A new route for obtaining chemically pure and ecological polycarbonates has been developed. The p... more A new route for obtaining chemically pure and ecological polycarbonates has been developed. The process was carried out without any amines with dimethylosulfoxide (DMSO) as interfacial catalyst. It was established that DMSO was between 80–120 mol % to the quantities of applied monomers. Bisphenol A and bisphenol C [2,2-bis(p-hydroxyphenyl),-1,-1 dichloroethylene] were applied as bisphenolic monomers
The Grenfell Tower fire in central London, started within a flat, engulfed the whole 24 storey bu... more The Grenfell Tower fire in central London, started within a flat, engulfed the whole 24 storey building in flames, killed 72 people and spread toxic effluent via the plume and particulate deposits. Soil samples from 6 locations up to 1,2 km from the Tower, together with semi-burnt fire debris and char samples, were collected 1 and 6 months after the fire. Additionally, dust samples and condensates were collected from a flat 160 m away from the Tower after 17 months. Samples were analysed for common potentially toxic components of fire effluents and synthetic vitreous fibres. 2 Samples collected within 140 m of the Tower showed, amongst other toxicants, polychlorinated dibenzo-p-dioxin concentrations 60 times greater than UK urban reference soil levels; benzene levels were 40 times greater; levels of 6 key polycyclic aromatic hydrocarbons (PAHs) were approximately 160 times greater. PAHs levels are approximately 20 times greater than those reported from nearby Hyde Park before the fire. To explain the presence of these pyrogenic contaminants char and partially burnt debris were also collected and analysed. Benzene, PAHs, isocyanates and phosphorus flame retardants were found. Hydrogen cyanide and synthetic vitreous fibres were present in both soil and debris. Particulate and pyrogenic contamination in the immediate vicinity is clearly evident, and may have leached out of fire debris, char and dust. Further analysis of the area around the Tower is necessary to understand potential health risks.
Inhalation of airborne isocyanates is associated with acute asthma attacks and inflammation in th... more Inhalation of airborne isocyanates is associated with acute asthma attacks and inflammation in the respiratory tract as well as cancer. These highly reactive compounds are used as monomers in various applications such as foams for insulation materials and upholstery furniture and are therefore commonly found in fire smoke from insulation materials, such as rigid polyisocyanurate (PIR) foams. Consequently, there is an increasing concern regarding the potential adverse health effects they may cause during this type of exposure. The aim of this study was to investigate the stability of generated isocyanates from aerobic pyrolysis of PIR after sampling in the derivatisation solution as well as after sample preparation to establish the optimal storage conditions and rate of degradation. Both airborne and particle-bound isocyanates were collected, using dibutylamine (DBA) as derivatisation agent in a midget impinger and impregnated filter after the impinger. The rapid degradation of the generated isocyanates after sampling emphasises the need for a prompt sample preparation and analysis, in particular for the collected mono-isocyanates, as the concentration decreased by 50% within 4-8 hours.
This paper uses fire statistics to show the importance of fire toxicity on fire deaths and injuri... more This paper uses fire statistics to show the importance of fire toxicity on fire deaths and injuries, and the importance of upholstered furniture and bedding on fatalities from unwanted fires. The aim was to compare the fire hazards (fire growth and smoke toxicity) using different upholstery materials. Four compositions of sofa-bed were compared: three meeting UK Furniture Flammability Regulations (FFR), and one using materials without flame retardants intended for the mainland European market. Two of the UK sofa-beds relied on chemical flame retardants to meet the FFR, the third used natural materials and a technical weave in order to pass the test. Each composition was tested in the bench-scale cone calorimeter (ISO 5660) and burnt as a whole sofa-bed in a sofa configuration in a 3.4 × 2.25 × 2.4 m test room. All of the sofas were ignited with a No. 7 wood crib; the temperatures and yields of toxic products are reported. The sofa-beds containing flame retardants burnt somewhat more...
Composites Part A: Applied Science and Manufacturing
Three metal hydroxide nanorods (MHR) with uniform diameters were synthesized, and then combined w... more 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 2 wt% GNS and 4 wt% 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.
