Concentrations Of Flame Retardants Research Articles

Preparation of Organic-Inorganic Phosphorus-Nitrogen-Based Flame Retardants and Their Application to Plywood.

The combustibility of wood can be improved by physical and chemical means, thus expanding the use of wood products. In this study, two novel phosphorus-nitrogen flame retardants (UCPR and MCPR) were developed, and the intercalated modified layered double hydroxides (LDH) thereof were designated as UCPR-LDH and MCPR-LDH. By impregnating poplar veneer with UCPR-LDH and MCPR-LDH solutions, the study investigated the effects of different concentrations (1%, 5%, 10%), processes (vacuum-pressure impregnation, room temperature impregnation, normal-pressure impregnation), and impregnation times (2 h, 3 h, 24 h, 48 h) on the weight-gain rate of veneer. The optimal process was then selected for preparing formaldehyde-free three-layer plywood. Nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) were used to characterize the UCPR and MCPR. Meanwhile, gel-permeation chromatography (GPC) demonstrated that the molecular weight of the synthesized flame retardants increased as their molecular distribution became more uniform. The impregnation process was performed at normal temperature and pressure for 48 h at a 5% flame retardant concentration. Results from cone calorimetry indicate that the UCPR-LDH plywood exhibits a peak heat release rate that is 30.43% lower than that of the control group, demonstrating superior thermal barrier performance. The smoke emission of the MCPR-LDH plywood was reduced by 33.62% compared to the control group, indicating superior smoke suppression performance. This method presents a viable approach for synthesizing organic-inorganic flame retardants.

A novel flexible flame-retardant phase change materials with battery thermal management test

The use of composite phase change materials (CPCM) for battery thermal management requires both great flexibility and excellent flame retardancy. In this study, a novel strategy of coating flame retardancy was adopted to prepare a highly flexible flame-retardant CPCM (FR-CPCM) by combining flexible flame-retardant coating (FRC) with flexible CPCM. Its thermophysical properties, flexibility, and flame retardancy were characterized and used for the thermal management of batteries. The results demonstrate that FRC significantly enhanced CPCM's flame retardance while preserving its thermophysical characteristics and flexibility. FRC has no impact on the thermal conductivity and flexibility of the CPCM and substantially improves the anti-leakage and high-temperature thermal load-bearing capabilities of FRCPCM. When the coating's flame retardant content reaches 36 %, FRCPCM achieves the best comprehensive flame-retardant performance, with an LOI value of 37.5 %, PHRR reduced by 79.2 %, and the whole heat release process is slowed down. Moreover, FRCPCM has an excellent heat dissipation capability for the battery under standard operating circumstances. And FRC-CPCM is effective in suppressing the heat transfer to the outside under the condition that the heating rod simulates the battery TR.

Влияние фосфорсодержащих антипиренов на показатели пожарной опасности газонаполненных полимеров на основе реакционноспособных олигомеров

Introduc tion. The reduction of flammability of gas-filled polymers prone to carbonization is based on the use of phosphorus- and boron-containing compounds that reduce the formation of combustible volatile pyrolysis products and increase the yield of coke residue. This reduces the rate of heat release, heat and mass transfer between the material and the flame. In the scientific literature the data about the influence of phosphorus-containing flame retardants on thermal stability, combustibility and smokeability of foams are given, but there are no data about the influence of phosphorus concentration on fire danger indicators of foams. The aim of this paper is the development of effective methods of production of casting foams based on reactive oligomers with low fire hazard and high-performance. Objectives: to reveal the influence of phosphorus concentration on the technological and physical-mechanical characteristics, thermal resistance and fire hazard indices of foams and to develop fire-proof thermal insulation materials possessing high performance. Methods. Physical-mechanical properties and fire hazard indices of gas-filled polymers were determined according to current GOST. Thermal properties and composition of combustion products of foams have been studied with thermoanalytical complex DuPONT-9900 and chromatography-mass spectrometry. Results and discussion. The concentration of phosphorus in the synthesis of rigid polyurethane foams with reduced flammability and high performance should exceed 2.1 % wt. The low-combustible urea foams have been obtained at a phosphorus concentration of 0.2–0.3 % wt. For the production of non-flammable, low-­flammable resin foams, the phosphorus concentration is 0.6–0.7 % wt. At the same time, organophosphorus flame retardants containing reactive groups are highly effective. Conclusion s. As a result of experimental studies the influence of phosphorus concentration and content of organophosphorus-containing flame retardants on physical-mechanical properties, thermal stability and fire hazard of foams based on reactive oligomers was revealed, the pouring foams with lowered fire hazard and high performance were developed.

