Heat resistant fabrics are used in fields of high-tech applications where exceptional strength is required. In industries like metal, aluminum and steel, workers are frequently exposed to heavy molten metal splashes. Hence flame resistant garments are worn over the secondary garments. They are also used in the uniforms of fire fighters, and as protective clothing. These fabrics are prepared with warp yarns consisting of a blend of cotton, nylon and heat resistant fibres.

 

Types of Heat Resistant Fibres:

 

Aramids:

 

Aramids are strong synthetic fibres, belonging to the family of nylons. They are polyamides obtained from aromatic amines and acids. Used as an asbestos substitute, aramid fibres posses' excellent heat resistant capacity, as it neither melts nor ignites in normal level of oxygen. Aramid yarns are an answer to the prayers of many military soldiers involved in dicey combat operations. Extremely resistant to fire, even upto 500°C, they secure the body from getting burned.

 

Para-aramids are one of the best known high-performance fibres. They posses high impact resistance and hence are used in high-tech applications like aerospace, military applications, puncture resistant bicycle tires, and in making bullet proof amours. For industries that do not require much tensile strength, aramids are blended with other fibres.

 

Carbon Fibres (Polyacroylonitrile and Pitch based):

 

Carbon fibres are made by carbonization of precursor fibres based on pitch, polyacrylonitrile (PAN) or rayon. They consist of extremely thin fibres of about 0.005-0.010 mm in diameter and mostly composed of carbon atoms. Carbon fibres posses qualities of high tensile strength, less weight, and thermal expansion, which makes it popular for making garments used in aerospace, military, motorsports and civil engineering.

 

Carbon Precursor Fibres:

 

Carbon precursor fibre is a flame retardant fibre made from pyrolytic carbonization of a modified acrylic fibre. They are partially carbonized fibres which change into carbon or graphite fibre under carbonization in a static atmosphere at high temperature. As carbon cannot be shaped into fibre form, they are made by extrusion of precursor material into filaments, followed by a carbonization process, converting the filaments into carbon. Different precursors and carbon filaments are used, depending on the product properties required.

 

These fibres are very weak in nature and lacks abrasion resistance; it is usually blended with para aramid fibres in a 50-50 proportion to make it strong and durable. Due to its difficulty in processing, the precursor fibres are converted into fabric form, and then carbonized to make the end product. Rayon and acrylic are common precursors for carbon fibres.

 

Poly-phenylene benzo-bisoxazole (PBO):

 

PBO fibres are a new entry into performance fibres market. They posses exceptional ignition resistance, low heat release rate, and very less smoke emission. It has high tensile strength and thermal properties two times more than aramid fibres. Fabrics made from these fibres exhibit good dimensional stability, and low shrinkage under high temperature treatments. These fibres can be used as electronic insulation material, military and aerospace applications. However, applications of PBO fibres are still at the budding stage in the textile industry.