Concentrations Of Flame Retardants Research Articles

Legacy halogenated flame retardants in Canadian human milk from the maternal-infant research on environmental chemicals study

Polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD) were measured in 298 human milk samples collected from across Canada between 2008 and 2011 as part of the Maternal-Infant Research on Environmental Chemicals study. PBDEs were detected in 100% of the samples analyzed and concentrations ranged from 0.071 to 267 ng·g-1 lipid (median 15.6 ng·g-1 lipid). The dominant contributors to ΣPBDEs (Σ15, 17, 28, 37, 47, 66, 71, 75, 77, 85, 99, 100, 119, 138, 153, 154, 160, 183, 190, 209) were PBDE 47 > PBDE 153 > PBDE 99 > PBDE 100 > PBDE 28 > PBDE 209. Previously, PBDE 209 was considered to be a minor contributor to ΣPBDE concentrations in Canadian human milk and, therefore, not reported by our lab. This study showed that when present, PBDE 209 can be an important contributor to ΣPBDEs (range: below detection - 85.3 ng·g-1 lipid; median - 0.083 ng·g-1 lipid). ΣPBDE concentrations declined slightly in Canadian human milk between the early and late 2000s. HBCD (Σ of α-, β-, and γ-) was observed in 94.0% of the samples measured and concentrations were dominated by α-HBCD (93.3%), with β- (9.7%) and γ- (28.5%) less frequently detected. The maximum ΣHBCD concentration observed was 7.66 ng·g-1 lipid (median value 0.303 ng·g-1 lipid). These data suggest that HBCD concentrations similarly decreased in Canadian human milk between the early 2000s and sampling for the present study. Maternal age did not impact the concentrations of these flame retardants in milk. Additionally, other maternal characteristics [e.g., the number of children a woman has had, pre-pregnancy body mass index (BMI), and education level] did not impact concentrations of these brominated flame retardant concentrations.

Mechanical, Dielectric and Flame-Retardant Properties of GF/PP Modified with Different Flame Retardants.

With the rapid development of electronic information technology, higher requirements have been put forward for the dielectric properties and load-bearing capacity of materials. In continuous glass fiber-reinforced thermoplastic composites, polypropylene matrix is a non-polar polymer with a very low dielectric constant and dielectric loss, but polypropylene is extremely flammable which greatly limits its application. Aiming at the better application of flame retardant-modified continuous glass fiber-reinforced polypropylene composites (FR/GF/PP) in the field of electronic communication, the effects of four different kinds of flame retardants (Decabromodiphenyl ethane (DBDPE), halogen-free one-component flame retardant (MONO), halogen-free compound flame retardant (MULTI), and intumescent flame retardant (IFR)) on the properties of FR/GF/PP were compared, including the mechanical properties, dielectric properties and flame-retardant properties. The results showed that among the FR/GF/PP, IFR has the highest performance in mechanical properties, MULTI has better performance in LOI, DBDPE and IFR have better performance in flame retardant rating, and DBDPE and IFR have lower dielectric properties. Finally, gray relational analysis is applied to propose an approach for selecting the optimal combination (flame retardant type and flame-retardant content) of comprehensive performance. In the application exemplified in this paper, the performance of IFR-3-modified GF/PP is optimized.

Reproductive toxicology of environmental endocrine-disrupting chemicals in women: a cohort study protocol.

Introduction: Epidemiological evidence over the last few decades has consistently shown that exposure to endocrine-disrupting chemicals (EDCs) is associated with adverse reproductive health outcomes, including male and female infertility, poor-pregnancy outcomes, and increased risk of diseases in childhood and beyond. To investigate the effects of EDCs and lifestyle on all aspects of reproduction (including early oocyte development, fertilization, embryo development, embryo implantation, abortion, and preterm birth). Methods: We performed this cohort study on patients receiving in vitro fertilization (IVF) treatment. Biological samples including urine, serum, follicular fluid, semen, fetal tissue, decidua, and placenta, were obtained. Results: By studying the correlations between reproductive outcomes and environmental pollutant exposure and lifestyle, we determined the toxicological mechanisms and health effects of EDCs on female reproductive health. We found that higher concentrations of per- and polyfluoroalkyl substances were correlated with polycystic ovary syndrome (PCOS). Using specific biomarkers, we also detected the concentrations of organophosphorus flame retardants (OPFRs) in urine and found that OPFRs may disrupt hormone homeostasis. Discussion: All of these results reveal EDCs may disrupt female reproduction.