Heat and fire-resistant nanofiber networks: Towards tailoring the new generation of lightweight intermeshing polymer composite systems

Safe use of materials is a primary focus of emerging low-carbon industry. Catastrophic fire incidents due to high flammability of polymers as versatile materials necessitate developing fire-proof polymer composites. In this study, a novel and robust strategy is implemented to fabricate non-flammable and fire-proof thermoplastics with remarkably lower flame retardant (FR) content leading to outstanding limiting oxygen index (LOI) of 30% and UL 94-V0. This can be achieved using nano-fibrillation by forming networks of heat-resistant polymeric nanofibers (polyphenylene ether (PPE) or polyphenylene sulfide (PPS)) within polystyrene (PS). Formation of heat-resistant nanofibers creates a continuous network-structured layer/shield to preserve the matrix against burning and suppresses dripping by boosting the melt-strength. Nanofibers also lead to promoting a graphitized char layer to thoroughly protect the polymer against fire. These synergistic effects enhance FR efficiency, as demonstrated by a 30% reduction in fire growth rate and peak heat release rate, upon inclusion of 15 wt% PPE nanofibers, compared to an equivalent composite with spherical particles. Only the PS sample containing 25 wt% FR and 15 wt% heat-resistant nanofibers meets UL 94-V0 while presence of a similar content of spherical PPE or PPS, graphene nanoparticles, or carbon nanotubes does not provide this feature. Nanofibers also strengthen energy absorption leading to high impact strength of PS composites (120%). Hence, this novel strategy can be extended to a wide range of polymer systems to fabricate novel generation of fire-proof devices with tunable properties for various potential applications including energy storages packs, electronic equipment, and robotics.

Enhancements in LOX compatibility and fracture toughness of carbon fiber/epoxy composite for liquid oxygen cryotank by simultaneously introducing Al(OH)3 and phosphorous-nitrogen flame retardants

Simultaneously enhancing the liquid oxygen (LOX) compatibility and fracture toughness at the cryogenic temperature of carbon fiber reinforced epoxy (CFRE) composites is critical for their successful application in LOX cryotanks. Herein, based on our previous work on optimizing the phosphorous-nitrogen containing organic flame retardant (TAD) content in epoxy resin for achieving the best LOX compatibility, the EP resins and CFRE composites modified with further incorporating inorganic flame retardant Al(OH)3 were fabricated. Specifically, the effects of introducing Al(OH)3 particles on the LOX compatibility and mechanical performances particularly at 90 K were thoroughly investigated. The results indicate that the Al(OH)3/TAD-EP resin (hence CFRE composite) with 4 phr Al(OH)3 exhibits an outstanding LOX compatibility without any impact reaction of burning, explosion, flash and charring observed in 20 samples. Moreover, the mode II fracture toughness of CFRE composites at room temperature and 90 K is improved by 27.3% and 16.7%, respectively with the addition of 4 phr Al(OH)3. Benefited with the simultaneous incorporation of 15 phr TAD and 4 phr Al(OH)3, the CFRE composite is promising for application in LOX tanks.

