Burning behaviour of intumescent coating and nanoparticles applied on flaxboard

This paper presents an experimental investigation of the ignition and burning behaviours ofintumescent coatings and nanoparticles applied on flaxboard using three standard tests: the cone calorimeter, single burning item (SBI) and reduced scale (1/3rd) ISO room. Results in the cone calorimeter and SBI, both representing open burning, showed that the intumescent coating is effective in delaying ignition and reducing the heat release rate (HRR). With nanoparticles, further delay in ignition and reduction in the HRR were observed owing to an increase in the thermal stability of the char in the presence of nanoparticles. In the 1/3rd ISO room tests, the reduction in the HRR is found to be less substantial than that in the cone calorimeter or SBI. This finding highlights the important difference between burning in an open condition or in an enclosure, because in an enclosure the sample is heated not only by the flame but, more importantly, by the hot smoke layer and surrounding walls. Furthermore, in an enclosure the maximum HRR is limited by the amount of oxygen entering the enclosure through the opening. In order to examine the performance of intumescent coatings inventilation-controlled condition, tests were performed in the 1/3rd ISO room with reduced opening sizes (50 and 75 % of the standard opening size). It is found that in the case of 50 % opening size, for which a ventilation-controlled condition was attained, the maximum HRRs for the materials w/wo intumescent coatings were found to be the same.