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This study examines the effects of heat and fire on the physical, mechanical and electrical properties of carbon fibre and those in carbon fibre reinforced composites (CFRCs). Carbon fibres were exposed to controlled heating (thermogravimetric analysis (TGA) and a tube furnace) in inert and air (oxygenated) environments and simulated fire (cone calorimetry at 35–75 kW m−2 and jet fire (propane burner) of 116 kW m−2) atmospheres. In inert atmospheres there was a minimal effect on the properties of carbon fibres, but in an oxygenated environment, significant oxidation began at temperatures ≥550 °C, resulting in a reduction in fibre diameter, which reduced further with increasing temperature and exposure duration. Tensile strength and electrical conductivity of carbon fibre decreased with reduction in fibre diameter. CFRCs exposed to 75 kW m−2 in a cone calorimeter and direct flame in a propane burner (116 kW m−2) showed varying degrees of oxidation in CFRC plies, with surface ply fibres experiencing more oxidation and consequent reductions in fibre diameter and tensile properties compared to fibres in underlying plies, where oxidation was limited due to restricted oxygen availability. Fibres exposed to the propane burner exhibited notable damage, including pitting and internal oxidation. Despite this, the overall electrical properties of residual carbon fibres did not significantly decrease, indicating that they still pose an electrical hazard if exposed during a high heat or fire event. [Display omitted] • Carbon fibres (CF) and composites (CC) exposed to different heat and fire environments. • Heat flux, temperature and exposure time are primary factors influencing CF oxidation. • Oxidation occurs >500 °C, fibre diameter decreases with increasing temperature and time. • CF tensile strength and electrical conductivity decrease with increasing oxidation. • CF oxidation and hence, electrical conductivity decreases through the CC thickness. [ABSTRACT FROM AUTHOR]

• Zinc, calcium and copper stannates catalyse the thermal decomposition of polyamide 6,6. • Mechanistic study involved TGA-FTIR, Py-GCMS and pyrolytic products analyses from a tube furnace. • Catalysis is by coordinating to C=O groups in PA66, leading to scission of the C(O)-C and C-N bonds. • Catalytic effect of stannates is in the order ZnSt ≈ CaSt > CuSt. Thermal and thermo-oxidative decompositions of polyamide 6.6 (PA66) in the presence and absence of zinc (ZnSt), calcium (CaSt) and copper stannates (CuSt), and in the presence of antimony trioxide (ATO), have been studied by TGA-FTIR and pyrolysis GC/MS. It is shown that whilst ATO has a negligible effect on the rate of decomposition and products of pyrolysis under both slow heating on a TGA and rapid heating on a pyrolysis/GC/MS apparatus, the stannates have a catalytic effect in the order ZnSt ≈ CaSt > CuSt, evident through release of volatiles at a lower temperature and in a different product distribution following rapid high temperature pyrolysis. In particular, rapid pyrolysis at high temperature in the presence of the stannates promotes formation amongst the pyrolysis products of, for example, 6-aminohexanenitrile. 1,6-hexanediamine, 1-methyl-3-formylindole and 1,2,3,7-tetramethylindole, whilst yields of others are reduced, e.g., hexanedinitrile, caprolactam, diaminomethylidene(2-hydroxypropyl)azanium, prop‑2-enenitrile (acrylonitrile) and azacyclodecan-5-ol. We suggest that these effects arise from complexation of the electropositive metal in the stannate (Zn, Ca or Cu) with the C=O groups of PA66, thus weakening the C(O)-C and C-N bonds adjacent to the C=O groups. The fact that ZnSt has the most pronounced effect on the pyrolysis product distribution and CuSt the least, we explain in terms of the order of electropositivity of the metal (Zn>Ca>Cu). [ABSTRACT FROM AUTHOR]

A phenolic novolac resin has been chemically reacted with 4-vinylbenzyl chloride to introduce polymerizable vinyl benzyl groups. The modified novolac spontaneously polymerizes like styrene, is physically and chemically compatible with a typical unsaturated polyester (UP) resin, and can be free-radically cured (crosslinked) alone and in mixtures with UP using styrene as a reactive diluent. The cured vinylbenzylated novolac and co-cured blends of it with UP show superior flame retardance to cured UP alone and have potential applications as matrix resins in glass-reinforced composite laminates especially for marine structures. [ABSTRACT FROM AUTHOR]

