•First report relating fire properties of construction products to the Grenfell fire.•Flammability increases by factors of 10 to 100 from best to worst products.•Smoke toxicity 15 times greater for ...polyisocyanurate insulation than mineral wool.•Novel fire growth mechanism shows flaming polyethene drips igniting insulation foam.•Simple models able to predict fire behaviour in BS8414 test costing 100 times more.
The 2017 Grenfell Tower fire spread rapidly around the combustible façade system on the outside of the building, killing 72 people. We used a range of micro- and bench-scale methods to understand the fire behaviour of different types of façade product, including those used on the Tower, in order to explain the speed, ferocity and lethality of the fire. Compared to the least flammable panels, polyethylene-aluminium composites showed 55x greater peak heat release rates (pHRR) and 70x greater total heat release (THR), while widely-used high-pressure laminate panels showed 25x greater pHRR and 115x greater THR. Compared to the least combustible insulation products, polyisocyanurate foam showed 16x greater pHRR and 35x greater THR, while phenolic foam showed 9x greater pHRR and 48x greater THR. A few burning drips of polyethylene from the panelling are enough to ignite the foam insulation, providing a novel explanation for rapid flame-spread within the facade. Smoke from polyisocyanurates was 15x, and phenolics 5x more toxic than from mineral wool insulation. 1 kg of burning polyisocyanurate insulation is sufficient to fill a 50m3 room with an incapacitating and ultimately lethal effluent. Simple, additive models are proposed, which provide the same rank order as BS8414 large-scale regulatory tests.
Millions of individuals routinely remain awake for more than 18 h daily, which causes performance decrements. It is unknown if these functional impairments are the result of that extended wakefulness ...or from the associated shortened sleep durations. We therefore examined changes in objective reaction time performance and subjective alertness in a 32-d inpatient protocol in which participants were scheduled to wakefulness durations below 16 h while on a 20-h “day,” with randomization into standard sleep:wake ratio (1:2) or chronic sleep restriction (CSR) ratio (1:3.3) conditions. This protocol allowed determination of the contribution of sleep deficiency independent of extended wakefulness, since individual episodes of wakefulness in the CSR condition were only 15.33 h in duration (less than the usual 16 h of wakefulness in a 24-h day) and sleep episodes were 4.67 h in duration each cycle. We found that chronic short sleep duration, even without extended wakefulness, doubled neurobehavioral reaction time performance and increased lapses of attention fivefold, yet did not uniformly decrease self-reported alertness. Further, these impairments in neurobehavioral performance were worsened during the circadian night and were not recovered during the circadian day, indicating that the deleterious effect from the homeostatic buildup of CSR is expressed even during the circadian promotion of daytime arousal. These findings reveal a fundamental aspect of human biology: Chronic insufficient sleep duration equivalent to 5.6 h of sleep opportunity per 24 h impairs neurobehavioral performance and self-assessment of alertness, even without extended wakefulness.
Naturally occurring mixtures of hydromagnesite and huntite have found important industrial use. Their endothermic decomposition over a temperature range similar to that of commonly used polymers and ...their release of water and carbon dioxide, has led to such mixtures being successfully used as fire retardants. They have replaced aluminium hydroxide and magnesium hydroxide in many applications. The current understanding of the thermal decomposition mechanism of both minerals and their combination in natural mixtures has been reviewed and related to their fire retardant action. Both minerals contribute to the reduction in flammability of polymers although the extent of these interactions has not been fully investigated. However, the fire retardant mechanism of these minerals appears more complicated than either aluminium hydroxide or magnesium hydroxide.
A novel oligomer (PFDCHQ) based on 9,10-dihydro-9-oxa-10-phosphaphenanthrene −10-oxide (DOPO) and ferrocene groups was synthesized successfully, aiming at improving the flame retardant efficiency of ...diglycidyl ether of bisphenol A epoxy resin (DGEBA). FTIR, 1H NMR and 31P NMR were used to confirm the chemical structure of PFDCHQ. The high char yields of 60.3 wt% and 20.1 wt% were obtained for PFDCHQ from TGA results in nitrogen and air atmosphere, respectively. The thermal degradation mechanism of PFDCHQ was investigated by TG-FTIR and Py-GC/MS. The limiting oxygen index (LOI) of EP-5 with 5 wt% loading of PFDCHQ increased to 32.0% and the UL-94 V-0 rating was achieved, showing a notable blowing-out effect. In contrast to EP-0, the peak of the heat release rate (pHRR) and total heat release (THR) of EP-5 decreased by 18.0% and 10.3%. The flame retardant mechanism of PFDCHQ in epoxy resin was studied by TG-FTIR, SEM and Raman. SEM and Raman results indicated the formation of coherent and dense char residue with high degree of graphitization due to the incorporation of PFDCHQ. In UL-94, the blowing-out effect dominantly accounted for the enhanced flame retardancy in combination with optimized char structure. Furthermore, the addition of PFDCHQ improved the Young's modulus compared to EP-0.
