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• A new hybrid, polyphosphate-coated silica (SZP), was prepared. • A phosphorus-silicon-nitrogen synergistic flame retardant system was constructed. • The prepared composites have excellent comprehensive properties in addition to high flame retardancy. In general, the addition of phosphate ester flame retardants can improve the flame retardancy of polymethyl methacrylate (PMMA), but the flame retardant efficiency is low when phosphate ester is used alone and the tensile strength and hardness of the material are reduced. It is a challenge to improve the flame retardancy of PMMA while maintaining its inherent mechanical properties. In this study, a polyphosphate-coated silica (SZP) was prepared, which was compounded with dimethyl methylphosphonate (DMMP). At the same time, methacrylamide (MAM), which can be copolymerized with PMMA, was introduced to construct a synergistic phosphorus-nitrogen-silicon flame retardant system. The three components can work together in the gas phase and condensed phase. The results showed that when 12.5% DMMP, 5% MAM and 2.5% SZP were added, the composite material had the best comprehensive performance, its limiting oxygen index (LOI) reached 25.1%, and its total heat release was only 70% of the pure sample. More importantly, the addition of DMMP would significantly reduce the mechanical properties of PMMA. The introduction of SZP and MAM alleviated this problem. Compared with the pure sample, the mechanical properties of PMMA7 did not decrease but increased slightly. The flame retardant mechanism was also analyzed. This study provides a new idea for the industrialization of flame retardant PMMA. [ABSTRACT FROM AUTHOR]

• A novel reactive m-xylylenediamine phytate ammonium (MPAP) flame retardant was synthesized and grafted to cellulose materials. • Cellulose paper with superior flame-retardant and hydrophobic properties was successfully prepared by surface spraying technology and impregnation process, through the reaction of flame retardant and PMHS with cellulose fibers. • The modified cellulose paper also exhibited excellent performance for oil/water-separation. • This effective and simple strategy can also be applied to other cellulose-contained substrates for the application in construction, textiles, furniture and other fields. Paper-based materials have become increasingly prevalent in the packaging and daily life. However, paper is flammable and hydrophilic, hindering its widespread application. Here, a novel reactive flame retardant of m-xylylenediamine phytate ammonium (MPAP) was prepared. Cellulose paper with superior flame-retardant and hydrophobic properties was successfully prepared by surface spraying technology and impregnation process, through the reaction of flame retardant and poly(methylhydrosiloxane) (PMHS) with cellulose fibers. The water contact angle (WCA) of the modified paper was 122.6°, while the limit oxygen index (LOI) value reached 41 %, which had significant self-extinguishing performance. The total heat release rate of the modified paper was reduced from 12.8 kJ/g to 0.6 kJ/g. The modified paper also exhibited excellent performance for oil/water separation. Furthermore, this effective and simple strategy can also be applied to other cellulose-contained substrates for the application in construction, textiles, furniture and other fields. [ABSTRACT FROM AUTHOR]

• Novel synthesis of bio-based coumarin phosphorus flame retardant (FR) is reported. • Thermoxidative study of FR on PLA matrix was performed. • Reactive extrusion of PLA and incorporation of FR in two-step-one-pot process was investigated. • Flame retardant PLA exhibited a LOI value of 26%. This study addresses very important aspects of the sustainable development of new flame retardant materials: (i) the preparation of a novel flame retardant (FR) additive from bio-resource, (ii) its use as FR additive in poly(lactic acid) (PLA) based composites and, (iii) the in vitro toxicity assessment of the FR. The synthesis of this bio-based FR additive was achieved through a phospha-Michael addition of diphenylphosphine oxide (DPPO) and the naturally occurring compound coumarin, yielding 4-(diphenylphosphoryl)chroman-2-one (CU-DPPO). The flame-retarded CU-DPPO PLA composites were prepared either via conventional melt blending of commercially available PLA or through reactive extrusion (REX) of L-lactide. Characterization of the composites was performed through nuclear magnetic resonance (NMR), size exclusion chromatography (SEC) and thermogravimetric analysis (TGA). TGA analysis of the FR-PLA composites showed an increase in thermal stability, confirming the beneficial effect of the CU-DPPO additive. Direct insertion probe mass spectrometry (DIP-MS) analysis was used to gain insight on the mechanism of action of the FR additive, suggesting gas-phase activity. Rheological measurements exhibited the thermo-oxidative stabilizing effect in the modified PLA. The flame retardancy of the melt-blended PLA composites with CU-DPPO was investigated by limited oxygen index (LOI), cone calorimetry and vertical burning tests (UL 94 and BKZ-VB). Samples containing 10 wt.% of CU-DPPO showed improved fire performance with a limiting oxygen index (LOI) of 29%, passing Swiss vertical burning test (BKZ-VB) and obtaining a V-0 rating in the UL 94 test. Moreover, a preliminary toxicity assessment of the CU-DPPO, carried out using an established in vitro platform, showing no adverse effects on cell viability. [Display omitted] [ABSTRACT FROM AUTHOR]

• Flame retardant mechanisms of the five phosphorus oxidation states are summarized. • High phosphorus oxidation states exhibit a variety of flame retardant mechanisms. • The selectivity of phenoxy is higher than that of phenyl in pyrolysis. • Phosphorus oxidation promotes P-C bond breaking, resulting in secondary products. • Flame retardants pyrolyze PO 4 , PO 3 , PO 2 and PO at high temperatures via C O bonds. Polymers are ubiquitous and find applications in various facets of daily life and industrial production. However, the fire incidents induced by polymers jeopardize the safety of human life and property. Improving the fire resistance of polymeric materials through halogen-free flame retardants has become a prominent direction guided by the regulatory framework. In this paper, the decomposition pathways and mechanisms of five phosphorus-containing flame retardants, PPh3, DPPO, PDPP, TPPO and TPP, were investigated. The reaction pathways primarily encompassed the generation of PO, PO 2 , PO 3 , PO 4 , phenyl, and phenoxy radicals. Through a comprehensive analysis of the dissociation energies of P-C, P-O, and C O bonds under diverse chemical environments, phenoxy radicals was the principal decomposition products, with the cleavage of P-O bonds being the predominant choice. Increasing phosphorus oxidation states favors the accumulation of a carbon layer, tending to retard flame propagation through condensed-phase mechanisms. Phosphorus oxidation states primarily facilitated secondary dissociation reactions. The presence of oxygen favored the cleavage of P-C bonds, offering diverse flame retardant mechanisms that concurrently mitigated flame spread. This work provided an in-depth exploration of the flame retardant mechanisms of phosphorus-containing agents and summarized the impact of phosphorus oxidation states on flame retardants. [ABSTRACT FROM AUTHOR]

• Flame retardant PAN fibers were prepared based on amination and mannich reaction. • The modified PAN fibers had good flame retardant durability. • The modification endowed PAN fibers improved mechanical properties. • Flame retardancy and improved tensile strength expanded its practical application. To improve the flame retardancy, smoke suppression and mechanical properties of polyacrylonitrile (PAN) fiber, it was first modified with diethylenetriamine to prepare the aminated PAN fiber (A-PAN). Second, diethyl phosphite (DEP) was grafted onto the A-PAN to fabricate flame retardant PAN fiber (DEP-A-PAN). XPS and FTIR analysis confirmed that phosphorus and nitrogen elements were covalently bonded to the surface of PAN fiber. TGA revealed that the incorporation of DEP promoted char formation of PAN matrix and suppressed the thermal degradation. DEP-A-PAN exhibited a significantly reduced peak heat release rate (pHRR) compared to the control sample. Moreover, the limiting oxygen index (LOI) of DEP-A-PAN was up to 34.3 %, and remained at 26.6 % even after 50 laundering cycles (LCs), demonstrating excellent durable flame retardancy. Interestingly, DEP-A-PAN exhibited improved tensile strength of 2.97 cN/dtex. This work developed a simple and feasible method for preparing mechanical-enhanced flame retardant and smoke suppressive PAN fiber, which could be large-scale preparation. [ABSTRACT FROM AUTHOR]

• Three glucose-based flame retardants (CG, SiG and UG) with different thermal stability have been successfully synthesized;. • At the addition amount of 20%, these three modified epoxy resin materials had good flame retardancy and excellent smoke suppression properties, the LOI values of EP/20 %CG, EP/20 %SiG and EP/20 %UG were 25.8%, 28.3% and 27.4%, respectively, while the latter two can reach UL-94 V-1 rating;. • Three flame retardants exerted flame retardancy effects in both gas and condensed phases during combustion;. • The mechanical properties of three modified EPs had also been improved;. • It provides a meaningful reference for the application of biomass in epoxy resin. To improve the poor thermal stability of glucose, three glucose-based Schiff bases, named CG, SiG and UG, were synthesized as flame retardants for epoxy resin (EP) through the condensation reaction between glucose and three -NH 2 containing substances, i.e. chitosan, 3-aminopropyltriethoxysilane and metal organic framework material (UIO-66-NH 2), respectively. Subsequently, three flame retardant-modified EPs were obtained using a melt copolymerization method. EP/20 %SiG and EP/20 %UG obtained UL-94 V-1 rating with LOI values of 28.3 % and 27.4 %, respectively. The results of the cone calorimetry tests showed that these three modified EPs had superior inhibition of smoke production. The flame-retardant mechanism was systematically investigated, and furthermore, the study also highlighted the mechanical properties of the three modified samples and all showed significant improvement. This work suggests that glucose-based environmentally friendly flame retardants could facilely and effectively improve the fire safety of epoxy resin. [ABSTRACT FROM AUTHOR]