This study investigates the thermal barrier efficiency of five commercially available ceramic nano and micro particles deposited on the surfaces of glass fibre-reinforced epoxy composites (GRE). Two approaches of application of deposition of ceramic particles have been undertaken, firstly where the ceramic particles were dispersed in a phenolic resin binder and applied on a GRE surface by a K-bar coater and the second where extra ceramic particles were sprayed on the first coating while the resin was partially cured to enable the surface to be completely covered by ceramic particles, leaving no resin exposed. The thermal barrier efficiency of these coatings was evaluated from the cone calorimetric parameters at incident heat fluxes of 35 and 50 kW/m 2 as well as from temperature gradient through the samples’ thicknesses, measured by inserting thermocouples on the exposed and back surfaces during the cone tests. The morphology and durability of the coatings to water absorption, peeling, impact and flexural loading were also studied. The results showed that the surface layers of all coated samples were uniform and there was a strong adhesion between the coating and the substrate. Moreover, they did not adversely affect the mechanical properties of GRE composite while improving the mechanical property retention of GRE composites after exposure to heat. [ABSTRACT FROM AUTHOR]

The effects of co-curing blends of an unsaturated polyester (UP) with inherently fire-retardant and char-forming phenolic resoles (PH) on the thermal stability and fire retardancy of the resulting resins have been investigated. To overcome the challenge of UP/PH incompatibility, arising from their different chemical structures and curing mechanisms (radical vs . condensation), different phenolic resoles have been used: ethanol-soluble, epoxy-functionalized, and allyl-functionalized. A traditional water-based resole has also been used to give a reference non-compatible system. In Part 1 of this series of publications it was shown that the compatibility of the two resins increases with functionalization; the allyl-functionalized resole showing the best compatibility with UP. Limiting oxygen index measurements and cone calorimetry have shown that fire performance of the functionalized PH resins and their blends with UP is worse than that from the unfunctionalized PH resin, but still significantly better than that of the UP. To understand this behaviour, thermal analyses coupled with infrared spectroscopy of volatile degradation products have been used on all resins and their blends, based on which, mechanisms of their decomposition and interactions are proposed, and the effects of these on flammability are discussed. [ABSTRACT FROM AUTHOR]

In this work, three commercially available ceramic particles have been used as thermal barrier coatings on glass fibre-reinforced epoxy composites. The coatings have been prepared by dispersing 70 wt.% ceramic particle in 30 wt.% flame retarded epoxy resin. The thermal barrier efficiency of the coatings on the composites has been studied in terms of temperature gradient through the thickness of the sample while the surface is exposed to a radiant heat of varying heat fluxes. The tests have been performed in a cone calorimeter by inserting two thermocouples, one underneath the coating and the other on the reverse side of the sample during the experiments. This also allowed evaluating their flammability performance. [ABSTRACT FROM AUTHOR]

This work reports the thermal barrier and flame retardant efficiency of an organically modified clay (organoclay, OC), when deposited on the surface of glass fibre-reinforced epoxy (GRE) composites. Two approaches were undertaken: 1) the OC was deposited on the surface of the epoxy composite and then polymerised using an atmospheric argon plasma in the presence and absence of a silicon-containing monomer and 2) the OC was dispersed in a phenolic resin binder and applied as a surface coating. Fourier transform infrared spectrometry confirmed the polymerisation of the silicon-containing monomer by plasma treatment. The adhesion between the coating and the substrate was measured using the tape pull method, which indicated that the OC was tightly embedded in the resin matrix after plasma treatment or with the resin binder. The surface morphology of coated surfaces was studied using scanning electron and digital microscopies. The thermal barrier effect of the OC-containing coatings studied by a cone calorimeter at 35 kW/m 2 heat flux was demonstrated by increase in time-to-ignition and time-to-peak heat release rate, and decrease in the peak heat release of the coated samples compared to the control sample. However, for the coatings to be effective enough to be self-extinguishing, the presence of an additional flame retardant element in the coating or on the surface layer of the GRE composite and beneath the clay layered coating is required. [ABSTRACT FROM AUTHOR]