Green Flame-Retardant Blend Used to Improve the Antiflame Properties of Polypropylene.

The flammability properties of polymers and polymeric composites play an important role in ensuring the safety of humans and the environment; moreover, flame-retardant materials ensure a greater number of applications. In the present study, we report the obtaining of polypropylene (PP) composites contain a mixture of two green flame retardants, lignin and clinoptilolite, by melt extrusion. These additives are abundantly found in nature. Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), mechanical properties, scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), cone calorimetry, UL-94, and carbonized residues analysis were carried out. TGA analysis shows that PPGFR-10 and PPGFR-20 compounds presented better thermal stability with respect to PP without flame retardants. The conical calorimetric evaluation of the composites showed that PPGFR-10 and PPGFR-20 presented decreases in peak heat release rates (HRRs) of 9.75% and 11.88%, respectively. The flammability of the composites was evaluated with the UL-94 standard, and only the PPGFR-20 composite presented the V-0 and 5VB classification, which indicates good flame-retardant properties. Additives in the polymer matrix showed good dispersion with few agglomerates. The PPGFR-20 composite showed an FRI value of 1.15, higher percentage of carbonized residues, and UL-94 V-0 and 5VB rating, suggesting some kind of synergy between lignin and clinoptilolite, but only at high flame-retardant concentrations.

Flame Retardant Exposure in Vehicles Is Influenced by Use in Seat Foam and Temperature.

Flame retardants (FRs) are added to vehicles to meet flammability standards, such as US Federal Motor Vehicle Safety Standard FMVSS 302. However, an understanding of which FRs are being used, sources in the vehicle, and implications for human exposure is lacking. US participants (n = 101) owning a vehicle of model year 2015 or newer hung a silicone passive sampler on their rearview mirror for 7 days. Fifty-one of 101 participants collected a foam sample from a vehicle seat. Organophosphate esters (OPEs) were the most frequently detected FR class in the passive samplers. Among these, tris(1-chloro-isopropyl) phosphate (TCIPP) had a 99% detection frequency and was measured at levels ranging from 0.2 to 11,600 ng/g of sampler. TCIPP was also the dominant FR detected in the vehicle seat foam. Sampler FR concentrations were significantly correlated with average ambient temperature and were 2-5 times higher in the summer compared to winter. The presence of TCIPP in foam resulted in ∼4 times higher median air sampler concentrations in winter and ∼9 times higher in summer. These results suggest that FRs used in vehicle interiors, such as in seat foam, are a source of OPE exposure, which is increased in warmer temperatures.

Properties of poplar veneer modified by Acid Red 3R dye in combination with ammonium dihydrogen phosphate

Ammonium dihydrogen phosphate (ADP) is a nitrogen-phosphorus-based inorganic flame retardant that is environmentally friendly and non-toxic. Wood treated with ADP has enhanced thermal stability and flame retardancy. Compounding ADP with Acid Red 3R dye further improves the decorative effect of the wood on the basis of excellent flame retardancy, resulting in a kind of dyeing and flame retardant multifunctionalized wood. Single-factor tests were designed to investigate the effects of flame retardant concentration, dye concentration, temperature, and time on three evaluation indexes: dye-uptake, color difference, and oxygen index, respectively. Through SEM and FTIR analysis, it was found that after the wood was simultaneously treated with flame retardant and dye, the two additives were aggregated in the grain pores of the cell wall by a simple physical combination. They did not undergo a chemical reaction. TG analysis showed that fire-retardant dyed wood had good thermal stability, which can delay the thermal degradation of wood and increase the residual charcoal rate of wood. XRD showed that the crystallinity of fire-retardant dyed wood increased compared to untreated wood. Through cone calorimetric test, it is found that flame retardant dyed veneer had excellent flame retardancy.

Impact of Legislation on Brominated Flame Retardant Concentrations in UK Indoor and Outdoor Environments: Evidence for Declining Indoor Emissions of Some Legacy BFRs.

