Effects of expandable graphite on char morphology and pyrolysis of epoxy based intumescent fire-retardant coating

Published in Journal of Applied Polymer Science, Vol. 138(41), 51206, 2021
DOI: 10.1002/app.51206

Abstract

The current study was designed to investigate the effects of expandable graph-ite (EG) on fire protection properties of intumescent fire-retardant coating forsteel structures. Several formulations of intumescent coating were preparedand tested according to ISO 834 for char expansion. The chars were foundwithout cracks and bonded with the steel substrate. The results showed thatthe coating slowly degraded during the test and char remained in contact withvertically tested coated substrate. The coated substrates were also tested forweather resistance using humid and ultraviolet environment. The char wascharacterized by using FESEM, XRD, FTIR, TGA, and XPS analysis. FESEMexamined char morphology of the coatings after furnace fire test. XRD andFTIR showed the presence of graphite, borophosphate; boron oxide andsassolite in the char. TGA and DTGA results disclosed that EG improved theresidual mass of coating. XPS analysis showed the percentages of carbon andoxygen are 48.50 and 43.45 in char of formulation with 12.8% EG. The resultsof weathering test coatings showed decreased in char expansion because of ahumidity and UV light. The formulation with 9.8% EG showed the maximumchar expansion and high residual mass among the formula tions investigated inthis study. The weathering tested coated samples showed their capability offire protection.