Smoke Suppression Performance Research Articles

Flame retardant and smoke suppression properties of 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene 10‐oxide derivative/zinc molybdate sepiolite modified acrylate emulsion

AbstractAcrylate emulsion is widely used in various industrial fields and is an important polymer emulsion. However, the high flammability limits its application. Besides, acrylate emulsion generally releases a large amount of smoke during combustion. To improve the fire resistance and smoke suppression properties of acrylate emulsions, methyl methacrylate‐butyl acrylate copolymer P(MMA‐BA)/DOPO‐based polymerizable monomer (HEPO)/zinc molybdate sepiolite (Mo‐Sep) composite emulsion was prepared by emulsion polymerization, and the effect of Mo‐Sep content on the flame‐retardant performance, thermal stability, and smoke suppression performance of the composite emulsion was studied. Through microcalorimeter and smoke density meter tests, it was found that the heat release rate (HRR) of the composite emulsion, added with 30% HEPO/3% Mo‐Sep, was reduced by 63.3%, and the peak heat release rate (PHRR) was reduced by 72.1%. The total heat release (THR) is reduced by 49.0%, while the peak‐specific optical density is reduced by 48.0%. It shows that the composite emulsion has excellent flame‐retardant and smoke suppression properties compared to pure MAA‐BA emulsion. In addition, scanning electron microscope (SEM) images show that the addition of Mo‐Sep increases the density of carbon residue. This composite emulsion may have potential application scenarios in the field of flame‐retardant coatings.

Highly Efficient Phosphazene-Derivative-Based Flame Retardant with Comprehensive and Enhanced Fire Safety and Mechanical Performance for Polycarbonate.

Polycarbonate (PC) as a widely used engineering plastic that shows disadvantages of flammability and large smoke production during combustion. Although many flame-retardant PCs have been developed, most of them show enhanced flame retardancy but poor smoke suppression or worsened mechanical performance. In this work, a novel nitrogen-phosphorus-sulfur synergistic flame retardant (Pc-FR) was synthesized and incorporated into PC with polytetrafluoroethylene (PTFE). The extremely low content of PC-FR (0.1-0.5 wt%) contributes significantly to the flame retardancy, smoke suppression and mechanical performance of PC. PC/0.3 wt% Pc-FR/0.3 wt% PTFE (PC-P0.3) shows the UL-94 V-0 and LOI of 33.5%. The PHRR, THR, PSPR, PCO and TCO of PC-P0.3 decreased by 39.44%, 14.38%, 17.45%, 54.75% and 30.61%, respectively. The impact strength and storage modulus of PC-P0.1 increased by 7.7 kJ/m2 and 26 MPa, respectively. The pyrolysis mechanism of PC-P0.3 is also revealed. The pyrolysis mechanism of PC-P0.3 is stochastic nucleation and subsequent growth and satisfies the Aevrami-Erofeev equation. The reaction order of PC-P0.3 is 1/2. The activation energy of PC-P0.3 is larger than PC-0, which proves that the Pc-FR can suppress the pyrolysis of the PC. This work offers a direction on how to design high-performance PC.

Synthesis of antioxidant functionalized nano-TiO2 for improving fire resistance and UV-shielding behavior of intumescent fire-retardant coatings for cable

A unique hybridized antioxidant named TiO2-KH550-PA, of which silane modified nano-TiO2 particles were grafted with 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid by acylation reaction, was applied to intumescent fire-retardant coatings for cable. Through fire protection test, contact angle test, thermogravimetric test and UV-ageing test, the effects of TiO2-KH550-PA on hydrophobicity, flame retardancy, smoke suppression, anti-ageing and charring performance for coatings were evaluated. The obtained results indicate that the TiO2-KH550-PA can enhance the hydrophobicity of the coating, thereby reducing the adhesion of dust on the coating surface. Additionally, TiO2-KH550-PA has a greatly promoting role in strengthening the fire protection abilities of the coating, but an appropriate amount is the key. Compared to coatings without composite, the intumescent fire-resistant coating for cable containing 1 wt% TiO2-KH550-PA (IFRCC2) exhibits excellent fire protection performance, including a prolongation by 2.6 times in failure time, an increase by 1.7 times in char layer height, and an increase by 0.4 times in light transmittance for smoke density test. Furthermore, the presence of TiO2-KH550-PA can also strengthen the oxidation resistance, charring ability and char layer stability of the coating, when the remaining mass of IFRCC2 increases to 49.0 % at 800 °C. The anti-ageing performance test demonstrates that the TiO2-KH550-PA can absorb ultraviolet light, eliminate free radicals, and raise the structural stability of the coating, thus reinforcing the durability of the fire resistance for the coating.