Abstract: The flame retardance of co-cured blends of an unsaturated polyester with various phenolic resoles is improved by the addition of the phosphorus-containing flame retardants: resorcinol bis(diphenyl phosphate), bisphenol-A bis(diphenyl phosphate) and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide. Cone calorimetric studies indicate reductions in important parameters such as total heat released and peak heat release rate. However, although the improved flame retardancy is accompanied by increased char yields, smoke evolution is also increased indicating contributions from both condensed-phase and gas-phase mechanisms of flame retardance. Improvements in flame retardance are particularly marked in systems in which the unsaturated polyester is at least partly compatible with the phenolic resole; TGA studies indicate that this may be due to better retention of the flame retardant in the condensed phase in the more compatible systems. [Copyright &y& Elsevier]

Abstract: This paper investigates the influence of char-forming, flame-inhibiting and intumescent surface coatings on the post-heat flexural behavior of glass fibre-reinforced epoxy composites exposed to one-sided radiant heating. The fire performance of glass/epoxy laminates surface-coated with varied formulations was evaluated using a cone calorimeter under various external heat fluxes (25, 50 and 65kW/m2). Self-sustained ignition was significantly delayed for fire-protected laminates relative to the control. The peak heat release rates and the time to reach this event were significantly reduced in thermally-protected laminates. In addition to the chemical nature of flame retardant chemicals present in the coatings, the time to reach the peak heat release rate and the magnitude of the total heat release were influenced by the quantity and morphology of the char formed by each type of surface coating. The post-heat flexural performance of heat-damaged laminates was determined via three-point bending. There was a significant improvement in the post-heat flexural moduli retention in thermally-protected glass/epoxy laminates. This may be due to the flame retardation efficacy of the coatings and the ability of the charred structures to reduce the heat transfer into the substrate thereby protecting the underlying composite and its mechanical integrity. [Copyright &y& Elsevier]

Abstract: This paper investigates the efficacy of varied (non-intumescent and intumescent) polymer-based surface coatings in providing fire protection to glass fibre-reinforced (GFR) epoxy composites exposed to one-sided radiant heating. In addition to an intumescent surface coating, two other non-intumescent surface coatings are considered – one that is active in the condensed phase and promotes surface char formation and another that is active in the gaseous phase and inhibits flaming combustion. The fire resistance of surface-coated GFR epoxy composite laminates is evaluated using the cone calorimeter at incident heat fluxes of 25, 50 and 65 kW/m2. For all tests conditions considered, there is a significant improvement in the fire performance of surface-protected GFR epoxy laminates relative to their unprotected counterparts. The intumescent surface-coated laminate showed the most significant variations in fire reaction properties with changes in irradiance. [Copyright &y& Elsevier]

Abstract: A thermoplastic toughener, polyether sulphone (PES) and a number of different types of flame retardants were blended in different ratios with a commercial epoxy resin triglycidyl-p-aminophenol (TGAP) and 4,4-diamino diphenyl sulphone (DDS) a curing agent. The effect of type and levels of flame retardants (FR) and the toughening agent on the curing, thermal decomposition and char oxidation behaviour of the epoxy resin was studied by the simultaneous differential thermal analysis and thermogravimetric techniques. It was observed that the toughener slightly increases the curing temperature (by up to 20 °C) but had minimal effect on the decomposition temperature of the resin. Flame retardants, however affected all stages depending upon the type of flame retardant used. The curing peak for samples containing tougher and flame retardants although slightly changed depending upon the type of FR, was not more than ± 20 °C compared to that of samples containing toughener only. All flame retardants lowered the decomposition temperature of the epoxy resin. Phosphorus- and nitrogen-containing flame retardants reduced the char oxidation leading to more residual char, whereas halogen- containing flame retardants had less effect on this stage. [Copyright &y& Elsevier]