Concentrations of polybrominated diphenyl ethers, hexabromocyclododecane (HBCDD), and novel brominated flame retardants (NBFRs) were measured in indoor dust, indoor air, and outdoor air in Birmingham, UK. Concentrations of ΣBFRs ranged from 490 to 89,000 ng/g, 46-14,000 pg/m3, and 22-11,000 pg/m3, respectively, in UK indoor dust, indoor air, and outdoor air. BDE-209 and decabromodiphenyl ethane (DBDPE) were the main contributors. The maximum concentration of DBDPE (10,000 pg/m3) in outdoor air is the highest reported anywhere to date. In contrast with previous studies of outdoor air in Birmingham, we observed significant correlations between concentrations of tri- to hepta-BDEs and HBCDD and temperature. This may suggest that primary emissions from ongoing use of these BFRs have diminished and that secondary emissions (e.g., evaporation from soil) are now a potentially major source of these BFRs in outdoor air. Conversely, the lack of significant correlations between temperature and concentrations of BDE-209 and DBDPE may indicate that ongoing primary emissions from indoor sources remain important for these BFRs. Further research to clarify the relative importance of primary and secondary sources of BFRs to outdoor air is required. Comparison with earlier studies in Birmingham reveals significant (p < 0.05) declines in concentrations of legacy BFRs, but significant increases for NBFRs over the past decade. While there appear minimal health burdens from BFR exposure for UK adults, dust ingestion of BDE-209 may pose a significant risk for UK toddlers.

A meta-analysis highlighting the increasing relevance of the hair matrix in exposure assessment to organic pollutants

Owing to a wide range of advantages, such as stability, non-invasiveness, and ease of sampling, hair has been used progressively for comprehensive biomonitoring of organic pollutants for the last three decades. This has led to the development of new analytical and multi-class analysis methods for the assessment of a broad range of organic pollutants in various population groups, ranging from small-scale studies to advanced studies with a large number of participants based on different exposure settings. This meta-analysis summarizes the existing literature on the assessment of organic pollutants in hair in terms of residue levels, the correlation of hair residue levels with those of other biological matrices and socio-demographic factors, the reliability of hair versus other biomatrices for exposure assessment, the use of segmental hair analysis for chronic exposure evaluation and the effect of external contamination on hair residue levels. Significantly high concentrations of organic pollutants such as pesticides, flame retardants, polychlorinated biphenyls and polycyclic aromatic hydrocarbon were reported in human hair samples from different regions and under different exposure settings. Similarly, high concentrations of pesticides (from agricultural activities), flame retardants (E-waste dismantling activities), dioxins and furans were observed in various occupational settings. Moreover, significant correlations (p < 0.05) for hair and blood concentrations were observed in majority of studies featuring pesticides and flame retardants. While among sociodemographic factors, gender and age significantly affected the hair concentrations in females and children in general exposure settings, whereas adult workers in occupational settings. Furthermore, the assessment of the hair burden of persistent organic pollutants in domestic and wild animals showed high concentrations for pesticides such as HCHs and DDTs whereas the laboratory-based studies using animals demonstrated strong correlations between exposure dose, exposure duration, and measured organic pollutant levels, mainly for chlorpyrifos, diazinon, terbuthylazine, aldrin, dieldrin and pyrethroid metabolites. Considering the critical analysis of the results obtained from literature review, hair is regarded as a reliable matrix for organic pollutant assessment; however, some limitations, as discussed in this review, need to be overcome to reinforce the status of hair as a suitable matrix for exposure assessment.

The mechanical strength of which in operation directly of the introduction into highly filled halogen-free plastics production

With the introduction into highly filled halogen-free plastics production, the mechanical strength of which in operation directly depends on the flame retardant content and application technology, it becomes important to control the cable sheath mechanical characteristics in a fireproof design. Polymeric materials and their compositions are viscoelastic materials for which the mechanical properties depend on the technological process of extrusion. The results of estimating the elongation at break of samples from the uniaxial stretching. It is shown that the inner and outer layers of the halogen-free plastic cable sheath have significantly different values of the plasticity normative parameter: differences evidence in the polymer structure in the inner and outer layers of the sheath due to the forced deformation process during extrusion, which is forced polymer structure orientation. It is shown that the inner and outer layers of the halogen-free plastic cable sheath have significantly different values of the relative change in specific mass of polymer samples. Analysis of the statistical covariance of the relative elongation at break and of the relative change in specific mass of polymer samples different in structure similar filled halogen-free polymers. With the introduction into highly filled halogen-free plastics application technology, it becomes important to control the cable sheath mechanical characteristics in fireproof design for the inner and outer layers

Synthesis and Characterization of Flame Retarded Rigid Polyurethane Foams with Different Types of Blowing Agents.