• Hydrolysis-resistant flame-retardant co-polyester fibers were prepared by adding reactive carbodiimide. • The processing stability and hydrolysis resistance of the flame-retardant copolyester were improved, and the microbranched structure formed enhanced the tensile property of the fiber. • The carbodiimide component and phosphorus-containing fragments formed a synergistic flame retardant effect to enhance the flame retardant performance. • This work provides a feasible strategy to improve the processing stability and flame retardant properties of commercialized flame retardant co-polyester fibers. Polyethylene terephthalate flame retardant copolyester (FRPET) copolymerized with 2-carboxyethyl (phenyl) phosphinic acid (CEPPA) is one of the major copolymerized commercial flame-retardant copolyesters. Similar to conventional PET fibers, the mechanical and flame retardant properties of FRPET fibers after alkaline water post-treatment are reduced. In this work, two kinds of carbodiimide-based masterbatches are added to FRPET fibers, the thermal processing stability, hydrolysis resistance and flame retardancy are significantly improved. The structural and physicochemical properties of the modified FRPET fibers were characterized. The processing thermal stability of FRPET is improved due to the reaction of the double bond structure in carbodiimide with the terminal carboxyl group of polyester to form an acyl urea structure. After melt extrusion, the viscosity reduction of the modified FRPET fiber is only 1.6 %, which is about 10 times lower compared to that of FRPET (17.6 %). After being treated with 50 g/L NaOH solution at 95 °C for 1 h, the tensile strength retention rates of the modified FRPET fibers are over 85.0 %, which is much higher than that of FRPET fibers (71.8 %), showing excellent hydrolysis resistance. In addition, the vertical burning performance of the modified FRPET fibers is improved from V-2 to V-0, and the limiting oxygen index could still reach 25.6 %. Besides that, the mechanism of the combustion process is further discussed. [ABSTRACT FROM AUTHOR]

• Flame-retardant effect of pyridazinone on bio-based epoxy resin was detected. • Strong yet tough N-rich hollow vesicles were formed via "radical capturing" effect. • Potential for high value-added conversion from resin carbon to functional carbon. Aromatic nitrogen heterocyclic structure is a key building block of high-performance polymer materials and nitrogen-doped porous carbons, yet systematic studies on its flame-retardant effects and carbonization mechanisms in thermoset materials is still lacking. Here, a pyridazinone embedded bio-based epoxy resin (CSPZ-EP) cured by 4,4ʹ-methylenedianiline (DDM) was prepared. Benefiting from the rigid biphenyl-like pyridazinone structure and the high cross-linking density originated from the self-catalyzed transesterification, the cured CSPZ-EP/DDM can easily pass the UL-94 test with a V-0 rating suggesting excellent intrinsic flame retardancy. The cone calorimeter results further demonstrated that the peak heat release rate, the total heat release and flame growth rate of CSPZ-EP/DDM were significantly reduced by 84.4 %, 28.4 % and 90.5 %, respectively, compared with those of bisphenol A epoxy resin. The higher graphitization degree of the char residues and a large amount of non-flammable pyrolysis gas ejection synergistically prevented the further spread of fire. Strong yet tough nitrogen-rich char layer formed after thermal ablation together with the renewable features and the facile preparation route of CSPZ-EP/DDM make it a potential precursor for heteroatom porous carbons. [ABSTRACT FROM AUTHOR]

• In-suit cemented TAIC-IFR microparticles were fabricated. • TAIC-IFR particle with roughed surface toughened flame retardant PP composites. • TAIC-IFR with particle-aggregation effect had good flame retardant efficiency. It is a widespread problem that loading intumescent flame retardant (IFR) into polypropylene (PP) always sacrificed the mechanical properties significantly. To develop PP composites with high flame retardancy and toughness, a new intumescent flame retardant (TAIC-IFR) with microparticle-aggregation structure was synthesized by a straightforward in-situ cemented method. Through its microparticle-aggregation effect, the TAIC-IFR enhanced the toughness and charring flame retardancy of PP composites, compared with the traditional intumescent flame retardant mixtures. The 3TAIC-24IFR/PP sample exhibited an increase in impact strength and elongation at the break by 71.8 % and 233.5 % respectively compared with 27IFR/PP. The cemented TAIC-IFR particles with rough surfaces and triallyl triazine triketone component enhanced the interface performance between the fillers and PP matrix. In addition, the TAIC-IFR with particulate microparticle-aggregation characteristics promoted charring reactions among different flame retardant components, thereby enhancing its char-forming flame retardant effect in PP. Specifically, 1TAIC-24IFR/PP with cemented aggregated flame retardant particles exhibited a UL 94 V-0 rating and 28.5 % of limiting oxygen index (LOI), while PP with IFR mixture performed no UL 94 rating and a lower LOI. Moreover, the residue rate of 1TAIC-24IFR/PP increased to 15.9 % from 0 % of PP in cone calorimeter test. These results were attributed to the microparticle-aggregation effect of the acid source, carbon source, and gas source in TAIC-IFR particles, which exhibited better charring effect and barrier effect. This work provides a new idea for designing construction way of flame retardants to develop polymer materials with high flame retardancy and good toughness. [ABSTRACT FROM AUTHOR]

• Effect of the change of PET/PPSU two-phase ratio on the overall flame retardancy of polymer alloys. • The effect of the selective distribution of flame retardants in two phases on the flame retardancy of polymer alloys was proposed. • A new flame retardancy mechanism of flame retardants in polymer alloys was proposed. Polymer alloys can obtain the excellent performance of a variety of polymers. The polymer blending system has been studied by many scholars, especially the multi-component system containing additives, which is receiving more and more attention from researchers. The flame retardancy behavior of polyethylene terephthalate (PET)/Polyphenylene sulfone (PPSU) blends containing A 9,10-dihydro-9-oxa-10 phosphophenanthrene-10-oxide based derivative tris-(3-dopo-propyl) -triazine trione (TAD) is explored. Flame retardancy of PET/PPSU composite was characterized by Limiting oxygen index (LOI), vertical combustion test (UL 94), and cone calorimeter test. PPSU is a less flammable material with an LOI value of 40.0 % when used alone. With a 5 % flame retardant TAD addition, the LOI value of the PPSU/TAD-5 composite can be increased to 42.6 %. Interestingly, the LOI of PET with 5 wt% of TAD was 30.2 %, whereas the LOI of PET/PPSU(70/30) composites with the same 5 wt% of TAD was reduced to 26.3 %. We investigated by SEM-EDS that the flame retardant TAD always preferred to be distributed in the PPSU phase in PET/PPSU composites with different ratios. When PPSU was wrapped by the PET phase, which is the sea structure, the flame tended to follow the sea structure combustion channel of the polymer alloys during combustion, and the island structure of PPSU had little effect on the overall flame retardancy of the polymer alloys. Similarly, when PPSU becomes a continuous matrix, even without flame retardant, it significantly reduces the combustibility of the blends. However, with the addition of flame retardants, most of the flame retardants are distributed in the PPSU matrix, which significantly increases the LOI value of the PET/PPSU(40/60)/TAD-5 composite. Therefore, we conclude that there is an uneven distribution of flame retardants in the two phases, so for polymer alloys, the distribution of flame retardant in the two phases, as well as the construction of the continuous phase and the dispersion phase, determine the overall flame retardant properties of the composites. The uneven distribution of flame retardants TAD and the flame channel formed by continuous phase are the two main factors affecting the flame retardancy of polymer alloys. [Display omitted] [ABSTRACT FROM AUTHOR]

• RP, MgO, EG enhance PA6 thermal stability without affecting T g or crystalline fraction. • Monomer conversion remains high (97%) with no significant impact from FRs. • RP and MgO with EG achieved synergistic effects due to different mechanisms. • 0.5 mm PA6/5%MgO/5%EGES100 coating reduced the composite pHRR by 27% and THR by 37%. • FRs formed a stable charred layer on the composites and increased the residual mass. Continuous fibre-reinforced polyamide 6 (PA6) composites are predominantly prepared by anionic ring-opening polymerisation of low viscosity ε-caprolactam monomer. PA6 melts easily when exposed to flames, which can lead to rapid fire spread due to dripping. For this reason, the use of flame retardants is necessary. We investigated the effects of magnesium oxide (MgO), red phosphorus (RP), and expandable graphite (EG) on the glass transition temperature, crystalline fraction, and thermal stability of PA6. After investigating the flammability properties, we selected the best compositions (MgO and RP combined with EG) and applied them as coatings on carbon fibre-reinforced polyamide 6 composites. A synergistic effect was achieved when RP or MgO were used together with expandable graphite. The 0.5 mm thick coating containing 5% RP and 5% EG reduced the peak heat release rate (pHRR) of the composite by 21% and the total heat release (THR) by 28%, while 5% MgO and 5% EGES100 reduced the pHRR by 27% and the THR by 37%. [Display omitted] [ABSTRACT FROM AUTHOR]

• A novel ladder aluminosilsesquioxanes (Al-L-PPSQ) has been prepared, and its synthesis mechanism was provided. • Combining the flame retardant characteristics of metals and siloxanes, the introduction of Al-L-PPSQ can improve the LOI of PC, reduce the heat release rate, smoke release rate and toxic gas release. Effectively improved the flame retardancy of PC. • The mechanism of Al-L-PPSQ flame retardant PC was provided. A ladder aluminosilsesquioxanes (Al-L-PPSQ) was synthesized using AlCl 3 as an auxiliary catalyst. The chemical structure of Al-L-PPSQ was confirmed by FTIR, 1H, 13C, 29Si-NMR, and MALDI-TOF MS. The well characterized Al-L-PPSQ was used for flame retardant polycarbonate (PC), and the PC/Al-L-PPSQ composite with 6 wt.% Al- L -PPSQ reached UL-94 V-0 rating (1.6 mm), with an oxygen index of 36.6 % and a decrease of 61.2 % in p-HRR. The smoke release of composite materials has also decreased. By analyzing the condensed and gaseous products during the thermal degradation process of PC/Al-L-PPSQ composite materials, it is demonstrated that Al-L-PPSQ can promote the early decomposition of PC into carbon and quickly form a stable and dense char layer to protect the internal substrate during combustion, thereby improving the flame retardancy of PC. [ABSTRACT FROM AUTHOR]