Abstract: The thermal degradation behaviours of flame-retarded unsaturated polyester resin formulations containing ammonium polyphosphate (APP), Cloisite 25A nanoclay and zinc based smoke suppressants have been studied using thermogravimetric analysis (TGA) combined with infrared analysis of the evolved gases (EGA) and pyrolysis/gas chromatography–mass spectrometry (GC/MS). In TGA–EGA experiments, the mass loss as a function of temperature has been correlated with the evolution of carbon monoxide (CO) and carbon dioxide (CO2) and oxygen (O2) consumption as measured by an oxygen analyser. The effect of APP, Cloisite 25A and the smoke suppressants on the evolution of CO and CO2 has been examined. The decomposition behaviour of flame-retarded polyester resins under isothermal pyrolytic conditions was investigated and the evolved gaseous products were collected and qualitatively and semi-quantitatively analysed via GC/MS. The addition of APP does not yield many new gaseous products relative to the unmodified polyester resin neither does the presence of zinc borate (ZB) and zinc stannate (ZS) together with APP. Possible chemical interactions are discussed in an attempt to explain the observed results. [Copyright &y& Elsevier]

Abstract: A predictive mathematical model to describe mass loss profiles of flame-retardant (FR) containing epoxy resin formulations is proposed. Mass loss is due to thermal degradation of the constituent components and can be described by a generic kinetic scheme with a given set of thermokinetic constants in the form of ordinary differential equations. The scope of this work is to determine the kinetic parameters of the thermal degradation of a known flame-retarded epoxy resin composition by using thermogravimetric analysis and using the acquired data to predict the degradation profiles for other formulations. The mass loss profiles of Visil and intumescent epoxy resin containing formulations were predicted by solving coupled systems of ordinary differential equations and then using Powell minimisation to find the optimal Arrhenius parameters, taking into account the mass ratio of the components in the mixture. The calculated kinetic constants for one formulation (85% resin–15% FR additives) are used to predict the mass loss profiles for other formulations (80% resin–20% FR additives and 90% resin–10% FR additives) with the assumption that the degradation mechanism does not change. The predicted thermal degradation profiles are compared with experimental data acquired using standard laboratory equipment in order to validate the proposed mechanisms. The kinetic parameters obtained adequately describe mass loss history of composite materials studied, even when extremely simplified kinetic schemes have been used. [Copyright &y& Elsevier]

Abstract: Thermogravimetric analysis (TGA) combined with infrared analysis of the evolved gases analysis (EGA) has been used to study the thermal degradation behaviour of epoxy resin both in air and nitrogen. The mass loss as a function of temperature has been correlated with the evolution of carbon monoxide (CO) and carbon dioxide (CO2), and oxygen consumption as measured using an oxygen analyser. An analytical technique has been developed to quantitatively measure the carbon monoxide and dioxide gases evolved. The effect of a range of flame retardants containing phosphorus, nitrogen and halogen elements on CO and CO2 evolution during thermal degradation of flame retarded epoxy resins has also been observed. [Copyright &y& Elsevier]

• Combined atmospheric plasma/UV exposure of polyester fabrics activate fibre surfaces. • Pre- and/or post-exposure of fabrics to which non-durable flame retardants have been applied have improved durability to cleansing treatments. • After cleansing, retained levels of flame retardants have been identified by EDX and XPS surface analyses. • The effect of plasma/UV process sequence (pre-exposure and/or post exposure with respect to FR impregnation) influences retained flame retardant levels. • Retained levels are sufficient to modify thermal degradative properties of polyester. Following application of three commercially available, flame retardants (FR) to polyester and exposure to an atmospheric plasma in the presence or absence of simultaneous UV 308 nm excimer laser radiation, the retentions to a 30 min 40 °C water-soak for the mono- and dimeric cyclophosphonate (PE-CONC and PCO 900 respectively) and a 30 min methanol-soak treatment for the resorcinol bis(diphenyl phosphate) (RDP) agents were generally enhanced with respect to unexposed controls. These results suggested that the formation of PET-FR bonding had occurred as a consequence of plasma/UV exposure. The effect of plasma/UV process sequence (pre-exposure and/or post exposure with respect to FR impregnation) as well as plasma gas type, showed that maximum post-soaking FR retentions occurred when both pre- and post-exposure conditions operated. Plasma/UV exposed fabrics both before and after soaking treatments were examined for morphological changes by SEM and surface phosphorus retention by EDX, FTIR-ATR, XPS as well as TGA/DTG/DTA, each of which showed evidence on the surface of changes in surface topography, increased phosphorus levels and modified thermal behaviour. When subjected to vertical fabric strip flammability testing, these changes were insufficient to generate significant changes in the burning rate apart from in post-methanol soaked, RDP-containing fabrics where almost all plasma/UV process sequences reduced specimen burning rates. During all experiments, the presence or absence of the UV laser radiation appeared to have no obvious effect on post-soaking FR retentions, suggesting that its presence is not required since plasma activation alone appears to be the key to improving PET-FR bonding. [ABSTRACT FROM AUTHOR]