Preparation and properties of epoxy resin modified with phosphorus and nitrogen flame retardants

Epoxy resins (EPs) require the addition of flame retardants to extend their application scope. High-efficiency flame retardants typically contain halogens, which can cause tremendous harm to humans and the environment. In this study, we investigated the syntheses of new phosphorus–nitrogen flame retardants (DIT) and flame-retardant EP. DIT is composed of 6-(2,5-dihydroxyphenyl) dibenzo[c,e][1,2] oxaphosphinine 6-oxide, 5-isocyanato-1-(isocyanatomethyl)−1,3,3-trimethylcyclohexane, and tris-(2-hydroxyethyl) isocyanurate. DIT chemical structure was analysed by Fourier-transform infrared spectroscopy. Several formulations of modified epoxy resins (DIT-EPs) were obtained by adding different quantities of DITs. We found that when the flame retardant content reached 25%, the limiting oxygen index of the DIT-EP was 29.0%. This finding expands the application range of EPs.

Exposure to legacy and alternative flame retardants in two harbor seal populations and the association with blubber fatty acid profiles

Flame retardants (FRs) are ubiquitously present in various environmental compartments due to widespread application. However, there have been few reports on the alternative FRs in harbor seals, and their relationship with fatty acid (FA) profiles have largely been overlooked. Here, we investigated the levels of legacy and alternative FRs and FA profiles in the blubber of harbor seals from the coasts of South Sweden (2009–2016) and Northeastern US (NE US) (1999–2010). We observed different proportions of mono- and poly-unsaturated FAs (MUFAs and PUFAs) between the two populations, which may reflect variations in the diet. Significantly higher concentrations of ΣPBDE were also observed in harbor seals from US compared to those from Sweden, both dominated by BDE 47. By comparison, the levels of alternative FRs, noticeably HBBZ and PBEB were much lower compared to those of PBDEs. Moreover, we found a positive correlation between BDE 99 and Σn-6/Σn-3 PUFA in harbor seals from Sweden. In addition, BDE 153 and BDE 154 were positively correlated with ΣUFA/ΣSFA in seals from Sweden and US, respectively. Our results imply the influence of diet in FA profiles and FR concentrations in top predators, as well as the importance of blubber FA characteristics in indicating FR exposure. Further investigations are required to assess the risk of exposure in these harbor seals, as well as to elucidate the underlying mechanisms associating FA profiles with FR exposure.

Effect of Flame Retardants and Electrolyte Variations on Li-Ion Batteries

Lithium-ion batteries are being increasingly used and deployed commercially. Cell-level improvements that address flammability characteristics and thermal runaway are currently being intensively tested and explored. In this study, three additives—namely, lithium oxalate, sodium fumarate and sodium malonate—which exhibit fire-retardant properties are investigated with respect to their incorporation into graphite anodes and their electro/chemical interactions within the anode and the cell material studied. It has been shown that flame-retardant concentrations of up to approximately 20 wt.% within the anode coating do not cause significant capacity degradation but can provide a flame-retardant effect due to their inherent, fire-retardant release of CO2 gas. The flame-retardant-containing layers exhibit good adhesion to the current collector. Their suitability in lithium-ion cells was tested in pouch cells and, when compared to pure graphite anodes, showed almost no deterioration regarding cell capacity when used in moderate (≤20 wt.%) concentrations.

A Systematic Investigation on the Influence of Intumescent Flame Retardants on the Properties of Ethylene Vinyl Acetate (EVA)/Liner Low Density Polyethylene (LLDPE) Blends.

