Previous work has demonstrated that flame height is one of the two most important parameters determining the rate of vertical flame spread on a wall. Flame spread models rely on empirical flame height correlations of the form X f ¼ K ' Q Q 0n , but there have been no carefully controlled experiments designed to establish the validity of such correlations and there are no data for values of ' Q Q 0 5 c.25 kW/m. Two new sets of data are presented here, one based on experiments with 6 mm thick PMMA slabs (heights 25-250 mm, width 50-150 mm) as the fire source, measuring ' Q Q 0 and X f simultaneously. This set relates to the early stages of a wall fire when ' Q Q 0 5 30 kW/m. The other set of data was obtained with a vertical gas-fired panel which consisted of an array of 14 independent burners arranged to allow the aspect ratio of the burning surface to be varied. The data confirm that the flame height correlates with ' Q Q 0 , but reveal (inter alia) that there are two regions, for values of ' Q Q 0 greater than and less than c. 20 kW/m. An existing upward flame spread model was modified to allow these two correlations to be incorporated to predict the development of a small fire on a vertical surface for these two regions, which would provide more realistic modelling information.
The study explores the effects of the flame-retardant properties of nano-particles on water-based fire-retardant coatings, which include the effects on thermal stability and combustion properties. The coating used by the paper is acrylate resin (VAC), which is added with 3 basic components, including fire-retardant ammonium polyphosphate, pentaerythritol and melamine (APP-PER-MEL), to form an itumescent fire retardant (IFR). Then the fire retardent is added with magnesium hydroxide (Mg(OH)2, MH) nano-particles, multiwall carbon nanotubes (MWNT) and zinc borate (ZB) nano-powders of different concentrations, to form water-based fire-retardant coatings. By adjusting and controlling the concentration ratios of flame retardant to the 3 kinds of nano-particles with different profiles, the study analyzes the fire-retardant multiplying effect of nano-particles on water-based coatings. The nano-coatings mixed in special proportion are coated on plywood. Through thermogeavimetric analyzer (TGA) and cone calorimeter (CCT), the study inspects the thermal stability and combustion properties of water-based fire-retardant nano-coatings. The experimental results show that when the fire-retardant nano-coating composed of MH of concentration 28% and MWNT of concentration 2% is compared with the fire-retardant coating added with flame retardant only, the amount of residue can be increased by around 80% at combustion temperature 580°C. Besides, when the fire-retardant nano-coating composed of MH of weight concentration 28% and MWNT of weight concentration 2% is compared with the fire-retardant coating added with flame retardant only, the maximum heat release can be decreased by about 15%. The time required for this fire-retardant nano-coating to achieve maximum heat release is delayed by around 70 seconds when compared with other samples. Besides, the char-layered structure formed during thermal decomposition of nano-coating is more compact than the char-layered structure of water-based coating composed of the flame-retardant APP-PER-MEL components only. Therefore, nano-coatings can effectively decrease the transfer of heat and inflammable volatiles to plywood surface, and can enhance the flame retardant performance of plywood.
In this study, synthesis and properties of green flame retardant of silane-functionalized expandable graphite (EG) composites were investigated. The coupling agent was used to improve the interface between the matrix and EG. Fourier transform infrared spectrophotometry and X-ray photoelectron spectroscopy were adopted to characterize the functionalized EG. It was affirmed that 3-aminopropyltriethoxsilane (APTS) has been grafted on EG. The modified EG composites improved thermal property, corresponding to functionalized EG. 29Si-nuclear magnetic resonance and scanning electron microscopies were used to study the structure and the morphology property of the modified EG composites. It showed that flake graphite existed in the matrix. Energy dispersive X-ray analysis indicated that Si atoms appeared due to APTS grafted on EG. The expanded structures of graphite were formed after burning. The foamed layer demonstrated the mechanism of protection of EG. The results present poly(methylmethacrylate)/silane-modified EG(PMMA, poly(methylmethacrylate) composites that have excellent thermal stability and flame-retardant property compared to pure PMMA resin.
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