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A novelflame retardant containing 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide(DOPO) and unsaturated bonds (DOPO-HEA) was synthesized and incorporatedinto epoxy acrylates (EA) in different ratios. The effects of DOPO-HEAon the thermal stability, flame retardant properties, and degradationmechanisms of EA were investigated. The flame retardant propertiesof the resins showed that the incorporation of DOPO-HEA into EA couldimprove the limiting oxygen index (LOI) values and greatly reducethe peak heat release rate (pHRR) of EA. The thermal properties ofthe resins indicated that the incorporation of DOPO-HEA into EA coulddistinctly improve the char residues. Moreover, the thermal degradationprocesses of the EA/DOPO-HEA resins were investigated by direct pyrolysis/massspectrometry (DP–MS). As for the variation in the condensedphase, FTIR and Raman spectroscopies were adopted to investigate thechar residues. Due to the catalyzing charring effect and the gas flameretardant effect of phosphorus, the resins exhibited significant improvementsin flame retardant properties. [ABSTRACT FROM AUTHOR]

[Display omitted] The development of high-performance thermosetting polymers has spawn extensive research interest over the past decade because of increasing awareness of environmental protection and sustainable policy. In this work, three cardanol-derived epoxy monomers named after CFGE, ECF, and ECFGE were synthesized, and ECFGE was selected to be further treated by flame-retardant owing to its superior thermal stability and mechanical strength. ECFGE was subsequently combined with cardanol-derived phosphate (DPP-CFR) to obtain flame-retardant bio-based epoxy materials as diglycidyl ether bisphenol A (DGEBA)-type epoxy substitutes. The chemical structure of CFGE, ECF, ECFGE, and DPP-CFR was well characterized by nuclear magnetic resonance and elemental analysis. The influence of DPP-CFR on the curing kinetics of the ECFGE/DDM system was investigated by the non-isothermal DSC. The addition of DPP-CFR imparted excellent flame-retardancy to the cured ECFGE/DDM system. Specifically, the cured ECFGE/DDM system with 15 wt% of DPP-CFR exhibited UL-94V-0 classification and LOI value of 31.0%, and its peak heat release rate was declined by 48% and 72%, respectively, compared to the cured ECFGE/DDM and DGEBA/DDM. Additionally, the cured ECFGE/DDM system with 15 wt% of DPP-CFR also showed better tensile strength and toughness than the cured DGEBA/DDM counterpart. This study demonstrates that cardanol can be utilized as a versatile platform for the fabrication of high-performance bio-based thermosetting polymers with excellent comprehensive properties. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nano-, submicron- and micron-sized Cu 2 O crystals were synthesized and confirmed. • The surface modification of Cu 2 O with PAPI improved the efficiency and dispersion. • Nano-sized Cu 2 O with the high surface area conduced to the complete combustion of RPUF. • The flame retardance and smoke toxicity suppression of Cu 2 O was explored. The development of flame retardant rigid polyurethane foam (RPUF) composites with low smoke toxicity emission, as well as excellent mechanical properties remains a huge challenge. Herein, a facile wet chemical approach was proposed for the preparation of cuprous oxide (Cu 2 O) crystals with different sizes, i.e. approximately 5 nm, 100 nm and 1 μm in lateral size, which were confirmed by X-ray diffraction and transmission electron microscopy. The effect of Cu 2 O crystals on the combustion behavior of RPUF was evaluated by cone calorimetry and steady state tube furnace tests. Significant reduction in peak carbon monoxide (CO) production rate (by 41.2%, 67.6% and 27.9%) and total smoke production (21.6%, 16.1% and 12.2%) were realized by the incorporation of 2 wt% Cu 2 O into the RPUF matrix in addition to a slight reduction in peak heat release rate. Notably, nano-sized Cu 2 O with high specific surface area is beneficial for the complete combustion of RPUF and the conversion of CO to carbon dioxide (CO 2), involving the reduction of Cu2+-Cu+-Cu0 by degraded gases and the oxidation of Cu0-Cu+-Cu2+ by oxygen. This work demonstrated that submicron-sized Cu 2 O is an effective smoke and toxic gases suppressant for RPUF, which is expected to find practical applications in polymeric materials. [ABSTRACT FROM AUTHOR]

• A liquid flame retardant, phosphorus-containing triacrylate, was synthesized. • Flexible polyurethane/phosphorus-containing polyacrylate IPN foams were prepared by simultaneous strategy. • Flame retardancy, thermal stability and mechanical properties of IPN foams were improved concurrently. Even though organophosphorus additives can improve flame retardancy and compress strength of flexible polyurethane foam (FPUF), but thermal stability and resilience are deteriorated. In this work, phosphorus-containing monoacrylate and triacrylate, (dimethoxyphosphoryl)methyl acrylate (DMPMA) and tris(acryloyloxymethyl)phosphine oxide (TAMPO), were synthesized. The liquid DMPMA and/or TAMPO were added into FPUF ingredients with radical initiator and polymerized in the heating process after foaming to form FPUF/polyacrylate composites. The neat and modified foams were controlled to have similar densities. Gel content of more than 96% was obtained for FPUF incorporated with TAMPO. And structure of interpenetrating polymer network (IPN) of FPUF3-5 loaded 20 wt% DMPMA and TAMPO of polyol (ratio of 3:1, 1:1 and 1:3 respectively) was further confirmed by their bicontinuous phase morphology with nanoscale domain uniformly distributed. All modified foams attain improved flame retardancy. Simultaneously increased thermal stability, compression force deflection (CFD) value and resilience were achieved by FPUF4-5. Especially, FPUF4 exhibits satisfied flame retardancy (limited oxygen index of 22.1%, pass of TB117-2000 vertical burning test, prolonged time to ignition, 49% decrement of peak heat release rate and 33% reduction of total heat release), elevated thermal stability and improved compressive (15% improvement of CFD) and resilient (5.2% raise of resilience) properties, concurrently. Therefore, DMPMA and TAMPO have great potential as liquid additive-type flame retardants for manufacturing flame retardant, supportive and comfort FPUF in seating and cushioning applications. [ABSTRACT FROM AUTHOR]

Organic-inorganic hybrid flame retardant technology integrates independent ingredients into a whole, thus showing advantage of simultaneous improvement in flame retardant, smoke suppressant and mechanical properties of polymers over traditional flame retardants. In this work, a novel organic-inorganic hybrid flame retardant denoted as IR-MOF-3-Mel was synthesized by covalent hybridization of isoreticular metal-organic framework-3 (IR-MOF-3) with melamine. A relatively low amount of IR-MOF-3-Mel nanoparticles dramatically decreased the fire risk of epoxy resin (EP). Specifically, the EP with only 2.0 wt% of IR-MOF-3-Mel achieved a limiting oxygen index (LOI) of 30.5% as well as a UL-94 V-0 classification, whereas its counterpart with 2.0 wt% of IR-MOF-3 showed a LOI of 25.0% and no classification in UL-94 test. Furthermore, the peak heat release rate, total heat release and smoke production rate of the EP with 2.0 wt% of IR-MOF-3-Mel was declined by 74.0%, 71.4% and 35.6%, respectively, compared to neat EP. Additionally, the glass transition temperature, the tensile strength, and the young's modulus were 11 °C, 38%, and 27% higher than those of neat EP, respectively. The flame retardant mechanism analysis clarified that IR-MOF-3-Mel contributed to formation of a char layer with a high level of thermal resistance and graphitization which accounted for significantly reduced fire risks. Image 1 • With only 1.5 wt% of IR-MOF-3-Mel, the EP composite achieved a UL-94 V-0 rating. • 2.0 wt% of IR-MOF-3-Mel leads to an unprecedented reduction in both PHRR (−74.0%) and THR (−71.4%) of epoxy composites. • IR-MOF-3-Mel hybrid also shows good smoke suppression effect. • 2.0 wt% of IR-MOF-3-Mel improves the tensile strength by 38% compared to neat EP. [ABSTRACT FROM AUTHOR]

