Flame-Retardant Wood Scrimber/Plywood Composites: Preparation, Characterization, and Enhanced Structural Performance

Seven halogen‐free flame retardant (FR) compounds were evaluated using pyrolysis combustion flow calorimetry (PCFC) and cone calorimetry. Performance of wires coated with the compounds was evaluated using industry standard flame tests. The results suggest that time to peak heat release rate (PHRR) and total heat released (THR) in cone calorimetry (and THR and temperature at PHRR in PCFC) be given more attention in FR compound evaluation. Results were analyzed using flame spread theory. As predicted, the lateral flame spread velocity was independent of PHRR and heat release capacity. However, no angular dependence of flame spread velocity was observed. Thus, the thermal theory of ignition and flame spread, which assumes that ignition at the flame front occurs at a particular flame and ignition temperature, provides little insight into the performance of the compounds. However, results are consistent with a heat release rate greater than about 66kW/m2 during flame propagation for sustained ignition of insulated wires containing mineral fillers, in agreement with a critical heat release rate criterion for burning. Mineral fillers can reduce heat release rate below the threshold value by lowering the flaming combustion efficiency and fuel content. A rapid screening procedure using PCFC is suggested by logistic regression of the binary (burn/no‐burn) results. Copyright © 2008 John Wiley & Sons, Ltd.

Ultra-high fire-safety unsaturated polyesters enabled by self-assembled micro/nano rod from Schiff base, diphenylphosphinyl group and nickel (II) metal

Co Hybrids modified piperazine pyrophosphate towards efficient flame retardancy, smoke suppression, and high mechanical properties of styrenic thermoplastic elastomer

Laponite-based inorganic-organic hybrid coating to reduce fire risk of flexible polyurethane foams

Polyurethane (PU) foam has a high flammability and is widely used in aircraft interiors, presenting a significant danger to occupants. This study analysed three composite intumescent flame-retardant (IFR) coatings for flexible PU foam; expandable graphite (EG), ammonium polyphosphate (APP) and alginate (AG). The coatings were prepared in concentrations of 5 wt%, 10 wt%, and 50 wt% with an acrylic binder. The coated samples were characterised using cone calorimetry, SEM, and mechanical testing. The findings showed peak heat release rate, total heat release, and carbon dioxide production from the 10 wt% triple-layer coating (EG:APP:AG) was 52%, 32%, and 58% less than the PU control. The char of the 10 wt% triple-layer sample effectively suppressed smoke release and inhibited the transfer of fuel and gas volatiles. Mechanical testing demonstrated a 3.4 times increase in tensile strength and a 15.4 times increase in compressive strength (50% compression) compared to the control PU with the 10 wt% triple-layer coating. A fire dynamics simulator model was developed that demonstrated large-scale flammability modelling for commercial aircraft. Future work can explore the integration of IFR coatings into computational analysis. These new bio-based coatings produced promising results for aircraft fire safety and flammability performance for PU polymers.

Temperate forests of Central Europe are exposed to increasing fire risk. However, little is known about combustion properties of leaf litter, which plays an important role in the spread of surface fires. We used cone calorimetry to compare combustion properties of leaf litter samples from seven common tree species of Central European forests by reconstructing a litter layer of original depth in sample holders with a size of 10 cm × 10 cm. In addition to mono-specific leaf litter beds, combustion experiments included mixtures of different litter types, mixtures of litter and bryophytes and one mixture of litter and fine woody debris, totalling to 13 different setups (i.e. litter types). Recorded combustion properties included ignitability, flaming duration and heat release. Differences in combustion properties were analysed using analyses of variance followed by pairwise post-hoc tests. Combustion properties mainly differed between different litter types (broadleaf, pine needle, short needle). Highest total and peak heat release were observed for Scots pine (Pinus sylvestris), while peak heat release rates showed only minor differences for litter of the remaining species. Broadleaf litter was characterized by highest ignitability. For short-needle litter, we observed long flaming duration and incomplete combustion, resulting in the lowest total heat release on a sample mass basis. For litter mixtures of pine and broadleaf litter, we observed lower peak heat release rates in comparison to mono-specific pine litter. Mosses reduced peak heat release rates and increased the proportion of unburned biomass. However, the magnitude of this effect differed between bryophyte species included in the mixtures. The addition of fine woody debris strongly increased total heat release, highlighting the importance of fine woody fuels for fire behaviour. The results of this study provide valuable baseline information on combustion behaviour of leaf litter from Central European forests. Due to the limitations of laboratory combustion experiments to reproduce conditions of real forest fires, there is a need for future field studies investigating fire behaviour under natural conditions.

A novel coating of hyperbranched poly(urethane-phosphine oxide) for poly(methyl methacrylate) with high fire safety, excellent adhesion and transparency

This paper reports two experimental studies wherein the combustion process of flame resistant (FR) thermal protective textiles is characterized in terms of thermal decomposition and heat release parameters before and after contamination and in terms of heat release parameters after contamination and decontamination. Aramid and FR cotton/nylon decomposed at higher and aramid/FR viscose at lower temperature in the presence of oil. Oil interferes with thermally induced interactions between aramid and FR viscose, altering the thermal decomposition rates and formation of char, and thereby increasing the effectiveness of the flame retardant present in the viscose. It is apparent that oily contaminants present in FR fabrics affect the initiation of the thermal degradation and formation of char. All contaminated FR fabrics showed significantly higher peak heat release rate (PHRR), total heat release (THR) and effective heat of combustion (EHC) compared to uncontaminated ones. Oily specimens laundered with no detergent or prewash product had higher PHRR, THR and EHC compared to other treatments regardless of the fabric type or number of contamination/decontamination cycles. Heat release increased with increased number of contamination/decontamination cycles for most laundry treatments for all FR fabrics. FR cotton/nylon had the highest and aramid had the lowest PHRR and THR whether specimens were uncontaminated, contaminated or decontaminated. In this study heat release from FR fabrics increased with increased oily contamination.

