Quantification of Thermal Barrier Efficiency of Intumescent Coatings on Glass Fibre-Reinforced Epoxy Composites

Piyanuch Luangtriratana,Sophie Duquesne,Serge Bourbigot,Baljinder K Kandola

doi:10.3390/coatings8100347

Abstract

In this work, the thermal barrier efficiency of three commercial intumescent coatings of varying thicknesses on glass fibre-reinforced epoxy (GRE) composites has been studied using cone calorimetric parameters and temperature profiles through the thicknesses, obtained by inserting thermocouples in the sample during the experiment. The methodologies developed to measure char expansion of the three coatings during the cone experiment as well under slow heating conditions using an advanced rheometric expansion system have been discussed. While the expansion ratios in the two experiments were different, the trends were similar. Thermal conductivities of the chars as a function of time were measured, which could be related to the intumescence steps of respective coatings. The accurate measurements of these parameters are important in predicting the surface requirements of an ideal coating that can enable a given composite structure to survive a defined thermal threat for a specified period of time.

Highlights

The use of intumescent coatings is an effective way of protecting flammable or non-flammable materials against fire and excessive heat without affecting the intrinsic properties of the underlying substrate
* The results presented are reproducible to within ±10%; ** fire hazard index (FHI) = peak heat heat release release rate rate (PHRR) divided by TPHRR of 2nd Peak;
The FHI values for glass fibre-reinforced epoxy (GRE)-Epoxy based intumescent coating (EI)-3 and GRE-EI-5 are very low (~0.3 kW/m2 ·s) compared to control sample (8.1 kW/m2 ·s), which reflects the thermal barrier efficiency of the EI charred coating. These results suggest that the EI epoxy-based intumescent coating provided a thermally insulating expanded char on the GRE composite surface to prevent heat transfer and a rapidly growing fire

Summary

Introduction

The use of intumescent coatings is an effective way of protecting flammable or non-flammable materials against fire and excessive heat without affecting the intrinsic properties of the underlying substrate. Intumescent coatings are designed to expand to form an insulating and fire resistant charred barrier between the fire and the underlying substrate This char protects the underlying structure, acting as a thermal insulator/barrier against flame and heat. This means of protecting flammable materials is called “passive fire proofing” as it serves to decrease heat transfer from the fire to the underlying materials. These coatings are helpful in case of fibre-reinforced polymeric structural composites, where with heat the resin part of the composite softens before degrading and combustion of composite laminate occurs.

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