Thermally protective textiles

Table 8.4 Maximum service temperatures for heat resistant fibres in thermally protective textiles ...

Mettananda CVR, Crown EM. Quantity and distribution of oily contaminants present in flame-resistant thermal-protective textiles. Textil Res J 2010 80(9) 803-13. 

Mettananda CVR, Torvi DA, Crown EM. Characterization of the combustion process of flame resistant thermal protective textiles in the presence of oily contaminants effects of contamination and decontamination. Textil Res J 80(10) 917-34. 

Zylon or PBO is a more recently developed fibre than PBI and has outstanding tensile properties, as well as thermal and fire properties superior to any of the polymer-based fibres mentioned in this chapter (see Table 4.2). While there are at least two variants of the fibre, Zylon-AS and Zylon-HM, of which the latter has the higher modulus, both have the same thermal and burning parameter values. Principal examples of thermally protective textiles include heat protective clothing and aircraft fragment/heat barriers, where its price, similar to that of PBI, restricts its use to applications where strength, modulus and fire resistance are at a premium. 

The reported world tonnage in 1990 was 20001 [688]. One of the major limitations to its use in visible applications is that it is available only in black. For protection against intense heat, however, it offers considerably more protection than conventional fire protection textile fibers. A PANOX-based fabric is reported to maintain a barrier against a 900°C flame for more than 5 min. In addition to its low flammability, it has an exceptionally low thermal conductivity [689]. 

In this chapter, issues in personal thermal protection are discussed, focusing on the needs of workers in selected sectors energy (oil and gas), electrical, other industry sectors, and both structural and wildland firefighting. The important protection concerns for workers in each sector are discussed, followed by a discussion of potential trade-offs between thermal protection and thermal comfort. Clothing issues such as fit, comfort, and other ergonomic factors are briefly discussed. Recent developments in protective textile materials are followed by a diseussion of serviceability concerns, including durability and maintenance. A review of international performance standards is followed by a summary of the development of test methods to assess protection from heat, flame, hot liquids, and steam. Issues for future development of technical textiles for personal thermal protection are then discussed briefly. 

The workplace hazards determine the protection needed and dictate the testing that is appropriate for the textiles and protective garments selected for various end-uses. Certain work places have always required protection from heat and flame (foundries, firefighting), but the interest in protective clothing has inaeased over the last 30 years, as reflected by the performance specifications for workwear and test methods developed to evaluate flame resistance and thermal protection (radiant, convective, hot liquids, and steam). 

Song et al. developed a numerical model of moisture transport in thermal protective clothing during exposure to a flash fire. The model assumes that textiles are treated as porous media The authors demonstrated that the model can be used to predict the thermal response of a protective fabric and the effects of air gaps in a... 

Rizvi SAH, Crown EM, Osei-Ntiri K, Smy PR, Gonzalez JA. Electrostatic characteristics of thermal-protective garments at low humidity. J Textil Inst 1995 86(4) 549-58. 

Grant TL, Crown EM. Electrostatic properties of thermal-protective systems. Part I simulation of garment-layer separation. J Textil Inst 2001 92(3/3) 395 02. 

Of great significance when technical textiles are used in contact with the human body are aspects such as moisture transport and breathability, as described in Chapters 2 (waterproof breathable fabrics), 5 (medical textiles), 9 (personal thermal protection) and 10 (survival). Medical textiles (Chapter 5), which has been a particular growth area in recent years, demonstrates the need for novel fibres, fabric structures and treatments that are revolutionising chnical science. 

Heat resistant fibres, however, are those having chemical structures that are little changed physically or chemically by temperatures above the 200°C, and even the 300°C, levels and, in the case of ceramic fibres, above 1000°C. For textiles used in high temperature industrial processes, such as gas and liquid filtration, long term exposure to temperatures of about 100°C is often required, but not all these fibres are used in thermally protective applications. However, in long term exposure thermally protective applications, we need to be able to define maximum service fife temperatures, and these are listed in Table 4.2 for selected heat resistant fibres. 

---