Because of their high filler loadings, commercial-grade clean flame-retardant materials have unstable mechanical properties. To address this issue, intumescent polymers can be used to develop clean flame retardants with very low levels of smoke and toxicity generation. An intumescent flame retardant (IFR) system composed of red phosphorus (RP), zinc borate (ZB), and a terpolymer of ethylene, butyl acrylate, and maleic anhydride (EBM) was used to prepare EVA (ethylene-vinyl acetate) and EVA/LLDPE (linear low-density polyethylene) composites; their mechanical and flammability properties were systematically investigated. The limiting oxygen index (LOI) of the EVA/LLDPE (as base material) composite containing RP and ZB mixed with nonhalogenated flame retardant, mainly magnesium hydroxide (MH) and coadditives, including processing aids and thermal stabilizers, was established. RP was found to have little effect on the tensile properties of EVA/LLDPE 118W/120 phr flame-retardant (MH + RP) composites. There was a minute difference in the effective trend of RP between tensile strength and elongation at break. Following the addition of ZB, the elongation at break of the composites gradually decreased with increasing RP content and then leveled off when the RP content was over 10 phr. Mechanical properties (elongation at break and tensile strength) can be best maintained at below 10 phr content of RP. The mechanical properties decreased with lower amounts of EBM content. In addition, flame retardancy increased when the EBM content decreased. The findings further revealed that MH and RP have poor compatibility, yielding poor mechanical properties. The LOI greatly increased with RP content, even though the total content of flame retardants (main + intumescent flame retardant) was the same in all formulations. Only over 5 phr RP content formulations passed V-0 of the UL-94 test. When under 5 phr, the RP content formulations did not pass V-0 of the UL-94 test.

Synthesis of High-Efficiency, Eco-Friendly, and Synergistic Flame Retardant for Epoxy Resin

It remains a challenge to prepare flame-retardant composites via the addition of a low content of flame retardant. In this work, a novel DOPO-functionalized reduced graphene oxide hybrid (DOPO-M-rGO) flame-retardant system was synthesized for epoxy resin (EP). The phosphorus-nitrogen-reduced graphene oxide ternary synergistic effect provided DOPO-M-rGO with high flame-resistance efficiency in EP; thus, the EP-based composite exhibited superior fire-resistant performance at extremely low DOPO-M-rGO loading. The limiting oxygen index (LOI) of the EP-based composite was increased from 25% to 32% with only 1.5 wt% DOPO-M-rGO addition, and the peak heat release rate (pHRR), total heat release (THR), and total smoke production (TSP) were significantly decreased by 55%, 30%, and 20%, respectively. In addition, as a halogen-free flame-retardant system, DOPO-M-rGO presents great application potential as an eco-friendly additive for the flame-resistance improvement of thermosetting polymer materials.

Exposure to flame retardants in European children - Results from the HBM4EU aligned studies.

Many legacy and emerging flame retardants (FRs) have adverse human and environmental health effects. This study reports legacy and emerging FRs in children from nine European countries from the HBM4EU aligned studies. Studies from Belgium, Czech Republic, Germany, Denmark, France, Greece, Slovenia, Slovakia, and Norway conducted between 2014 and 2021 provided data on FRs in blood and urine from 2136 children. All samples were collected and analyzed in alignment with the HBM4EU protocols. Ten halogenated FRs were quantified in blood, and four organophosphate flame retardants (OPFR) metabolites quantified in urine. Hexabromocyclododecane (HBCDD) and decabromodiphenyl ethane (DBDPE) were infrequently detected (<16% of samples). BDE-47 was quantified in blood from Greece, France, and Norway, with France (0.36ng/g lipid) having the highest concentrations. BDE-153 and -209 were detected in <40% of samples. Dechlorane Plus (DP) was quantified in blood from four countries, with notably high median concentrations of 16ng/g lipid in Slovenian children. OPFR metabolites had a higher detection frequency than other halogenated FRs. Diphenyl phosphate (DPHP) was quantified in 99% of samples across 8 countries at levels ∼5 times higher than other OPFR metabolites (highest median in Slovenia of 2.43ng/g lipid). FR concentrations were associated with lifestyle factors such as cleaning frequency, employment status of the father of the household, and renovation status of the house, among others. The concentrations of BDE-47 in children from this study were similar to or lower than FRs found in adult matrices in previous studies, suggesting lower recent exposure and effectiveness of PBDE restrictions.