The development of new flame retardants is of ever increasing importance because of ecotoxicity concerns over existing systems and related regulatory pressures. From a range of low-toxicity, water-insoluble reagents, a total of 151 metal complexes were assessed for their potential to impart flame retardant behaviour in polymer matrices. These were successfully synthesised on a small scale and possible interactions were explored with a model engineering polymer, namely polyamide 6.6 (PA66). Powder mixtures of each complex with PA66 in a 1:3 mass ratio were analysed under air using TGA/DTA. Based on the stability of each at the typical processing temperature of 290 °C and its char forming potential (the final residue requirement at 580 °C being > 25%), selected mixtures were then analysed further using a differential mass loss technique. Metal complex/PA66 mixtures in which the differential residual mass above 470 °C was >10% with respect to the theoretical value were considered to have a positive char forming interaction. Only eight of the metal complexes passed this last criterion including aluminium, tin (II) and zinc tungstates, three tin (II) phosphorus oxyanion complexes, iron (II) aluminate and iron (III) hypophosphite. These selected compounds were synthesised on a larger scale (c.a. 100 g), characterised and compounded into PA66 at 5 wt% for flammability assessment using LOI, UL94 and cone calorimetry. Of these, only aluminium tungstate and iron (II) aluminate showed some degree of FR behaviour with LOI values ≥ 23.0 vol% compared with PA66 (LOI = 22.9 vol%) and the former almost achieved a UL94 V-2 rating. However, while up to 32% reductions in total heat releases and up to 49% reduction in PHRR in cone calorimetric tests were observed for the metal complex/PA66 composites generally, those for Al 2 (WO 4 ) 3 were 6 and 29% respectively and for Fe(AlO 2 ) 2 were 18 and 45% respectively. [ABSTRACT FROM AUTHOR]

Montmorillonite (Mt) hold a great potential in improving inflammability of polyamide nanocomposites. This paper presents research on a novel class of flame retardants prepared by adsorption of disodium H-phosphonate (DHP) on the sodium montmorillonite (Mt) and organophilized montmorillonite (OMt) - clay surface. Using instrumental analyses including X-ray diffraction (XRD), thermogravimetric analysis (TGA), cone calorimetry, limiting oxygen index (LOI), UL-94 technique and scanning electron microscopy (SEM) the influence of DHP and Mt or OMt in PA6 on the thermal stability and fire reaction properties of PA6 was investigated. The adsorption of DHP on Mt and OMt delayed the onset of the degradation temperature of PA6 by 8 and 23 °C, respectively. The flame resistance of nanocomposite with 0.75 wt% of DHP stabilizer adsorbed on OMt surface was significantly improved as 59% reduction in maximum peak of heat release rate compared to neat PA6 was observed. The UL-94 and cone calorimeter results have shown that the tested materials burn differently, which are reported here as three behaviors during combustion. Based on these results it was found that the surface-modified Mt protects the polymeric material against the degradation within the temperature range used by formation of phosphorus-mineral char. [ABSTRACT FROM AUTHOR]

Multifunctional cotton fabric was prepared through a two-step layer-by-layer spray coating method, where the first layer of the coating comprising chitosan and ammonium phytate provided fire retardancy, and the second one with PDMS-ZnO composite imparted hydrophobicity to the fabric. A molecular dynamics (MD) simulation study was carried out to calculate interfacial adhesion of different components of the coating, based on which the sequencing of the coating layers was determined and used to prepare coated samples. The coated fabric demonstrated a significant improvement in fire retardancy through an increase in LOI from 18 % in control to 30 %, a reduction in char length from 30 cm to 7 cm, and a decrease in peak and total heat release rate values by 75 % and 33 %, respectively. The hydrophobicity of coated fabric was tested via water drop test where coated sample maintained a contact angle of 148° for up to 120 s, while the control sample showed 0°. [ABSTRACT FROM AUTHOR]

