Thermogravimetric Analysis/infrared Spectrometry Research Articles

The influence of well-dispersed mesoporous hydroxystannate ferrate anchored magnesium hydroxide hybrids on enhancing interfacial compatibility and fire safety of EVA/EPDM composites

In this work, an innovative methodology for enhancing the fire safety of EVA/EPDM (EE) composites by employing an in-situ encapsulation technique to integrate magnesium hydroxide (MH) within the mesoporous hydroxystannate ferrate (mHSF) framework via ion-driven self-assembly. Comprehensive characterization involving X-ray diffraction, scanning electron microscopy, and transmission electron microscopy was employed to investigate the structure, elemental composition, and morphology of the resulting hybrids. In comparison to EE/MH composites, the MH@mHSF hybrids exhibited favorable dispersion within the EE matrix, demonstrating minimal aggregation. Upon incorporation of MH@mHSF hybrids, a significant reduction in peak heat release rate and total heat release (73.5 and 50%) compared with pristine EE, and an achievement in limiting oxygen index value of 32.5% from 19% for pristine EE was achieved. Notably, when contrasted with the findings of EE/MH/mHSF, the EE/MH@mHSF composite showcased superior tensile strength and enhanced fire safety properties. This improvement can be ascribed to the catalytic charring behavior and adsorption effects facilitated by well-dispersed MH@mHSF hybrids within the polymer matrix. Thermogravimetric analysis/infrared spectrometry (TG-IR) corroborated a substantial reduction in organic volatiles and the suppression of carbon monoxide emissions upon integration of MH@mHSF hybrids, underscoring the alleviation of fire hazards. The observed synergy of the catalytic and adsorption effects of mesoporous HSF, combined with the flame-retardant characteristics of MH, plays a pivotal role in the suppression of smoke generation.

Synthesis and Properties of Moisture‐Crosslinkable Poly(Urethane‐Urea) With Intrinsic Flame Retardancy

To improve the deteriorated performance caused by CO2 release during the curing process of traditional moisture‐crosslinked polyurethane or polyurea and poor flame retardancy, this work realized an effective in situ crosslinking technique triggered by moisture for poly(urethane‐urea) with intrinsic flame retardancy, through the incorporation of trimethoxysilane and phosphorus groups via a continuous two‐stage process. Moisture‐triggered crosslinking reaction of trimethoxysilane groups resulted in the establishment of a robust Si─O─Si network, as confirmed by Fourier transform infrared spectroscopy (FTIR) test. The structure transformation considerably enhanced the material’s strength, with the stress at break increasing from 1.0 to 3.2 MPa and modulus from 32.9 to 46.9 MPa. The flame retardant properties of PUUS1 (poly(urethane‐urea) sample) were investigated through limiting oxygen index (LOI) and cone calorimeter (CCT) analysis, demonstrating satisfactory flame resistance, as evidenced by high LOI value of 29%, high char yield of 46.2%, and controlled smoke production. Combining thermogravimetric analysis‐infrared spectrometry (TG‐IR), X‐ray photoelectron spectroscopy (XPS), and flame retardant performance, it is speculated that the generation of phosphorus‐free radical scavengers in gas phase from diethyl bis(2‐hydroxyethyl) aminomethyl phosphonate (DBHAP), coupled with the barrier effects of charred layer and distinctive Si─O─Si framework in condensed phase inhibited combustion and toxic gas emission. The results highlight the successful synthesis of a moisture‐crosslinkable poly(urethane‐urea) with intrinsic flame retardancy, promising for applications necessitating moisture‐crosslinkable materials with superior flame resistance.

Application of Silver-Loaded Halloysite Nanotubes in Flame Retardant and Smoke-Suppressive Coating for Polyester-Cotton Fabric.

Despite the wide applications in clothing, furniture, and transportation, the well-known "scaffolding effect" in polyester-cotton fabric has caused significant fire hazards compared to sole polyester or cotton fabrics. Therefore, it is of practical significance to endow polyester-cotton fabric with excellent fire safety. In this work, an organic-inorganic composite coating comprising nitrogen-phosphorus-silicon-containing flame retardant and silver nanoparticle-loaded halloysite nanotubes (Ag@HNTs) was designed and prepared to improve the fire safety of polyester-cotton fabrics. Microscale combustion colorimeter results indicated that the peak heat release rate of the modified polyester-cotton fabric with such a composite coating was reduced by 47%. Meanwhile, it could self-extinguish in 9 s after being ignited, and the limiting oxygen index was up to 25%, indicating excellent fire safety. In addition, the total smoke release of the coated polyester-cotton fabric was reduced by 21%, illustrating that the coating of Ag@HNTs could eliminate the smoke generated. The treated fabric also exhibited superior water resistance. Flame retardant mechanisms were well investigated using thermogravimetric analysis-infrared spectrometry analysis and chemiluminescence by studying the gaseous degradation products and hydroxyl radical in the gas phase. This work provides an effective approach to fabricating high-performance flame retardant and smoke-suppressive coatings for textiles.