Application of Taguchi methods (DOE) in composite engineering

In the paper, a design of experiment (DOE) in terms of the Taguchi method was used for the optimization of the manufacturing process. This approach makes it possible to do fewer experiments while still getting the desired outcomes. This research programme will use this tool to optimize the resin casting process by monitoring manufacturing parameters like temperature, curing time, and flame-retardant concentration. Thus, this study aims to determine the ideal set of parameters for the resin casting of composite materials. Based on experimental results, it was possible to find crucial factors and their influence on the fracture strength of resin for composite manufacturing systems.

Flame-retardant phase change material (PCM) for thermal protective application in firefighting protective clothing

Phase change material (PCM) can adjust the heat transfer performance of clothing through thermal storage, thus providing extra thermal protection to wearer. In order to meet the flame-retardant (FR) requirement of firefighting protective clothing, the PCM coated fabric with the FR property was prepared by a dry coating process. The effects of FR type, FR content and phase change temperature (PCT) on the FR property were analyzed by a cone calorimeter. The PCM coated fabrics were added to different positions of the firefighting protective clothing, and the influence of PCM coated fabric on thermal protective performance (TPP) was investigated experimentally. The results demonstrated that the FR of organic silicon significantly decreased the heat release rate due to the FR effect in condensed and gas phases. The maximum decreasing of heat release rate was 144.37 kW/m2, which was far lower than that of the PCM coated fabric without the FR. The phosphorus-nitrogen FR expanded the ignition time by 16 s at most owing to the FR effect in condensed phase. The TPP of clothing incorporated with the PCM coated fabric was determined by the type, the PCT and the position of PCM coated fabric. Based on experimental investigation of thermal response of the PCM coated fabric, the study provides some reference for the selection of PCM coated fabric and configuration design of firefighting protective clothing in different fire environments.

Passivation of black phosphorus by triazine-based silica coating: Hierarchical BP@SiO2-N@Co(OH)2 structure for enhanced fire safety and toughness of unsaturated polyester resins

The fire and toxic smoke hazards of polymer combustion and the weak oxidation resistance of pure black phosphorus nanosheets (BPNSs) are hot and difficult issues. Here, triazinylsilane and Co(OH)2 nanoflowers are sequentially encapsulated on the surface of BPNSs to generate a novel multifunctional flame retardant (BP@SiO2-N@Co(OH)2), and incorporated into the unsaturated polyester resin (UPR). Specifically, with the addition of 2 wt% BP@SiO2-N@Co(OH)2, the nanocomposite exhibits superior thermal hazard suppression efficiency relative to previous related work. In particular, BP@SiO2-N@Co(OH)2 exhibits a superior ability to suppress toxic smoke than BPNSs, with a 42.3 % reduction in total smoke production (TSP) at 2 wt% flame retardant content. In addition, UPR with 0.5 wt% BP@SiO2@-N@Co(OH)2 achieves 76.5 % increases in impact strength, revealing excellent mechanical properties. Therefore, a novel multifunctional nano flame retardant is successfully synthesized and provided an innovative strategy for the preparation of multifunctional UPR nanocomposites.

Synthesis of a novel flame retardant with phosphaphenanthrene and phosphazene double functional groups and flame retardancy of poly (lactic acid) composites

A novel flame retardant hexa (4- (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10 -sulfide)-hydroxymethylphenoxy) cyclotriphosphazene (HAP-DOPS) with double functional groups was synthesized, and poly (lactic acid) (PLA) composites were prepared by melt extrusion. The flame retardancy and thermal degradation behavior of flame retardant PLA composites were studied by limiting oxygen index (LOI), vertical burning test (UL-94), cone calorimeter test (CCT), and thermogravimetric-infrared spectroscopy analysis (TG-IR). The experimental results showed that HAP-DOPS had a good flame-retardant effect on PLA. At flame retardant content of 5 wt%, the PLA/HAP-DOPS composite achieved a V-0 rating (UL-94, 3.2 mm) and a LOI value of 26.6%. The heat release rate (HRR) and total heat release (THR) of PLA composites were decreased by adding HAP-DOPS. The flame retardancy index (FRI) of PLA/HAP-DOPS-7.5 wt% was 1.0257, which showed good flame retardancy. The results of TG-IR showed that HAP-DOPS mainly had a gas-phase flame-retardant effect in PLA.