Construction of Fire Safe Thermoplastic Polyurethane/Reduced Graphene Oxide Hierarchical Composites with Electromagnetic Interference Shielding.

Incorporating outstanding flame retardancy and electromagnetic interference shielding effectiveness (EMI SE) into polymers is a pressing requirement for practical utilization. In this study, we first employed the principles of microencapsulation and electrostatic interaction-driven self-assembly to encapsulate polyethyleneimine (PEI) molecules and Ti3C2Tx nanosheets on the surface of ammonium polyphosphate (APP), forming a double-layer-encapsulated structure of ammonium polyphosphate (APP@PEI@Ti3C2Tx). Subsequently, flame-retardant thermoplastic polyurethane (TPU) composites were fabricated by melting the flame-retardant agent with TPU. Afterwards, by using air-assisted thermocompression technology, we combined a reduced graphene oxide (rGO) film with flame-retardant TPU composites to fabricate hierarchical TPU/APP@PEI@Ti3C2Tx/rGO composites. We systematically studied the combustion behavior, flame retardancy, and smoke-suppression performance of these composite materials, as well as the flame-retardant mechanism of the expansion system. The results indicated a significant improvement in the interface interaction between APP@PEI@Ti3C2Tx and the TPU matrix. Compared to pure TPU, the TPU/10APP@PEI@1TC composite exhibited reductions of 84.1%, 43.2%, 62.4%, and 85.2% in peak heat release rate, total heat release, total smoke release, and total carbon dioxide yield, respectively. The averaged EMI SE of hierarchical TPU/5APP@PEI@1TC/rGO also reached 15.53 dB in the X-band.

Functionalized Zr‐MOFs for Enhancing Flame Retardancy and Smoke Suppression Performance on TPU

AbstractMetal‐Organic Framework (MOF) materials can be used as flame‐retardants and smoke suppressants for polymers. As a MOF material, UIO‐66(Zr) possesses higher thermal stability and controllable pore size. In this paper, UIO‐66(Zr), NH2‐UIO‐66(Zr), and SiO2, MWCNT, and GO functionalized NH2‐UIO‐66(Zr) was fabricated to improve the flame retardant and smoke suppression performance of thermoplastic polyurethanes (TPU). The experimental results show that compared with neat TPU (LOI value 19.1 %), 2 % usage of UIO‐66(Zr) and NH2‐UIO‐66(Zr) can endow TPU with 26 % LOI value and vertical combustion rating of V‐1. Moreover, SiO2, MWCNT, and GO functionalized NH2‐UIO‐66(Zr) provide TPU with above 27.8 % LOI value and vertical combustion rating of V‐0. Meanwhile, the CCT results showed that the peak heat release rate and total heat release of TPU‐U5 (added 2 % GO‐modified NH2‐UIO‐66(Zr)) are 299.52 Kw ⋅ m−2 and 68.21 MJ m−2, much lower than that of neat TPU, which are 1180.05 Kw ⋅ m−2and 104.87 MJ m−2, respectively. The TGA, char residue EDS and XRD analysis show that SiO2, MWCNT, and GO functionalized NH2‐UIO‐66(Zr) could generate zirconium metal oxide during the combustion process, which acts as a physical barrier to prevent the TPU matrix by promoting the generation of carbonization layer. The zirconium metal oxide and carbonization layer also can confine flammable gases, which can delay the ignition time and hinder the overflow of gas. In addition, NH2‐UIO‐66(Zr) could generate non‐flammable N2 diluting the concentration of flammable gases. The mechanical properties of TPU composites can maintain more than 87 % of the neat TPU after the addition of 2 % SiO2, MWCNT, and GO functionalized NH2‐UIO‐66(Zr). These results indicate that functionalized Zr‐MOFs composites could act as excellent flame‐retardants in TPU.

