Flame Retardant Effect Research Articles

Synthesis of P-N-S elemental flame-retardant waterborne polyurethane and its application in polyamide fabric

A new type of flame-retardant polyether diols containing phosphorus, nitrogen, and sulfur (SPAE) was first synthesized by using phosphoryl chloride, 2-aminobenzothiazole and ethylene glycol. The SPAE as the soft segment was then utilized to prepare a series of flame-retardant waterborne polyurethanes (SPAE-WPU) through emulsion polymerization. Subsequently, SFR-WPU as a finishing agent was coated on polyamide fabric. When the content of SPAE-WPU was 18 wt%, the coated fabric exhibited a limiting oxygen index (LOI) of 28.2 %, afterflame time of 4.6 s, afterglow time of 0 s and damaged length of 11.2 cm, respectively. After 10 washes, the coated fabric retained its good flame-retardancy and anti-dripping properties. Furthermore, the flame-retardant mechanism of SPAE-WPU was investigated using various spectral analyses, which revealed that the P, N and S elements worked together to create non-combustible gas compounds, release free radicals, and promote dehydration and carbonization, leading to synergistic flame-retardant effects in both gas- and condensed-phase.

One-pot synthesis of aluminum hypophosphite encapsulation in expanded halloysite lumen for reducing fire hazard and environmental pollution

Halloysite nanotubes (HNTs) have been studied and applied in the field of flame retardant. It is still a challenge to realize a facial method to accommodate more flame retardants while expanding the inner lumen of HNTs simultaneously. In this work, the inner cavity expansion and the encapsulation of aluminum hypophosphite of HNTs is obtained (AHP@HNTs) by a simple one-pot synthesis. The prepared AHP@HNTs were applied to the flame retarded Epoxy resin (EP) and the results show that AHP@HNTs can achieve better flame retardant effect at a lower addition (3 %) than individual additions of AHP or HNTs at higher addition (5 %) manifested by the reduction of the heat and smoke release. The decrease of effective heat combustion (EHC) reveals a gaseous phase flame retardant mechanism. Moreover, the environmental pollution after combustion was evaluated by an innovative method based on the particulate collection from smoke. The reduction of particulate formation and the improvement of char residue confirms the condensed flame retardant mechanism of AHP@HNTs on EP.

Study on the effect of novel intumescent flame retardant composed of β-cyclodextrin modified ammonium polyphosphate and THEIC on the flame retardancy of LDPE composites

Enhancing polymer flame retardancy is crucial for lowering combustion-related exothermic heat and flue gas production. β-cyclodextrin microencapsulated ammonium polyphosphate (β-CD@APP) were synthesis through in-situ polymerization and combined with 1, 3, 5-tris (2-hydroxyethyl) isocyanurate (THEIC) as a novel intumescent flame retardant (IFR) to enhance the flame retardancy of low density polyethylene (LDPE). The results showed that APP's hydrophobic characteristic increased, which enhanced its polymer dispersibility. Compared with LDPE, the LOI value of β-CD@APP/THEIC/LDPE (LDPE5) was enhanced from 17.5% to 28.7% and the composites could meet the UL-94 V-0 standard. Smoke volume and thermal decomposition rate were reduced. Furthermore, a stable char layer was found, which can be seen from the SEM of the char slag and the Raman results. According to the above results, the thermal decomposition and possible mechanism of flame retardants in LDPE composites during combustion were studied.

The synergistic flame retardant effect of biobased phytic acid arginine salt and hydroxylated montmorillonite in polybutylenes succinate