• The strength of chars was heightened significantly by the bi-component flame retardant (PODSE/APP). • 20 wt% PODSE/APP led to an 88.1 % and 87.0 % reduction in pSPR and TSP. • The char residue was substantially increased by 89.2 % with 20 wt% PODSE/APP. • PODSE/APP changed the internal structure of chars into honeycomb with higher expanded ratio. The intrinsic flammability and high smoke production are two major defects that epoxy resin (EP) must overcome during the practical application. However, few current studies have acknowledged in both fire resistance and smoke suppression performance, which is vitally interrelated with quality of char layers. Herein, a P/S-containing compounds (PODSE) was prepared via esterification and then supplemented with ammonium polyphosphate (APP) to develop an intumescent flame retardant for heightening the strength of char. With 20 wt% PODSE/APP, the peak of smoke produce rate (pSPR) and total smoke production (TSP) of EP3 reduced by 88.1 % and 87.0 %, respectively, indicative of superior smoke suppression performance. It attained a limited oxygen index (LOI) value of 40.0 % with V-0 rating during vertical burning test (UL-94) and the char residues at 700 °C increased from 15.8 % to 29.9 % compared with pure EP. More importantly, in order to figure out the reason for such highly-improved performance, the residual chars after cone calorimeter (CC) test were comprehensively investigated. The result showed that the internal chars of the samples modified by PODSE/APP exhibited honeycomb-like structure instead of irregular network structure of the one modified with single PODSE, endowing the char layers with higher expanded ratio and strength, which responded to excellent insulation effect. This finding provided theoretical and experimental basis for further exploration of P/S synergistic intumescent flame retardant. [ABSTRACT FROM AUTHOR]

• Intumescent flame retardant (IFR) and zinc oxide (ZnO) were successfully microencapsulated by polysiloxane. • The addition of microencapsulated IFR and ZnO significantly enhanced the flame retardancy of polypropylene (PP). • Water resistance of PP composites was also enhanced by the presence of microencapsulated IFR and ZnO. Intumescent flame retardant (IFR) and zinc oxide (ZnO) were successfully microencapsulated by polysiloxane, resulting in the preparation of Si-IFR and Si-ZnO, respectively. These microencapsulated additives were then incorporated into polypropylene (PP), leading to a synergistic enhancement of the flame retardancy, mechanical properties, and water resistance. By means of limiting oxygen index (LOI), UL-94 vertical burning test, and cone calorimetry test, an assessment was conducted to analyze the combustion characteristics of PP composite materials containing 2% Si-ZnO and 24% Si-IFR additives. The LOI value and UL-94 of PP/24%Si-IFR/2%Si-ZnO achieved to 39.8% and V-0 rating respectively, with significant decreases in both the total heat release (THR) and total smoke production (TSP). Furthermore, the introduction of polysiloxane significantly improved the water resistance of the PP composites. After a 168-hour water immersion test, notable reductions were observed in water absorption, the precipitation of flame retardants, as well as alterations in the mechanical properties of PP/24%Si-IFR/2%Si-ZnO. [ABSTRACT FROM AUTHOR]

• A novel Schiff base epoxy thermoset was prepared based on renewable vanillin. • It showed a high t g and controllable degradation properties. • The Schiff base and the fluorenyl cardo structure endowed it with excellent flame retardancy. • The hydrophobic fluorenyl cardo structure effectively reduced the water absorption of it. • This work proposed a dual strategy to protect the Schiff base based on conjugation and low water absorption. Given the issues of non-renewability, poor degradability, and high flammability associated with petroleum-derived bisphenol A-type epoxy (DGEBA) resins, developing degradable and flame-retardant epoxy resins from renewable biomass is of great importance. However, it is still a challenge at present. Herein, a novel Schiff base diepoxy compound (BV-EP) was successfully synthesized from lignin-derived vanillin and commercial amine 9,9-Bis(4-aminophenyl)fluorene (BAPF) through a simple, two-step procedure. After cross-linking with 4,4ʹ-diaminodiphenylmethane (DDM), the vanillin-derived Schiff base epoxy thermoset (BV-EP/DDM) displayed better thermal properties (glass transition temperature T g : 197 °C) and flame retardancy than the control sample (DGEBA/DDM). The peak heat release rate (PHRR) and the total heat release (THR) of BV-EP/DDM were reduced by 60.1 % and 19.8 %, respectively, compared with those of DGEBA/DDM. Furthermore, the degradable Schiff base and the hydrophobic fluorenyl Cardo structure provide the BV-EP/DDM with good acid-catalytic degradation and low water absorption properties. In this work, the fluorenyl Cardo structure plays the role of "killing three birds with one stone" in enhancing the performance of BV-EP/DDM. This synergistic strategy paves the way for fabricating more practical degradable and intrinsically flame-retardant epoxy resins from renewable biomass resources. [Display omitted] [ABSTRACT FROM AUTHOR]

• Two kinds of coated flame retardant rigid polyurethane foams were successfully prepared by hydrothermal method and layer-by-layer self-assembly method, respectively. • The coatings made the rigid polyurethane foam exhibit good brittleness and toughness. • Flame retardants improved the thermal stability and flame retardancy of rigid polyurethane. • Coated rigid polyurethane exhibited smoke suppression and low thermal conductivity. A flame retardant for rigid polyurethane (RPUF) was designed and synthesized to expand the application field of RPUF. The flame retardants, namely MXene/PEI/PA-L and MXene/PEI/PA-H, were synthesized using phytic acid (PA), polyethyleneimine (PEI), and MXene through layer-by-layer (LBL) self-assembly method and hydrothermal method, respectively. In terms of mechanical performance, MXene/PEI/PA-L imparted brittleness to RPUF while MXene/PEI/PA-H enhanced its toughness, enabling RPUF to adapt to diverse application scenarios. The flame retardant properties were evaluated via vertical combustion test, cone calorimetry test, and thermogravimetric test, and the gas phase flame retardant mechanism was analyzed by TG-FTIR. MXene/PEI/PA constituted a N-P-Ti synergistic flame retardant system. During combustion, MXene/PEI/PA formed a layered dense carbon layer to cut off the external oxygen transport channel and absorbed many oxygen-containing free radicals. MXene/PEI/PA-L demonstrated efficient smoke suppression capability, while MXene/PEI/PA-H showed superior thermal insulation performance. The ignition time (TTI) of the composite foam reached 47 s, the total smoke release (TSR) value decreased by 92 %, and the flame retardant grade reached 5VA. Coated RPUF had excellent flame retardant ability. [ABSTRACT FROM AUTHOR]

• A novel dimethylglyoxime-bridged phosphinate (DMG-DC) was synthesized successfully. • EP/DMG-DC with the P-content of 0.9 wt.% possessed a V-0 rating and LOI of 28.4 %. • The PHRR, THR, and CO 2 P of EP/DMG-DC were reduced by 54.1 %, 35.2 %, and 64.4 %. • The flame-retardant mechanism of DMG-DC was found in the vapor and solid phases. Considering the need for flame retardancy in epoxy resin (EP), a novel dimethylglyoxime-bridged phosphinate (DMG-DC) has been suggested and applied for the purpose of flame-retardant modification of epoxy resin. As a result of the substitution reaction between dimethylglyoxime (DMG) and diphenylphosphoryl chloride (DPPC), DMG-DC was successfully characterized chemically. The research has demonstrated a notable enhancement in the flame-retardant characteristics of EP/DMG-DC. Especially, with the addition of 15 wt.% DMG-DC, the EP composite passed the UL-94 test with a V-0 rating and achieved a limiting oxygen index (LOI) value of 28.4 %. In addition, cone calorimetry test (CCT) results showed that the peak heat release rate (PHRR), total heat release rate (THR), and carbon dioxide production (CO 2 P) of EP/DMG-DC-15 were reduced by 54.1 %, 35.2 %, and 64.4 %, respectively, compared to EP. Not merely, the activities of DMG-DC in the gas and condensed phases also enhanced the flame retardancy of EP. That was the decomposition of DMG-DC not only released phosphorus-containing radicals to trap reactive radicals and nitrogen-containing inert gases to dilute flammable materials but also promoted the epoxy matrix to form more char residues. Generally, this work develops a novel dimethylglyoxime-bridged phosphinate with the potential in the application of flame-retardant polymers. [ABSTRACT FROM AUTHOR]

• Cross-linked char layer was formed in PET/ADP/VPPSQ. • Fire hazards are reduced by altering the charring process of PET. • The reaction pathway of the PET/ADP/VPPSQ pyrolysis products is proposed. • The preparation of the material is economical, simple and green. Polyethylene terephthalate (PET), a widely used engineering thermoplastics, is inherently flammable, presenting significant fire risks. Aluminum diethyl phosphinate (ADP) is widely used in PET, while they tend to increase smoke hazards in its flames retardancy. A novel flame-retardant ladder phenyl/vinyl polysilsesquioxane (VPPSQ) acting as both a charring flame retardant and smoke suppressant was introduced into the PET/ADP composites. For PET/ADP6/VPPSQ4, the limiting oxygen index increased to 32.8 % from 23.3 %, and the amount of heat and smoke released was significantly reduced, compared with neat PET. Additionally, the hazard of dripping was eliminated and the UL 94 rating reaches to V-0 level. This work provides a new strategy for eliminating multiple fire hazards of smoke, heat and dripping of PET. The gas phase flame retardancy effect of ADP is primarily present during the initial stages of combustion, with the carbonization action of ADP becoming more crucial during the middle and later stages of burning. However, the char layer formed by PET/ADP is unstable and undergoes further degradation. When VPPSQ is introduced into PET/ADP, the pyrolysis products of VPPSQ, including silicon fragments, SiO 2 , and graphitized structures, significantly enhance the thermal stability and barrier effect of the char layer. [Display omitted] [ABSTRACT FROM AUTHOR]

• The coated polyester/spandex (T/S) fabrics displayed excellent washing and rubbing fastness. • The coated T/S fabrics had excellent UV protection and antistatic properties. • The coated T/S fabrics possessed significantly improved flame retardancy and anti-dripping performance. • This study offers a sustainable and promising technique to impart multi-functionalities to T/S fabrics. This study focused on the development of liquid carbon black nanoparticles (nano-CB) and the fabrication of black-colored polyester/spandex (T/S) fabrics with antiultraviolet, antistatic, and flame-retardant properties by a facile pad-cure technique. The flame retardancy efficiency and fastness of nano-CB on the fabric were enhanced by using a cyclic phosphate ester-based flame-retardant and polyacrylate adhesive binder HF-901. The morphology and particle size of nano-CB were investigated, and the color features, antiultraviolet and antistatic properties, combustion behavior, flame retardancy, and mechanism of coated T/S fabrics were also explored. The flaky nano-CB particles provided excellent light shielding and color fastness to the fabrics. The homogeneous coating of nano-CB also significantly improved the antiultraviolet and antistatic performance of the fabrics. Moreover, the coated T/S fabrics exhibited self-extinguishing capacity and a reduced damaged length of approximately 7.9 cm without molten drops. The formation of cross-linked char networks in the condensed phase and the trapping of combustible radicals in the gas phase during combustion synergistically enhanced the flame retardancy and anti-dripping capacity of the coated T/S fabrics. This study offers a facile and industrial applicable approach to enhance the multifunctionality of T/S fabrics and expand their potential applications. [Display omitted] [ABSTRACT FROM AUTHOR]