In this study, rigid polyurethane foams modified with non-halogenated flame retardant were obtained. The foams were synthesized using two systems containing different blowing agents. In the first one, cyclopentane and water were used as a mixture of blowing agents, and in the second one, only water was used as a chemical blowing agent. The systems were modified with the additive phosphorus flame retardant Roflam F5. The obtained modified foams were tested for their flammability and basic properties, such as apparent density, closed-cell contents and analyses of the cell structures, thermal conductivity, mechanical properties, and water absorption. Increasing the content of Roflam F5 caused a decrease in temperature during the combustion of the material and extended the burning time. The addition of 1.0 wt.% phosphorus derived from Roflam F5 caused the modified rigid polyurethane foam to become a self-extinguishing material. The increase in the content of Roflam F5 caused a decrease in the total heat release and the maximum heat release rate during the pyrolysis combustion flow calorimetry. The foams with the highest content of flame retardant and foamed with a chemical-physical and chemical blowing agent had a lower total heat release by 19% and 11%, respectively, compared to reference foams.

An eco-friendly, highly efficient, and transparent coating derived from guar gum and citric acid for flame retardant treatment of cotton fabrics

A highly efficient, bio-ecofriendly, and transparent flame retardant (FR) for cotton fabric was developed and deposited onto the cellulose skeletal structure of cotton fabric through a one-pot sol-gel process. The flame retardant functional coating is composed of ammonium polyphosphate (APP), guar gum (GG), citric acid (CA), and a negligible amount of catalyst. Cotton fabrics were impregnated with different concentrations of ammonium polyphosphate and guar gum, with citric acid as a crosslinking agent. The overall crosslinking and grafting process was proven by FTIR and XPS. Based on the results, the designed coating exhibits over 90 % transmittance in the visible region. A 15 g/m2 flame-retardant coating induces excellent flame retardant efficiency at ultra-low flame-retardant concentrations of less than 6.25 wt%. Only a 5.25 wt% flame retardant concentration demonstrated condensed phase action, which resulted in 58.5 % and 73.6 % reductions in the pHRR and THR, respectively. Moreover, the limiting oxygen index (LOI) value showed a 74 % increase. The mechanical performance of FR coated cotton fibers was slightly reduced.

Leaching of triphenyl phosphate and tri-n-butyl phosphate from polystyrene microplastics: influence of plastic properties and simulated digestive fluids.

Microplastics have gained considerable attention as a growing environmental problem owing to their potential to serve as vectors for harmful chemicals. However, the leaching of these chemicals from microplastics is unclear. In this study, we investigated the leaching of two organophosphate flame retardants, triphenyl phosphate and tri-n-butyl phosphate, from polystyrene microplastics in simulated digestive fluids and water, and polypropylene microplastics were simultaneously used for comparison with polystyrene microplastics. The results indicated that the first-order kinetic model best explained the leaching process, suggesting that leaching was related to the release of organophosphate flame retardant molecules at the polymer surface. Additionally, the size and crystalline state of the microplastics had a significant effect on the leaching, whereas organophosphate flame retardant content had a minimal impact. Simulated digestive fluids facilitated the leaching to a different extent, and under these influencing conditions, leaching percentages from polystyrene microplastics did not exceed 0.51%. Therefore, leaching from PS microplastics may not be an important source of OPFRs in the environment. However, the release of organophosphate flame retardants can be considerably enhanced with the breakdown of polystyrene microplastics to polystyrene nanoplastics.