In this research, hydroxylated nano montmorillonite (DK2) was used as a synergistic agent in combination with phytic acid arginine salt (PaArg). The flame retardancy and mechanical properties of PBS with different amounts of PaArg and DK2 were studied. Furthermore, the synergistic effect and mechanism of PaArg and DK2 in PBS were explored. The results showed that adding 23.5 % PaArg and 1.5 % DK2 increased the limiting oxygen index value (LOI) of the composite to 31.4 %, passing the UL 94 V-0 rating. By adding 25 % PaArg alone, the LOI value of the composite is 26.2 %, and the vertical burning test result is only V-2 rating. The cone calorimetry test results show that the peak heat release rate, total heat release rate, and total smoke production of PBS/23.5 % PaArg/1.5 % DK2 composite are 55.8 %, 17.1 %, and 44.7 % lower than those of PBS/25 % PaArg composite, respectively. All the results showed that PaArg and DK2 exhibited good synergistic flame retardancy in PBS. In addition, the impact strength and bending strength test results show that the impact strength and bending strength of PBS/23.5 %PaArg/1.5 %DK2 composite are higher than those of PBS/25%PaArg composite. This work improved the flame retardant efficiency of biobased flame retardants in PBS.

Analysis of the pyrolysis process of ionic liquid-based flame retardant rigid polyurethane foam

In this study, flame retardant polyurethane rigid foam was prepared by incorporating 15 wt% ammonium polyphosphate (APP) and ionic liquid (1-butyl-2,3-dimethylimidazolium tetrafluoroborate, abbreviated as B4F). The flame retardant and thermal stability of the material were evaluated using vertical combustion (UL-94), limiting oxygen index (LOI), cone calorimeter (CONE), and thermogravimetric analyzer (TG) tests. Additionally, scanning electron microscopy (SEM), Raman spectroscopy (Raman), and X-ray photoelectron spectroscopy (XPS) were utilized to explore the flame retardancy mechanism in the carbon layer after combustion. The experimental results showed that the addition of 1 wt%B4F and 14 wt% APP to the polyurethane (RPUF/14APP/1B4F) significantly improved the vertical combustion test, upgrading it from the V-1 level to the V-0 level. This improvement was attributed to the increased degree of graphitization of the material, as evidenced by the reduced ratio of amorphous carbon to graphitic carbon (ID/IG) from 2.68 to 1.38. XPS analysis revealed that RPUF/14APP/1B4F exhibited a higher C/O ratio in the residual carbon (3.03) compared to RPUF/15APP (1.84), indicating that B4F effectively enhanced the antioxidant properties of the flame-retardant materials. Under the air atmosphere, RPUF/14APP/1B4F demonstrated an increased char formation at 800 °C (21.24 %), which was 71.01 % higher than RPUF/15APP. The interaction between B4F and APP led to the formation of a more stable char layer structure in polyurethane, further enhancing its flame retardancy. In conclusion, the RPUF/14APP/1B4F demonstrated a synergistic flame retardancy effect and enhanced thermal stability. The addition of B4F improved the graphitization degree of the material and increased the C/O ratio in the residual carbon, enhancing the antioxidant properties of the system. Moreover, the interaction between B4F and APP promoted the formation of a more stable char layer, effectively improving the flame retardant properties of the polyurethane. These findings provide valuable insights for the development of advanced flame retardant polyurethane materials with improved fire safety in various applications.

Development of Halogen‐Free Flame Retardant Acrylonitrile Butadiene Styrene (ABS) Based Composite Materials

AbstractNatural flammability properties of acrylonitrile butadiene styrene (ABS) seriously limit the use of ABS polymers in industries. Improving the flammability performance of ABS by using halogenated additives has been a very common method in the past. However, with increasing environmental awareness, the use of halogen‐containing additives has been severely limited over time. Therefore, we aimed to use halogen‐free flame‐retardant additives in our study to improve the flame‐retardant properties of ABS. ABS‐based composites containing 20, 25, 30 % aluminum diethyl‐phosphinate (AlPi) and ammonium polyphosphate (APP) halogen‐free flame‐retardant additives by weight, were prepared using a twin‐screw extruder. V0 rating according to UL 94 standard for the thickness of 1.5 mm, limiting oxygen index (LOI) value higher than 28 %, and glow wire flammability index of 960 °C were aimed in this study. To improve the LOI values of flame‐retardant ABS composites, pentaerythritol (PER), zinc borate (ZB), and magnesium hydroxide were used. The highest LOI value was obtained to be 28.1 % by using 12.5 wt.% AlPi, 12.5 wt.% APP, 5 wt.% PER and 3 wt.% ZB. The effect of flame retardants on mechanical properties (flexural and tensile properties), impact properties (Izod and Charpy‐notched impact strength), thermal properties, melt flow index, and morphology (scanning electron microscopy) of ABS were also examined.

