Journal of Fire Sciences

In this study, a variety of additives have been evaluated as potential fire retardants for polyureas with cone calorimetry being the method of evaluation. The additives that have been evaluated include minerals (alumina trihydrate), bromine-, nitrogen-, and phosphorus-based fire retardants. The major criteria for evaluation are the reductions in the peak heat release rate and the total heat released, the evolution of smoke and dripping.

Transport of larger smoke particles generated by a fire in a compartment is studied. An atrium fire with three different heat release rates is taken as an example. The air flow pattern and temperature contours are predicted by a fire field (or application of computational fluid dynamics (CFD) model. The paths of smoke particles are modeled by the Lagrangian method coupled with the air movement induced by hot smoke. Distribution of smoke particles and their trajectories are then calculated. By superimposing the trajectories of particles of different sizes, the shape of the smoke plume is observed.

A thermal wave skin model incorporating surface heat flux from a skin simulant sensor is developed to characterize the thermal performance of flame-resistant (FR) fabrics covering the skin simulant sensor. Comparison of the results of time to 2nd degree skin burn and temperature elevation of skin beneath a layer of fabric obtained from the newly developed thermal wave skin model to the results obtained by using the Pennes' equation is performed in this research. Results of tolerance time from Stoll criterion method are also compared with Henriques burn damage integral from two skin models between constant–flux exposures in TPP calorimeter. Investigations have been conducted to find the effects of structural parameter, air pressure, and air layer thickness on the thermal performance of the selected FR fabric determined by the newly developed skin model and the method. It is concluded that the thermal protective performance of FR fabrics can be characterized here more precisely than in previous work.

SiO₂ has long been recognized as an inert diluent and usually used as an enhancing agent in thermoplastic polymers. Few reports are presented about its use as additive flame retardant. In this article, the flame retardant synergistic effect of SiO₂ with aluminum hydroxide (ATH) on linear low density polyethylene and ethylene-vinyl acetate (LLDPE/EVA) composites in the presence of a new compatibilizer, polyethylene (PE) grafted by fluoropolysiloxane (FS), prepared to improve the compatibility between polymers (LLDPE/EVA) and inorganic fillers (ATH and SiO₂), is investigated by means of limited oxygen index (LOI), cone calorimeter (CONE) and thermogravimetric analysis (TGA). The results show that the addition of SiO₂apparently increases the LOI value and decreases the heat release rate (HRR), mass loss rate (MLR), and specific extinction area (SEA). The TGA data shows further evidence that the synergistic mechanism of SiO₂ with ATH is mainly due to the physical process in the condensed phase leading to the formation of a more stable and compact barrier, which efficiently prevents the heat and mass transfer in fire. The good mechanical properties of the flame retardant materials implies the improved compatibility by the newly prepared compatibilizer.

Wood is treated with a new composite flame retardant, whose components guanyl urea phosphate (GUP) and boric acid (BA) impart flame retardance. The flame retarding behavior of these samples is measured by cone calorimeter. The thermal behavior of samples has been studied by differential thermogravimetry (DTG) and thermogravimetry (TG) in air. The activation energies for different stages of thermal degradation are obtained following the method of Broido, A. (1969). J. Polym. Sci., Part 2, 7: 1761. It is found that the combustion parameters of wood, including rate of heat release (RHR) and total heat release (THR) are decreased considerably by the treatment, especially for wood treated with the composite flame retardant of wood (FRW) because of a strong synergistic effect of flame retardance between GUP and boric acid. The mechanism of synergism is explained by analyzing the TG data. The GUP can accelerate dehydration and carbonization while BA can relatively increase thermal stabilization of wood. Their synthetical actions result in more char and less flammable volatile products, obtaining good flame retardance.