Silicone wristband- and handwipe-based assessment of exposure to flame retardants for informal electronic-waste and end-of-life-vehicle recycling workers and their children in Vietnam

Measuring personal exposure to flame retardants (FRs) is crucial for assessing and controlling human health risks posed by FRs during the recycling of electronic waste (e-waste) and end-of-life vehicles (ELVs). Here, we examined the use of handwipes and silicone wristbands to measure personal FR exposure for e-waste and ELV recycling workers and their children in Vietnam. On the handwipes from the e-waste recycling workers, the predominant five FRs detected were TBBPA (median concentration: 3700 ng/wipe), BDE-209 (1700 ng/wipe), TPHP (500 ng/wipe), DBDPE (410 ng/wipe), and BPA-BDPP (360 ng/wipe). On the handwipes from ELV recycling workers, TPHP (60 ng/wipe), IPPDPP (47 ng/wipe), BIPPPP/DIPPDPP (33 ng/wipe), BDE-209 (26 ng/wipe), and TCIPP (23 ng/wipe) were detected as the five predominant FRs. On the wristbands from the e-waste recycling workers, the five predominant FRs detected were TBBPA (median concentration: 340 ng/g), BDE-209 (330 ng/g), DBDPE (65 ng/g), TPHP (50 ng/g), and TMPP (34 ng/g). On the wristbands from the ELV recycling workers, TPHP (34 ng/g), IPPDPP (18 ng/g), TCIPP (14 ng/g), TDMPP (13 ng/g), BIPPPP/DIPPDPP (9.3 ng/g) and TMPP (9.3 ng/g) were detected as the predominant FRs. The data obtained with the wristbands were comparable to those obtained with the handwipes. Similar FR profiles were found in between the workers and their children. The profiles indicate that the informal e-waste and ELV recycling caused FR exposure not only for workers but also for their children who live in the workshops. By using the handwipe and wristband sampling approaches, we determined types and concentrations of FRs to which the workers and their children were dominantly exposed. Silicone wristband- and handwipe-based assessment is expected to be effective means of measuring personal FR exposure for the informal e-waste and ELV recycling workers and their children.

Profiling of multiple classes of flame retardants in house dust in China: Pattern analysis and human exposure assessment

Legacy [e.g., brominated- (BFRs)] and alternative [e.g., organophosphate- (OPFRs) and nitrogenous- (NFRs)] flame retardants have a propensity to migrate out of consumer products, and thus are dispersed in indoor microenvironments. In this study, simultaneous presence of 11 BFRs, 18 OPFRs and 11 NFRs were measured in house dust collected from Tianjin, China. OPFRs were found at the highest concentrations, with a median value of 3200 ng/g, followed by NFRs (2600) and BFRs (1600). Tris(2-butoxyethyl) phosphate (median: 1800 ng/g), melamine (1100), and BDE-209 (870) were the top three most abundant chemicals in the respective groups. Location-specific patterns of flame retardant concentrations were found with 30%, 20% and 10% of samples were predominated by OPFRs, NFRs and BFRs, respectively, and the remaining samples contained by two or more of the chemical groups occurring concurrently. Network and cluster analysis results indicated the existence of multiple sources of flame retardants in the indoor microenvironment. Estimated human daily intakes via indoor dust ingestion were approximately several tens of ng/kg bw/day and were below their respective reference dose values. Our results indicate widespread occurrence of multiple flame retardant families in indoor dust and suggest need for continued monitoring and efforts to reduce exposures through dust ingestion.