A DOPO‐based reactive flame retardant containing benzimidazole groups: Synthesis and its flame‐retardation on epoxy resin

AbstractDOPO based flame retardants demonstrate exceptional flame retardancy efficiency when applied to epoxy resins. However, the crosslinking degree of epoxy resin may decrease due to the addition of DOPO, leading to a deterioration in flame retardancy and mechanical properties. Herein, a reactive DOPO derivative flame retardant 6‐((1H‐benzo[d]imidazol‐2‐yl) amino) dibenzo oxaphosphinine 6‐oxide (BADO) was successfully synthesized, which contains multiple reactive sites, thus ensuring a higher degree of crosslinking in the system. As a result, the modified epoxy resin exhibits excellent flame retardancy. The limiting oxygen index value of the modified epoxy resins increased from 19.8% to 29.7% by adding 7.5 wt% BADO, and its UL‐94 test passed V‐0. Flame retardancy mechanism analysis reveals that BADO exhibits both gas‐phase and condensed‐phase flame retardant effects. In particular, the formation of a porous inside‐char layer is a significant factor in reducing smoke release. The 7.5% BADO/EP composite exhibited a 43.2% reduction in total smoke production and a 43.6% reduction in total smoke rate compared to neat epoxy resins (EP). Furthermore, the addition of BADO slightly deteriorates the mechanical properties of the modified epoxy resin.

Synthesis of brominated flame retardants with different brominated structures and study on flame retardancy of polystyrene resin

Brominated flame retardants can be divided into aromatic brominated flame retardants and fat brominated flame retardants. In this paper, six kinds of polymers with different bromine structures were synthesized, Includes two aromatic bromine structure polymers polytribromophenyl acrylate (PTrA) and Poly 2, 6-dibromophenyl ether (PBO)，two adipose bromine polymer tribromoneopentyl polyacrylate (PBVT) and Polybromoethyl acrylate (PBBT), two aliphatic bromine aromatic bromine mixed polymer tribromoethyl acrylate (BCB) and fatty bromine aromatic bromine copolymer (BCVB). The effects of different bromine structure flame retardants on flame retardancy of polystyrene were investigated from the aspects of thermal stability, compatibility and molecular weight. Furthermore, the flame retarding mechanism of BCB and its effect on the mechanical properties of polystyrene were elucidated. The results showed that there was a negative correlation between molecular weight and flame retardancy. And the advantage of aliphatic bromine is that the thermal decomposition temperature is lower than that of aromatic bromine, bromine is released earlier, which can block the flame spread in the early stage of combustion. The poor thermal stability of the flame retardant will lead to its decomposition at 200. However, polystyrene processing is at this temperature, which resulted in reduced flame retardant performance. Moreover, aromatic structure had the advantage of better compatibility with polystyrene. BCB has the best flame retardant performance, and the limiting oxygen index (LOI) value is 24.5% under 15% addition, PHRR and THR were reduced to 670 kW/m2 and 63 MJ/m2. Meanwhile, the tensile strength, bending strength and impact strength of PS/BCB composites (15% BCB content) were decreased respectively 19.7%, 6.4% and12.2%. BCB plays a flame retardant role in the gas phase.

A graphene@Cu-MOF hybrid synthesized by mechanical ball milling method and its flame retardancy and smoke suppression effect on EP

The traditional method of preparing graphene will cause serious environmental pollution, and the combustion of polymer materials will seriously harm people's health. In this paper, a Cu-MOF-coated graphene composite flame retardant (G@Cu-MOF) rich in flame retardant elements such as B and N was synthesized through green mechanical ball milling method. Flame retardants reduce the threat to the environment and people's lives and property. After adding 6 wt% G@Cu-MOF, the peak heat release rate, total heat release rate, CO production and CO2 production of epoxy resin (EP) composite samples decreased by 55, 14, 59, and 55%, respectively. This type of Cu-MOF releases incombustible gases such as boron trifluoride (BF3) and ammonia (NH3) during combustion, diluting the concentration of combustible gases and producing copper borate in the condensed phase. Cu2+ is reduced to Cu, and boron compounds are converted into boron oxides. The thermal conductivity of graphene can reduce the temperature of the matrix, and has good flame retardancy. It synergistically acts with Cu-MOF to promote the formation of high-quality residual char, and can significantly inhibit the heat and smoke release of EP. It plays a role in flame retardancy and protecting the substrate from fire. This study provides a new approach for preparing graphene hybrid flame retardants through mechanical ball milling, in order to improve the flame retardancy of EP and suppress the release of smoke and toxic gases.