• A novel macromolecular phosphorus and nitrogen containing flame retardant named PDPSB was synthesized and characterized. • The flame retardancy of PC was significantly improved by incorporation with PDPSB. • PDPSB had a slight influence for PC matrix on the mechanical properties due to the good compatibility and dispersion. • PDPSB could exert excellent flame retardancy both in the gaseous phase and the condensed phase. In this paper, an innovative macromolecular phosphorus-nitrogen containing flame retardant (PDPSB) was successfully designed and synthesized to investigate its impact on the flame retardancy, burning behavior, thermal stability, mechanical properties of polycarbonate (PC) composites. Furthermore, an in-depth exploration of the potential flame-retardant mechanism was conducted. The combustion results indicated that PC-3 with 3 wt% PDPSB reached V-0 rating in UL-94 test and showed a high limiting oxygen index (LOI) of 33.0 %. Compared to pure PC, the values for peak of heat release rate (PHRR), total heat release (THR) and total smoke production (TSP) of PC-3 were decreased by 37.9 %, 11.1 % and 4.9 %, respectively. It was noteworthy that the amount of char residue for PC-3 was raised from 7.4 % for pure PC to 15.8 % with increasing 113.5 %. The thermogravimetric analysis (TGA) results under N 2 atmosphere revealed that PDPSB possessed preferable thermal stability with initial decomposition temperature (T initial) of 342.6 °C and higher char residue yield of 48.4 %. With increasing the amount of PDPSB, the maximum mass loss rate (R peak) was reduced and the char residue yield was increased for PC/PDPSB composites. In addition, the mechanical properties of PC/PDPSB composites were well maintained due to the good compatibility and dispersion between PDPSB and PC matrix. The tensile, flexural and izod impact strength of PC-3 were weakened by 4.3 %, 1.7 % and 16.8 % in comparison of pure PC, respectively. Based on the investigation into the flame-retardant mechanism of PDPSB, the excellent flame retardance of PC/PDPSB composites has been validated. In gaseous, the release of pyrolysis gases was suppressed and active radicals were captured by generated phosphorus free radicals. In condensed phase, the stable char residue with phosphorus and nitrogen elements acted as a barrier to hinder heat, flame and oxygen. This high-efficient single-component multifunctional additive presented a novel approach to the development of fire-resistant polymers with enhanced performance characteristics. [Display omitted] [ABSTRACT FROM AUTHOR]

• By foam finishing with sodium polyborate, cotton fabric obtains good flame retardancy and maintains softness and breathability. • The flame retardant does not involve Cl or P-containing chemicals. • Foam finishing consume lower water or solvent than dip-padding finishing. The conventional process of imparting flame retardancy to cotton fabrics requires the consumption of large amounts of water, chemicals, and energy, which usually involves halogen-containing and phosphorus-containing chemicals. In this work, an eco-friendly sodium polyborate (SPB) foam was creatively introduced onto the cotton fabric surface by a bladed coater to improve the fire resistant performance. For the cotton sample with only 6.7% weight gain (WG) of SPB coating, the LOI value of cotton fabric (SPB treated cotton-1) was enhanced to 32.6% from 18.5%, the damaged length was decreased to 5.7 cm, and the sample self-extinguished in the vertical burning test. The peak of heat release rate value, total heat release value, and total smoke production (TSP) value decreased by 87.0%, 72.7%, and 22.2% respectively compared with those of the control sample. The TSP was further decreased by 80.6% when the WG of SPB was 16.7%. Besides, the SPB treated cotton showed enhanced antibacterial activities against S.aureus and E.coli. Particularly worth mentioning is in the SPB foam finishing procedure, no organic solvent and P or Cl-containing chemicals were involved, and the processing time was only around 3 min with obviously reduced water consumption, compared with dip-padding finishing. More importantly, SPB treated cotton kept good softness, whiteness, water vapor permeability, and air permeability. The SPB foam finishing in this work shows considerable potential in realize good flame retardancy on cotton fabrics by eco-friendly and high-efficient strategy. [ABSTRACT FROM AUTHOR]

• Gel-like polyelectrolyte complexes are produced form cellulose nanocrystals. • The produced gel is applied to cotton by doctor blade coating. • The treated fabrics self-extinguish the flame during flammability tests. • The deposited coating displays promising char forming abilities. In this work, polyelectrolyte complexes (PECs) are employed as an efficient way for the deposition of functional flame retardant coatings based on cellulose nanocrystals (CNCs). To this aim, CNCs have been combined with branched polyethyleneimine (BPEI) obtaining gel-like PECs to be deposited on cotton by an easy doctor-blading approach. The morphology of the coated fabrics was investigated by scanning electron microscopy. The thermal stability was evaluated by thermogravimetric analyses while the achieved flame retardant properties were assessed by horizontal flammability tests. The deposition of the CNCs/BPEI PECs produces a homogeneous coating capable of self-extinguishing the flame with only 8 % of weight added to the fabric. Post combustion residue investigations highlighted how these CNCs/BPEI PECs can produce a swelled charred barrier consisting of polyaromatic structures embedded within an amorphous carbon. The results reported in this paper open up to a practical and industrially viable strategy for the exploitation of CNCs in the field of flame retardant coatings. [Display omitted] [ABSTRACT FROM AUTHOR]

• A quantitatively method is developed to analyze coupling pyrolysis of composites. • Coupling effect on FR-composites in N 2 are stronger than those in air in 250–350 °C. • Coupling reaction of MDH and acid decreases the temperature of DTG peaks in 350–450 °C. • Coupling effect on FR-composites in N 2 are weaker than those in air in 450–800 °C. • Temperatures of first peaks for F exp (T) always 30 °C higher than those of F cal (T). The coupling pyrolysis behavior and mechanism of composites with multi-components are important for the formula optimization of future flame-retardant (FR) materials. Series of thermogravimetry (TG) experiments are carried out for five FR-composites with different ratios of aluminum hydroxide (ATH)/magnesium hydroxide (MDH) additives, as well as some binary material samples in N 2 and air atmospheres, respectively. A method is developed to quantitatively evaluate the different pyrolysis of real flame-retardant samples through the comparison with the corresponding mass-weighted curves of each component. It indicates that the real DTG curves of FR-composites are narrowed with larger peaks and shift towards higher temperatures always about 30 °C than the calculated ones during their pyrolysis at 250–350 °C. The results of binary systems(EVA+MDH, MDH+MCA) indicate the enhancing of acid on the early reaction of MDH at 350–450 °C. In addition, the DTG in higher temperatures are not as large as the calculated ones in air atmosphere, especially for the FR-composites with smaller ATH/MDH ratio. Finally, the morphology evolution of samples also suggests that the bubbling, breaking and charring behaviors play an important role in their coupling pyrolysis mechanism in different temperature ranges. This is a new method for investigating the pyrolysis mechanism of FR-composites through quantitatively analyzing the DTG data and real-time morphology monitoring, which deepens the understanding of their complicated chemical and physical reactions when heated. [ABSTRACT FROM AUTHOR]

• A novel flame-retarding T/C blended fabric was developed via independent flame-retardation for two components strategy. • The LOI of treated fabric reached 37.2 %, and the PHRR and THR values decreased by 54.3 % and 66.5 %, respectively. • The independent charring of two components inhibited the "scaffolding effect" of T/C blended fabrics. Polyester/cotton (Terylene/cotton, T/C) blended fabrics are universally applied in clothing and household textiles due to the combination of excellent moisture absorption properties from cotton and dimensional stability from polyester, but high flammability and combustion resulting from the "scaffolding effect" become a major obstacle. Herein, we developed a novel flame-retarding T/C blended fabric to inhibit the "scaffolding effect" via independent flame-retardation for two components strategy, in which the copolymerized flame retardant of the polyester fibers and the cotton fibers were blended, and then halogen-free ammonium vinyl phosphonate (AMVP) was grafted onto the cotton component. The flammability and combustion behavior of the flame-retarding T/C blended fabric were assessed, and the mechanism of the flame retardant was analyzed. The results indicated that the limiting oxygen index (LOI) of the treated blended fabric could be increased to 37.2 %, which had excellent self-extinguishing property. The peak heat release rate (PHRR) and total heat release (THR) values of treated blended fabrics were severally reduced by 54.3 % and 66.5 % in comparison with the blended fabrics without grafted of AMVP. Furthermore, the combustible products of blended fabric generated during the thermal degradation process were effectively decreased in the gas phase due to the independent flame retardant char-formation of two components inhibited the "scaffolding effect". This study offers a new flame retardant strategy for the fabrication of blended fabrics. [ABSTRACT FROM AUTHOR]

• Furan resin has low ignitibility, but burns readily only under forced combustion. • Inorganic P-containing FRs reduce flammability of resin by catalysing charring. • Organic P-containing FRs, RDP, BAPP and DOPO, are only minimally effective in resin. • Organic FRs show unexpected behaviours in TGA vs. LOI and cone calorimetric tests. • Differences in behaviour attributed to high boiling and flash points of organic FRs. A study of the flammability of a biobased furan resin via limiting oxygen index and UL-94 has shown its inherent flame retardant properties. In a cone calorimetric test at 50 kW/m2 external irradiance, however, it ignited within 50 s and burnt, producing 489 kW/m2 peak heat release and 24 MJ/m2 total heat release but minimal smoke production. The flame retardance of the furan resin was further improved by the addition of the phosphorus-containing inorganic flame retardants, ammonium polyphosphate (APP) and melamine polyphosphate (MPP), and their well known condensed phase activity was further supported by thermogravimetric analysis (TGA). The organic flame retardants, resorcinol bis(diphenyl phosphate) (RDP) and bisphenol-A bis(diphenyl phosphate) (BAPP) had no effect on flame retardance, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) had only minimal effects in LOI and cone calorimetric tests, which was at variance to the results of TGA tests. This disconnect between the tests involving flaming combustion (LOI and cone calorimetry) and slow controlled heating (TGA) was attributed to the low flash points and high boiling points of the organic flame retardants, respectively. [ABSTRACT FROM AUTHOR]