Facile Preparation and Improved Electrochemical Performance of Oxygen‐Enriched Porous Carbon Materials Based on Diacetal‐Containing Polybenzoxazine

AbstractPorous oxygen‐doped carbon materials based on the copolymers of a diacetal‐type benzoxazine (ACE‐a) and melamine with different ratios are prepared by a facile template‐free method. The oxygen‐rich diacetal structure in ACE‐a allowed for a high oxygen content of 66.2% in surface in these porous carbon materials, and the degradation of the melamine at a high temperature gave an ideal pore structure with a specific surface area of 1383.9 m2 g−1 and a pore capacity of 0.748 cm3 g−1. The electrochemical performances are analyzed by Cyclic voltammetry (CV) and Galvanostatic charge‐discharge (GCD) tests, and the effects of melamine contents and electrolyte types are also investigated. The results suggested that this material possessed specific capacitance of 430 F g−1 in 0.5 M H2SO4 and 194 F g−1 in 6 M KOH (0.5 A g−1), respectively, and showed excellent charge‐discharge behavior and magnification characteristic. Moreover, the copolymerization reactions, crosslinking structures, and degradation process of the benzoxazine/melamine copolymers are studied by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis‐infrared spectrometry (TGA‐IR), respectively. This kind of oxygen‐enriched porous carbon material has a good applicative prospect in the field of supercapacitor.

Effects of flame retardants containing POC and PC structures on the flame retardant properties of epoxy resin

AbstractSo far, discussions on the effects of elements on flame retardant properties have been widespread in flame retardant‐related fields, but reports on the effects of specific structures on flame retardant properties are rare. In this work, two novel phosphorus‐nitrogen flame retardants were synthesized from diphenylphosphinyl chloride and diphenyl chlorophosphite. It was proved that the POC structure of the DOAT flame retardant is beneficial to form a more stable carbon layer with high phosphorus content and reduce the total amount of smoke, while the PC structure of DPAT flame retardant is conducive to produce a large amount of phosphorus‐containing substances in the gas phase, while the phosphorus content in the residual carbon is very low. Therefore, the DOAT flame retardant mainly plays a flame retardant role in the condensed phase. The DPAT flame retardant mainly plays a flame retardant role in the gas phase. The flame retardant action mechanism of the combustion process was also investigated by using scanning electron microscope (SEM), energy dispersive spectrometer (EDS), and Thermogravimetric analysis/infrared spectrometry (TG‐IR).

Strongly-coupled magnetic nanospheres@trimetallic LDH hooding with thin MXenes veil: Sandwiched ternary nanostructure towards forging fire-safe EP with low toxicity

Transition metals carbides/nitrides (MXenes) have been utilized as flame retardants for epoxy resin (EP) with inherently high fire hazard. However, when the dosage of MXenes is low, the corresponding flame retardant efficiency is hard to meet the demand. Up to now, MXenes-based nanostructure with high flame retardation effectiveness has been rarely investigated. Hence, we have employed the assembly strategy to acquire a sandwiched ternary nanostructure (MX-Fe@LDH), based on strongly-coupled magnetic nanospheres@trimetallic LDH hooding with thin MXenes veil, which has never been reported before. With only 3.0 wt% MX-Fe@LDH dosage, the peak heat release rate, peak CO production rate, peak CO2 production rate, total CO production are reduced by 51.3%, 70.2%, 49.4%, 74.1%. Comparison with reported works also indicates the high effectiveness of MX-Fe@LDH in flame retardation. The curbed emissions of toxic NO and HCN gases are uncovered via Thermogravimetric analysis-infrared spectrometry test. Postmortem analyses have indicated that using MX-Fe@LDH contributes to engender char with high graphitized degree, which acts as safeguard for basal matrix. Stemming from the rational design, there is a strong mechanical interlocking action between MX-Fe@LDH and EP chains, further prompting the mechanical capabilities. This work may motivate the design of MXenes-based nanostructure towards forging fire-safe polymer composites.