Synthesis and application of silicone modified flame retardant for polyester fabric

The flame-retardant treatment of polyester fabrics has been widely reported, but most of these treatments cause a significant decrease in the fabric’s handle, such as fluffiness and softness. This study designed and synthesised a new phosphorus-nitrogen-containing silicone oil (PNSO). Then, PNSO as a flame-retardant was treated on polyester fabric through a pad-dry-cure procedure. The limiting oxygen index (LOI), afterflame time and damaged length of the finished polyester fabric (PNSO-F) were enhanced from 20.5%, 73.1 s and 26.8 cm to 28.3%, 4.5 s and 12.3 cm, respectively. After 12 washes, PNSO-F retained its good flame-retardancy and anti-dripping properties. Furthermore, the flame-retardant mechanism of PNSO on fabric was investigated using different spectral methods, which revealed that nitrogen acting in the gas phase, and phosphorus and silicone in the condensed phase worked together to produce a synergistic flame-retardant effect. In addition, KES tests indicated that the fluffiness and softness of PNSO-F were significantly improved.

Harmonization of semi-objective ANP with explained CRITIC for quantitative evaluation of fire hazard risks for flame-retardant materials

The fire hazard assessment of polymers and the effect of flame retardants constitutes the foundation for preventing and managing fire risks to public safety. This study addresses key challenges by considering intrinsic hazards, indicator volatility and correlations, while overcoming subjectivity in weight assignment and the neglect of flame-retardant treatments. Firstly, we initiate two novel steps of Pearson correlation analysis and predefined comparative scales for indicators, which enhance the objectivity, scalability and repeatability of analytic network process (ANP) weights. Secondly, we utilize the CRITIC method to incorporate indicator volatility and correlations, surpassing the limitations of separate calculations and subsequent combinations. The newly developed pure sample normalization method enhances the interpretability and scientific validity of CRITIC weights. Combining the ANP and CRITIC weights using Nash equilibrium theory, the results rectify the underestimated T-5% from 0.72% to 3.64%, reducing the overestimated PCO2, PSP and TSP from 11.98%, 9.62% and 9.59–7.25%, 9.12% and 5.69%, respectively. Finally, the fire hazards value effectively captures the increased fire hazards resulting from specific degraded indicators following flame retardant treatments. The research findings provide a fresh perspective for the safe design of flame-retardant polymers and fire hazard assessment, offering valuable insights for fire risk prevention and management.

Synthesis of Zinc Oxide Doped Magnesium Hydrate and Its Effect on the Flame Retardant and Mechanical Properties of Polypropylene.

In this work, an effective flame retardant consisting of nanoscale zinc oxide doped on the surface of hexagonal lamellar magnesium hydrate (ZO@MH) has been successfully synthesized via a hydrothermal process. Approximately 3-methacryloxypropyltrimethoxysilane (KH-570) is chosen as a modifier of ZO@MH for the purpose of enhancing the interfacial interaction between ZO@MH and the polypropylene (PP) matrix and reducing the agglomeration of ZO@MH. Afterwards, ZO@MH and KH-570 modified ZO@MH (KZO@MH) filled PP (PP/ZO@MH and PP/KZO@MH) composites are respectively prepared via the melt blending method. The flame retardant and smoke suppression properties of PP/ZO@MH and PP/KZO@MH composites are estimated by a cone calorimetry test (CCT). The peak value of the heat release rate of the PP/40KZO@MH composite is 327.0 kW/m2, which is 6.1% and 31.2% lower than that of the PP/40ZO@MH and PP/40MH composites, respectively. The lowest peak values of CO and CO2 production, 0.008 and 0.62 g/s, also appeared in the PP/40KZO@MH composite, which are 11.1% and 10.1% lower than those of the PP/40ZO@MH composite. Analysis of char residues indicates that nanoscale ZO and modification of KH-570 improve the amount and quality of char residues, which should be the main reason for the good flame retardant and smoke suppression properties of KZO@MH. Impact strength and nominal strain at break results show that the PP matrix is toughened by ZO@MH rather than KZO@MH. Tensile properties and the quantitative interfacial interaction calculated by the Turcsányi equation both prove the reinforcement of KZO@MH on the PP matrix.

