Study of the thermal behaviours of intumescent silicate materials
The fire retardant properties of inorganic silicate based materials were characterised by Thermal, Infrared (IR), Karl Fischer (KF), Mass Spectrometry (MS) and Cone Calorimetry (CC) techniques. Scanning Electron Microscopy (SEM) was also employed to study the sample morphologies. In this study, spectral data were analysed by multivariate Target Factor Analysis (TFA) to determine the relative evolution profiles of selected fire gases. A combination of the gas evolution profiles and further numerical treatment of the thermal characterisation data provided a novel set of protocols to assess the high temperature behaviour of the fire protective silicate materials. In the context of this work, the study discusses the structure-property relationships of the silicates, identifies the degradation stages and elucidates the processes involved during thermal treatment by comparison with mechanistic findings in published literature. The following conclusions were drawn. Five transitions were detected by thermal analyses, which correspond to; i) the evolution of water and flammable species ii) the rearrangement of interstitial ions and water molecules iii) the evaporation of water of condensation from silanol groups iv) the decomposition of samples and i) structural rearrangement. Cone calorimetry studies revealed that samples with low polyol (P) and high SiO2:Na2O weight ratio (WR) exhibited very low heat release rates (HRR) and vice versa. It was observed that in general, low polyol content and high SiO2:Na2O WR enhanced fire resistivity. This provided a better understanding of the thermo-degradation patterns of samples and the underlying chemistry influencing the performances of the inorganic silicate based materials.