Effectiveness of Fire Retardant Coating on the Basis of LOI Analysis of Polymeric Materials: A Review

Abstract

The growing use of polymers in construction, transportation, electronics, and consumer products has raised serious concerns about fire safety due to their high flammability and production of toxic gases during combustion. Flame retardant coatings offer a proven and efficient passive fire protection method. These coatings function by forming a thermal insulation barrier when exposed to heat or flame. They work through mechanisms such as intumescence (expanding and forming a protective char layer), endothermic decomposition (absorbing heat), release of non-flammable gases (like water vapor or ammonia), and drip suppression, thereby delaying ignition, reducing flame spread, lowering heat release, and minimizing smoke generation. Recent fire disasters such as the Grenfell Tower fire (UK, 2017), AMRI Hospital fire (Kolkata ,india,2011) and warehouse fires in Delhi (2022) and Beijing (2023) have emphasized the importance of applying flame retardant coatings on to polymeric materials used in public and industrial spaces to prevent rapid fire propagation .This paper includes the process of preparation of flame retardant intumescent coating using monoammonium phosphate, boric acid, paraffin liquid light, cation and anion exchange resins, fire suppression gel, xylene, silicon or acrylic binders, and calcium carbonate. Every material\'s role in improving flame resistance by studying the fire behavior of polymeric material .it is observed that The Limiting Oxygen Index (LOI) method, following ASTM D2863–19 can be used as the primary evaluation technique for proposing its effectiveness to flame retardancy of polymer.

Introduction

• Polymers are widely used in various industries due to their favorable properties like light weight, cost-effectiveness, and mechanical strength.

• However, they are highly flammable, posing fire hazards and often releasing toxic gases during combustion.

• To address this, flame retardant (FR) coatings—especially intumescent flame retardant (IFR) types—have been developed. These coatings form an insulating char layer when exposed to heat, which blocks oxygen and heat, thereby slowing or stopping fire spread.

2. Composition & Mechanism of IFR Coatings

Typical IFR coatings consist of:

• Acid source: Monoammonium phosphate (MAP) or Ammonium polyphosphate (APP)

• Carbon source: Pentaerythritol

• Gas source: Melamine

???? When heated, these components undergo chemical reactions to produce a swollen, protective char layer that serves as a thermal and oxygen barrier.

3. Additives & Enhancements

Various additives enhance the flame retardant efficiency, char structure, and application properties:

4. Evaluation Method: Limiting Oxygen Index (LOI)

• LOI is a standard test (ASTM D2863, ISO 4589-2) used to measure the minimum oxygen concentration required to sustain combustion.

• Higher LOI values indicate better flame retardancy.

• LOI testing involves igniting a sample in an oxygen-nitrogen mix to determine the lowest oxygen % that supports burning.

5. Key Findings from Literature Review

Conclusion

This study shows a thorough study of a multi-component, intumescent, flame retardant (IFR) by a coating to improve the fire performance of polymeric surfaces. For a flame retardant coating useful to fireproof polymeric surfaces, the coatings included some key ingredients such as monoammonium phosphate, boric acid, calcium carbonate, ion-exchange resins, paraffin liquid light, xylene, fire suppression gel, and other binders and fillers. The coating demonstrated excellent flame-retardant characteristics when tested in a controlled setting. We quantitatively showed that the coating was less flammable and had better thermal insulation benefits relative to our control directly using pastel work with Limiting Oxygen Index (LOI) method specified in the ASTM D2863-19.Each of the ingredients had an important role, where MAP and boric acid provided char formation, and then the ion-exchange resins provided some structure and integrity of the coating, and with the fire suppression gel provided improvements to swelling and improved ignition delay. Some of the inorganic fillers such as CaCO? improved the stability of the residues or char. Together these materials formed a stable char that both insulated heat and prevented flame propagation, while also limiting the release of smoke and toxic gases.This study successfully provided more than just a confirmation of how IFR coatings could perform as passive fire protection, but showed different methods in forming and measuring IFR coatings as a helpful study. This study and results are beneficial for multiple applications in the realms of construction, electronics, transport and many other applications where there are polymers used as composites or plastics. The coating developed in this study can be considered an affordable effective, possible scalable and effective solution for improve]E4ng fire safety in real-world scenarios.

References

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Copyright

Copyright © 2025 Suresh Lade, Sonu Kumar, Parmar Surajkumar, Shubham Kumar Jha, Manjit Kumar, Shivangi Sonowal. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.