Cognitive Performance and Exposure to Organophosphate Flame Retardants in Children: Evidence from a Cross-Sectional Analysis of Two European Mother-Child Cohorts.

The knowledge of the effects of organophosphate flame retardants on children's neurodevelopment is limited. The purpose of the present research is to evaluate the association between exposure to organophosphate flame retardants and children's neurodevelopment in two European cohorts involved in the Human Biomonitoring Initiative Aligned Studies. The participants were school-aged children belonging to the Odense Child Cohort (Denmark) and the PCB cohort (Slovakia). In each cohort, the children's neurodevelopment was assessed through the Full-Scale Intelligence Quotient score of the Wechsler Intelligence Scale for Children, using two different editions. The children's urine samples, collected at one point in time, were analyzed for several metabolites of organophosphate flame retardants. The association between neurodevelopment and each organophosphate flame retardant metabolite was explored by applying separate multiple linear regressions based on the approach of MM-estimation in each cohort. In the Danish cohort, the mean ± standard deviation for the neurodevelopment score was 98 ± 12; the geometric mean (95% confidence interval (95% CI)) of bis(1,3-dichloro-2-propyl) phosphate (BDCIPP) standardized by creatinine (crt) was 0.52 µg/g crt (95% CI = 0.49; 0.60), while that of diphenyl phosphate (DPHP) standardized by crt was 1.44 µg/g crt (95% CI = 1.31; 1.58). The neurodevelopment score showed a small, negative, statistically imprecise trend with BDCIPP standardized by crt (β = -1.30; 95%CI = -2.72; 0.11; p-value = 0.07) and no clear association with DPHP standardized by crt (β = -0.98; 95%CI = -2.96; 0.99; p-value = 0.33). The neurodevelopment score showed a negative trend with BDCIPP (β = -1.42; 95% CI = -2.70; -0.06; p-value = 0.04) and no clear association with DPHP (β = -1.09; 95% CI = -2.87; 0.68; p-value = 0.23). In the Slovakian cohort, the mean ± standard deviation for the neurodevelopment score was 81 ± 15; the geometric mean of BDCIPP standardized by crt was 0.18 µg/g crt (95% CI = 0.16; 0.20), while that of DPHP standardized by crt was 2.24 µg/g crt (95% CI = 2.00; 3.52). The association of the neurodevelopment score with BDCIPP standardized by crt was -0.49 (95%CI = -1.85; 0.87; p-value = 0.48), and with DPHP standardized by crt it was -0.35 (95%CI = -1.90; 1.20; p-value = 0.66). No clear associations were observed between the neurodevelopment score and BDCIPP/DPHP concentrations that were not standardized by crt. No clear associations were observed with bis(1-chloro-2-propyl) phosphate (BCIPP) in either cohort, due to the low detection frequency of this compound. In conclusion, this study provides only limited evidence of an inverse association between neurodevelopment and exposure to BDCIPP and DPHP. The timing of exposure and effect modification of other organophosphate flame retardant metabolites and other substances should be the subject of further investigations that address this scientific hypothesis.