• A bio-based epoxy monomer (HECarCP) was synthesized from cardanol and cyclophosphazene. • HECarCP/DDM thermoset showed a high LOI value of 33.0% and UL-94 V-0 classification. • Peak heat release rate of HECarCP/DDM was 63% lower than that of DGEBA/DDM. • Total smoke production of HECarCP/DDM was 72% lower than that of DGEBA/DDM. • HECarCP/DDM displayed much better toughness than the DGEBA/DDM. Petroleum-based diglycidyl ether bisphenol A (DGEBA)-type epoxy is one of the most popular thermosetting materials currently, but it suffers from brittleness, flammability and non-renewability. In this study, an intrinsically flame retardant bio-based epoxy monomer (HECarCP) was synthesized from cardanol and cyclophosphazene. Subsequently, HECarCP was cured by 4,4'-diaminodiphenyl methane (DDM) to obtain a thermosetting material. Compared to the cured DGEBA/DDM thermoset, the cured HECarCP/DDM thermoset showed lower initial decomposition temperature; however, the earlier thermal decomposition caused by cyclophosphazene core contributed to char formation in return. As well, the HECarCP/DDM exhibited slightly lower tensile strength but much higher elongation at break than the DGEBA/DDM, overcoming the drawback of brittleness of the DGEBA/DDM. More importantly, the cyclophosphazene core provided intrinsic flame retardancy to the HECarCP/DDM thermoset, which displayed a relatively high LOI value of 33.0% and UL-94 V-0 classification. In cone calorimeter measurement, the peak heat release rate, total heat release and total smoke production of the HECarCP/DDM thermoset was declined by 63%, 24% and 72%, respectively, compared to those of the DGEBA/DDM, owing to the formation of a thermally stable and insulating char layer during combustion. This study paves the way for broadening applications of cardanol in fabrication of high-performance bio-based thermosetting polymers with excellent comprehensive properties. [ABSTRACT FROM AUTHOR]

• A dual interaction-based and bio-inspired LbL assembled coating was prepared. • Improved flame retardancy and super-hydrophilicity of PA6.6 fabrics were realized. • Simultaneous PCS grafting and LbL deposition with 8 QLs raised LOI value up to 23.5%. • A reduction in pHRR by 45% and in THR by 25% was achieved with 8 QLs deposition. • The dual-interaction in LbL assembly could stabilize coatings up to 20 laundering cycles. A dual interaction-based (i.e., ionic/covalent) deposition of carbohydrate polymers, namely chitosan (CS) and oxidized sodium alginate (OSA) along with a plant-derived phosphorus-rich compound like phytic acid (PA) and a nitrogen rich compound like melamine (ME) was considered onto the phosphorylated chitosan (PCS) modified polyamide 6.6 (PA6.6) fabric surfaces in order to impart durable flame retardancy along with super-hydrophilicity of the same. Firstly, the pure PA6.6 textile surfaces were modified by PCS via UV-induced grafting and subsequently, the above-mentioned polyelectrolytes were assembled onto the fabric surfaces in a quadralayer fashion [i.e., (CS/ME-OSA-CS/ME-PA) n ; "n" represents the number of quadralayers (QLs)]. Here, the amino groups of CS/ME and the aldehyde groups of the OSA were stabilized via covalent interaction and the deposition of positively charged CS/ME and negatively charged phytic acid (PA) formed ionic interaction. In the vertical burning (UL-94) test, both the only PCS grafted and the simultaneously PCS-grafted along with LbL assembled fabrics could completely stop the melt dripping tendency and attained a V-1 rating. In the meantime, the limiting oxygen index (LOI) value received a moderate increase from 18.5 % of pure PA6.6 to 23.5 % for the PCS grafted and 8-QLs deposited fabric sample (i.e., PA6.6-g-PCS-8QL). Moreover, the PA6.6-g-PCS-8QL fabric sample exhibited a dramatic decrease in the peak heat release rate (pHRR) and total heat release (THR) by about 45 % and 24.7 % respectively alongside enhanced thermal stability. Apart from the appreciable flame retardancy, this fabric sample (i.e., PA6.6-g-PCS-8QL) could boost up the hydrophilicity to attain a water contact angle of 0°. Finally, this dual interaction-based deposition of bio-inspired polyelectrolytes posed a positive impact in enhancing the coating stability in laundering and imparting durable flame retardancy to sustain even up to 20 laundering cycles. [ABSTRACT FROM AUTHOR]

A phosphaphenanthrene-containing vanillin-derived compound (VDG) was synthesized by a one-pot nucleophilic addition reaction from vanillin, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), and 3,5‐diamino‐1,2,4‐triazole. The molecular structure of VDG was characterized by Fourier transform infrared (FTIR), and 1H, 13C, and 31P nuclear magnetic resonance (NMR) spectrometer. Various loadings of VDG were incorporated into diglycidyl ether of bisphenol A (DGEBA) as a co-curing agent together with 4, 4′-diaminodiphenylmethane (DDM) to produce an epoxy thermoset. The thermomechanical, thermal and fire-retardant properties of EP thermosets were evaluated by dynamic mechanical analyzer (DMA), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), limiting oxygen index (LOI), UL-94, and cone calorimetry. The results showed that a linear decrease in glass transition temperature with increasing loading of VDG owing to the declined cross-linking density. The cured DGEBA/DDM system with 2.0 wt% of VDG exhibited super anti-flammability in terms of a high LOI value of 37.0% and UL-94 V-0 rating, whereas the cured DGEBA/DDM and DGEBA/DDM with 2.0 wt% of DOPO systems showed no rating in UL-94 test. In addition, cone calorimetry test showed that the cured DGEBA/DDM system with 2.0 wt% of VDG exhibited a reduction of up to 47.5% and 34% for peak heat release rate and total heat release, respectively, compared to the cured DGEBA/DDM system. The enhanced flame-retardant property was attributed to the formation of the compact and continual structure of char layer residue with good thermo-oxidative stability. In addition to good anti-flammability, the cured DGEBA/DDM/VDG thermoset showed antibacterial property against E. coli , with an inhibition zone diameter of 10 mm. Thus, this bio-based co-curing agent could impart flame-retardant and antibacterial performance to epoxy for developing high performance functional thermosetting materials. Image 1 • With only 2.0 wt% of VDG, the EP composite achieved a UL-94 V-0 rating. • 2.0 wt% of VDG leads to a significant reduction in PHRR (−47.5%) of epoxy composite. • The cured epoxy thermoset with VDG showed anti-bacterial property against E. coli. [ABSTRACT FROM AUTHOR]