• P-derived flame retardants were covalently added to EP using diisocyanate as bridge. • Mechanical properties of EP were obviously enhanced due to the formed PU network. • P-derived flame retardants conferred flame retardant properties to EP. The high brittleness and flammability issues of epoxy resins (EPs) seriously limit their high-performance applications in industries. However, most of the current research has been failing to simultaneously enhance both toughness and flame retardancy of EP by a facile method. In this work, three phosphaphenanthrene derivatives (DOPO, ODOPM and DOPA) were applied to prepare intrinsic flame-retardant epoxy resins by using diphenylmethane-4,4′-diisocyanate (MDI) as a bridge. The as-prepared EP/MDI/DOPO, EP/MDI/ODOPM, and EP/MDI/DOPA exhibited obviously enhanced flame retardancy and mechanical performance relative to EP. As the P content reached 1 wt%, the limiting oxygen indexes (LOIs) and vertical combustion (UL-94) levels of EP/MDI/DOPO, EP/MDI/ODOPM and EP/MDI/DOPA reached 28.9 %, 31.2 %, and 33.4 %, and V-1, V-0, and V-0. The impact strengths of EP/MDI/ODOPM and EP/MDI/DOPA containing 0.75 wt % of phosphorus were higher than that of EP by 209.3 % and 212.4 %, respectively, due to the covalent linkage between the phosphaphenanthrene-derived groups, MDI, and polymer network. Thereby, a simple method is revealed in this work to improve both fire retardance and toughness of EP, which facilitates its high-performance development. [ABSTRACT FROM AUTHOR]

• The binary block copolymer owned morphology adaptability during processing with TPV. • TPV with PAPO-MP both increased tensile strength and elongation at break than with PAPP/MPP. • PAPO-MP promoted the char layer with the resistance to thermal oxidative degradation. The micro-morphology of flame retardant particles in the polymer matrix is a critical determinant for its flame retardancy efficiency, dispersion, compatibility, and mechanical properties. In this thesis, a binary block copolymer flame retardant (PAPO-MP), possessing the capability to undergo morphology changes during processing, was incorporated into the thermoplastic vulcanizate (TPV) composites. Compared to the intumescent flame retardants consisting of piperazine pyrophosphate and melamine polyphosphate (IFR), the addition of PAPO-MP significantly enhanced the mechanical properties, while also further increased the flame retardancy. In terms of mechanical properties, 26 %PAPO-MP/TPV composite demonstrated a remarkable improvement with 48.2 % higher tensile strength (TS) and 20.7 % higher elongation at break (EB) than the 26 %IFR/TPV composite. The reason for the enhancement and toughening was that PAPO-MP exhibited thermoplasticity and morphology adaptability, which can disperse as water droplets particles in the TPV matrix after thermal processing, demonstrating exceptional dispersibility, processability, and robust interfacial interactions. In terms of flame retardancy, PAPO-MP also demonstrates superior flame retardancy than IFR compounds. The addition of 26 % PAPO-MP in TPV achieved UL 94 V-0 rating, and increased the limiting oxygen index from 17.9 % to 25.4 % (higher than 24.2 % of 26 %IFR/TPV). During combustion, PAPO-MP primarily inhibited combustion intensity and exerted its flame-retardant effect in the condensed phase, particularly by promoting the formation of a char layer that exhibits excellent resistance to thermal oxidative degradation. In summary, this binary block copolymer with morphology adaptability enhanced both the mechanical properties, processability and flame retardancy of TPV composites. [ABSTRACT FROM AUTHOR]

• Integrative transparent fire-retardent coating was facilely constructed. • Integrative coating preserves the texture and structure of the wood. • Introduction of nano-CeO 2 imparts super fire resistance to integrative coatings. • Adding nano-CeO 2 achieves long-term fire protection of integrative coatings. • Integrative coating containing nano-CeO 2 impedes the growth of bacteria. To prevent the coatings applied in historical buildings from aging failure due to environmental factors, an integrative coating with decorative, antibacterial, weather-resistant and flame-retardant properties is particularly important in practical applications. The nanocomposite flame retardants named CPPBs are obtained from the successful grafting of the phosphate esters to the surface of cerium oxide nanoparticles, which are physically blended with film-forming polymer to construct integrative coating named MCPPBs. The results show that adding nano-CeO 2 greatly strengthens the mechanical property, fire protection performances, weather resistance, antibacterial activity of the integrative coatings, and maintains high light transmittance in the meantime. Especially, when the addition of nano-CeO 2 in flame retardant is 0.5 wt.%, the expansion ratio of the MCPPB3 coating increases to 65 and the char index reduces to 15.7cm3, concomitant with a high transparency of 80.3 %. By combining FTIR, SEM and EDS analyses, the MCPPBs char containing nano-CeO 2 is compact and dense. In the accelerated aging test, the back equilibrium temperature of the MCPPB3 coating at 900 s is still less than 220 °C concomitant with a complete surface morphology after 6 aging cycles. In addition, the MCPPB3 coating exerts a negative effect on the growth of E. coli and S. aureus , and the antibacterial activities against E. coli and S. aureus are 92.8 % and 96.2 %, respectively. [Display omitted] [ABSTRACT FROM AUTHOR]

• AAP flame retardant contains the -N-P(= O)-(ONH 4) 2 and CH 2 =CH- reactive groups. • The flame retardant could form the -N-P(= O)-O-C- with cellulose. • AAP-treated cotton could meet the AATCC 61-2013 3A washing standard 50 LCs. • The finished cotton fabrics without formaldehyde. Ammonium acryloyl phosphite (AAP) flame retardant with multiple reactive functional groups has been synthesized for use in cotton textiles. Nuclear magnetic resonance was utilized to analyze the structure of AAP flame retardant. The scanning electron microscopy images indicated that some flame retardants penetrated the amorphous region of cotton fibres. The energy-dispersive X-ray and Fourier transform infrared (FTIR) spectroscopy spectra suggested that AAP flame retardant was grafted with cellulose through forming the -N-P(= O)-O-C- connection. The laundering cycles (LCs), limiting oxygen index (LOI), cone calorimetry, and vertical flame test (VFT) suggested that AAP-treated cotton (CF/AAP) possessed exceptional flame retardance and durability. The CF/AAP3 demonstrated an initial LOI value of 47.2 %, which remained at 40.7 % even after undergoing 50 LCs following the washing standard (AATCC 61–2013 3A). The thermogravimetric and infrared spectroscopy, thermogravimetric, and VFT analyses showed that AAP grafting groups underwent a condensed-phase flame retardance mechanism. The X-ray diffraction patterns indicated that the AAP flame retardant affected the diffraction peak structure of cotton fibres crystal a little during the finishing process. After finishing, the cotton fabrics retained their breaking strength and softness effectively. The overall results indicated that incorporating reactive groups such as -N-P(= O)-(ONH 4) 2 and CH 2 CH- into flame retardants could reinforce the durability of flame-retardant cotton fabrics. [Display omitted] [ABSTRACT FROM AUTHOR]

• A 3D boron nitride skeleton was fabricated by the ice template method. • The thick skeleton layer provides a more efficient heat transfer path. • The synergistic flame retardant mechanism of boron nitride and ammonium polyphosphate was revealed. • The char residue left in the combustion can support weights more than 1100 times of its own mass. Epoxy (EP) is widely used in the field of high-speed communication and microelectronics. However, its poor thermal conductivity and high flammability bury the hidden danger of fire accident. In this work, the hexagonal born nitride (h-BN) combined with ammonium polyphosphate (APP) constructs a three-dimensional skeleton (3D-BN) via bidirectional freezing technology. The 3D-BN skeleton is immersed into the EP matrix to obtain the EP/3D-BN composite, which is endowed with high thermal conductivity and flame retardancy. When the loading of hexagonal born nitride (h-BN) is 9.1 vol%, the thermal conductivity of EP/3D-BN 3 composite reaches 1.67 W m−1 K−1, which is increased by 944 % compared with that of the control EP. The peak heat release rate (PHRR) and total heat release (THR) of EP/3D-BN 3 are significantly reduced by 54 % and 34 % respectively. This EP/3D-BN composite provides potential applications toward the industrial production for microelectronic devices. In this work, the hexagonal born nitride (h-BN) combined with ammonium polyphosphate (APP) constructs a three-dimensional scaffold (3D-BN) via bidirectional freezing technology. The 3D-BN scaffold is immersed into the epoxy (EP) matrix to obtain the EP/3D-BN composite, which is endowed with high thermal conductivity and flame retardancy. [Display omitted] [ABSTRACT FROM AUTHOR]