Preparation of a Flame-Retardant Curing Agent Based on Phytic Acid-Melamine Ion Crosslinking and Its Application in Wood Coatings.

To broaden the applications of wood, it is necessary to prepare flame-retardant coatings that can protect wood substrates during combustion. In this study, a bio-based, intumescent, flame-retardant phytic acid-melamine polyelectrolyte (PM) was prepared using phosphorus-rich biomass phytic acid and nitrogen-rich melamine as raw materials through an ion crosslinking reaction. Subsequently, a series of bio-based, flame-retardant wood coatings were prepared by optimizing the structure of urea-formaldehyde resin with the addition of melamine, sodium lignosulfonate, and PM as a flame-retardant curing agent. Woods coated with PM-containing coatings displayed significantly improved flame-retardant performances in comparison to uncoated woods. For PM-cured woods, the measured values of total heat release and total smoke production were 91.51% and 57.80% lower, respectively, compared with those of uncoated wood. Furthermore, the fire growth index decreased by 97.32%, indicating a lower fire hazard. This increase in flame retardancy and smoke suppression performance is due to the dense expanded carbon layer formed during the combustion of the coating, which isolates oxygen and heat. In addition, the mechanical properties of the flame-retardant coatings cured with PM are similar to those cured with a commercial curing agent, NH4Cl. In addition, the prepared flame-retardant coating can also stain the wood. This study proves the excellent flame-retarding and curing effect of ammonium phytate in urea-formaldehyde resin coatings and provides a new approach for the application of bio-based flame retardants in wood coatings.

Improved flame resistance and thermal insulation properties of steel fireproof coatings based on polyvinyl alcohol @ expandable graphite

Intumescent fireproof coating (IFC) can effectively slow down the temperature rise of base materials by constructing intumescent heat isolation chars. Expandable graphite (EG), combined with a typical intumescent flame-retardant system, shows an excellent expansion effect. However, it is difficult to be evenly dispersed in the coating system due to its low surface energy, thus limiting its application in IFC. In this research, EG encapsulated by polyvinyl alcohol (PVA) film was used in combination with conventional intumescent flame retardants to prepare a fireproof coating. Due to the increased hydrophilicity caused by the hydroxy groups of the PVA, both the dispersion and adhesion of EG can be greatly improved in the coating. Additionally, PVA also plays the role of a charring agent to further upgrade the quality of the produced carbon layer. The prepared IFC displays a satisfying synergistic effect. The experimental results showed that the back-surface temperature of the steel plate coated by PVA@EG was reduced to 232 °C after 20 min, far lower than the 250 °C of the unmodified EG system, and the thermal insulation performance was enhanced significantly. Compared with the untreated EG coating, the HRR, THR, and TSR decreased by 79.5 %, 86.0 % and 24.8 %, respectively, and combustion and smoke suppression performance were improved greatly. All in all, PVA@EG endows the coating with superior flame-retardant and thermal insulation performance and greatly improves the safety of steel structures in buildings.

A promising strategy for enhancing fire resistance of steel structure: a composite thermoplastic polyurethane sheet adhered to steel plate

It is an effective passive fire protection method for the steel structure by painting fireproof coatings. Here, a feasible strategy for enhancing the fire resistance of steel structures is proposed. Specifically, a kind of adhesive composite sheet based on thermoplastic polyurethane (TPU), ammonium polyphosphate (APP), polyhedral oligomeric octaphenylsilsesquioxane (OPS), titanium dioxide (TiO2) and sodium silicate was constructed and named as Sheet-Ti/Na. The as-prepared Sheet-Ti/Na exhibited excellent flame retardancy and smoke suppression performance. In addition, the Sheet-Ti/Na can firmly adhere to the steel plate through hot pressing and adhesive bonding methods, acting as a non-traditional fireproof “coating”. This feasible coating method can effectively enhance the fireproof and thermal insulation of the steel plates under the action of the hydrocarbon fire at about 1100 ℃. After testing, the char layer of Sheet-Ti/Na can still firmly adhere to the steel plate without any detachment or cracking. Finally, a ceramic-like reaction among TiO2, APP, OPS and sodium silicate to generate pyrophosphates (TiP2O7 and SiP2O7) was clarified. The thermal insulation, flame retardancy and smoke suppression mechanisms of the Sheet-Ti/Na system also were stated. This work offers a promising strategy for rapidly and efficiently preparing fireproof and thermal insulation “coatings” for steel structures.