A novel oligomeric intumescent fire retardant chelate, zinc phosphonated poly(ethylene imine) (Zn... more A novel oligomeric intumescent fire retardant chelate, zinc phosphonated poly(ethylene imine) (Zn-PEIP), with a changeable Zn 2+ loading, was synthesized. The chemical structure of Zn-PEIP was confirmed by FTIR, 13 C NMR and 31 P NMR spectroscopy. The thermal behavior and fire retardancy of low density polyethylene (LDPE) containing 25 wt% Zn-PEIPs with different amounts of Zn 2+ were investigated by thermogravimetric analysis (TGA), limiting oxygen index (LOI) and cone calorimetry. The TGA results showed that higher concentrations of Zn 2+ improved the thermal stability and increased the residue yield of LDPE. However, the data from the LOI and cone calorimetry showed that there is an optimum concentration of Zn 2+ for the best fire retardant performance of LDPE. This is ascribed to the high crosslink density resulting from zinc bridges, preventing normal swelling of the intumescent system. The surface morphology of the char was characterized by digital photographs and scanning electron microscopy (SEM). This confirmed the optimum intumescence, coherent and strong barrier layer formation at an intermediate Zn 2+ loading.
The soot and hydrocarbon generation behaviour from four common polymers has been investigated und... more The soot and hydrocarbon generation behaviour from four common polymers has been investigated under different fire conditions using different bench scale apparatuses. While well-ventilated flaming typically has high CO 2 /CO ratios and high combustion efficiency, in under-ventilated flaming, higher yields of the many products of incomplete combustion are generally observed, including carbon monoxide, soot and hydrocarbons. Hydrocarbon and soot production from polyethylene, polystyrene, polyamide and polyvinyl chloride were investigated using the steady state tube furnace (ISO TS 19700) under well-ventilated, small underventilated and large under-ventilated fire conditions; and in the smoke density chamber (ISO 5659-2) under the three standard test conditions; and the results have been compared to published data from the fire propagation apparatus (ASTM E 2058). The steady state tube furnace and the fire propagation apparatus show good agreement, for hydrocarbon and soot yields. Conversely it proved impossible to identify correlations with these tests for the soot and hydrocarbon yields in the smoke density chamber. To investigate the soot generation further, the particle size distribution was determined using a cascade impactor. This showed the predominance of 1-5 μm particulates for all polymers, except PVC, in underventilated conditions, and a smaller yield and a more even particle size distribution for well-ventilated burning. For PVC, no significant difference was observed for different fire conditions, with no clear trend of particle size distribution.
ISO 13571:2007 describes the calculation of safe escape time using yields of asphyxiant and irrit... more ISO 13571:2007 describes the calculation of safe escape time using yields of asphyxiant and irritant gases for performance based design. Hydrogen chloride (HCl) gas is an incapacitating irritant, reported to be intolerable at concentrations above 100 ppm, but lethal to rats only at concentrations around 5000ppm for a 30 minute exposure. It is evolved from burning PVC, and other chlorine containing plastics. The experimental evidence of the concentration/dose effects on a range of animal species has been reviewed, and concludes that the HCl concentration leading to incapacitation of 1000 ppm, used in ISO 13571, is rather too high to ensure safe escape. Experimental data is presented from burning unplasticised PVC, plasticized PVC cable, and LDPE to show that HCl interferes with the flame chemistry, particularly the conversion of CO to CO 2 , further increasing the hazard from the fire effluent. The product yields are used to estimate the fire effluent toxicity, comparing the standard based on rat lethality, ISO 13344 with the newer standard, which also takes the effect of incapacitating irritants into account, showing the large contribution of HCl to the fire hazard. Finally, the relationship between the toxicity and a simple analysis of effluent acidity (EN 50297-2-3) is discussed.
Graphene are uniformly coated with Co 3 O 4 and NiO by chemical method. The graphene hybrids coul... more Graphene are uniformly coated with Co 3 O 4 and NiO by chemical method. The graphene hybrids could confer PA6 with improved fire safety. The graphene hybrids perform well in inhibiting the smoke emission of PA6. This work attempts to design a novel graphene based hybrids as flame retardants.