A facile method for synthesis of novel phenyl phosphates flame retardants and their application in epoxy resin

AbstractPiperazinyl phenyl phosphate (PPOP) and 4,4‐diaminodiphenylmethyl phenyl phosphate (DPOA) containing phosphorus and nitrogen elements as flame retardants applied for epoxy resin (EP) were successfully synthesized, and substantiated by Fourier transform infrared spectra (FTIR), 1H and 31P nuclear magnetic resonance (NMR) and elemental analysis (EA). The limiting oxygen index (LOI) of the EP composites with 3 wt% of PPOP and DPOA attained 33.6% and 34.2%, both acquired the UL‐94 V‐0 rating, respectively. The peak of heat release rate (pHRR), the total heat release (THR) and the total smoke production (TSP) of EP/PPOP‐1 decreased by 21.0%, 25.6%, and 18.7%, respectively. For EP/DPOA‐1, the pHRR, THR, and TSP were brought down by 23.5%, 21.8%, and 26.4%, respectively. Flame‐retardant mechanisms were explicitly evaluated by the scanning electron microscope (SEM), Raman spectroscopy and thermogravimetric analysis‐infrared spectrometry (TG‐IR). This proposed method not only could produce efficient flame retardant for EP but provide new ideas for replacing existing halogenated flame retardants.

Ternary MXenes-based nanostructure enabled fire-safe and mechanic-robust EP composites with markedly impeded toxicants releases

Transition metals carbides/nitrides (MXenes) have been a hot spot in constructing fire-safe polymer composites, benefiting from their unique 2D nanostructure and catalytic activity. Here, a ternary hierarchical nanoarchitecture of Cu2O@LMX is constructed, towards impairing the heat and toxic volatiles emissions of epoxy (EP) resin, thus extending its usage. After incorporating 6.0 wt% Cu2O@LMX, the marked reductions of 43.4%, 31.2%, 42.8%, 42.1% on peak heat release rate, total heat release, peak smoke production rate, total smoke production are acquired. The superiority of Cu2O@LMX in inhibiting the heat and toxic volatiles emissions is confirmed via comparison with reported fillers. Thermogravimetric analysis-infrared spectrometry (TG-IR) results confirm the greatly impeded releases of toxic CO, NO, HCN gases. Interestingly, using Cu2O@LMX boosts the mechanical performances. Shortly, the simultaneous improvements in fire safety and mechanical property are achieved by adding Cu2O@LMX. This work may offer valuable inspirations for the construction of high-performance MXenes based polymer composites.

Thermal Stability and Flame Retardancy of Epoxy Resin with DOPO‐Based Compound Containing Triazole and Hydroxyl Groups

AbstractA reactive flame retardant (DTP) is successfully synthesized and characterized, and then incorporated into epoxy resin (EP) as a co‐curing agent. The thermal stabilities and flame‐retardant properties of epoxy thermosets are evaluated. Compared to neat EP, the thermogravimetric analysis (TG) results show that the thermal decomposition rate of EP/DTP is reduced by 45% and the char yield at 750 °C is increased by 67%, when the addition amount of DTP is 12 wt%. In the cone calorimetry test (CCT), the values of the peak of heat release rate (pk‐HRR), total heat release (THR), total smoke produce (TSP), and average of effective heat combustion (av‐EHC) of EP‐DTP‐12 are exhibited a reduction of 36.6%, 26.4%, 40.5%, and 23.6% relative to neat EP, respectively. Meanwhile, the value of the limiting oxygen index (LOI) of EP/DTP‐12 can reach 34.83%, and 6 wt% or more loading of DTP make EP/DTP pass the V‐0 rating in the UL‐94 test. Moreover, the flame‐retardant mechanism is investigated by thermogravimetric analysis/infrared spectrometry (TG‐IR) and scanning electron microscopy (SEM), which can be summarized into two aspects: the quenching effect of phosphorus‐containing radicals and diluting effect of nonflammable gases in the gas phase, and the barrier effect of char layer in the condensed phase.

Chitosan-bridged synthesis of 2D/2D hierarchical nanostructure towards promoting the fire safety and mechanical property of epoxy resin

Chitosan-bridged 2D/2D hierarchical nanostructure based on boron nitride (BN) and molybdenum disulfide (MoS2) nanosheets (CBN-Mo-B) is constructed, towards impairing the fire hazard of epoxy resin (EP). With the loading of 2.0 wt% CBN-Mo-B, the peak heat release rate and total heat release are reduced by 28.1% and 25.7%, with the decreases of 35.4% and 36.4% in peak smoke production rate and total smoke production. The peak CO production rate and total CO production are decreased by 43.9% and 40.9%, verifying the obviously hindered CO emission. Also, the peak CO2 production rate is reduced by 32.6%. Thermogravimetric analysis-infrared spectrometry (TG-IR) analyses illustrate the depressed toxic gases production. The merit of CBN-Mo-B is certified via flame retardation contrast with reported fillers. Greatly enhanced mechanical performance is obtained, stemming from the well-generated nanosheet-polymer interfaces. This work may provide valuable inspirations for fabricating fire-safe and mechanic-robust polymer composites via developing 2D/2D hierarchical nanostructure.