Synthesis of CoMn‐LDH@MXene Hybrid Materials as Flame Retardant to Effectively Improve the Fire Safety of Thermoplastic Polyurethane

AbstractIn recent years, MXene 2D materials have shown good performance in enhancing the flame retardant properties of composite materials, but it is still tricky to improve the compatibility with the polymer matrix. This work explores a simple method for the synthesis of MXene based nanohybrids (CoMn‐LDH@MXene) by hydrothermal synthesis using MXene and layered double hydroxides (CoMn‐LDH) to construct a flame retardant system with excellent performance. The results show that the MXene nanosheets are less built up and more dispersed in the TPU collective due to the inclusion of LDH, giving the TPU composites excellent flame retardant and smoke suppressant properties. Compared to TPU without flame retardant, TPU composites with 2 wt% CoMn‐LDH@MXene reduced PHRR by 33.7 % and THR by 28.7 %. The TPU/2wt %CoMn‐LDH@MXene composites also showed better flame and smoke suppression performance, PSPR, TSP, PCO and PCO2 were reduced by 44.4 %, 22.7 %, 37.7 % and 27.2 % respectively, the production of Hydrocarbons and HCN were also reduced. Barrier effect of transition metal oxide catalysed carbon layer formation, combustion blocking effect of hybrid material nanosheets, cooling effect of water vapour from thermal decomposition of LDH and the gas phase dilution effect are the main reasons for the increased fire safety of TPU composites.

Preparation of bio‐based soybean oil polyol modified 3630 polyol‐based rigid polyurethane foam and its improved thermal stability, flame retardant, and smoke suppression performances

AbstractRigid polyurethane foam (RPUF) with 3630 polyol‐based components was modified using bio‐based soybean oil (SO) polyol. The effects of soybean oil polyol on the thermal stability, flame retardant and smoke suppression performances of the modified RPUFs were investigated by thermogravimetric analysis, integral programmed decomposition temperature (IPDT), pyrolysis kinetic analysis, limiting oxygen index, conical calorimetry and smoke toxicity analysis. The results indicated that the RPUF‐SO2 (10 wt% soybean oil polyol) had the highest thermal decomposition rate temperature, initial thermogravimetric temperature, termination temperature, residual rate, IPDT and activation energy. Under various circumstances, the total heat release (THR) of RPUF‐SO2 was 1.41, 1.61, and 2.51 MJ/m2, respectively, and the peak heat release rate (PHRR) was lowered by 22.40%, 45.68%, and 19.86% in comparison to the original RPUF‐0. In the meantime, RPUF‐SO2 had the best light transmittance (57.20 and 60.60%), the lowest toxic gas emissions (0.31, 0.44, and 0.38 kg/s), and the lowest Ds (32.46 and 29.07). It also had an excellent smoke suppression effect. According to the current study, RPUF‐SO2 performed better in terms of heat stability, flame retardancy and smoke suppression. This made it a good benchmark for further bio‐based soybean oil polyol modified RPUFs.

A Gas-Steamed Route to Mesoporous Open Metal-Organic Framework Cages Enhancing Flame Retardancy and Smoke Suppression of Polyurea.