A new route for obtaining chemically pure and ecological polycarbonates has been developed. The p... more A new route for obtaining chemically pure and ecological polycarbonates has been developed. The process was carried out without any amines with dimethylosulfoxide (DMSO) as interfacial catalyst. It was established that DMSO was between 80–120 mol % to the quantities of applied monomers. Bisphenol A and bisphenol C [2,2-bis(p-hydroxyphenyl),-1,-1 dichloroethylene] were applied as bisphenolic monomers
The Grenfell Tower fire in central London, started within a flat, engulfed the whole 24 storey bu... more The Grenfell Tower fire in central London, started within a flat, engulfed the whole 24 storey building in flames, killed 72 people and spread toxic effluent via the plume and particulate deposits. Soil samples from 6 locations up to 1,2 km from the Tower, together with semi-burnt fire debris and char samples, were collected 1 and 6 months after the fire. Additionally, dust samples and condensates were collected from a flat 160 m away from the Tower after 17 months. Samples were analysed for common potentially toxic components of fire effluents and synthetic vitreous fibres. 2 Samples collected within 140 m of the Tower showed, amongst other toxicants, polychlorinated dibenzo-p-dioxin concentrations 60 times greater than UK urban reference soil levels; benzene levels were 40 times greater; levels of 6 key polycyclic aromatic hydrocarbons (PAHs) were approximately 160 times greater. PAHs levels are approximately 20 times greater than those reported from nearby Hyde Park before the fire. To explain the presence of these pyrogenic contaminants char and partially burnt debris were also collected and analysed. Benzene, PAHs, isocyanates and phosphorus flame retardants were found. Hydrogen cyanide and synthetic vitreous fibres were present in both soil and debris. Particulate and pyrogenic contamination in the immediate vicinity is clearly evident, and may have leached out of fire debris, char and dust. Further analysis of the area around the Tower is necessary to understand potential health risks.
Inhalation of airborne isocyanates is associated with acute asthma attacks and inflammation in th... more Inhalation of airborne isocyanates is associated with acute asthma attacks and inflammation in the respiratory tract as well as cancer. These highly reactive compounds are used as monomers in various applications such as foams for insulation materials and upholstery furniture and are therefore commonly found in fire smoke from insulation materials, such as rigid polyisocyanurate (PIR) foams. Consequently, there is an increasing concern regarding the potential adverse health effects they may cause during this type of exposure. The aim of this study was to investigate the stability of generated isocyanates from aerobic pyrolysis of PIR after sampling in the derivatisation solution as well as after sample preparation to establish the optimal storage conditions and rate of degradation. Both airborne and particle-bound isocyanates were collected, using dibutylamine (DBA) as derivatisation agent in a midget impinger and impregnated filter after the impinger. The rapid degradation of the generated isocyanates after sampling emphasises the need for a prompt sample preparation and analysis, in particular for the collected mono-isocyanates, as the concentration decreased by 50% within 4-8 hours.
This paper uses fire statistics to show the importance of fire toxicity on fire deaths and injuri... more This paper uses fire statistics to show the importance of fire toxicity on fire deaths and injuries, and the importance of upholstered furniture and bedding on fatalities from unwanted fires. The aim was to compare the fire hazards (fire growth and smoke toxicity) using different upholstery materials. Four compositions of sofa-bed were compared: three meeting UK Furniture Flammability Regulations (FFR), and one using materials without flame retardants intended for the mainland European market. Two of the UK sofa-beds relied on chemical flame retardants to meet the FFR, the third used natural materials and a technical weave in order to pass the test. Each composition was tested in the bench-scale cone calorimeter (ISO 5660) and burnt as a whole sofa-bed in a sofa configuration in a 3.4 × 2.25 × 2.4 m test room. All of the sofas were ignited with a No. 7 wood crib; the temperatures and yields of toxic products are reported. The sofa-beds containing flame retardants burnt somewhat more...
Composites Part A: Applied Science and Manufacturing
Three metal hydroxide nanorods (MHR) with uniform diameters were synthesized, and then combined w... more 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 2 wt% GNS and 4 wt% 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.