• A melamine resin-cobalt@piperazine pyrophosphate microcapsule was prepared. • Flame retardancy and mechanical performance of RPUF was improved with MF-Co@PAPP. • Smoke suppression achieved by the synergic effect of the components of MF-Co@PAPP. • Microcapsule structure of MF-Co@PAPP imparts long-lasting fire safety to RPUF. The persistent challenge of maintaining fire safety in flame retardant modified rigid polyurethane foams (RPUF) under humid conditions continues to be a concern. To address this challenge, a microcapsule named MF-Co@PAPP has synthesized, composed of melamine resin (MF, shell) and piperazine pyrophosphate (PAPP, core). This microcapsule was developed to enhance the long-lasting flame retardancy and smoke suppression of RPUF. These composites demonstrated a significant reduction in total heat release and total smoke release compared to pure samples, with decreases of 44% and 29%, respectively. The MF-Co@PAPP facilitated the carbonization process of RPUF, leading to the formation of a more stable char layer. The RPUF/MF-Co@PAPP composites exhibited the highest limiting oxygen index values, even after a 14-day immersion in water. This study introduces a target-driven design approach to enhance the fire safety of RPUF, offering inspiration for future development of tailored flame retardants. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, chitosan (CS) from fish waste was used to prepare bio-based environmentally friendly flame retardants. The hydroxyl group (-OH) of CS and the ammonium group (NH 4 +) of ammonium polyphosphate (APP) formed CS-APP, which was to serve as the core material. Melamine–formaldehyde (MF) resin was synthesized as the shell material through microencapsulation technology with CS-APP to prepare the novel core-shell structured flame retardant, which was subsequently introduced into polyurethane (PU) to prepare the composites. This study employed thermogravimetric analysis (TGA), the limiting oxygen index (LOI), UL-94, cone calorimetry tests (CCT), thermogravimetric analysis-FTIR (TGA-FTIR), SEM, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, smoke concentration test and tensile test to characterize the structure, thermal properties, flame retardancy, char analysis and mechanical properties of the composites. The TGA results revealed that after the addition of flame retardant, the char yield increased from 0.5 wt% (pristine PU) to 12.0 wt% (the composite), and the thermal stability of the pristine PU was improved. Furthermore, the LOI increased from 18.2 % to 28.4 %, and the UL-94 level increased from fail to V-0 for the composites. These results revealed that adding MF(CS-APP) to pristine PU resulted in high flame-retarding performance of the composites. [Display omitted] [ABSTRACT FROM AUTHOR]

• BN can simultaneous exert excellent flame retardancy and thermal conductivity properties. • BN can improve the thermal conductivity of PC by stacks structure with certain orientation. • Stacks structure of BN can adhere phosphorous fragments of HPCP to form a hard network char layer. • Stacks network of BN/HPCP can absorb and filter more smoke particles to increase density of char layer. Polycarbonate (PC), as an engineering plastic, has excellent mechanical properties and electrical insulation properties. Nevertheless, with the rapid spread of 5 G applications, there is an increasing demand for functional PC materials with both thermal conductivity and flame retardant properties. In this study, the flame retardant thermal conductivity composite system of boron nitride (BN) and hexaphenoxy cyclotriphosphazene (HPCP) was constructed to study the simultaneous improvement of the flame retardant and thermal conductivity of PC. The results reveal that the inclusion of HPCP and BN in PC can significantly enhance its flame retardancy. This enhancement is evidenced by prolonged ignition time, reduced heat release rate and decreased total smoke production. In particular, 20BN/3HPCP/PC composite shows the best flame retardant effect. Through the investigation of flame retardant mechanisms, it has been found that the network structure formed by the BN sheets with phosphorus-containing products of HPCP decomposition can effectively filter and adsorb pyrolysis debris and increase the residence time of burning fragments in the pyrolysis zone promoting the pyrolysis products further fully burned to reduce the smoke caused by incomplete combustion. The phosphoric acid substances after the decomposing of HPCP can promote PC matrix to dehydration and carbonization to form the phosphorus-containing residues, which adheres on the BN network structure to form hardness char layers in the condensed phase to play an excellent role in blocking heat and combustible flue gas, which has a positive effect on reducing heat release rate and improving flame suppression. In terms of improving thermal conductivity, the infrared thermal imaging experiment further confirmed that BN sheets can increase the thermal conductivity of PC composites by more than 4 times, and the layer and layer stacks structure of BN sheets can endow an efficient thermal conductivity path for PC matrix to improve the thermal conductivity. Therefore, this study is meaningful practical exploration for developing the PC composites with excellent thermal conductivity and flame retardancy. [ABSTRACT FROM AUTHOR]

• Cavity expansion and flame retardant encapsulation of HNTs simutaneously. • One-pot synthesis of aluminum hypophosphite encapsulation in expanded halloysite. • An innovative method based on the smoke particulate collection was proposed. 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. [ABSTRACT FROM AUTHOR]

• A facile and efficient coating technique to improve flame retardancy of EPS foam composites by introducing polydopamine is developed. • The phosphorus-nitrogen flame retardant coating is applied for development of light weight and high toughness flame retardant EPS. • The studied flame retardant coating displays low toxicity, high efficiency and simplicity, which is crucial to EPS industry and human health. Green flame retardants have drawn much attention because of their environmental friendliness. But for the high flame retardancy of flammable polymers, most existing green flame retardants are unsatisfactory, even the flame-retardant process can not achieve high efficiency and environmental protection. In this work, flame retardants and flame-retardant process are addressed in a two-pronged approach. An eco-friendly bio-based synergistic flame retardant (PAU) was synthesized based on phytic acid (PA) and urea (U) through simple complexation assembly in water. The designed flame retardant coating can be directly coated on the surface of any topological shape with polydopamine as an adhesive. Flame retardant expandable polystyrene (EPS-PAU) with light weight and high toughness is prepared with the designed PAU flame-retardant coating. The coated EPS plates exhibit V-0 UL-94 rating and 42.0 % of limited oxygen index and excellent smoke suppression. Moreover, the density of EPS-PAU is slightly increased only by 2.27 % on the basis of the neat EPS, and the hard shell formed using PDA as an adhesive layer is beneficial for the improvement of impact strength. This novel biomass-based PAU system provides a promising strategy for manufacturing polymer products with excellent flame retardancy, smoke inhibition and light weight. [Display omitted] [ABSTRACT FROM AUTHOR]

• A novel flame retardant (HLD) was prepared using bio-based reaction monomers. • HLD was mixed with EPs as a co-curing agent and flame retardant. • Addding 7 wt.% of HLD could achieve a high limited oxygen index and a V-0 rating. • HLD boosts fire safety of the EPs through a biphasic flame-retardant effect. • Flame-retardancy mechanism was explored by studying the pyrolytic behaviour of HLD. A reactive flame retardant (HLD) is prepared for epoxy (EP) resin using tryptamine (PTM), 9,10-dihydro-9-oxa-10-phospha-phenanthrene-10-oxide (DOPO), and vanillin (VN) as reaction monomers. The effects of HLD on the thermal stability, mechanical characteristics, and flame resistance of the EP are evaluated. When 7 wt.% of HLD (only 0.43 wt.% of phosphorus) is added to pure EP, the thermal breakdown rate of the resulting EP/HLD7 composite is lowered by 28 %, and its coke output at 700 °C is raised by 45 %. In the cone calorimeter test (CCT), the peak heat release rate (PHRR), total heat release (THR), total smoke production (TSP), and average effective thermal combustion (av-EHC) of the EP/HLD7 decrease by 52.1 %, 24.8 %, 25.1 %, and 34.0 %, respectively, compared to those of pure EP. A high limited oxygen index (31.86 %) and a V-0 rating in the UL-94 test are also achieved for EP/HLD7. The flame-retardancy mechanism is studied using thermogravimetric analysis/infrared spectroscopy (TG-IR) and scanning electron microscopy (SEM). The quenching effect of phosphorus-containing radicals, the dilution effect of noncombustible gases, and the impeding effect of the carbon layer in the condensed phase contributed collectively to the excellent flame-retardancy of EP/HLD7. [ABSTRACT FROM AUTHOR]

• Two latent phosphorus-containing imidazole curing agents (PHI-HPP and EMI-HPP) were synthesized by a simple method. • PHI-HPP and EMI-HPP simultaneously endowed one-component epoxy resins with long shelf life and fast curing properties. • The prepared one-component epoxy resin exhibited excellent flame retardancy, transparency, mechanical properties and T g. Highly evolving 5G and electronic packaging technologies require one-component epoxy resins with high flame retardancy, long shelf life, and fast curing while maintaining transparency & mechanical properties. However, it's tricky and challenging to meet this requirement simultaneously. Herein, two latent phosphorus-containing imidazole curing agents (PHI-HPP and EMI-HPP) were synthesized from 2-ethyl-4-methylimidazole (EMI) and 2-phenylimidazole (PHI). PHI-HPP x /EP exhibits a superior shelf life than EMI-HPP x /EP. PHI-HPP x /EP allows stable storage at room temperature exceeding 91 days, which is better than previous one-component epoxy resins cured by phosphorus-containing imidazole. PHI-HPP20/EP and EMI-HPP20/EP allow for fast curing at 150 °C and also feature excellent fire safety. In particular, PHI-HPP20/EP features a limiting oxygen index (LOI) of 35.8% and achieves the UL-94 V-0 rating. Its peak heat release rate (PHRR) is reduced by 59.3% compared to PHI/EP. Notably, PHI-HPP x /EP and EMI-HPP x /EP maintain the inherent excellent transparency, mechanical properties and glass transition temperature (T g) of epoxy resins. Therefore, this research presents a viable approach for preparing one-component epoxy resin with long shelf life, fast curing, flame retardant, transparency and high performance. [Display omitted] [ABSTRACT FROM AUTHOR]

• Innovation: Improving flame-retardancy through inhibiting the volatilization of borane fragments. • Mechanism: The mechanism of enhancement in flame-retardancy and mechanical properties at high temperatures were proposed. • High-efficiency: The THR and TSP of bcBD-20 % were reduced by 52.03 % and 59.82 %, respectively. • Prevent secondary combustion through formation of complete B 2 O 3 protective film. Although Bismaleimide/2,2′-diallyl bisphenol A (BD) resin emerging as one of the most successful commercially available Bismaleimide (BMI) resins in the past decade, its flame retardancy and thermal stability are constrained by the thermal instability of 2′-diallyl bisphenol A (DBA). Previous studies focused on enhancing the flame retardancy of BD resins by incorporating P, N, and S. However, this approach often leads to a decrease in the time to ignition (TTI). Herein, hyperbranched o -carborane was introduced into BD resin to achieve improved high-temperature mechanical properties and flame retardancy. Compared to traditional C-H functionalized o -carborane, the hyperbranched o -carborane modified BD resin was more thermally stable and inhibited the release of borane fragments through the anchoring effect. The hyperbranched o -carborane demonstrated a more effective reduction in the heat releasing capacity (HRC) of BD resin. Remarkably, this improvement was achieved adopting only half of the o -carborane loadings required by traditional C-H functionalized one. Furthermore, the introduction of hyperbranched o -carborane in the BD resin prolonged the TTI and led to an enhancement of 72.41 % in the fire performance index (FPI) compared to the neat BD resin. Additionally, when the loading of hyperbranched o -carborane reached 2.41 wt %, a 59.82 % reduction in the total smoke production (TSP) was achieved. In all, this research offered a new design strategy of novel flame-retardant high-performance polymers for harsh environments by utilizing the anchoring effect of hyperbranched o -carborane. [Display omitted] [ABSTRACT FROM AUTHOR]