Up to now, metal-organic frameworks (MOFs) with open nanostructures have shown outstanding capabilities in trapping smoke particles compared to the original MOFs. However, only a few MOF-based strategies have been reported to synthesize hierarchical porous cages thus far, which are mainly restricted to environmentally unfriendly wet-chemical liquid methods. Herein, as a proof-of-concept, a gas-steamed metal-organic framework approach was designed to fabricate a series of cheeselike open cages with hierarchical porosity. Briefly, zeolitic imidazolate framework-67 (ZIF-67) and phytic acid were employed as precursor and etchant, respectively. Abandoning the conventional wet-chemical method, the coordination bond of ZIF-67 was cleaved by acidic steam, forming an open framework with a high specific surface area and a hierarchical porous structure. The universality of this method was also confirmed by the selection of different etchants. Impressively, they also show outstanding fume-toxic adsorption capability and labyrinth effects based on abundant and complex porous channels. At only 5 wt % loading, Co3O4@open ZIF-67 cage-2 (Co3O4@OZC-2) imparted polyurea (PUA) composites with a 21.2% limiting oxygen index, and the peak of heat release rate, total heat release, and total smoke production were reduced by around 37.5, 25.5, and 40.4%, respectively, compared to neat PUA. This work will shed light on the advanced structural design of polymer composites with high fire safety, especially smoke suppression performance, so as to obtain more feasible applications.

A biphosphophenanthrene structure intumescent flame retardant with superior smoke suppression performance for epoxy resin

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.

Preparation and thermostability of a Si/P/N synergistic flame retardant containing triazine ring structure for cotton fabrics

A new synergistic flame retardant named Bisiminopropyl trimethoxysilane-1,3,5-triazine-O-bicyclic pentaerythritol phosphate (BTPODE) was synthesized, which is a type of Si/P/N flame retardant. This was accomplished by grafting aminopropyl trimethoxysilane and bicyclic pentaerythritol phosphate onto a triazine ring structure, serving as an intermediate. The structure of BTPODE was determined using nuclear magnetic resonance (1H NMR, 13C NMR, and 31P NMR) and Fourier transform infrared spectroscopy (FT-IR). SEM was used to detect the surface morphology of cotton fabrics, which suggested that BTPODE had been resoundingly stick to cotton fabrics. The flame retardant properties of cotton fabrics were evaluated by measuring the limiting oxygen index (LOI) and conducting vertical flammability experiments. Cotton fabrics with a weight gain of 20.73 % achieved an LOI value of 32.5 %. Thermogravimetric (TG) experiments demonstrated the samples' good thermostability. Furthermore, under nitrogen conditions, the char residue of cotton fabric with a weight gain of 20.73 % was 36.85 %. The cone calorimetry test (CONE) showed a significant reduction in the TSP value, indicating a certain level of smoke suppression performance. Finally, based on the obtained experimental results, the fire-retardant mechanism principle of the flame retardant was deduced.

The preparation of layered double hydroxide wrapped with triazine-based organic framework to enhance the flame retardancy for polypropylene

Layered double hydroxide (LDH) can be used as a flame retardant (FR) for polypropylene (PP) because of its excellent flame retardancy and smoke-suppression effects. However, the agglomeration of LDH seriously affects its dispersity in the PP matrix, thus limiting its application as a FR polymer. This study aimed to enhance the dispersion of LDH in the PP matrix for improving its flame retardancy performance. Herein, a reactive triazine-based organic framework (TOF) was designed and formed by the in situ polymerisation of cyanuric chloride and melamine, and then the LDH surface was covered with TOF to obtain a novel core–shell FR (LDH@TOF), with TOF as the ‘shell’ and LDH as the ‘core’. Subsequently, LDH@TOF was melted into the PP matrix as nanofillers to prepare PP and LDH@TOF composites (PP/LDH@TOF). As expected, the PP/LDH@TOF composites exhibited superior flame-retarding performance (limiting oxygen index of 29.2% and UL-94 V-0 rating) and favourable smoke-suppression performance at 20 wt% of LDH@TOF loading. Moreover, the peak heat release rate, total heat release and total smoke production of PP/LDH@TOF composites decreased by 29.9%, 12.1% and 12.4%, respectively, compared with those of PP and LDH composites. The outstanding flame retardancy properties of the PP/LDH@TOF composites were attributed to the better dispersibility of LDH@TOF in the PP matrix, the synergy of the physical barrier effect of nanosheets and the dense carbonisation acceleration of LDH@TOF. The findings of this study provide a highly efficient approach for functionalising LDH for expanding its application value of PP composites.

Effect of Compounded Aluminum Hydroxide Flame Retardants on the Flammability and Smoke Suppression Performance of Asphalt Binders.