Synthesis and Characterization of P-PPD-Ph-Conjugated Flame Retardant

The conjugated flame retardants have rarely been studied. A conjugate flame-retardant 4, 4'-{1″, 4″-phenylene-bis [amino- (10‴-oxy10‴-hydro-9‴-hydrogen- 10‴λ5-phosphaphenanthrene-10″-yl)-methyl]}-diphenol (P-PPD-Ph) was synthesized and added into the polylactic acid (PLA) matrix. The P-PPD-Ph-conjugated flame-retardant structure was tested by FTIR, 1H, and 31P NMR analysis. The thermal and rheological properties of PLA/P-PPD-PH-conjugated flame-retardant composites were investigated. The results showed that P-PPD-Ph-conjugated flame retardant affects PLA/P-PPD-PH-conjugated flame-retardant composites for promoting the formation of a carbon layer when the P-PPD-Ph-conjugated flame-retardant content was 15% and the residual carbon ratio for PLA/P-PPD-PH-conjugated flame-retardant composites increased by 4.2%.

Phosphorus‐Fixed Stable Interfacial Nonflammable Gel Polymer Electrolyte for Safe Flexible Lithium‐Ion Batteries

AbstractA high content of flame retardant in non‐combustible electrolytes leads to deterioration of the electrochemical performance of lithium‐ion batteries (LIBs). Besides, fire hazard of most non‐flammable electrolytes is studied in coin cell, for which it is impossible to reveal real performance. Thus, the stable interfacial, phosphorus‐fixed nonflammable gel polymer electrolyte (GPE) with low content of flame retardant (7.5 wt.%) has been designed by in situ polymerization of tri(acryloyloxyethyl) phosphate and triethylene glycol dimethacrylate in electrolyte. After being heated by fire for &gt;10 s, the GPE is still not ignited. The average capacity attenuation rate of graphite//GPE//Li (0.008%) is much lower than that of the liquid electrolyte (0.039%). Besides, the nonflammable GPE based pouch cell with good flexibility and excellent fire safety is prepared. No fire, no thermal runaway and no electrolyte leakage occur for 1 Ah flexible pouch cell with 100% SOC. The mechanism for high safety of pouch cell has also been revealed. First the amount of combustible pyrolysis products from thermal degradation of GPE is reduced through forming P and F containing char. Second, the combustion of GPE is extinguished through OH free radical quenching effect of flame retardant molecular. This work provides a guideline for designing high‐safety LIBs.

Flame retardancy of PET foams manufactured from bottle waste

Supercritical CO2-assisted extrusion technique was used to produce flame retarded foams from recycled poly(ethylene terephthalate) (rPET). Synergistic combination of aluminium-alkylphosphinate flame retardant (FR) and natural montmorillonite (MMT) was utilised to provide adequate flame retardancy at moderate loadings, i.e. with less than 9% of additives. Addition of FR was found to increase the rate of degradation during production (compounding and foam extrusion), which was effectively compensated by chain extender (CE) addition that ensured the melt strength required to obtain proper foam structure. The effects of the FR content and the CE addition on the viscosity of the rPET compounds and on the morphological, thermal, flammability and mechanical properties of the foam products were comprehensively investigated. When compared to injection moulded bulk materials of identical compositions, the highly porous structure of foams was found to increase flammability according to UL94 tests and LOI measurements but has not been shown to be detrimental to heat release rates as measured by cone calorimetry. It was concluded that with well-balanced composition, i.e. 8% FR + 1% MMT + 1% CE, low-density foams (with porosities higher than 70%) of uniform microcellular structure and prominent flame retardant characteristics (such as V0 rating according to UL94 standard, LOI of 28.5% and by 50% reduced peak of heat release rate and by 30% reduced total heat emission) can be manufactured even from rPET.