The designing of 3D ternary-structure based on SnO 2 nanoparticles anchored hollow polypyrrole microspheres interconnected with N, S co-doped grapheme (NSG-P-SnO 2). • A 3D ternary-structure of NSG-P-SnO 2 is rationally designed. • Remarkable enhancement in polymer fire safety is achieved by adding NSG-P-SnO 2. • The flame retardancy comparison with reported work affirms the superiority of NSG-P-SnO 2. • Obviously improved mechanical performance is also observed. Inherent nature of serious fire hazard including considerable heat and toxicants releases, have definitely compromised the extensive usage of epoxy resin (EP). In this investigation, a three-dimensional (3D) ternary-structure based on SnO 2 nanoparticles anchored hollow polypyrrole microspheres interconnected with N, S co-doped graphene (NSG-P-SnO 2) is rationally designed, and further incorporated into EP matrix. The markedly suppressed fire hazard is achieved after its incorporation. By adding 3.0 wt% NSG-P-SnO 2 , the reductions on peak heat release rate and total heat release values are 42.4 and 47.8%, separately, reflecting the impeded heat generation. Meanwhile, the peak smoke production rate and total smoke production values are obviously reduced by 27.0 and 40.2%, manifesting the attenuated fire toxicity. The flame retardancy comparison with reported work demonstrates the superiority of NSG-P-SnO 2. Notably, the enhanced mechanical performance is also observed. By using 1.0 wt% NSG-P-SnO 2 , the storage modulus is remarkably elevated by 29.1%. Thus, it is concluded that, using this 3D ternary-structure can endow polymer with high fire safety and mechanical capability, synchronously. This work may provide effective inspiration towards developing multicomponent integrated architecture, optimizing their prospects in polymer-matrix composite as well as other fields. [ABSTRACT FROM AUTHOR]

• Few-layer BP was scalable exfoliated by solvent-heat method via ion intercalation. • BP-PDA nanohybrids showed remarkable decrease in PHRR, THR and the amount of CO. • Significant tensile strength enhancement was achieved due to the adhesion effect. • PVA/BP-PDA exhibited high air stability even after exposed to air for five months. As a rising star of two-dimensional (2D) materials, single or few-layer black phosphorus (BP) possess great potential as nanofiller in fabricating polymer nanocomposites, due to its thermodynamic stability, nano-size effect and structural characteristics. Herein, few-layer BP nanosheets were scalable exfoliated via solvent-thermal method, the Lithium ion intercalation was achieved during this procedure. Follow by a polydopamine (PDA) encapsulated BP sandwich nanostructure was developed by oxidation–reduction strategy, which improved the air stability of few-layer BP and its interfacial compatibility with polymer matrix. As could be expected, the PDA encapsulated BP (BP-PDA) can effectively enhance the mechanical properties and flame retardancy of polyvinyl alcohol (PVA) nanocomposite films. For instance, the PVA/BP-PDA5.0 nanocomposite film loaded with 5 wt% BP-PDA exhibited 57.2% maximum decrease in peak heat release rate and 47.9% maximum reduction in total heat release. Meanwhile, while the BP-PDA loading achieved 2 wt%, PVA/BP-PDA2.0 nanocomposite film revealed an 81.1% increase in the tensile strength. In particular, on account of dual protection of the PDA encapsulation and polymer matrix embedding, the air stability of BP in PVA matrix was significantly improved. As an evidence, the ratio of A g 1/A g 2 in Raman spectra of BP-PDA decreased from the initial 0.72 to 0.62, even after exposed to air for five months, indicating a low level of oxidation. This work provides a novel strategy for scalable exfoliation and functionalization of BP, and enables a wide range of potential applications of BP in polymer nanocomposites. [ABSTRACT FROM AUTHOR]

• Innovation: novel g-C 3 N 4 @PPZ to promote flame retardant and toughness of BMI. • High-efficiency: PHRR and TSPR of BMI/g-C 3 N 4 @PPZ2.0 reduced by 52.1%, 53.8%. • The best impact strength of BMI/g-C 3 N 4 @PPZ increased by 184.0%. • Mechanism: the flame retardant and toughening mechanism was proposed. It's acknowledged that the inferior toughness of bismaleimide resin (BMI) is the crucial problem hindering its development and application especially in aerospace, mechanical and electronic fields. While the poor fire safety of toughened BMI is another problem urgently needed to be resolved. Therefore a novel g-C 3 N 4 @PPZ hierarchical architecture constituted of porous g-C 3 N 4 tubes modified by polyphosphazene was designed and fabricated to improve the fire safety and mechanical properties of BMI in this work. Especially compared to pure BMI, the peak heat release rate (PHRR) and peak smoke production rate (PSPR) of BMI with an incorporation of 2 wt% g-C 3 N 4 @PPZ (BMI/g-C 3 N 4 @PPZ2.0) are at 246.3 kW/m2 and 0.12 m2/s accompanying with 52.1% and 53.8% reduction respectively. The total heat release (THR) and total smoke production (TSP) of BMI/g-C 3 N 4 @PPZ2.0 are endowed with reductions of 29.4% and 42.9% as well, which demonstrates that the fire safety including heat and smoke hazards of BMI/g-C 3 N 4 @PPZ2.0 is significantly improved. With regard to the mechanical performance of BMI composites, the impact strength of BMI/g-C 3 N 4 @PPZ1.5 is 18.89 kJ/m2 which increases by 184.0% in comparison with that of pure BMI resin (6.65 kJ/m2). And it's found that the impact strength of BMI/g-C 3 N 4 @PPZ are still higher than pure BMI in hot-humid environment, which signifies that the BMI/g-C 3 N 4 @PPZ would be preferred in the industrial applications. Meantime the possible flame retardant and toughening mechanism of g-C 3 N 4 @PPZ in BMI is detailed investigated and proposed as well. [ABSTRACT FROM AUTHOR]