Occurrence and dietary intake of dioxins, furans (PCDD/Fs), PCBs, and flame retardants (PBDEs and HBCDDs) in baby food and infant formula

This study determines the levels of 49 persistent organic pollutants which were grouped into polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and hexabromocyclododecanes (HBCDDs), in infant formula and varieties of baby food. The analyzed samples (n = 80) came from stores all over Poland.The presence of PCDD/F, PCDD/F/PCB and non dioxin-like (ndl)-PCB congeners above the maximum levels stipulated in Commission Regulation (EU) No 1259/2011 was not detected in any sample. The determined average content of PCDD/Fs/dl-PCBs in the tested baby foods was in the range of 4–10 % of the maximum level, and content of ndl-PCBs was in the range of 2–6 % of the maximum level. Despite these low levels of dioxins, furans, and PCBs, a risk analysis assuming weekly consumption of the recommended food intake showed exceedances of the tolerable weekly intake (TWI).The content of flame retardants was low in all examined categories of food for children and infant formula. The lower-bound concentration of the sum of HBCDD isomers (LB ∑HBCDDs) ranged from below the limit of quantification (LOQ) to 0.0313 ng/g w.w. and the concentration of ∑PBDEs was in a 0.001–1.014 ng/g w.w. range. Neither infant formula nor baby food contributed considerably to infant exposure to HBCDDs or PBDEs.Our research indicates that the safe exposure thresholds for dioxins and PCBs in foods for infants and young children may be too high and perhaps it may be necessary to amend the legislation setting acceptable limits for baby food. It seems reasonable to introduce a recommendation on the frequency of food consumption for children and the control of raw materials for food production, in particular fish and cow milk, should be a permanent control point in the food safety assurance system.

International Comparison, Risk Assessment, and Prioritisation of 26 Endocrine Disrupting Compounds in Three European River Catchments in the UK, Ireland, and Spain.

Endocrine-disrupting compounds (EDCs) constitute a wide variety of chemistries with diverse properties that may/can pose risks to both humans and the environment. Herein, a total of 26 compounds, including steroids, flame retardants, and plasticizers, were monitored in three major and heavily urbanized river catchments: the R. Liffey (Ireland), the R. Thames (UK), and the R. Ter (Spain), by using a single solid-phase extraction liquid chromatography-mass spectrometry (SPE-LC-MS/MS) method. Occurrence and frequency rates were investigated across all locations over a 10-week period, with the highest concentration obtained for the flame retardant tris(2-chloroethyl) phosphate (TCEP) at 4767 ng∙L-1 in the R. Thames in Central London. Geographical variations were observed between sites and were partially explained using principal component analysis (PCA) and hierarchical cluster analysis (HCA). In particular, discrimination between the R. Ter and the R. Thames was observed based on the presence and concentration of flame retardants, benzotriazole, and steroids. Environmental risk assessment (ERA) across sites showed that caffeine, a chemical marker, and bisphenol A (BPA), a plasticizer, were classified as high-risk for the R. Liffey and R. Thames, based on relative risk quotients (rRQs), and that caffeine was classified as high-risk for the R. Ter, based on RQs. The total risks at each location, namely ΣRQriver, and ΣrRQriver, were: 361, 455, and 723 for the rivers Liffey, Thames, and Ter, respectively. Caffeine, as expected, was ubiquitous in all 3 urban areas, though with the highest RQ observed in the R. Ter. High contributions of BPA were also observed across the three matrices. Therefore, these two compounds should be prioritized independently of location. This study represents a comprehensive EDC monitoring comparison between different European cities based on a single analytical method, which allowed for a geographically independent ERA prioritization to be performed.

Health Risk Assessment of Organophosphate Flame Retardants in Soil Across China Based on Monte Carlo Simulation.

Health risks from exposure to contaminants are generally estimated by evaluating concentrations of the contaminants in environmental matrixes. However, accurate health risk assessment is difficult because of uncertainties regarding exposures. This study aims to utilize data on the concentrations of organophosphate flame retardants (OPFRs) in surface soil across China coupled with Monte Carlo simulations to compensate for uncertainties in exposure to evaluate the health risks associated with contamination of soil with this class of flame retardants. Results revealed that concentrations of ∑OPFRs were 0.793-406 ng/g dry weight (dw) with an average of 23.2 ng/g dw. In terms of spatial distribution, higher OPFRs concentrations were found in economically developed regions. Although the values of health risk of OPFRs in soil across China were below the threshold, the high concentrations of OPFRs in soil in some regions should attract more attentions in future. Sensitivity analysis revealed that concentrations of OPFRs in soil, skin adherence factor, and exposure duration were the most sensitive parameters in health risk assessment. In summary, the study indicated that the national scale soil measurement could provide unique information on OPFRs exposure and health risk assessment, which was useful for the management of soil in China and for better understanding of the environmental fate of OPFRs in the global perspective.

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.