Investigation on the Performance of Fire and Smoke Suppressing Asphalt Materials for Tunnels

The volatilization of asphalt fumes not only affects the health of construction workers, but also damages the environment. It even affects the construction quality of asphalt pavement in tunnels. This article focuses on solving the emission of asphalt fumes to better protect human health and the environment, while satisfying the use of asphalt pavement. A flame retardant and smoke suppressant (compound) with Mg(OH)2 as the main component was developed, and flame retardant asphalt mixture and asphalt mastics were prepared to evaluate the flame retardant and smoke suppressant properties and performance effects. Firstly, its low- and high-temperature performances were investigated with BBR and DSR, respectively. Then, the indoor combustion test and the cone calorimeter test were used to evaluate the fire retardant smoke suppression effect of the asphalt mastic. Thirdly, the flame retardant effect of asphalt mastic mixed with the compound was further analyzed by the TG test and SEM. The pyrolysis temperature, mass loss, and microscopic state of the asphalt surface were used to verify and explain the flame retardant reaction effect and process of the compound. Finally, the asphalt mixture performance was evaluated, as well as the flame retardant smoke suppression effect by asphalt mixture combustion tests. The results showed that the flame retardant smoke suppression time of the flame retardant asphalt mixture was reduced by 66%, and the smoke emission area was reduced by 20%. The flame retardant smoke suppression effect of the asphalt mixture was improved by 44%. It is proven that this kind of fire retardant and smoke suppressing asphalt mastic and mixture met performance needs in use, and the fire retardant and smoke suppressing effect was obvious. This solution addresses the issue of asphalt smoke generated during the construction of asphalt pavement, providing better support for the construction of asphalt pavement in tunnels.

Facile alteration of the molecular structure of phosphonamide for efficient flame retardancy in TPU

In this work, three phosphonamide flame retardants with different chain segment structures (PPP, PPDA, EDP) were designed and synthesized, and efficient flame-retardant TPU systems were obtained by comparing the flame-retardant effects of three phosphonamide flame retardants in TPU. First, it was found that phosphonamide flame retardants containing p-phenylenediamine groups in the chain segment structure had better flame retardant effects than those containing piperazine groups. This was reflected in the experiment that the TPU/9%PPP only achieved UL 94 V-2 rating, but TPU/9%PPDA successfully passed the V-0 test. Then, EDP was obtained by further replacing the phenyl in PPDA with ethoxy and p-phenylenediamine group retained, which had the highest flame-retardant efficiency among all phosphonamide flame retardants. Its limited oxygen index (LOI) value exceeded 30 %, higher than that of TPU/9%PPDA (27.8 %), and achieved anti-melt dripping during UL-94 test. The LOI value of TPU/9%EDP was increased by 36 %, while the peak heat release rate and total heat release were significantly reduced by 77 % and 52 %, respectively, compared with pure TPU. Based on the analysis of char residue, EDP formed a protective char layer at the earliest time, playing a barrier protection role. This work provides a pathway for efficient flame retardant TPU. Also, the design idea of phosphonamide flame retardants is a useful reference for the preparation of multifunctional flame retardants.

Properties and flame retardancy of polylactide composites incorporating tricresyl phosphate and modified microcrystalline cellulose from oil palm empty fruit bunch waste

One of the major environmental issues that have an impact on humans, animals, and their surroundings is plastic garbage. The use of biodegradable polymers in place of traditional plastics is one of the best solutions to this significant issue. The bio-circular-green (BCG) economic model is supported by the use of microcrystalline cellulose (MCC) as a bio-filler for polylactide (PLA) composites, which may also help to address the issue of improper plastic waste management. This study explores the chemical modification of MCC derived from oil palm empty fruit bunch waste (OPMC). Maleic anhydride-modified OPMC (MAMC) is successfully synthesized by a solvent-free and low temperature heating procedure. MAMC and tricresyl phosphate (TCP) were used as additives in PLA composites which were processed by melt extrusion and compression molding. Characterization studies confirmed the successful modification of MAMC and indicated that TCP played a crucial role as an effective plasticizer and flame retardant for PLA. All PLA/TCP composites showed significantly improved toughness and delayed ignition. The appropriate TCP level was 10 phr. The incorporation of TCP and MAMC resulted in a synergistic enhancement of impact strength and maintained excellent flame inhibition. Moreover, the thermal stability of the PLA composites increased with increments of MAMC.