Abstract: Fire reaction properties of flax/epoxy laminates and their corresponding balsa-core sandwich composites with/without fire protection were evaluated at an applied heat flux of 50kW/m2. A strategy for improving the fire reaction properties of flax/epoxy composite materials without adversely altering their intrinsic mechanical properties was investigated. A thin glass fiber veil impregnated with ammonium polyphosphate was bonded onto the composite surface intended for heat exposure. There was no significant change in the time-to-ignition with the introduction of the fire retardant glass fiber veil. While similar PHRR values were measured in both flax/epoxy laminates and balsa-core sandwich composites, the total heat release was significantly higher in the later. It is noteworthy, the heat release rates (including the peak values) measured for fire-protected composites were significantly lower than those measured for their unprotected counterparts. Through-thickness temperature profiles across the sandwich composite revealed the effectiveness of the fire retardant veil in minimizing thermal damage of underlying substrate composites. [Copyright &y& Elsevier]

Abstract: The effect of layered silicate nanoclays, nano-silica and double-walled carbon nanotubes (DWNTs) on the thermal stability and fire reaction properties of two aerospace grade epoxy resins (a high temperature curing tetra-functional and a low temperature curing bi-functional resin) has been investigated using thermal analysis, cone calorimetry, LOI and UL-94 techniques. The morphology of the polymer–clay nanocomposites, determined by X-ray diffraction and transmission electron microscopy indicated intercalated structures. The addition of nanoclays (5-wt%) to both resins had a thermal destabilisation effect in the low temperature regime (<400 °C), but led to higher char yield at higher temperatures. The inclusion of nano-silica at 30-wt% significantly improved the thermal stability of the resins while DWNTs had an adverse effect due to their poor dispersion in the matrix. The nanoclays and carbon nanotubes significantly increased the fire resistance of the tetra-functional epoxy resin while a minimal effect was observed for the bi-functional resin. [Copyright &y& Elsevier]

Aluminium (AlW), tin (II) (SnW) and zinc (ZnW) tungstates were previously found to increase char formation in polyamide 6.6 (PA66), but have never before been studied for their potential as synergists when present with phosphorus-containing (PFRs) flame retardants. We investigate this gap in the scientific knowledge in this publication. Tungstate-PFR interactions of PA66 composites were investigated by thermal analysis, limiting oxygen index (LOI), UL94, cone calorimetry and evolved gas analysis (TGA-FTIR). Of the three tungstates, AlW in the presence of aluminium diethylphosphinate (AlPi) or a mixture of AlPi and melamine polyphosphate (MPP), promotes the highest level of flame retardancy in terms of a balance of high LOI, V-rating and TGA residual char in air at 500 °C and reduction in cone calorimetric peak heat release rate (R PHRR = 80%). This observation has been related to AlW having the highest Lewis acidic properties. While zinc tungstate displays the lowest levels of interaction with either PFR, it shows significant smoke suppressant properties. Elemental analysis of cone calorimetric chars suggests that while some loss of phosphorus occurred from SnW/AlPi/MPP-containing composites, most likely via volatile diethyl phosphinic acid formation, nearly 10% reduction also occurred in the Sn/W molar ratio indicating some volatilisation of tin. The TGA (in air)-FTIR results for carbon dioxide, ammonia and hydrocarbon fuel species evolution enabled discussions of the effect that each tungstate had on the flame retardant mechanisms operating. • Metal tungstates investigated for potential synergistic activity in PA66 with FRs. • FRs were aluminium diethyl phosphinate alone with/without melamine polyphosphate. • TGA shows that AlW in particular interacts positively with both FRs. • Zinc tungstate suppresses smoke. • TGA-FTIR results shed light on mechanisms involved. [ABSTRACT FROM AUTHOR]

Bicomponent filaments of polyamide 6 (PA6) were produced with core/sheath geometries containing aluminium diethyl phosphinate (AlPi), and/or a montmorillonite nanoclay located individually or together in the sheath or core. A characterisation protocol based on thermogravimetric analysis (TGA) under both flowing air and nitrogen and pyrolysis combustion flow calorimetry (PCFC) enabled the effects of AlPi, clay and atmospheric oxygen to be assessed on PA6 thermal degradation. Knitted fabrics were assessed for flammability by vertical strip testing, which demonstrated that the relative location of the clay and flame retardant has a significant effect on burning behaviour. Correlation of the TGA/DTG, PCFC and burning sample results were discussed in terms of the effects of the roles of atmospheric oxygen and flame retardant components on the thermal degradation of PA6, especially when located in the sheath. • Bicomponent PA6 filaments produced with flame retardant and clay in sheath or core. • Fibres characterised for tensile, morphological, TGA/DTG, PCFC, and flammability behaviour. • TGA of PA6 in air promotes char formation, influencing flame retardancy with AlPi/clay. • Superior flame retardancy obtained when both AlPi and clay present in sheath of filaments. • Combined condensed and gas phase action of AlPi in air together with clay determine FR properties. [ABSTRACT FROM AUTHOR]