Flame retardant synergy between interfacial and bulk carbonation in glass fiber reinforced polypropylene

Flame retardancy and synergistic flame retardant mechanisms of acrylonitrile-butadiene-styrene composites based on aluminum hypophosphite

Synthesis of a bio-based flame retardant via a facile strategy and its synergistic effect with ammonium polyphosphate on the flame retardancy of polylactic acid

A novel phosphorus-containing cardanol (PCC) derived from cardanol—a renewable meta-substituted phenol and harmful by-product of the cashew industry—in combination with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) was used to produce bio-based phenolic foams (PFs). The properties of the PFs were then characterized in detail. The PCC was fully characterized by using Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (1H NMR), while the thermal degradation was studied and monitored by thermogravimetry coupled to FTIR (TGA/FTIR) and TGA coupled with mass spectrometry (TGA/MS). It was found that PCC exhibited high thermal stability. The total heat release, peak heat release rate and mean heat release rate of PF containing 4% PCC decreased by 13.55, 33.43 and 13.42%, respectively, in comparison with pristine PF. The enhanced flame-retardant behavior was attributed to the free radicals PO· produced during combustion, which captured free radicals in the gas phase; moreover, the phosphaphenanthrene group may create a char residue barrier against the further combustion of the polymer. Meanwhile, bio-based PFs showed excellent mechanical properties, as the compressive and flexural strength of PF with 4% PCC increased by 79.59 and 20.98%, respectively, in comparison with pristine PF. The pulverization ratio of bio-based PFs was reduced with the increase in PCC content. The findings in this study demonstrate that PCC could be used as a phenol substitute in the synthesis of PFs to overcome their intrinsic brittleness and high flammability.

Unbleached (grey or greige) cotton nonwoven fabrics (with 12.5% polypropylene scrim) were treated with three phosphate–nitrogen–based flame retardant formulations and evaluated with micro-scale combustion calorimeter. Heat release rate, peak heat release rate, temperature at peak heat release rate, heat release capacity, total heat release and char yield were determined. The peak heat release rate and total heat release results demonstrated that nonwoven fabrics treated with a formulation having higher diammonium phosphate and no dimethylol dihydroxyethyleneurea were superior to those treated with a formulation containing dimethylol dihydroxyethyleneurea. Nonwoven fabrics treated with these formulations were both superior to the nonwoven fabrics treated with a commercially available flame retardant formulation. These results were supported by the percentages of phosphorus and nitrogen on these fabrics, confirming that P–N synergism imparts high flame retardancy to the nonwoven fabrics. Grey cotton (untreated) consistently showed better flame resistance than (untreated) bleached cotton. As a result, its flame retardant products had lower heat release rate/peak heat release rate and other flammability characteristics than those of the bleached cotton. Additionally, grey cotton is softer than bleached cotton and saves the cost of bleaching and waste disposal. These three flame retardant formulations were used primarily to treat the cotton component of the nonwoven blend to make it flame retardant without flame retardant improvement for the polymer component.

This work presents a simple algebraic method for calculating heat release rate (HRR) considering the three-dimensional flame spread and burning over a cubical-shaped polyurethane foam block. Flame spread area is calculated by flame spread velocity toward multiple directions over top and side surfaces. Burnt-out area is calculated by projected area of the burnt-out portion onto original top and side surfaces. Mass burning rate per burning area is calculated by radiation from flame to each burning surfaces. HRR is calculated by multiplying burning area with mass burning rate and heat of combustion. The calculated results were compared with experiments. In cases of the cubical shape or wide shape, HRR is predicted fairly well until peak HRR. In case of tall blocks, the calculated peak HRR was smaller than experiments due to HRR per unit area over vertical surface was under estimated.

ABSTRACTTo improve the flame retardancy of waterborne polyurethane (WPU), two novel DOPO‐containing melamine‐based flame retardants were synthesized by combining Schiff bases (derived from p‐hydroxybenzaldehyde, terephthalaldehyde, and melamine) with 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO). FTIR and NMR confirmed the chemical structures. The flame retardants were chemically incorporated into WPU to prepare modified films. Comprehensive testing showed significant improvements: water contact angle increased to 138.79° with 6.45% lower absorption; thermal stability improved by 60°C; LOI reached 33.1% with UL‐94 V‐1 rating. Cone calorimetry revealed 52.33% and 60.47% reductions in peak heat release rate (pHRR) and total heat release (THR), with 11 s longer ignition time. Total smoke production (TSP) decreased by 91.81% and average effective heat of combustion (AEHC) by 53.99%. Although CO and CO2 emissions increased by 144.23% and 86.29%, the overall fire safety performance was markedly enhanced. Mechanical properties improved substantially, with tensile strength reaching 2.12 MPa (2.83× higher than unmodified WPU). The simultaneous enhancement of flame retardancy, thermal stability, water resistance, and mechanical properties demonstrates the effectiveness of this modification approach for WPU applications requiring improved fire safety.