l Three different P-compounds were used to prepare the flame retardant coatings for PA66 textiles. l Chitosan, alginate and MMT as additives were also incorporated with the P-compounds. l Graphene phosphonic acid based coating offered a maximum LOI by 27.5% and reduction in pHRR by 45%. l Phytic acid based coating brought a substantial reduction in pHRR and increase in char yield%. l P-compound active in the condensed phase and well-supported with a physical barrier effect seemed to be well-suited for PA66. Three different phosphorus (P) compounds, namely phytic acid (PA), graphene phosphonic acid (GPA) and a DOPO derivative [3-H-P-DOPO HQ (DOH)] having a diverse origin, structure and chemical activity were used along with some naturally derived polyelectrolytes like chitosan (CS), sodium alginate (SA) and montmorillonite (MMT) in a layer-by-layer (LbL) fashion to enhance the flame retardant performance of polyamide 66 (PA66) textiles. Obtained results showed that these P-compounds, irrespective of their varied action surely played a positive role in improving the flame retardancy; though a typical P-compound was effective in modifying a specific type of flame retardant parameter. The formulation containing phytic acid particularly brought a considerable reduction in the peak heat release rate (pHRR) and a handsome increase in residue% due to its dominant activity in the condensed phase flame retardant mechanism. Meanwhile, the application of GPA further modified this condensed phase activity via providing added thermal stability to these residues and thus, a sharp increase in limiting oxygen index (LOI) value up to 27.5% and a maximum reduction in pHRR by 45% was handed. In contrast, the DOPO derivative (DOH) was quite effective in the gas phase mechanism through its radical quenching effect and offered a moderate increase in LOI values (i.e., 24.5%). Finally, it was realized that the formulation containing an engineered structure of a P-compound with graphene, basically worked in the condensed phase mechanism and well supported by thermal insulation effect available from graphene nanosheets and MMT platelets seemed to be an effective solution in escalating the fire performance of PA66 textiles. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Similar to graphene, few-layer black phosphorus possesses many excellent properties such as good thermal stability, mechanical properties and unique characteristic dimension effects, which is considered as promising nanoadditives. But the low yield and inferior interfacial adhesion with polymer matrix are unavoidable obstruction to fabricate high performance nanocomposites. Herein, we report a facile and environmentally friendly approach to simultaneously exfoliate and modify black phosphorus (BP) by electrochemical cathodic exfoliation, where BP crystal acted as the cathode and ethylene imine polymer (PEI) acted as electrolyte and modifier. The positively charged PEI would uniformly anchor on the surface of the newly peeled-off BP nanosheets through electrostatic attraction effect, resulting in preventing the agglomeration of BP nanosheets and improve the compatibility between BP and waterborne polyurethane (WPU) matrix. Significantly, with the addition of 2.0 wt% PEI modified BP in WPU matrix, the fire safety of WPU composites was enhanced. The peak heat-release rate, total heat release, total smoke production and total CO yield are decreased by 34.3%, 21.2%, 22.3% and 50.2% compared to pure WPU, respectively. Also, the tensile strength of WPU composites was increased by 71% (from 21.9 to 31.0 MPa) at the cost of the breaking elongation slightly decreased by 5.6%. This work provides the possibility for the scalable preparation and a real application of BP in polymer nanocomposites. Image 1 • A facile and environmental route to simultaneously exfoliate and modify BP. • BP-PEI had good flame-retardant contributions in both gaseous and condensed phase. • Functionalized BP enhanced flame-retardant properties of WPU composite. [ABSTRACT FROM AUTHOR]

• BPNSs and RGO were combinated via stable chemical bonds. • BP-RGO nanohybrids showed remarkable decrease in PHRR, THR. • BP-RGO nanohybrids exhibited a significant inhibitory effect on smoke and toxic gases. • EP/BP-RGO nanocomposites exhibited high air stability The black phosphorus (BP) can be compounded with other two-dimensional materials with flame retardant effect to achieve better synergistic effect. Herein, the multifunctional BP-RGO nanohybrids was fabricated by solvothermal strategy to improve the dispersion state of BP in epoxy resin (EP) and enhance its fire safety performance, where the reduced graphene oxide (RGO) was attached on the surface of BP via P C and P O C bonds. With the incorporation of 2.0 wt% BP-RGO into EP matrix, 54.4 % reduction in total heat release (THR) was achieved along with 55.2 % decrease in peak heat release rate (PHRR) compared with neat EP. As a similar trend, the toxic CO and aromatic compounds were significantly inhibited, and the maximum decrease (28.5 %) in total smoke production (TSP) was achieved, indicating the enhanced fire safety performance of EP nanocomposites. These positive results is attributed to the synergistic effect of physical nano-barrier, free radicals trapping and char formation between BP and RGO components. Meanwhile, the EP/BP-RGO2.0 nanocomposites exhibited satisfying air stability even after being immersed in water for a month. This work enriches the strategies for enhancing the air stability of BP, and confirms its potential for smoke toxicity and fire hazard suppression in polymer nanocomposites. [ABSTRACT FROM AUTHOR]

Cotton fabrics are prone to ignite fire accidents as well as breed bacteria and fungi, which have hampered their applications in the field of packaging and home decorations. Guanazole complexes with silver and zinc ions were deposited to cotton fabrics through self-assembly to prepare the flame-retardant and antibacterial cotton fabrics. The effect of the guanazole-metal complexes on the morphological structure, flammability and thermal degradation of cotton fabrics was studied by field emission scanning electron microscopy, limiting oxygen index (LOI), UL-94 vertical burning test, and thermogravimetric analysis. The antibacterial and antifungal activities of the coated fabrics were evaluated as well. The guanazole-zinc and guanazole-silver treated cotton fabrics showed a high LOI of 29.5% and 27.5%, respectively. In the vertical burning test, both the guanazole-zinc and guanazole-silver treated cotton fabrics self-extinguished when removing the ignition source, displaying a UL-94 V-0 classification, while the untreated one and the guanazole-treated one burned out. Thermogravimetric analysis results confirmed that the guanazole-metal complexes promoted the thermal decomposition of cotton and thus improved the char yield significantly. Micro-scale combustion calorimeter measurements clarified that the guanazole-zinc and guanazole-silver treated cotton displayed dramatically decreased peak heat release rate (64.4% and 59.1%, respectively) and total heat release (26.4% and 14.8%, respectively) in comparison to the untreated one. The significantly improved flame retardancy of guanazole-metal complexes treated cotton fabrics could be attributed to their enhanced charring capability that blocked flammable volatiles into flame zone. The treated cotton fabrics with guanazole-metal complexes exhibited better antibacterial capacity against Staphylococcus aureus and Escherichia coli than the untreated and guanazole-treated ones. Furthermore, the guanazole-silver treated cotton fabrics also showed good antifungal activity against Penicillium, Fusarium chlamydosporum and Aspergillus niger. Image 1 • Guanazole-metal complex was used to simultaneously improve flame retardant and antibacterial property of cotton fabrics. • Limiting oxygen index increases to 27.5% for guanazole-silver treated cotton from 19.5% for untreated one. • The peak heat release rate of guanazole-silver treated cotton was reduced by 59% compared to untreated one. • The guanazole-silver treated cotton showed self-extinguishing behaviors owing to promotion of char formation. • The guanazole-silver treated cotton showed good antibacterial and antifungal ability. [ABSTRACT FROM AUTHOR]

• Flame-retardant and superhydrophobic coatings were constructed on cotton fabrics by a facile two-step method. • The treated cotton showed super flame retardancy in terms of self-extinguishing behavior. • The peak heat release rate of the treated cotton was significantly reduced by 70% compared to pure cotton. • The treated cotton exhibited fascinating anti-fouling and water-oil separation abilities. • The coatings on cotton fabrics displayed good abrasion resistance and washing durability. A flame-retardant and superhydrophobic coating was deposited on cotton fabrics using a simple two-step spraying method. In detailed, the first step involved flame-retardant layer consisted of alkylammonium functional silsesquioxane (A-POSS)/phytic acid (PA) complex, while the second step generated superhydrophobic layer that was composed of hierarchical structured titanium oxide@polydimethylsiloxane (TiO 2 @PDMS) composite. The influence of the components' loading in the coating on flame-retardant, thermal and wetting properties of the coated cotton fabrics was investigated systematically. The optimized coated cotton sample denoted as C3-PDMS-TiO 2 was screened through limiting oxygen index (LOI), UL-94 flammability test, cone calorimetry measurement and water contact angle (WCA). Specifically, C3-PDMS-TiO 2 sample showed self-extinguishing behavior in the vertical burning test, as well as a significantly enhanced LOI to 29% from 18% for pristine cotton fabrics. Furthermore, the peak heat release rate (PHRR) and the total heat release (THR) values of C3-PDMS-TiO 2 were significantly declined by 70% and 41%, respectively, compared to those of pristine cotton fabrics. Additionally, C3-PDMS-TiO 2 exhibited super self-cleaning ability as a consequence of its superhydrophobic surface. Furthermore, C3-PDMS-TiO 2 was applied for water-oil separation, and exhibited robust ability even in strong acid- or alkali-oil mixtures. The C3-PDMS-TiO 2 fabrics also displayed super abrasion resistance (WCA > 139° after 50 abrasion cycles) and washing durability (self-extinguishing after 5 laundering cycles). This facile finishing technique has great potentials in application as multifunctional advanced textiles. [ABSTRACT FROM AUTHOR]