• A thermostable flame retardant, PBPO, featuring N H groups for hydrogen bonding with PET, was successfully synthesized. • PET/PBPO composites exhibited the improved melt spinnability due to the formation of hydrogen bonds and the similar t m values of PBPO and PET. • PET/PBPO6 composite with 6 wt % of PBPO in PET presented a PHRR over 30 % higher than PET and achieved non-ignitability with meeting the V-0 level. • PET/PBPO6 filaments, prepared by melt spinning PET/PBPO6 composite, showed pleasing tensile strength and were self-extinguished within 3 s. Poly(ethylene terephthalate) (PET) presents a persistent challenge in achieving satisfactory fire safety while maintaining its melt spinnability primarily due to its poor compatibility with flame retardants (FRs). In this study, the issue was effectively addressed through the application of suitable phosphorus/nitrogen (P/N)-based FRs (PBPO), which can form strong hydrogen bonding with PET and have a close melting temperature (T m) to PET. As a result, the prepared PET/PBPO composites showed high fire safety and good melt spinnability simultaneously. Specifically, PET/PBPO6 (containing 6 wt% of PBPO in PET) exhibited a peak heat release rate (PHRR) over 30 % lower than that of pure PET, and was found to be non-ignitable with only one molten droplet generated during the vertical burning test, achieving the UL 94 V-0 level. Significantly, PET/PBPO6 filaments, which were prepared by melt spinning the PET/PBPO6, showed pleasing tensile properties and were self-extinguished within 3 s. [Display omitted] [ABSTRACT FROM AUTHOR]

• A novel DOPO derivative was synthesized and employed as a multi-functional additive for EP. • The EP composite with superior fire-retardancy, mechanical properties and anti-aging performance was obtained. • HP-DOPO shows good compatibility, while accelerate the curing procedure and do not sacrifice the transparency of cured EP. Aiming to develop high performance flame-retardant epoxy resin (EP), a novel phosphorus-containing flame retardant named 6-(3-(2-hydroxyphenyl)propyl)dibenzo-[1,2]oxaphosphinine 6-oxide (HP-DOPO) was synthesized and employed as a multi-functional additive for EP with simultaneously excellent flame retardancy, transmittance, mechanical enhancement and anti-aging. With 5 wt.% loading of HP-DOPO, EP composites showed outstanding flame retardancy with a high limiting oxygen index of 35.6 % and V-0 rating in UL-94 test, while the cone calorimetric test results demonstrated that HP-DOPO could efficiently restrain the heat and smoke release. Compared with pure EP, the resultant EP/5 %HP-DOPO exhibited superior mechanical properties with 27.9 % and 56.2 % increase in tensile and impact strengths, respectively. Furthermore, HP-DOPO accelerated the curing procedure and did not sacrifice the transparency of cured EP, while anti-aging performance was obtained at the same time. The exploration of this novel multi-functional additive provided a powerful basis for the technologies and potential industrial applications of epoxy materials. [ABSTRACT FROM AUTHOR]

• An eco-friendly coating (APP-LA) was prepared based on ammonium polyphosphate (APP) and tyramine (LA). • The APP-LA treated lyocell showed improved flame retardancy. • The possible flame retardant mechanism of APP-LA was proposed. Low-carbon emissions are a sustainable development approach, among which lyocell is a renewable and zero carbon biodegradable cellulose fiber. The flammability of lyocell fabric poses a threat to people's lives and property. In response to this issue, a bio-based flame retardant, tyramine polyphosphate (APP-LA), was synthesized and applied to the treatment of lyocell fabrics. The synthesis of APP-LA adopted an eco-friendly and organic solvent-free method. In the combustion test, the limiting oxygen index of APP-LA treated lyocell fabrics increased to 35.8% compared to control lyocell (18.5%), and the damage length was only 6.7 cm. Meanwhile, the peak heat release rate and total heat release decreased by 92.9% and 58.7% respectively, compared to the control lyocell. Besides, the P-containing compounds generated by APP-LA accelerated the decomposition of the matrix to produce a dense char layer. The fewer flammable volatiles and more non-flammable gases were released. This work provided a low-cost and eco-friendly strategy for the simple preparation of commercial flame-retardant lyocell fabrics. [ABSTRACT FROM AUTHOR]

• Developed a fire-retardant acrylic yarn based on a thermal stabilisation process. • Clarified the impact of temperature and residence time on fire retardancy of a low cost acrylic yarn. • Complete oxidation conferred excellent fire retardancy to the yarns. • The oxidised acrylic yarn possessed physical characteristics required for weaving. • The woven fabric was fire retardant even after cyclic exposure to flame. Acrylic fibre is considered to be artificial wool in the textile industry, but in contrast with natural wool, it vigorously burns producing black smoke and toxic gases. This not only has hindered its technical applications, but also poses safety risks to the end-users of acrylic-based products. This research aims at enhancing the fire-retardancy of acrylic yarns using a facile thermal stabilisation process which is based on controlling the oxidation temperature and residence period. To this end, acrylic yarns are thermally processed according to six different time and temperature profiles ranging from 220 to 280 °C, with residence periods ranging from 22 to 28 min. The oxidised yarns were characterised using FTIR, DSC, and TGA techniques and the effects of the oxidative thermal treatment on physical characterises, and surface morphology of yarns and fibres were discussed. The results showed that the acrylic yarn undergone the oxidation process based on 240–255–270–280 °C heating profile for 28 min at each step had a sufficiently high degree of cyclisation with an excellent fire retardancy. Furthermore, the stabilised acrylic yarn was strong enough to be woven into a plain weave fabric using a laboratory scale loom while displaying non-combustible behaviour during cyclic exposure to flame. These results present a novel pathway for the development of a low cost, non-combustible fabric ideally suited for applications in extreme environments. [Display omitted] [ABSTRACT FROM AUTHOR]

• The multifunctional mono-component flame retardants comprising of sulfenamide and phosphate moieties exhibit inherently an exceptionally high synergistic fire retarding effect. • Polypropylene films containing any of the different multifunctional flame retardants at the low loading of 0.5 wt% passed the DIN4102 B2 fire test. • The multifunctional flame retardants denoted NS2 and NS3 passed the UL94 V2 criteria as standalone flame retardants at the low loading of 4 w%. A strategy to enhance flame retardant properties of polypropylene (PP) has been investigated by the design of six multifunctional mono-component flame retardants denoted from NS1 to NS6, where sulfenamide and phosphate moieties have been integrated into a single molecule. Herein, the synthesis and characterization of six different mono-component flame retardants are presented. Thermal decomposition characteristics of the multifunctional flame retardants were studied by thermogravimetry analysis, and a 5% mass lose was recorded in the temperature range between 220 °C to 267 °C for the samples. Moreover, the flame retardant samples were oven aged up to 260 °C in the presence and absence of 9, 10-dihydroantracene and the formed decomposition products were analyzed using GC/MS, LC/MS, 13C NMR and 31P NMR. The results indicate that the sulfenamide bond dissociates before the phosphorus moiety for samples NS1, NS2, NS3 and NS6. Whereas the phosphorus moiety breaks first in case of NS4 and NS5. The prepared flame retardants were then admixed with polypropylene in a Haake Rheocord melt blender at loadings ranging from 0.5 to 4 wt%. Thereafter, polypropylene films and plaques were prepared by hot pressing and their flame retardant properties were evaluated according to DIN 4102-B2 and UL94V standards, respectively. All the PP film samples containing any of the different multifunctional flame retardants at the low loading of 0.5 wt% passed the DIN4102 B2 test and for NS1film sample no burning dripping nor ignition of paper were recorded. Noteworthy, is that NS2 and NS3 samples reached the UL94V2 classification as standalone flame retardants even at a loading of only 4 wt%. From this standpoint, it seems the multifunctional mono-component flame retardants may exhibit inherently an exceptionally high synergistic effect. [ABSTRACT FROM AUTHOR]

• Two types of charring composite materials are targeted and explored for pyrolysis modeling study. • Pyrolysis models of charring composites in a fire are evaluated. • The input parameters at different scales for modeling study are explored. Charring composite materials occupy a critical position in industrial applications or more broadly in our daily life. The disadvantage of these materials involves the disability in maintaining their mechanical characteristics in a fire scenario, and the study of their fire resistance is therefore a major issue. This paper aims to review the current modeling study of charring composites in the fire scenario. A complete background and a broad range of knowledge are presented related to the two types of charring composite materials(wood and carbon/epoxy composites) for pyrolysis modeling study. Their fundamental chemical and physical properties are evaluated, especially different components inside the materials, and their similarities and differences are discussed. The pyrolysis processes of these two materials in the fire scenario are described under chemical, heat, and mass transfer as well as physical structure change aspects. Different types of pyrolysis models are evaluated from simple to comprehensive pyrolysis models. Then the pyrolysis models developed in the fire community are described briefly, their benefits and inefficiencies are evaluated. The pyrolysis model validation process are discussed and different types of experiments are introduced for the model validation, as well as the input parameters for modeling study consisting of kinetic, thermophysical and boundary parameters. This review could be a good background for those targeting the experimental or modeling study of charring composites in the fire scenario. [ABSTRACT FROM AUTHOR]