•A novel oligmer (PFDCHQ) based on DOPO and ferrocene groups was synthesized successfully.•A possible thermal decomposition mechanism for PFDCHQ is proposed.•The EP-5 composite containing 5 wt% PFDCHQ can easily achieve UL-94 V-0 rating with LOI value of 32% and improved Tg.•PFDCHQ shows a significant fire retarding effect both in condensed and gas phase.
Naturally occurring mixtures of hydromagnesite and huntite are important industrial minerals. Their endothermic decomposition over a specific temperature range, releasing water and carbon dioxide, ...has lead to such mixtures being successfully used as fire retardants, often replacing aluminium hydroxide or magnesium hydroxide. The current understanding of the structure and thermal decomposition mechanism of both minerals and their combination in natural mixtures is reviewed. The crystalline structure of both minerals has been fully characterised. The thermal decomposition of huntite has been characterised and is relatively simple. However, the thermal decomposition mechanism of hydromagnesite is sensitive to many factors including rate of heating and the composition of the atmosphere. The partial pressure of carbon dioxide significantly affects the decomposition mechanism of hydromagnesite causing magnesium carbonate to crystallise and decompose at a higher temperature instead of decomposing directly to magnesium oxide.
•A methodology for testing furniture composites in the cone calorimeter has been described in detail.•The investigation used commercially available flame retardant fabrics and fillings.•Simultaneous ...quantification of flammability and smoke toxicity are reported.•Comparing components that comply with UK regulations, the study shows large differences in smoke toxicity.
Since the 1980s, mass market upholstered furniture sold in the United Kingdom has incorporated flame retardant chemicals to meet regulatory flammability requirements. However, UK fire deaths remain comparable with similar European countries which have no such regulations. Quantitative measures of the effect that different chemical flame retardants additives have on the flammability and smoke toxicity of UK regulatory-compliant upholstered furniture remain limited. It has been shown that most fatal fires involve upholstered furniture; most fire deaths result from toxic gas inhalation; gas phase flame retardants increase the toxicity of smoke; and the fall in fire deaths over the last 30 years is the same in countries with and without furniture flammability regulations. Moreover, the presence of certain flame retardants in furniture is a significant obstacle to any meaningful end-of-life processing.
The burning behaviour and smoke toxicity of nine upholstered furniture composites using a range of flame retardant technologies were assessed in the cone calorimeter. The total heat release (THR) varied from 46 MJ m−2 to 68 MJ m−2, the time-to-ignition (tti) from 8 s to 105 s, and peak heat release rate (pHRR) from 230 kW m−2 to 430 kW m−2. The composite filled with PET showed the longest tti while the expandable graphite fabric on the FR-foam showed the lowest pHRR. The composite with the Br-FR fabric and the FR-foam had the shortest tti, the greatest smoke, the second highest CO and the highest HCN yield. The composite with the non-FR fabric and the PET filling had the longest tti. For all the fabrics, the transition from non-FR to FR foam resulted in significant increases in the smoke, CO and HCN, except CO of Br-FR and FR-foam was slightly lower than non-FR foam.
Smoke toxicity predictions show that the use of gas phase flame retardants in both the fabrics and fillings of upholstered furniture contributes to the high proportion of smoke-related fire casualties. The work shows that the smoke toxicity of upholstered furniture can be reduced by using condensed phase FRs, such as expandable graphite, or less flammable materials, such as polyester wadding. The regulatory component tests which focus on ignitability have been shown to be ineffective at assessing the fire safety of composites representative of furniture as sold. The alternative approach of assessing heat release and smoke toxicity, as described here, would improve the fire safety of furniture while reducing reliance on additive flame retardants acting in the gas phase.
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Three metal hydroxide nanorods (MHR) with uniform diameters were synthesized, and then combined with graphene nanosheets (GNS) to prepare acrylonitrile–butadiene–styrene (ABS) copolymer composites. ...An excellent dispersion of exfoliated two-dimensional (2-D) GNS and 1-D MHR in the ABS matrix was achieved. The effects of combined GNS and MHR on the mechanical, thermal and flame retardant properties of the ABS composites were investigated. With the addition of 2wt% GNS and 4wt% Co(OH)2, the tensile strength, bending strength and storage modulus of the ABS composites were increased by 45.1%, 40.5% and 42.3% respectively. The ABS/GNS/Co(OH)2 ternary composite shows the lowest maximum weight loss rate and highest residue yield. Noticeable reduction in the flammability was achieved with the addition of GNS and Co(OH)2, due to the formation of more continuous and compact charred layers that retarded the mass and heat transfer between the flame and the polymer matrix.
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