Advances in Fire Protection:

The Promise of Graphene Oxide in Intumescent Coatings

Intumescent coatings are specialized paints applied to concrete and steel structures in industrial and residential buildings to offer fire protection. They provide safety by allowing enough time for evacuation and assistance in the event of a fire.

During a fire, these coatings expand and form a carbonized foam that isolates the fire and limits its spread, while simultaneously releasing non-combustible gases that reduce the oxygen concentration around the structures, protecting them from significant damage for approximately 1 to 3 hours.

The main components of intumescent coatings are a polymeric binder, an acid source (e.g., ammonium polyphosphate – APP), an expansion additive (e.g., melamine – MEL), a carbon source (e.g., pentaerythritol – PER), and other filler elements (e.g., expandable graphite), which often influence the expansion factor and fire retardancy.

Despite their efficiency, the carbonized foam formed by the APP-MEL-PER system may have poor oxidation resistance at high temperatures, leading to lower fire-retardant efficiency and easier destruction during combustion. Therefore, other additives such as calcium carbonate, aluminum hydroxide, silica, and certain carbon materials have been explored to enhance their protection. For example, expandable graphite in epoxy coatings improves thermal degradation and fire resistance; carbon nanotubes reduce the heat release rate in polymers, and graphene oxide (GO), thanks to its reticular nanostructure, has been identified as an effective thermal barrier to prevent flame diffusion and reduce heat propagation. This occurs because GO, when evenly dispersed within the coating matrix, forms a “tortuous path” that reduces the thermal diffusion rate and matrix decomposition, thus improving fire resistance and mechanical strength.

Although no intumescent coatings with graphene oxide are currently on the market, research has shown that GO can improve the APP-MEL-PER system by promoting the decomposition reaction of APP, which accelerates the formation of phosphoric acid that reacts with PER to form carbon. While it has been observed that GO may slightly decrease the thermal stability of coatings, its presence encourages gas production and intumescent coefficients, reducing thermal conductivity.

Energeia-Graphenemex®, in collaboration with a renowned Mexican specialized coatings company, is working on a new development to launch the first intumescent coating with graphene oxide to continue placing Mexico at the forefront of new technologies.

Authored by: EF/DHS

References:

1. Wang Zhan et al., Influence of graphene on fire protection of intumescent fire retardant

coating for steel structure, Energy Reports 6 (2020) 693;

• Qiuchen Zhang et al., Effects and Mechanisms of Ultralow Concentrations of Different Types of Graphene Oxide Flakes on Fire Resistance of Water-Based Intumescent Coatings, Coatings 2024, 14, 162;
• M. Sabet, et al., The Effect of Graphene Oxide on Flame Retardancy of Polypropylene and Polystyrene, Materials Performance and Characterization 9, no. 1 (2020): 284;
• Cheng‑Fei Cao et al., Fire Intumescent, High‑Temperature Resistant, Mechanically Flexible Graphene Oxide Network for Exceptional Fire Shielding and Ultra‑Fast Fire Warning, Nano-Micro Lett. (2022) 14:92;
• Quanyi Liu et al., Recent advances in the flame retardancy role of graphene and its derivatives in epoxy resin materials. Composites Part A: Applied Science and Manufacturing, 2021, 149, 106539