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This study investigated suspending two fire retardants in sugar-cane bagasse plies used for manufacturing natural fibre reinforced composites. Sugar-cane bagasse was alkali treated, blended with either APP (Ammonium Polyphosphate) or ATH (Aluminium Hydroxide), pressed and dried to form plies. Composites were manufactured using a light resin transfer moulding process with epoxy resin. Composites manufactured with fire retardant suspended plies were compared to composites with plies layered with equivalent amounts of fire retardants. The composites were characterised using thermogravimetric analysis (TGA) for thermal stability and char yield, isotropic hot disc method for thermal properties, and cone calorimeter for studying ignition and flammability. Plies suspended with APP had the highest char yield of 58% (in nitrogen), reducing to 26% in the composite form, with degradation driven by the epoxy matrix. The composite layered with ATH had the latest ignition times of 118 s when tested with a radiant heat flux of 35 kW/m2. The composite layered with APP displayed the lowest average heat release rate (179.7k W/m2), peak heat release rate (305.6k W/m2), and total heat released (135.5 MJ/kg). When assessing the fire growth, the composite layered with APP was again favourable. While the layering yielded more favourable results than the suspension of the same retardants, this study showed that a rudimentary process was able to suspend enough retardants to improve the behaviour of the resulting composites in a fire scenario. [ABSTRACT FROM AUTHOR]

Summary: The interactions of Calcium carbonate (e.g., eggshell powder) and Lignin with ammonium polyphosphate (APP) when used as fire retardants were investigated. Three mixing ratios ‐ 1:3, 1:1, and 3:1, were used with natural fibre reinforced composites containing a hemp mat and an epoxy matrix manufactured using a light resin transfer moulding (L‐RTM) process. The thermal decomposition of the retardant mixtures and composites was investigated using thermogravimetric analysis (TGA). The findings showed that even though the decomposition reactions of APP with eggshell powder and lignin mixtures interacted and overlapped, the same interactions could not be seen in the composites. In the composite form while the residue was affected by the retardant, the decomposition reactions were driven primarily by the hemp and epoxy. Flammability of the composites was studied by testing to 20, 35, 50, and 75 kW/m2 with a cone calorimeter, and determining the critical heat flux. While the samples with eggshell powder had higher ignition times, the critical heat flux for ignition was 13 kW/m2 for all sample groups except for a ratio of 1:3 APP to eggshell powder, which was 14 kW/m2. The lowest burning rates (mass loss and heat release) occurred in composites containing only APP, however, the addition of eggshell powder or lignin at even a ratio of 3:1 APP to either provided a notable reduction. [ABSTRACT FROM AUTHOR]

Summary: The feasibility of using sugar‐cane bagasse as a reinforcement for natural fiber composites and the performance of these composites under fire conditions was investigated. Plies were manufactured using a process, which involved alkali‐treating bagasse, blending, pressing, and drying. Soaking durations of 30 minutes and 24 hours were compared. Composites were then made with these plies using a light resin transfer molding process. The composites were characterized and compared to a commercial hemp fabric using thermogravimetric analysis for thermal stability and char yield, isotropic hot disc method for thermal conductivity and specific heat capacity, and cone calorimeter for flammability. The investigation found that bagasse plies could be successfully used in composite manufacture, but posed a greater ignition hazard, and a comparable burning behavior hazard to the commercial product when tested at a radiant heat flux of 35 kW/m2. Thirty minutes treating resulted in a ply, which resulted in a char yield of 28%. Although in the composite form, there were no significant differences between all sample groups. With regards to ignition, the hemp composite had the latest time‐to‐ignition of 137 seconds. Comparison of the thermal properties to the ignition times showed that higher values of thermal properties resulted in later ignition times. The composite with the 30‐minute treated bagasse had a total heat release of 159 MJ/m2 and average heat release rate of 263 kW/m2, while the peak heat release rate was lower for the 24‐hour treated bagasse at 537 kW/m2. Overall, no significant differences in the two treatment durations were observed. [ABSTRACT FROM AUTHOR]

Fuel moisture content is one of the key parameters controlling the flaming ignition of wildland fuel. However, the role of fuel moisture content in assessing the flammability of different fuel curing (dead and live fuel) is still not well understood. This paper presents the results of ignition tests of fuel beds consisting of dead and live Eucalyptus saligna leaves under a wide range of moisture contents. External heat flux and fuel moisture content are shown to significantly influence time to ignition and mass loss rate at the ignition of Eucalyptus saligna leaves, thus illustrating distinctive heating processes in the fuel bed. The thermal behaviour of the leaf bed before ignition is analysed using the analytical solution to the heat conduction equation, as the classical ignition correlations yield inconclusive results. This approach allows identification of thermally thick and thin behaviours for distinct ranges of heating, with the transition (thermally intermediate) region observed at higher external heat fluxes for higher moisture content. Additionally, a flammability assessment based on time to ignition confirms the inadequacy of the common assumption that live fuel can be considered as moist dead fuel. The flammability and thermal behaviour of dead and live Eucalyptus saligna leaves before ignition are studied. The results indicate that the flammability of dead and live leaves cannot be solely assessed by moisture content. The external heat flux and fuel moisture content govern thermal behaviour before ignition. [ABSTRACT FROM AUTHOR]

