rinf = Nil); and

• Enhanced evaporative cooling (Ret of A = 17.5 Pa m²/W, Rinf = Infinite).