• The vinyl ester resin monomer is prepared by structural design. • The intrinsic flame-retardant vinyl ester resin shows higher T g , better flame retardancy, lower smoke release and excellent mechanical properties. • The intrinsic flame-retardant vinyl ester resin shows better fiberglass wettability than VER901. • The composite GFOPBMAR shows better comprehensive properties than the composite GFVER901. High-performance polymers and composites with excellent flame retardancy, smoke suppression, and mechanical properties arouse interest in academia and industry. In this work, the intrinsic flame-retardant vinyl ester resin (OPBMAR) and its composite (GFOPBMAR) with a Schiff-base moiety was prepared by structural design. Bisphenol A vinyl ester resin (VER901) and its composite (GFVER901) were also fabricated as a control. The glass transition temperature (T g) of OPBMAR is 190 °C, much higher than that of VER901 (127 °C). In cone calorimetry tests, the peak of heat release rate (p-HRR), peak of smoke production rate (p-SPR), total heat release (THR), and total smoke production (TSP) of OPBMAR were found to be 39.3 %, 62.2 %, 32.0 %, and 72.4 % respectively, lower than those of the control. OPBMAR shows good wettability to fiberglass, resulting in greatly improved comprehensive performance of GFOPBMAR. The flexural strength of GFOPBMAR is 741 MPa, far higher than that of GFVER901 (511 MPa). Limiting oxygen index (LOI) tests yielded a value of 39 % for GFOPBMAR, higher than that for GFVER901 (27 %). Further cone calorimetry tests showed the p-HRR, p-SPR, THR, and TSP of GFOPBMAR to be 36.7 %, 52.9 %, 23 %, and 65.4 % lower, respectively, than those of GFVER901. Thus, an intrinsic flame-retardant vinyl ester resin and its composite with excellent comprehensive properties have been produced through structural design, which is a promising substitute for petroleum-based vinyl ester resin in fire-resistant and low-smoke applications. [ABSTRACT FROM AUTHOR]

• A variety of biological phosphorus nitrogen synergistic flame retardants were synthesized from the perspective of molecular design. • Tannic acid (TA) modified Graphene (GE) and multiwalled carbon nanotubes (MWCNTs) nanomaterials were prepared by combining nanocomposite technology. • The flame retardant was applied to expandable polystyrene (EPS) through a coating process to prepare toughened composites, and the effect of the synthesized high-efficiency phosphorus containing flame retardant on the flame retardancy efficiency and brittleness of EPS was studied. In this paper, a variety of biological phosphorus-nitrogen synergistic flame retardants were synthesized from the perspective of molecular design. At the same time, tannic acid (TA) modified graphene (GE) and multiwalled carbon nanotubes (MWCNTs) nanomaterials were prepared by combining nanocomposite technology. Then, the flame retardant was applied to expandable polystyrene (EPS) through a coating process to prepare toughened composites. And the effect of the synthesized high-efficiency phosphorus-nitrogen flame retardant on the flame retardancy efficiency and brittleness of EPS was studied. The flame retardant (PAU) was synthesized by complexing phytic acid (PA) and urea (U) in an aqueous medium, and then using polydopamine (PDA) as an adhesive. Next, on the basis of PAU, using GE and MWCNTs as tougheners, EPS-PAUCG composites were prepared by coating method. Research has found that in the UL-94 test, the flame-retardant EPS-PAUCG composites could reach V-0 level. In the CCT experiment, compared to pure EPS, the PHRR, THR, PSPR, and TSP of EPS-PAUCG2 decreased by 88.4 %, 72.3%, 74.9 %, and 80.9 %, respectively. Through mechanism analysis, it has been proven that PAUCG undergoes thermal decomposition to form a dense expandable protective carbon layer, preventing further degradation of the matrix. In addition, compared to EPS, the compressive strength of the EPS-PAUCG2 composites have increased by 22.5%. This was because the composites contained GE and MWCNTs with high molecular chain structure rigidity and specific surface area, which had a toughening effect of ductile particles. [Display omitted] [ABSTRACT FROM AUTHOR]

• A high molecular phosphoramidite ammonium phosphate flame retardant (AHPEIPA) was synthesized from PEI and H 3 PO 4. • Flame retardant has implemented on polyester/cotton (TC) blended fabric through chemical grafting and cross-linking. • Stable -N-P(=O)-O-C bonds reinforce the adhesion between flame retardants and substrates due to the p-π conjugation between n atom and P=O group. • Environmentally modified TC fabric with superior flame retardancy and durability, satisfy 50 laundering cycles under AATCC 61–2013 3A criterion. A neotype high molecule reactive flame retardant, phosphoramide ammonium salt of polyethyleneimine derivatives for polyester/cotton (TC) blended fabrics was synthesized, and its structure and thermostability was characterized by 1H, 31P- nuclear magnetism resonance (1H NMR, 31P NMR), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric (TG) analysis. Results of FTIR, X-ray photoelectric spectrometer, surface morphology and energy dispersive X-ray and durability testing for the treated TC samples indicated that the flame retardants uniformly grafted onto the surface of fabrics especially on cellulose fibers. Vertical flame test, limiting oxygen index (LOI) values, conical calorimetric measurements showed a good flame retardancy of the treated fabrics. LOI of the treated fabric increased to 28.8 % at 14.8 % loading rate of flame retardants, and the loading rate remained above 93 % after 50 laundering cycles under AATCC 61–2013 3A standard. TG and TG-FTIR results suggested that the synthesized high molecular compounds mainly performed a condensed phase mechanism of flame retardancy. The finished fabrics tremendously sustained the original tensile strength. These results revealed that this high molecule reactive phosphoramide ammonium phosphate compounds can effectively endow a stable flame retardancy to the composite polyester/cotton blended textiles. [ABSTRACT FROM AUTHOR]

• A green organic-inorganic PAbz@ZIF hybrid has been prepared. • 5.0 wt% of PAbz@ZIF allows EP to easily achieve a UL-94 rating of v0. • PAbz@ZIF hybrids endow EP with efficient flame retardancy and smoke suppression. • PAbz@ZIF hybrids improve the heat insulation performance and mechanical performance of EP. Developing sustainable bio-based flame retardants for flammable polymers has been a research trend. However, applying bio-based flame retardants to confer excellent flame retardancy, smoke suppression, and mechanical properties to polymers remains a formidable challenge. Herein, a green organic-inorganic hybrid (PAbz@ZIF) was readily prepared through a simple neutralization reaction and in-situ generation method and applied to fabricate high-performance flame-retardant epoxy coatings (EP-PAbz@ZIF). It has been shown that PAbz@ZIF hybrids can enhance the curing activity of epoxy coatings in addition to their excellent dispersibility and interfacial compatibility. In addition, the epoxy coating containing 5.0 wt% PAbz@ZIF (EP-5%PAbz@ZIF) exhibits a higher char yield (from 25.1 wt% to 31.5 wt%) in comparison to pristine epoxy resin (EP). More importantly, the PAbz@ZIF-based epoxy coatings show more efficient flame retardancy and smoke suppression compared to pristine EP. For instance, the 5.0 wt% PAbz@ZIF enables EP-5%PAbz@ZIF to obtain a satisfactory UL-94 rating of V0. Meanwhile, the peak heat release rate, total smoke production, peak CO production rate, and peak CO 2 production rate of EP-5%PAbz@ZIF are remarkably decreased by 48.6%, 20.5%, 38.6%, and 56.7%, respectively. Furthermore, EP-5%PAbz@ZIF exhibits enhanced heat insulation performance, flexural strength, and impact strength. This work offers a feasible idea for designing green organic-inorganic PAbz@ZIF hybrids and fabricating high-performance flame-retardant epoxy coatings. [Display omitted] [ABSTRACT FROM AUTHOR]

• Renewable sources have been used to improve the fire performance of PA66. • PA66 composite had good flame retardant and anti-dripping performance. • The generated ammonia of FR-PA66 decreased by 69.4% than pure PA66. • Vegetable tanning was expanded to prepare flame retardant and anti-dripping PA66. Vegetable tanning is an ancient process that uses polyphenols to transform animal hides and pelts into durable and structurally stable leather. Inspired by this, polyamide 66 (PA66) and keratin (Ker) were blended to fabricate a PA66 composite (PA66/Ker) by solution casting, which was then tanned to prepare flame retardant and anti-dripping PA66/Ker composite (FR-PA66). The results indicated that the peak of heat release rate (PHRR) and total heat release (THR) of FR-PA66 decreased by 75.3% and 38.4%, respectively. The limiting oxygen index (LOI) of FR-PA66 reached 29.65% and a UL-94 V-0 rating was obtained. In addition, the char residue of FR-PA66 was 21.6% at 800 °C under N 2 atmosphere, indicating good char-forming ability. This work provides a new idea by using renewable biomass keratin and tannin to endow PA66 with flame retardant and anti-dripping performance. The preparation process is simple and feasible, suitable for large-scale preparation. [Display omitted] [ABSTRACT FROM AUTHOR]

• The optimal design of RPUF raises its fire safety and mechanical performances. • The bio-nanosheets exhibit remarkable catalytic carbonization capacity on RPUF. • The coatings endow RPUF with excellent fire resistance and char-formation ability. • The coatings show high resistance against hydrolysis. • The coated RPUF nanocomposite possesses superior thermal insulation properties. The adoption of rigid polyurethane foam (RPUF) in construction and rail transit offers energy conservation and emissions reduction benefits, but its inherent flammability presents challenges. Traditional fireproofing methods often disrupt foaming balance, ultimately compromising flame retardancy and mechanical properties. While flame retardant coatings preserve the bulk physical properties of materials, it tends to be sensitive to moisture. In this study, we propose to address the issues by employing a combined approach of nano-reinforcement and surface treatment. The results demonstrate that the addition of 3 wt.% bio-based Phosphorus-Nitrogen-containing nanosheet (HACP-PA) to RPUF increases its yield strength and compressive strength (at 60% strain) by 63% and 86%, respectively. Subsequently, the surface coating comprising of polydopamine-encased ammonium polyphosphate (APP@PDA), polyethyleneimine (PEI) and 1-octadecanethiol-wrapped polydopamine (PDA@ODT) imparts the RPUF nanocomposite with remarkable properties, including an LOI as high as 42.5%, a satisfactory V-0 rating in the UL94 test, 44% reduction in PHRR, 30% reduction in THR, 507% increase in residues, and a water contact angle of 137° More importantly, this method does not affect the excellent thermal insulation properties of the RPUF. In summary, this advancement tackles the challenges associated with RPUF's flammability and provides a bio-based, low-cost, and eco-friendly approach for developing multifunctional flame retardant RPUF with superior comprehensive properties. [ABSTRACT FROM AUTHOR]