Summary: A series of experiments have been conducted to measure the in‐depth heating of laminated bamboo samples subjected to heat fluxes of 5, 10, 30, and 60 kW/m2, either perpendicular or parallel to the grain. These heat fluxes were chosen to induce different phenomena within the material—from inert heating to moisture evaporation, pyrolysis, oxidation, and flaming—so that the effects of these can be isolated and evaluated separately by simple heat‐transfer models. Moisture migration along the fibres becomes a critical factor when bamboo is heated parallel to the grain, resulting in increased convective heat transfer to deeper parts of the material and an accumulation of moisture in depth that accentuates the endothermic plateau in the temperature profiles around 100°C. Average charring rates for 60 minutes of exposure under 60 kW/m2 were 0.74 and 0.70 mm/min for perpendicular and parallel heating, respectively. The thickness of the heated layer was much larger for parallel heating due to moisture migration, which is less significant perpendicular to the grain. Inert heat diffusion is a good approximation at heat fluxes of 5 and 10 kW/m2, but exothermic oxidation reactions become critical above 400°C and must be included in future models. [ABSTRACT FROM AUTHOR]

Summary: This paper presents an experimental study on the fire performance of two types of plastic charring insulation materials when covered by a plasterboard lining. The specific insulation materials correspond to rigid closed‐cell plastic foams, a type of polyisocyanurate (foam A) and a type of phenolic foam (foam B), whose thermal decomposition and flammability were characterised in previous studies. The assemblies were instrumented with thermocouples. The plasterboard facing was subjected to constant levels of irradiation of 15, 25, and 65 kW m−2 using the heat‐transfer rate inducing system. These experiments serve as (1) an assessment of the fire behaviour of these materials studied at the assembly scale and (2) an identification of the fire hazards that these systems pose in building construction. The manifestation of the hazards occurred via initial pyrolysis reactions and release of volatiles followed by various complex behaviours including char oxidation (smouldering), cracking, and expansion of the foam. Gas‐phase conditions may support ignition of the volatiles, sustained burning, and ultimately spread of the flame through the unexposed insulation face. The results presented herein are used to validate the insulation "critical temperature" concept used for a performance‐based methodology focused on the selection of suitable thermal barriers for flammable insulation. [ABSTRACT FROM AUTHOR]

Four sandwich panel rooms were constructed as prescribed in the ISO 13784-1 test. However, the construction followed normal industry practice, and the panels were also subjected to the kinds of damage typically found in commercial premises, although such damage may not typically be concentrated in such a small room. The fire load was increased to simulate fires actually occurring in commercial premises by stepping up the propane burner output from the usual maximum of 300-600 kW, and by placing a substantial wooden crib in two of the rooms. The results showed significant differences in fire growth rate and burning behaviour between those panels filled with polyisocyanurate (PIR) and those filled with stone wool in both the experiments without and with the wooden crib. Most significantly, the PIR pyrolysis products caused earlier ignition (by radiation from above) of the wooden crib 11 min into the experiment (1 min after the burner was stepped up to 300 kW), whereas the crib ignited 22 min into the test (2 min after the burner had been stepped up to 600 kW, which is beyond the test standard both in time and heat input) for the stone wool panels. This interaction between building and contents is most often ignored in fire safety assessments. After a few minutes, the PIR pyrolysis products that escaped outside the room, from between the panels, ignited. The extra thermal exposure from the PIR-fuelled flames distorted the panels, which in turn exposed more PIR, resulting in large flames on both the inside and outside of the enclosure. From a fire safety perspective this is most important as it shows that with the large fire loads that are commonly found in commercial premises, steel-faced PIR filled panels are not capable of acting as fire barriers, and may support flame spread through compartment walls and ceilings. In addition, the PIR panelled rooms produced very large quantities of dense smoke and toxic effluents, whereas the stone wool panelled rooms produced small amounts of light smoke of lower toxicity. Furthermore, the experiments showed that modifications to the standard test can lead to extremely different outcomes for some of the products. As the modifications simulated real-life situations, it seems important to discuss whether the standard is robust enough for property safety scenarios encountered in industrial premises. [ABSTRACT FROM AUTHOR]

Summary: Results are presented from 2 series of ad hoc experimental programmes using the cone calorimeter to investigate the burning behaviour of charring closed‐cell polymeric insulation materials, specifically polyisocyanurate (PIR) and phenolic (PF) foams. These insulation materials are widely used in the construction industry due to their relatively low thermal conductivity. However, they are combustible in nature; therefore, their fire performance needs to be carefully studied, and characterisation of their thermal degradation and burning behaviour is required in support of performance‐based approaches for fire safety design. The first series of experiments was used to examine the flaming and smouldering of the char from PIR and PF. The peak heat release rate per unit area was within the range of 120 to 170 kW/m2 for PIR and 80 to 140 kW/m2 for PF. The effective heat of combustion during flaming was within the range of 13 to 16 kJ/g for PIR and around 16 kJ/g for PF, while the CO/CO2 ratio was within 0.05 to 0.10 for PIR and 0.025 to 0.05 for PF. The second experimental programme served to map the thermal degradation processes of pyrolysis and oxidation in relation to temperature measurements within the solid phase under constant levels of nominal irradiation. Both programmes showed that surface regression due to smouldering was more significant for PF than PIR under the same heat exposure conditions, essentially because of the different degree of overlap in pyrolysis and oxidation reactions. The smouldering of the char was found to self‐extinguish after removal of the external heat source. [ABSTRACT FROM AUTHOR]