A novel oligomeric intumescent fire retardant chelate, zinc phosphonated poly(ethylene imine) (Zn... more A novel oligomeric intumescent fire retardant chelate, zinc phosphonated poly(ethylene imine) (Zn-PEIP), with a changeable Zn 2+ loading, was synthesized. The chemical structure of Zn-PEIP was confirmed by FTIR, 13 C NMR and 31 P NMR spectroscopy. The thermal behavior and fire retardancy of low density polyethylene (LDPE) containing 25 wt% Zn-PEIPs with different amounts of Zn 2+ were investigated by thermogravimetric analysis (TGA), limiting oxygen index (LOI) and cone calorimetry. The TGA results showed that higher concentrations of Zn 2+ improved the thermal stability and increased the residue yield of LDPE. However, the data from the LOI and cone calorimetry showed that there is an optimum concentration of Zn 2+ for the best fire retardant performance of LDPE. This is ascribed to the high crosslink density resulting from zinc bridges, preventing normal swelling of the intumescent system. The surface morphology of the char was characterized by digital photographs and scanning electron microscopy (SEM). This confirmed the optimum intumescence, coherent and strong barrier layer formation at an intermediate Zn 2+ loading.
The soot and hydrocarbon generation behaviour from four common polymers has been investigated und... more The soot and hydrocarbon generation behaviour from four common polymers has been investigated under different fire conditions using different bench scale apparatuses. While well-ventilated flaming typically has high CO 2 /CO ratios and high combustion efficiency, in under-ventilated flaming, higher yields of the many products of incomplete combustion are generally observed, including carbon monoxide, soot and hydrocarbons. Hydrocarbon and soot production from polyethylene, polystyrene, polyamide and polyvinyl chloride were investigated using the steady state tube furnace (ISO TS 19700) under well-ventilated, small underventilated and large under-ventilated fire conditions; and in the smoke density chamber (ISO 5659-2) under the three standard test conditions; and the results have been compared to published data from the fire propagation apparatus (ASTM E 2058). The steady state tube furnace and the fire propagation apparatus show good agreement, for hydrocarbon and soot yields. Conversely it proved impossible to identify correlations with these tests for the soot and hydrocarbon yields in the smoke density chamber. To investigate the soot generation further, the particle size distribution was determined using a cascade impactor. This showed the predominance of 1-5 μm particulates for all polymers, except PVC, in underventilated conditions, and a smaller yield and a more even particle size distribution for well-ventilated burning. For PVC, no significant difference was observed for different fire conditions, with no clear trend of particle size distribution.
ISO 13571:2007 describes the calculation of safe escape time using yields of asphyxiant and irrit... more ISO 13571:2007 describes the calculation of safe escape time using yields of asphyxiant and irritant gases for performance based design. Hydrogen chloride (HCl) gas is an incapacitating irritant, reported to be intolerable at concentrations above 100 ppm, but lethal to rats only at concentrations around 5000ppm for a 30 minute exposure. It is evolved from burning PVC, and other chlorine containing plastics. The experimental evidence of the concentration/dose effects on a range of animal species has been reviewed, and concludes that the HCl concentration leading to incapacitation of 1000 ppm, used in ISO 13571, is rather too high to ensure safe escape. Experimental data is presented from burning unplasticised PVC, plasticized PVC cable, and LDPE to show that HCl interferes with the flame chemistry, particularly the conversion of CO to CO 2 , further increasing the hazard from the fire effluent. The product yields are used to estimate the fire effluent toxicity, comparing the standard based on rat lethality, ISO 13344 with the newer standard, which also takes the effect of incapacitating irritants into account, showing the large contribution of HCl to the fire hazard. Finally, the relationship between the toxicity and a simple analysis of effluent acidity (EN 50297-2-3) is discussed.
Graphene are uniformly coated with Co 3 O 4 and NiO by chemical method. The graphene hybrids coul... more Graphene are uniformly coated with Co 3 O 4 and NiO by chemical method. The graphene hybrids could confer PA6 with improved fire safety. The graphene hybrids perform well in inhibiting the smoke emission of PA6. This work attempts to design a novel graphene based hybrids as flame retardants.
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