• Layer-by-layer assembled fully bio-based coating protected flexible polyurethane foam (FPUF) from fire. • Coated FPUF by 9 bilayers of alginate, chitosan and hydroxyapatite showed self-extinguishing behavior. • Peak heat release rate of coated FPUF by 9 bilayers of alginate, chitosan and hydroxyapatite reduced by 77.7 %. • Smoke production rate of coated FPUF by 9 bilayers of alginate, chitosan and hydroxyapatite declined by 53.8 %. The present study reports the successful synthesis of the flame-retardant and smoke-suppressant flexible polyurethane foam (FPUF) through a fully bio-based coating. Hydroxyapatite (HAP) is added to the solutions containing sodium alginate (SA) and chitosan (CH), respectively, to create negative and positive polyelectrolytes for Layer-by-Layer (LbL) assembly. The influence of the solution concentrations and bilayers numbers deposited on the flame-retardant and mechanical properties of FPUF samples is investigated systematically. Benefitting from the presence of such a fully bio-based coating, the resultant FPUF affords excellent smoke-suppressant and flame-retardant features. In particular, the FPUF coated by 9 bilayers of HAP-SA/HAP-CH exhibits significantly declined peak heat release rate, total release rate and smoke production release by 77.7 %, 56.5 % and 53.8 %, respectively. The compression test verifies the coated FPUFs exhibit lower recovery properties compared with the uncoated one. These results demonstrate that a green and cost-effective strategy is provided for producing flame-retardant, anti-dripping and smoke-suppressant FPUFs. [ABSTRACT FROM AUTHOR]

As is well known, polyethylene (PE) is flammable with the release of abundant heat, confirming its low fire safety. Consequently, the extended application of PE is restrained. In this work, we propose the facile preparation of multi-component hybrid (functionalized montmorillonite anchored with ZnO, defined as FMZH) and its promising utilization in PE. With the aid of functionalized compound, the obtained hybrid shows good dispersion state, as well as strong interfacial interaction with polymer matrix. By incorporating FMZH fillers, the marked reductions in peak heat release rate (PHRR) and total heat release (THR) can be obtained, corroborating the enhanced fire safety. Specifically, with the addition of 5.0 wt% 1-2FMZH and 1-4FMZH, the PHRR values are reduced to 567 and 667 kW/m2, respectively, corresponding to 54.7 and 46.8% decrease. Also, the suppressing effect on the release of decomposition fragments can be evidenced by the decreased absorbance intensity in FTIR spectra. Furthermore, the presence of these fillers shows marginal influence on the nonisothermal crystallization behavior of PE. Additionally, the FMZH composite with hierarchical structure shows superior gas barrier function over pristine ZnO and montmorillonite. • Preparation of multi-component hybrid of FMZH is proposed. • With the aid of functionalized compound, the obtained hybrid shows good dispersion. • By adding FMZH fillers, the marked reductions in peak heat release rate are obtained. • This hierarchical structure of FMZH shows more superior gas barrier function. [ABSTRACT FROM AUTHOR]

• This paper summarizes the flame retardant applications of synthetic textiles. • The common drawbacks like melt-dripping and limited charring are addressed. • Surface modification is done in many cases to address these issues. • Recently, bio-based fire retardants are widely used compared to petro-based compounds. • Metal-oxide nanoparticles, inorganic and nano-carbon compounds are also considered. Synthetic textiles make a great contribution as the apparel, industrial and technical textile goods, though most of them are inherently flammable. Thus, the fire retardant treatment of synthetic textile materials always puts a huge significance to deal with; meanwhile the art of flame retardant application is taking a new shape globally considering the modification of the textile surfaces as well as the structure of applied flame retardant compounds. Thus, this review depicts the fire retardant treatment of some common synthetic textiles like polyamide 66 (PA66), polyamide 6 (PA6), polyethylene terephthalate (PET) and polyacrylonitrile (PAN) etc. focusing on the traditional approaches as well as the recent practices. In addition, this article aims to be established as a kind of general review that summarizes all relevant works carried out till the date with a view to realize the growing trend of this field in terms of applied compounds and application techniques and try to discover their impacts on anti-dripping, fire and thermal behaviors. In this review, it is seen that the very common drawbacks of most of the synthetic textiles are the melt-dripping and limited charring. Thus, to overcome these phenomena, in many instances, researchers adopt the surface modification technique prior to the final finishing in attaining the fire retardant behaviors. This kind of surface engineering usually using some epoxidized and acyrated aliphatic chains surely modifies the flame retardant and combustion behaviors where some improvements in the reduction of the peak heat release rate (pHRR) and a significant increase in char yield% are realized. In addition, this kind of modification also seems to be much effective in stopping the melt-dripping phenomenon of synthetic textiles. In parallel, it is noticed that the researchers also take initiative to modify the chemical structure of applied flame retardant compounds; especially they do incorporate several flame retardant elements like phosphorus (P), nitrogen (N), silicon (Si) and boron (B) etc. in a single structure to intensify the fire retardant efficacy of the same. For example, some of these compounds are effective both in the condensed and gas phase flame retardant mechanism or in some cases, some structures can enhance the limited charring of synthetic textile materials or can provide thermal stability of these char residues via providing a physical barrier effect due to their synergistic involvement in a typical flame retardant system and thus, an optimum level of flame retardancy are realized for the treated textiles. So, it is thus indispensable to realize the physio-chemical interactions between the polymeric structures (i.e., textiles) and the applied flame retardant compounds to design the future fire retardant treatment through selecting a right compound and an appropriate application method for a typical textile material. From this point of view, this review is a significant work to focus on some key flame retardant and combustion parameters like limiting oxygen index (LOI) values, vertical burning test (VBT) and peak heat release rate (pHRR) data along with an exploration of the flame retardant mechanism and durability issues of such applications. [ABSTRACT FROM AUTHOR]