Compounded aluminum hydroxide (ATH) flame retardants have been widely used for their low cost and environmentally friendly characteristics. However, previous research lacks a systematic and comprehensive comparison. In addition, the combustion characteristics and phase characterization of asphalt binders are not taken into account either. In this work, flame retardants, for instance, APP, Sb2O3, ZB, and LDHs, were compounded with ATH. The flame retardant behavior, together with the smoke suppression behavior, of asphalt binders with compounded flame retardants was determined by LOI and CCT. Furthermore, mechanisms on flame retardants were investigated. It was found that ATH compounded with ZB significantly reduced the heat smoke release and suppressed the formation of toxic volatiles during asphalt combustion. This was because ATH/ZB facilitated the formation of polyaromatic structures and improved the resistance of the char layer. ATH compounded with APP showed an antagonistic effect in the limiting oxygen test because the reaction between ATH and APP inhibited and delayed the decomposition of ATH during asphalt combustion with more aluminum phosphate presenting relatively poor barrier properties produced.

Intercalated kaolinite with ammonium dihydrogen phosphate as an effective flame retardant to enhance the flame retardance and smoke suppression of epoxy resins

AbstractTo improve the compatibility and flame retardance of kaolinite (Kaol) in polymeric materials, ammonium dihydrogen phosphate (ADP) was intercalated into kaolinite to obtain a novel intercalated kaolinite (K‐ADP) for enhancing thermal stability, flame retardance, smoke suppression, and mechanical performance of epoxy resins (EPs). The results show that the presence of K‐ADP exerts a more positive effect on reducing the heat release and smoke generation of EPs than the same addition of Kaol. Condensed phase analysis shows that EP/K‐ADP composite generates more aromatic cross‐links in the condensed phase to reinforce the compactness and intumescence of char compared to EP/Kaol composite. Especially, 5 wt% K‐ADP confers a 43.7% reduction in peak heat release rate value and a 36.3% reduction in peak smoke production rate value to EP. Toxic gases analysis shows that K‐ADP conduces to inhibiting the release of combustible gases including isocyanates and aromatic volatiles, and generating incombustible gases including ammonia and carbon dioxide to reduce the intensity of EP combustion. The mechanical test shows that K‐ADP imparts less adverse impact on mechanical behavior to EP composites than Kaol due to the good dispersion and compatibility between K‐ADP with EP matrix.

Preparation and performance of intumescent water-based coatings with both thermal insulation and flame retardant functions

Functional flame retardant polymer materials are of great strategic relevance in reducing energy consumption in the wake of accelerated advances in materials science. In this paper, boehmite sol was employed to modify the surface of hollow glass microspheres (HGMs), self-designed a new type of intumescent flame retardant with melamine polyphosphate and starch (M-S system), which subsequently achieved synergistic flame retardant effects and produced high-performance water-based HGMs@Al2O3/M-S composite coatings that could be successively manufactured. As revealed from findings, HGMs@Al2O3 retained the fundamental structure and characteristics of HGMs and enhanced the interfacial compatibility with the water-based polymer matrix. The thermal conductivity of 0.097 W/(m·K) was achieved at 7 wt% HGMs@Al2O3, which notably strengthened the fire resistance of the coating when compounded with 20 wt% M-S. HGMs@Al2O3 also acted as a catalyst for carbon formation and achieves self-extinguishing off fire when the LOI value reached 36 % and UL94 passed the V-0 test. The maximum pyrolysis temperature of the HGMs@Al2O3/M-S composite coatings was 410.1 °C. The results of conical calorimetry indicate that the HRR were reduced by 76.9 % and the THR by 83.8 %, the superior smoke suppression performance of the material. FPI and FGI were 0.21 m2s/kW and 3.02 kW/m2/s separately, indicating a significant improvement in the fire performance of the material, with high residual carbon strength. When burned, HGMs@Al2O3 migrates to the surface of the material and acts as a flame retardant. It demonstrates that the material is superior to previous resemble products and has tremendous potential for application and further industrialization.

