Influences of expandable graphite modified by polyethylene glycol on fire protection of waterborne intumescent fire resistive coating

Modified expandable graphite (MEG, expandable graphite modified by polyethylene glycol) was used as modifier to improve the fire protection of intumescent fire resistive coating. The FTIR spectra, TGA analysis and SEM images well demonstrated that the surface of EG flakes was successfully modified by polyethylene glycol. After adding 4 wt.% EG or MEG into the coatings, the thermal degradation and char formation of the coatings were investigated in detail by using TGA, XRD, X-ray fluorescence spectrometry (XRF) and SEM. The TGA results showed that the addition of EG and MEG could improve the thermal degradation of the coatings and enhanced the anti-oxidation of the char layers at high temperature. The XRF results showed that anti-oxidation of the coatings was improved by adding EG or MEG. The SEM images demonstrated that the cell size of the char layer increased and the cell size distribution of the char layer became narrow after adding MEG into the coating.