The black phosphorus (BP) nanosheets were firstly obtained by the modified lithium ion intercalation method and then functionalized by cetyl-trimethyl ammonium bromide (CTAB). Owing to the electrostatic interactions, the positively charged CTAB was successfully loaded onto the surface of negatively charged exfoliated BP and the BP-CTAB hybrids were finally obtained. It is found that BP-CTAB hybrids exhibits superior promotion effect on fire safety of Polylactic acid (PLA), which can be attributed to its typical layered structure, abundant phosphorus and good dispersion in matrix. Compared with neat PLA, the peak heat release rate (PHRR) of PLA composite with 2 wt% BP-CTAB decreases by 38.8%. Under the same loading of 2 wt%, the PLA/BP-CTAB2.0 shows better flame retardancy than PLA composites with BP or red phosphorus (RP). Moreover, the time to peak heat release rate (T PHRR) of PLA/BP-CTAB2.0 is postponed from 157 to 200 s. Derived from the uniform dispersion of BP-CTAB, the tensile strength of PLA composites are also improved. Meanwhile, the air stability of BP-CTAB in polymer is investigated. It is observed that the A g 1/A g 2 value of BP-CTAB only decreases from 0.57 to 0.54 even after immersion in water for one month, which can be ascribed to the double coating of polymer matrix and CTAB. This work enriches the method of exfoliating BP, and first explores the influence of BP on the flame retardant and mechanical properties of PLA. • Modified lithium ion intercalation method enriches the way of exfoliating BP. • BP-CTAB nanohybrids exhibit significant effect on decrease in PHRR and postponing in T PHRR. • BP-CTAB nanohybrids significantly improve thermal stability of PLA composites. • The air stability of BP-Li nanosheets is enhanced by the double coating of polymer matrix and CTAB. [ABSTRACT FROM AUTHOR]

In this work, a series of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) derivative salts containing phosphorus and nitrogen were synthesized, and their effects on mechanical properties, thermal stability and flame retardancy of flexible polyurethane foam (FPUF) were investigated. Studies have shown that the addition of DOPO derivatives will increase the tensile strength, compression set, and compression hardness of FPUF, but it will lead to a decrease in elongation at break. Thermogravimetric analysis showed that the initial decomposition temperature of FPUF containing DOPO derivatives was reduecd, but the char reside was significantly improved. A series of combustion tests indicated that the addition of DOPO derivative salts can improve the flame retardancy of FPUF, of which 10-hydroxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide dicyandiamide salt (D-DICY) exhibited the best flame retardancy. When the load of D-DICY was 20 phr, the limiting oxygen index (LOI) of foam reached 24.5%, and the peak heat release rate and total heat release were decreased by 55.7% and 52.9%, respectively. Furthermore, based on the analysis of the gas phase combustion products and the char residue of the condensed phase, the possible flame retardant mechanism was proposed. • Novel phosphorus-nitrogen-containing DOPO derivatives were synthesized. • Tensile strength and compression hardness of FPUF are enhanced with the addition of DOPO derivatives. • When the load of D-DICY is 20 phr, the LOI of FPUF reaches 24.5%. • The synthesis steps are simple, low cost and environmental-friendly. [ABSTRACT FROM AUTHOR]

• A hybrid coating was prepared from chitosan, melamine, urea, phytic acid and GO. • Improved flame retardancy and hydrophilicity of PA6.6 fabrics were realized. • Hybrid coating raised LOI value up to 25 % and stopped the melt dripping completely. • A maximum reduction in pHRR by 56 % was achieved with 5 BLs depositions. • Hybrid coatings could withstand against 10 home laundering cycles. The layer by layer (LBL) deposition of chitosan/melamine/urea (CS/ME/UREA) and phytic acid (PA) onto the acrylic acid (AA) grafted Polyamide 6.6 (PA6.6) fabrics including a pad-dry-cure treatment with chitosan/graphene oxide (CS/GO) nanocomposites were considered to improve the hydrophilicity and durable flame retardancy. Obtained results indicated that these hybrid coatings could significantly improve the flame retardancy as the limiting oxygen index (LOI) value reached up to 25 % from 18.5 % and could completely stop the melt dripping where the fabric sample with two bilayers deposition and simultaneously treated with CS/GO nanocomposite (PA6.6-g-AA-2BL-CS/GO) achieved a V-1 rating. A 2BLs deposited hybrid coating (i.e., PA6.6-g-AA-2BL-CS/GO) could decrease the peak heat release rate (pHRR) by 47.1 %; whereas a maximum reduction of pHRR by about 56 % was achieved for 5BLs deposition. Moreover, a considerable improvement in thermal stability and char yield% were also realized in the thermogravimetric analysis (TGA) test. Furthermore, the as-prepared hybrid coatings imparted better hydrophilicity as a 2BLs deposition along with pad-dry-cure treatment by CS/GO could boost up the hydrophilicity of the treated fabrics further compared to the only 2BLs deposited fabric sample. In addition, the application of CS/GO nanocomposite could improve the stability of this coating and able to stop the dripping tendency even after 10 laundering cycles as well. [ABSTRACT FROM AUTHOR]

An ecofriendly flame retardant was synthesized by hydrothermal method. The structure and morphology of h-BN@ZnFe 2 O 4 were characterized. PVA nanocomposites were prepared by adding h-BN@ZnFe 2 O 4 as filler into PVA. The effect of h-BN@ZnFe 2 O 4 on the flame retardant properties of PVA composites was studied and the flame retardant mechanism was also analyzed. The results showed that the peak heat release rate of PVA nanocomposites was slightly lower than that of pure PVA and the amount of CO, CO 2 , and hydrocarbons produced by the pyrolysis of PVA nanocomposites is less than that of pure PVA. The main reasons for this are the physical barrier effect of h-BN and catalytic carbonization effect of zinc ferrate. An ecofriendly flame retardant was synthesized by hydrothermal method, which is conducive to the formation of dense carbon layer during the process of PVA thermal degradation. The char layer acted as a physical barrier, inhibiting the exchange of heat between the fire and the matrix, isolating O 2 , preventing the permeation of volatile production to the fire zone, and thereby retarding the further degradation of PVA. Image 1 [ABSTRACT FROM AUTHOR]

In this work, a novel three-dimensional nanoarchitecture metal-organic framework@polyaniline (Sn-MOF@PANI) was designed and applied to address the fire hazards of epoxy resins (EP). Fourier transform infrared (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) results proved that the Sn-MOF@PANI was successfully synthesized. Compared with pure EP, the peak heat release rate (PHRR) and the total heat release (THR) of EP/Sn-MOF@PANI were reduced by 42% and 32%, respectively. Meanwhile, the total smoke production (TSP) and total gaseous products of EP/Sn-MOF@PANI were also reduced during the combustion. The above results illustrate that the fire safety of EP was improved. Based on the analysis of the gaseous products and the condensed phase, a possible flame retarding mechanism was proposed. Moreover, the addition of Sn-MOF@PANI improved mechanical properties of EP, including storage modulus and impact strength. Image 1 • A Sn-based metal organic framework@polyaniline (Sn-MOF@PANI) was synthesized. • When the loading was 2 wt%, EP/Sn-MOF@PANI showed good flame retardancy. • Based on the analysis of the gaseous products and the condensed phase, a possible flame retarding mechanism was proposed. • EP/Sn-MOF@ PANI had better mechanical properties than pure EP. [ABSTRACT FROM AUTHOR]