This work seeks to address the effect of simultaneous use of three flame retardants, having three different modes of action, (magnesium hydroxide, expanded and expandable graphite) on the thermal degradation and flame retardancy of poly(ethylene-co-vinyl acetate). Thermal conductivity of samples was measured in order to investigate the effect of the use of expanded and expandable graphite on the time-to-ignition and the peak of heat release rate in cone calorimeter test. Thermal shielding performances of chars were studied as well. It was found that there is an optimum ratio between expanded and expandable graphite in order to control thermal conductivity and therefore fire properties. Some correlations were also found between the char thickness and the first peak of heat release rate. [ABSTRACT FROM AUTHOR]

In this study, a facile approach to fabricate a novel bio-based hybrid (BBH) with core/shell structure is presented by taking advantage of plant-derived resources. The BBH developed herein comprises of an inorganic core of ammonium polyphosphate (APP), covered with an organic shell that is constructed via layer-by-layer assembly of a novel bio-based polyelectrolyte (BPE) and polyethylenimine (PEI). BBH can simultaneously enhance the flame retardancy and toughness of polylactic acid (PLA) with very high efficiency. The flame retardant PLA composite can pass UL94 V0 rating at the BBH loading content of 10 wt%. The efficient flame retardant performance is due to its effectiveness in both gas and condensed phases. More importantly, the flame retardant PLA composite containing 10 wt% BBH exhibits ductile fracture with an elongation at break of 27.3%, which is much higher than that of neat PLA (8%). The debonding and plastic void deformation of the PLA matrix around the BBH are responsible for the enhanced toughness. This work provides important hints for devising highly efficient multifunctional flame retardant and broadening the application field of renewable resources. [ABSTRACT FROM AUTHOR]

Abstract: Flammability of synthetic fibres is significantly worse than that of bulk polymers because of the high surface area to volume ratio and the low tolerance to high filler loadings in the fibre production process. Introducing nanocomposite structures has the potential to enhance the char formation at relatively low loadings of nanoparticulate fillers and hence can reduce the flammability of synthetic polymers and fibres. This paper reports thermal degradation analysis results in conjunction with TG analysis under different atmospheres and further studies of X-ray diffraction characterisation of fibre-forming polypropylene containing selected dispersed nanoclays. The concentrations of hydrocarbons, carbon monoxide and carbon dioxide released during the TG analysis have been monitored and analysed by using a combined electrochemical infrared analyser. The intensity changes of the crystallinity peaks and nanoclay peaks in the polymer and composites are discussed. [Copyright &y& Elsevier]

Abstract: We have shown previously that the introduction of nanoclays can reduce the flammability of synthetic fibre-forming polymers like polyamides 6 and 6.6 only if used in conjunction with conventional flame retardants. In this work we report initial studies of the effects of dispersed nanoclays with low concentrations of selected flame retardants introduced into polypropylene on flammability, thermal degradation and X-ray diffraction behaviours. Flame retardants used include ammonium polyphosphate as a conventional char-former and a hindered amine stabiliser known to have flame retarding characteristics in polypropylene. [Copyright &y& Elsevier]

The burning behaviours of polyurethane foam/cotton fabric combinations were investigated using cone calorimetry. One non-flame retarded and two flame retarded polyurethane foams containing melamine and melamine plus a chlorinated phosphate respectively, were combined with four cotton fabrics, i.e. two types of commercial cotton, one without flame retardant (CN) and another flame retarded with Proban (CPR); and another two flame retardant cottons which were treated with Pyrovatex (CPY) and (NH4)2HPO4 (CDA) respectively in the laboratory. [Copyright &y& Elsevier]