Environmentally friendly, non-toxic flame retardant material for nylon, which is capable of imparting high flame retardancy, containing neither halogen nor phosphorus.



Nylon is one of the most important engineering polymers broadly used in textile, electronic and automotive industries. In addition to its excellent mechanical properties, flame retardancy is also desirable in most applications. Nylon is typically processed at high temperature and very few synthetic flame-retardant additives are stable at the processing temperatures of Nylon. Phosphorus compounds (Red phosphorus), halogenated compounds and metal oxides have been used to make nylon less flammable. They are extremely toxic and environmentally persistent having significant long-term impacts on the ecosystem. These additives liberate toxic products and generate toxic/corrosive gases during combustion. There is a need for the development of environmentally friendly, non-toxic flame retardant material which is capable of imparting high flame retardancy, containing neither halogen nor phosphorus.


Dr Ramaswamy Nagarajan has explored an abundantly available bio-based polyphenol [Tannic acid (TA)] that plays a major biological role in the natural protection system of plants. Upon heating, TA exhibits good intumescence and char forming characteristics. However, the poor thermal stability of TA has severely limited its utility as a fire retardant or char forming additive. 

Dr Nagarajan has overcome this limitation by cross linking tannic acid to yield a thermally stable cross-linked tannic acid with desired characteristics:

Structurally characterized by FTIR, TGA-FTIR and 1H NMR.
Thermally stable up to 230 °C
30% higher char yield over tannic acid
Extremely low heat release capacity of
Low heat release capacity in nylon 6 as compared to phosphorus based commercial flame retardant material


Textiles e.g. protective clothing, carpets, curtains, and rugs
Building construction - flooring, panels, piping, and other construction products
Insulated wire and cable e.g. building wiring, and connectivity wiring, such as fiber optics
Home furnishings e.g. furniture and mattresses
Automotive - FRs allow the use of lighter weight plastic and composite materials that offer both improved fuel efficiency, and elevated temperatures in under-the-hood applications in hotter running engines.
Aerospace market - Efforts by Boeing and Airbus to improve airplane fuel efficiency through the increased use of composites and other plastics, along with the industry’s strict flame retardance standards, will drive gains in the aerospace market


As more countries establish stricter regulations and restrictions against halogenated flame retardants, the scope for non-halogenated FR is expected to continue growing.

Ability to preserve physical properties over a wide range of temperatures
Low heat release capacity FRs
Combustion products are non-toxic as halogen, phosphorous and metal oxide based FRs
No metal oxides used - Heavy loading of metal oxides as flame retardant additives, alter the properties of the material to be protected
Phosphorus & halogen-free materials - Meets European standards, no toxic fumes released upon burning, no leaching of dangerous chemicals into the environment
Significant cost saving - Synthesis process requires low cost of starting materials 

Market Potential:

 US demand for flame retardants are set to expand 6.0 % per year to 1.1 billion pounds in 2016. Robust gains in building construction particularly for new housing as well as in other closely associated markets, such as wire & cable, and home furnishings, will drive advances. The shift in product mix toward lower cost, non-halogenated flame retardants will be offset by their higher loading levels, with overall sales of flame retardants rising 7.8% per annum to $1.2 billion in 2016. 

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