Flexible polyurethane (FPU) foam as a primary softening material is utilized in soft furnishings of upholstered mattresses and furniture. High flammability of this soft furnishing material usually leads to residential fires, causing severe fatalities. In the present study, we proposed a bio-based and environmentally-friendly flame retardant multilayered coating consisted of laponite (LAP), branched polyethyleneimine (BPEI), sodium alginate (SA) and chitosan (CH) that was deposited onto FPU foams to enhance their fire safety property. Based on the thermogravimetric analysis results, it was indicated that after the deposition of LAP, the thermal stability of the coated FPU foams increased sharply. Foam treated with 9 quad layers (QL) of BPEI/SA/CH/LAP multilayered coating showed self-extinguishing behavior in an open flame burning test. Furthermore, the values of peak heat release rate (PHRR), total heat release (THR) and smoke release rate (SPR) of the coated FPU foams reduced considerably in comparison to those of the pure FPU foam. Specifically, 9 QLs of BPEI/SA/CH/LAP declined the PHRR and the THR by 74% and 42.6%, respectively. The coated FPU foam also showed self-extinguishing and anti-dripping features in an open flame testing. Therefore, it can be stated that LAP-based coating has incredible benefits in decreasing fire risk of FPU foams. Moreover, the flame retardant mechanism of this LAP-based multilayered coating was proposed. The LAP-based coating functioned as a physical insulating barrier that successfully retarded the permeation of the flammable volatiles, heat and oxygen. Hence, the significant decrease in PHRR with the self-extinguishing behavior was achieved, implying promising potential of this LAP-based multilayered coating to enhance the fire safety of FPU foams. • Laponite-based inorganic-organic hybrid coating is deposited on FPU foams. • The coated FPU foam shows a 74% lower peak heat release rate than the uncoated one. • The coated FPU foam exhibits a 62% lower smoke production rate than the uncoated one. • Laponite strengthens the barrier effect that accounts for reduced fire hazards. [ABSTRACT FROM AUTHOR]

• Cuprous oxides with sheet morphology (Mn@Cu 2 O-M nanosheets) are rationally designed and successfully prepared. • The prepared Mn@Cu 2 O-M sheets could endow epoxy composites with high flame retardancy and smoke suppression properties. • The mechanism are probably due to the physical barrier effect and catalytic carbonization awarded by Mn@Cu 2 O-M sheets. To date epoxy resins have been extensively used in the field of chemical engineering, aerospace and building materials. Nevertheless, the utilization of flammable epoxy resins has posed a huge threat to lives and properties, which restricted their applications. In this work, manganese-based cuprous oxides two-dimensional nanosheets (Mn@Cu 2 O-M) are rationally designed and successfully prepared to improve the toxic effluent elimination of epoxy resin. The fire safety properties of the prepared Mn@Cu 2 O-M based nanocomposites improved the heat release rate (<35 %) and total heat release (<40 %) compared to the control epoxy. Moreover, the production of smoke and toxic volatiles of the composites with Mn@Cu 2 O-M nanosheets is significantly reduced. The mechanism investigations indicate that the improved flame retardancy and toxic effluent elimination of epoxy composites are attributed to the physical barrier effect and catalytic carbonization awarded by Mn@Cu 2 O-M nanosheets during burning. This work provides a promising strategy to develop eco-friendly, efficient and fire-safe polymers by both physical barrier effect and catalytic carbonization. [ABSTRACT FROM AUTHOR]

• The ambient stability was imparted to BP nanosheets. • The radicals quenching effect of TA was developed to reduce the CO release. • The flame retardancy and toxic gases suppression of BP nanosheets was explored. Herein, as a natural antioxidant, tannin (TA) is firstly used to functionalize black phosphorous (BP) nanosheets to improve the ambient stability and toxic suppression, thus decreasing the fire hazards of polymer materials. Compared to pure BP nanosheets, higher temperature for thermal oxidation decomposition is achieved for TA-BP nanosheets, directly confirming the ambient stability of TA-BP nanosheets. Meanwhile, from high resolution TEM and XPS results, TA-BP nanosheets after being exposed at air for 10 days present well-organized crystal structure and low PO x bonds content. Cone calorimeter results illustrate that the incorporation of 2.0 wt% TA-BP nanosheets significantly decreases the peak value of heat release rate (−56.5 %), total heat release (−43.0 %), CO 2 concentration (−57.3 %) of TPU composite. Meanwhile, with addition of low to 1.5 wt%, the release of highly-toxic CO gas is significantly suppressed, confirmed by lower peak value (0.52 mg/m3) and decreased total release amount (−55.1 %). The obviously enlarged tensile strength (36.7 MPa) and desirable elongation at break (622 %) are also observed. This strategy not only firstly adopts bio-based antioxidant to impart excellent environmental stability for BP nanosheets, but also promotes the promising potentials of BP nanosheets in the fire safety application of polymer composites. [ABSTRACT FROM AUTHOR]

Polyamide materials are regarded as one promising plastic, deriving from its exceptional physical and chemical properties. Unfortunately, the intrinsic high fire hazard (considerable heat, smoke and toxic gases generation) of polyamide strongly hinders its versatile applications. Utilizing suitable strategy to reduce its fire hazard has been more crucial. Here, the biologically-based polyamide materials are synthesized. In this work, the replacement of terephthalic acid with isophthalic acid contributes to the reduction on the melting point of polymer, which is beneficial to the processing in industry. It is found that PA10T/10I shows lower mechanical property and worse flammability than PA10T. By using halogen and halogen-free flame retardants, the dramatically reduced values of peak heat release rate can be observed. It is found that less halogen-free flame retardant are loaded to achieve V-0 rating, substantiating its higher flame retarded efficiency. Also the markedly improved limited oxygen index values are observed. TGIR results confirms the suppressed releases of toxic CO and HCN gases. Besides, the inhibited smoke generation can be found. Overall, both halogen and halogen-free strategy are effective in reducing the fire hazard of polyamide and halogen-free method show higher efficiency. Image 1 [ABSTRACT FROM AUTHOR]

• BP nanosheets and MCNTs were combinated via stable phosphorus carbon bonds. • EP/BP-MCNTs exhibits low PHRR, THR, SPR, TSR, FGI and smoke toxicity. • BP-MCNTs possessed naao-barrier, synergistic charring and radicals trapping effect. • MCNTs bonding and EP matrix wrapping improve the air-stable of EP/BP-MCNTs. As a rising star of two-dimensional material, black phosphorus (BP) has attracted tremendous attention in applications of photovoltaics, transistors and batteries due to its unique characteristics. Inspiring, we developed a simple strategy to fabricate BP-MCNTs as highly promising inorganic phosphorus-based flame retardant. After incorporation 2 wt% BP-MCNTs11(the mass ratio of BP:MCNTs=1:1) nanohybrid, the peak of heat release rate and total heat release of EP nanocomposites reduced by 55.81% and 41.17% at a phosphorus content of only 1 wt%, and the comprehensive index FGI for evaluating the flame retardant of materials decreased from 17.35 to 6.97. In addition, the typical flammable volatile are suppressed significantly, and the first stage of carbon monoxide release is disappeared. The improvement of fire safety and inhibition of smoke toxicity could be attributed to the the synergistic effects of nano-barrier, catalytic charring and radicals trapping of BP-MCNTs nanohybrid. More importantly, BP hybrid with MCNTs and wrapped in EP matrix which formed effective isolation protection against the ambient degradation. Raman spectra and SEM results confirmed that EP/BP-MCNTs performed enhanced ambient stability than EP/BP-BS nanocomposites after three months. This study demonstrates its great potential for preparation of air-stable BP based nanocomposites with enhanced fire safety. [ABSTRACT FROM AUTHOR]

