The need for flame retardant textile finishing is discussed in the light of hazards associated with textile flammability, related regulations and procedures for determining textile burning behaviour. This explains in detail the functions of flame retardant finishes and durable finishes produced specifically for cellulose, wool and man-made fibers. Multipurpose finishes are being studied for both cellulose and wool textiles in which flame retardance is just one property bestowed on the textile. Fibre blends pose a specific challenge and careful attention is paid to addressing certain finishes applied to fabrics blended in polyester / cotton. It tests the laundering actions and the consequent durability of the end. In addition, consideration is given to the effects that applying flame retardant finishes has on textile properties and efficiency. It outlines recent advances in methods for applying flame retardant finishes.
Flame-Resistant Textiles are most commonly made from synthetic fibers that have been individually treated with flame-resistant additives. However, they may also be made from synthetic fibers having inherent flame-resistant quality, natural fibers treated with flame-resistant additives, or fabrics coated with flame-resistant additives during finishing process. Flame-Resistant Textiles do not easily catch fire. Moreover they deter combustion and block flames. Flame-Resistant Textiles are commonly used in fabrics for infant wear, children’s pajamas, general apparel, wall coverings, furniture decorations, curtains, tents, special work apparel and many other applications.
Agents used in Flame Retardant
Antimony tri bromide is a dense white powder which is one of the major components of the traditional white smoke seen from burning polymers that contain halogen which antimony oxide. High water levels from normal combustion induce reversal of SbBr3 to HBR and Sb203. The resulting antimony oxide is then available for reaction from decomposing brominated compound with fresh HBR. Usually materials used in flame retardant applications contain either 40 to 70 percent chlorine or 45 to 80 percent bromine, depending on the flame retardant specifications of 20 to 40 parts of Brominated compound per 100 parts of polymer should be used. Usually the antimony oxide used is 1/4th that of the halogenated material.
Mechanism of Flame Retardant
Combustion- Is an exothermic process requiring three components: heat, oxygen, fuel that is suitable.
Pyrolysis temperature, to- At this temperature, the fibre undergoes irreversible chemical changes, producing
Non-flammable gases (carbon dioxide, water vapour and the higher oxides of nitrogen and sulfur)
carbonaceous char, tars (liquid condensates) and, flammable gases (carbon monoxide, hydrogen and many oxidisable organic molecules).
The combustion temperature,TC-
At this point, the flammable gases combine with oxygen in the process called combustion. which is a series of gas phase free radical reactions.
These reactions are highly exothermic and produce large amounts of heat and light.
Process of Flame Retardant
Flame retardants are chemicals are applied to fabrics to inhibit or suppress the combustion process. They interfere with combustion at various stages of the process e.g. during heating, decomposition, ignition of flame spread. Fire is gas phase reaction. For a substance to burn, it must become a gas. As with any solid, a textile fabric exposed to a heat source experiences a temperature rise. If the temperature of the source (either radiative or gas flame) is high enough and the net rate of heat transfer to the fabric is great, pyrolytic decomposition of the fiber substrate will occur. The products of this decomposition include combustible gases, non combustible gases and carbonaceous char. The combustible gases mix with the ambient air and its oxygen. The mixture ignites, yielding a flame, when its composition and temperature are favorable. Part of the heat generated within the flame is transferred to the fabric to sustain the burning process and part is lost to the surroundings.
Health and environmental issues
The key interest beside flame retardants are that they may persevere in the atmosphere, build up living organisms and be harmful to human health or toxic to wild life.
Products can typically only be bio-synthesized if they are obviously dissolvable in fats and hardly dissolvable in water, because water-soluble chemicals are released from the body through urine without any difficulty. Further bio-synthesis chemicals require to build up as being used by the body in series from food, water, or air. When it is in use, they also require being adequately stable and resistant to biochemical degradation. Simply if these circumstances are satisfied, bio-synthesis can happen. From the numerous flame retardants in
commercial application, merely extremely a small number of are possible to build up for organisms. Though, levels of experimental are extremely low, match up to possible toxicity.
Flame retardants need a strong chemical permanence to play their role; most of them are used in polymers that are performed at 200-3500 degree C temperatures depending on polymer use. They would cause weakening during this active stage if they were not sufficiently stable. In addition, flame retardants are widely used in comprehensive survivable objects such as television sets, computers, cars, aircraft, building materials. And they will live and deliver fire protection for the manufactured products’ entire lifespan. Chemical stability is also helpful if someone wants to recycle polymers, as recycles will hold up the properties of fire retardant. Unluckily, this necessary chemical stability, which is normally recounted to constancy in the environment , i.e. resolving adjacent to microorganisms, sunlight or water.
Possible toxic tests for FRs seem to be near to the ground as they are chemically behaved in reaction to the substance on which they are applied to treatment, or physically incorporated inside it and thus not capable of having significant external effects. Certain flame retardants are by no means harmful in contrast with other widely used chemicals. There are different forms of chemical flame retardant classes available and rates of interactions with living species. And within a chemical community there can be significant dissimilarity in toxic properties seen, since depending on the degree of molecular interaction with cells, little modification to a molecule may have major effects.
End-Uses of flame retardant
Flame retardant end-uses are- For fire fighters, Curtain and carpet of chinema hall, Military and Airline industry, Furniture, Electronic goods and insulation, Building insulation, Foam furniture, Wires and Cabling.
Advantages and Disadvantages of Flame Retardant Fabric
In today’s special protection market, the flame retardant fabrics used in traditional flame retardant clothing can be loosely divided into two groups. One type of tissue is treated with a flame retardant fabric. Many fabrics, however, are made by combining one part of flame retardant fiber with another part of ordinary fiber, and then being treated with flame retardant. Nevertheless, repetitive repeated processing can cause waste, and even harm to the fiber, at least for flame retardant fiber, so it is typically not done. Flame retardant treated fabrics are not normally used as high-end products, as they have defects in terms of washing resistance, handle, strength, especially tear strength. Cotton flame retardant fabrics are the staple of flame retardant products because of the fairly advanced flame retardant processing technology of all-cotton and terylene products, and the low cost of base material. They are commonly used as decorative textiles in public places in fields such as mine, windpipe, and wall cloth. Cotton flame retardant fabrics from the number of the main market, such as China’s protective clothing network provided by the flame retardant clothing, can be said to be using cotton flame retardant fabric.
Kajal Arya, NIFT Bhubaneswar