Improvement of the flame retardance of epoxy resin composites reinforced with cyclodextrin phosphate melamine salt

AbstractEpoxy resin is widely applied in civil aircraft, automobile and electronics products because of its good processing, adhesion, and mechanical properties, but its application is limited due to its easy combustion. Therefore, it is worthwhile to carry out flame‐retardant treatment for epoxy resin. In this study, a new bio‐based three‐source integrated intumescent flame‐retardant cyclodextrin phosphate melamine salt (CDPM) was synthesized from β‐cyclodextrin, phosphoric acid, and melamine, and it was employed as an additive flame retardant to fabricate CDPM/epoxy resin (CDPM/EP) composites. Thermogravimetric analysis results manifested that CDPM slightly improved the thermal stability of CDPM/EP composites. The CDPM/EP composite containing 10 wt.% CDPM acquired a limiting oxygen index of 32.9% and passed UL94 V‐0 rating. Moreover, the peak heat release rate, total heat release, and total smoke production, were respectively decreased by 46.4%, 55.5%, and 61.8% in contrast with neat epoxy resin. These results demonstrated that CDPM/EP could exert excellent flame retardance and smoke suppression performance. Scanning electron microscope and Raman results confirmed that CDPM facilitated the formation of residual char. Moreover, thermogravimetric/infrared results showed that CDPM/EP produced plenty of phosphorus‐containing free radicals and nonflammable NH3 during pyrolysis process, which played a good flame retardance effect in gas phase. This study provides a new approach for the design and development of low‐cost intumescent bio‐based flame retardant for epoxy resin.Highlights Novel three‐source intumescent bio‐based flame‐retardant CDPM was successfully synthesized. CDPM was incorporated into epoxy resin as an additive flame retardant. Only 10 wt.% CDPM provided 55.5% and 61.8% reductions of total heat release and total smoke production, respectively. CDPM/EP composites exhibited an excellent flame retardancy and smoke suppression properties. The outstanding promoting carbonization effect of CDPM in condensed phase contributes to reduce the release of heat and smoke.

Core-shell flame retardants based on Chitosan@MMT coated ammonia polyphosphate for enhancing flame retardancy of polyurethane

In this manuscript, the core-shell flame retardants based on chitosan@MMT coated ammonia polyphosphate (APP@CS@MMT) was prepared and then incorporated into the TPU matrix. Through analyzing the effects of the flame retardant on the property reinforcements, it’s found that TPU/APP@CS@MMT composites have the excellent flame retardant and smoke suppression performance. The pHRR, THR, pSPR and TSP of TPU/APP@CS@MMT composites were remarkably decreased by 62.58%, 71.56%, 90.43%, 83.22%, and 93.60%, respectively. Furthermore, the mass of residual chars increased significantly from 0.85% for pure TPU to 21.95% for TPU/APP@CS@MMT composites. The TPU/APP@CS@MMT composites can improve both the flame-retardant and smoke suppression performances of TPU. Through the thermogravimetric test, cone calorimetry test, and char structure analysis, the flame retardant mechanism of the TPU/ APP@CS@MMT composites was also investigated. The APP@CS@MMT mainly plays its flame retardant role in the condensed phase. This work also provides a green and facile methodology for creating flame retardant TPU and helps broaden the TPU’s practical application in industry.

Biomass intumescent flame retardant polyacrylonitrile composite: flame retardancy, smoke suppression and recycling

A fully biomass intumescent flame retardant (IFR) system was fabricated by combining the reaction product ([email protected]) of phytic acid (PA) and hydrolyzed silk (HS) with potato starch (PS), which was then blended with polyacrylonitrile (PAN) to obtain flame retardant PAN (FR-PAN). The tensile strength and elongation at break for PAN-10%[email protected]/5%PS sample increased by 18.8% and 86.3%. The peak heat release rate (PHRR) and peak smoke production rate (PSPR) decreased by 54.8% and 79.3% respectively, exhibiting excellent flame retardant and smoke suppression performance. Furthermore, the PAN-10%[email protected]/5%PS sample was carbonized to prepare FR-PAN Char (FRPC), which was then used for cellulose and polyvinyl alcohol (PVA) modification. The maximum thermal decomposition rate and PHRR of modified cellulose and PVA were significantly reduced, showing the improved fire safety. This work not only prepared an eco-friendly fully biomass flame retardant PAN composite, but also realized the successful recycling of waste flame retardant PAN materials.