Polystyrene sulfonate functionalized graphene nanosheets (PSS@GNS) with high quality (I D /I G = 0.17) were fabricated through electrochemical exfoliation of bulk graphite followed by simple free radical polymerization in water solution, which is a promising strategy for mass production of polymer functionalized graphene. P-styrene sulfonate anions were used to intercalate into the bulk graphite under voltage and also as monomers of the macromolecule modification agents for the exfoliated graphene nanosheets. Besides, benzene rings and carbon double bonds are considered to be able to capture hydroxyl free radicals which produce defects on graphene sheets during electrochemical exfoliation process, thus improve the quality of the exfoliated graphene nanosheets. Then the graphene nanosheets were incorporated into polystyrene (PS) through a solution blending method to reduce the fire hazards and improve mechanical properties of PS resin. According to the results of cone calorimeter, the introduction of functionalized graphene nanosheets into PS reduces heat release rate (decreased by 40%), total heat release (decreased by 35%) and increases the amount of char residues. The flame retardant improvement is attributed to the barrier effect of well-dispersed graphene nanosheets, limiting the mass transfer of the volatile compounds and forming char layers which blocked polymers from heat and oxygen. Meanwhile, the introduction of PSS@GNS into PS also contributed to increase its strength and elongation rate thanks to the pristine properties of graphene nanosheets and their interfacial interaction with the PS matrix. • This method to fabricate functionalized graphene nanosheets in aqueous solution is easy to operate. • Obtained graphene nanosheets with high quality and few defects were functionalized by polystyrene sulfonate. • Fire safety and mechanical strength of the functionalized graphene/polystyrene nanocomposites were improved. • Favorable dispersion, compatibility and interfacial interaction contributed to the enhancement of PS nanocomposites. [ABSTRACT FROM AUTHOR]

The inherent chemical inertness presents a huge challenge for the functionalization of hexagonal boron nitride (h-BN), thus limiting its potential in flame retardant and toxic gas suppression of thermoplasticity polyurethane (TPU). Here, with the assistance of Lewis acid-base interactions, an operable platform formed by SiO 2 coating is constructed onto the surface of h-BN nanosheets, offering an opportunity for introducing phytic acid (PA). The resultant h-BN nanohybrids present an enhancement effect for flame retardancy of thermoplastic polyurethane (TPU), confirmed by obvious reductions in peak value of heat release rate (−23.5%) and total heat release (−22.1%). Meanwhile, the smoke product rate and total smoke release of TPU composite containing 2.0 wt% h-BN nanohybrids are decreased by 29.2% and 8.6%, respectively. Through CO 2 detector and AtmosFIR, specially, it is found that the toxic gases (CO, CH 4 , C 2 H 6 , TOC) are turned into CO 2. Through a series of analytic methods, it was found that the introduced PA suffered from a pre-gradation process to release P-containing compounds, reacting with TPU matrix to produce protective char. In addition, the presence of SiO 2 was also contributed to improve the robustness of char residue. In view of high temperature condition, the catalysis effect of h-BN is responsible for the conversion of toxic gases. Therefore, the enhanced fire safety of TPU was attributed to the cooperation mechanism of h-BN, SiO 2 , and PA. Such a functionalization approach provides a novel route to overcome the chemical inertness of h-BN, thus promoting its application in fire safety fields of polymer materials. Image 1 • Chemical inertness of h-BN nanosheets was overcame. • Heat release of TPU was decreased by h-BN@SiO 2 @PA. • Toxic combustion gases were turned into CO 2. • The break strength of TPU was effectively enhanced. [ABSTRACT FROM AUTHOR]

The SiO 2 @metal organic framework (Universitetet i Oslo-66, UiO-66) core–shell microspheres were constructed through covalent linkage between amine groups in UiO-66-NH 2 and epoxy groups on the surface of silica. The morphology and size of the SiO 2 @UiO-66 core–shell microspheres could be simply controlled by tuning the ratio between UiO-66-NH 2 and epoxy terminated silica (E-SiO 2). As observed by TEM, the SiO 2 @UiO-66 hybrids showed better dispersion state within epoxy matrix compared to either E-SiO 2 or UiO-66-NH 2. The incorporation of SiO 2 @UiO-66 hybrids slightly promoted the thermal degradation of the resultant epoxy composites but improved residual yield. The dynamic mechanical analysis results indicated that the SiO 2 @UiO-66 hybrids slightly increased the glass transition temperature and the modulus. The SiO 2 @UiO-66 hybrids exhibited higher efficiency in reducing the heat release rate and the smoke production rate compared to either E-SiO 2 or UiO-66-NH 2. The influence of the component ratio in SiO 2 @UiO-66 on flame retardancy of the epoxy composites was also studied by cone calorimeter. Specifically, the SiO 2 @UiO-66 hybrid with medium ratio (SiO 2 @UiO-66-2) exhibited maximum reduction in peak heat release rate (−31%), total heat release (−23%) and total smoke production (−16%). The char residues were investigated by the Fourier transform infrared spectra, scanning electron microscopy and X-ray photoelectron spectroscopy, which demonstrated that the enhanced flame retardancy of EP/SiO 2 @UiO-66-2 was attributable to the continual morphology and high thermal resistance originated from the presence of the silicon and zirconium complex. These favorable characteristics including high flame retardant efficiency and good smoke suppression make SiO 2 @UiO-66 hybrids promising for flame retardant polymers application. • The SiO 2 @UiO-66 hybrids showed core–shell microsphere structure. • The addition of 3 wt% SiO 2 @UiO-66-2 caused 31% reduction in peak heat release rate. • The addition of 3 wt% SiO 2 @UiO-66-2 led to 16% reduction in total smoke production. [ABSTRACT FROM AUTHOR]

• Boric acid treated highly aligned fibers reinforced epoxy composite was prepared. • The tensile strength of the resultant composite increased by 234% relative to epoxy. • The impact strength of the resultant composite increased by 177% relative to epoxy. • The peak heat release rate of the resultant composite was decreased by 63%. We report a simple and effective approach to process natural bamboo directly into a high-performance composite material with light weight, high tensile strength, high modulus, and low flammability. Our process involves delignification of natural bamboo followed by surface treatment of highly aligned cellulose fibers in the delignified bamboo and finally infiltration of epoxy resin into the porous structure of the surface-treated delignified bamboo. Surface treatment of the highly aligned cellulose fibers by boric acid (BA) under alkaline conditions resulted in the formation of cross-linked structures between the hydroxyl groups of BA and the diol or carboxylic groups of the cellulose backbone. Because the aligned bamboo fibers were well-preserved, the BA-bamboo/epoxy composite showed increases of 234% and 177% in tensile strength and impact strength, respectively, compared to the pristine epoxy. The BA-bamboo/epoxy composite exhibited comparable mechanical properties but significantly improved flame retardancy compared to the delignified bamboo/epoxy composite. Specifically, the limiting oxygen index of the BA-delignified bamboo/epoxy composite was 26.5% larger and the peak heat release rate was 63% smaller than those of the pristine epoxy resin in cone calorimeter measurements. Thermogravimetric analysis indicated that BA promoted charring of the bamboo/epoxy composite, which was responsible for the significantly improved flame retardancy. The simultaneous enhancement of the mechanical properties and flame retardancy makes such bamboo-based composites highly suitable for use as structural materials. [ABSTRACT FROM AUTHOR]