Modified Gallic Acids as Both Reactive Flame Retardants and Cross‐Linkers for the Fabrication of Flame‐Retardant Polyurethane Elastomers

AbstractPolyurethane elastomers (PUEs) serve a vital role in our daily life and various industrial applications, but their flammability has been proven to be a significant drawback. In this work, we have successfully fabricated two modified gallic acids (GAP and GAN) by simple esterification, both of which are effective flame retardants and cross‐linkers for PUEs. According to thermogravimetric analysis (TGA) and limiting oxygen index (LOI) tests, the introduction of GAP and GAN conspicuously improves the char yield (4.9~5.8 wt.%) and LOI value of PUEs (33~35 %). The cone calorimetry tests suggest that the peak heat release rate (PHRR) and total heat release (THR) of PUE decrease significantly, while the fire performance index (FPI) value increase after GAP or GAN modification. Both GAP and GAN enhance the density and strength of carbon residues, and inhibit the generation of combustible volatile gas during the combustion process, thereby improving the fire safety of PUEs. In addition, both GAP and GAN contain multiple benzene rings and hydrogen bonding, which can improve the cross‐linking density of PUEs to enhance their mechanical properties (the elongation at break: 844~951 %; tensile strength: 6.37~8.13 MPa).

Polyaniline/chitosan coating as the novel and sustainable flame retardant and UV protection route for silk fabric

The growing awareness of human health and environmental protection stimulates the development of more sustainable flame retardant (FR) approaches. In this study, polyaniline (PANI) with a nitrogen-containing aromatic structure was synthesized as a novel functional compound to improve the FR and UV protection performance of silk fabric. Biobased chitosan was applied to develop the PANI/chitosan coating to improve the binding capability and dispersion uniformity of PANI on the silk surface. The surface morphology, thermal resistance, heat generation capacity, flame retardancy and UV protection performance were explored. The PANI/chitosan coating with 3 wt% PANI endowed the silk fabric with effective flame retardancy. The coated silk fabric self-extinguished during vertical flammability test and possessed a decreased char length of 9.5 cm versus 30 cm of the pristine silk fabric; it could also withstand 20 launderings, showing good laundering resistance. The coated silk fabric displayed markedly decreased heat release behavior. A combined condensed phase and gas phase FR action was suggested for the PANI/chitosan coating on silk fabric. The coated silk fabric also exhibited excellent UV protection with the UPF of 50+ because of the UV-shielding of PANI.

A ternary polymer flame retardant and its synergistic flame retardant effect with piperazine pyrophosphate in EP

A ternary polymer flame retardant and its synergistic flame retardant effect with piperazine pyrophosphate in EP

3D hierarchical fireproof gel polymer electrolyte towards high-performance and comprehensive safety lithium-ion batteries

Gel polymer electrolyte (GPE) stands as an extensively investigated solid-state electrolytes for next-generation lithium-ion batteries (LIBs). Nonetheless, their inherent flammability necessitates the addition of flame retardants, which adversely impact LIBs’ electrochemical performance. Herein, we propose a groundbreaking conceive of a fireproof cross-linking composite GPE that united phosphene and a P-N synergistic flame retardant (DPM), equipping a dual-enhanced conduction effect on Li+ ions and a cooperative P-N flame-retardant effect. By strategically manipulating the polymer segments hierarchy and incorporating efficient function groups from DPM, freely Li+ mobility has been propelled, thereby delivering satisfactory ionic conductivity (1.263 mS cm−1, 20 ℃), elevated oxidative stability (5.42 V vs. Li+/Li) and improved Li+ transference number (0.53). The composite GPE-based batteries (LFP||Li, NCM523||Li and LFP||Graphite) indicate acceptable specific capacities at 1 C, together with good reversible capacity retention rate and stable coulombic efficiency after 200 cycles. Noticeably, the pouch cells (LFP||Graphite) assembled with composite GPE demonstrate superior safety robustness and fire-resistance under mechanical mishandling and ignition situations. Finally, the elucidation of Li+ ions interaction mechanism with polymer matrix is unraveled through molecular orbital energy levels and density function theory (DFT) calculation. This study offers valuable insights for harnessing novel electrolyte materials in high-safety LIBs.