Covalently functionalized hierarchical MnO2@LDH nanostructure as building blocks for fire-safe and mechanic-robust epoxy composites

The notorious issue of high fire hazard, including the generation of considerable heat and release of plentiful toxic volatiles, is recognized as the bottleneck of extensive use of epoxy resin (EP). Hence, a covalently functionalized hierarchical MnO2@LDH nanostructure (FA-MnO2@LDH) is rationally designed to alleviate these problems. With the incorporation of 2.0 wt% FA-MnO2@LDH, the peak heat release rate and total heat release are reduced by 44.9% and 33.1%, while the total smoke production is decreased by 50.2%, corroborating the greatly impaired heat and smoke emissions. Meanwhile, the reductions on peak CO production rate and total CO production are 46.3% and 41.3%, demonstrating the markedly impeded CO emission. Moreover, the peak CO2 production rate and total CO2 production are reduced by 46.7% and 30.0%, signifying the inhibited burning. Thermogravimetric analysis-infrared spectrometry results also confirm the impeded releases of CO and NO gases. The merit of FA-MnO2@LDH is also confirmed via the flame retardation comparison with other reported fillers. Stemming from the well-generated hierarchical nanostructure-polymer interfaces, the mechanical property is also promoted. Hence, this investigation can provide useful inspirations for fabricating fire-safe and mechanic-robust polymer composites via designing hierarchically tailored nanostructure.

The effect of strawberry-like nickel-decorated flame retardant for enhancing the fire safety and smoke suppression of epoxy resin

Organic-inorganic hybrid materials have received widespread attention because they combine the excellent characteristics of organic polymers and inorganic materials. In this work, a nanohybrid flame retardant PZS@PDA@Ni(OH)2 with strawberry-like architecture is prepared via the coating of biomimetic polydopamine (PDA) on polyphosphazene microspheres (PZS), followed by the self-assembly of Ni(OH)2. The effects of PZS@PDA@Ni(OH)2 on combustion behavior and smoke release of epoxy resin (EP) are characterized by cone calorimetry test (CCT), Thermogravimetric analysis-infrared spectrometry (TG-IR) and Raman tests. The results show that EP composites with 5 wt% PZS@PDA@Ni(OH)2 give rise to 69.8% reduction in peak heat release rate (pk-HRR) and possess the limiting oxygen index (LOI) of 31.8%, achieving UL-94 V-0 rating. Besides, owing to the synergistic effect of phosphorus-nitrogen and catalytic charring effect of Ni(OH)2 nanoparticles, the char residual of EP composites exhibits compact and dense structure, which is responsible for the remarkable flame retardancy. Meanwhile, Ni(OH)2 nanoparticles play a catalytic role in conversion of flammable gases, and the carbon monoxide production (COP) of EP composites with 5 wt% PZS@PDA@Ni(OH)2 is reduced by 58.3%. As a highly efficient flame retardant, PZS@PDA@Ni(OH)2 has promising potential in reducing the fire hazards of EP composites.

A halogen-free, flame retardant, waterborne polyurethane coating based on the synergistic effect of phosphorus and silicon

In this study, p-hydroxybenzaldehyde, 3-aminopropanol and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) were used as raw materials, and a novel flame retardant with dihydroxy groups, namely 4-DOPO-((3-hydroxypropyl) imino) methyl) phenol (PHID), was synthesized. Then, a flame retardant, water-based polyurethane with phosphorus (P) and silicon (Si) units (FR/Si-WPU) was successfully prepared. Limited oxygen index (LOI), vertical burning tests, and cone calorimetry were employed to investigate the flammability characterizations of the WPU. In contrast to pure WPU, the LOI value of FR/Si-WPU was found to be increased from 18.2% to 28.6%, the UL 94 rating was upgraded to V-0. The peak heat release rate (pk-HRR) and peak smoke production rate (pk-SPR) were found to be decreased by 80.5% and 70.5%, respectively. In addition, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), thermogravimetric analysis-infrared spectrometry (TG-IR), laser Raman spectroscopy (LRS), and X-ray photoelectron spectroscopy (XPS) were employed to evaluate the synergistic mechanisms of P and Si. The results demonstrated that the synergistic effect of PHID with hydroxyl silicone oil (HO-Si) can generate a more compact char to protect the underlying polyurethane, the decomposition of PHID can produce PO· radicals that combine with H· and OH· radicals to interrupt the combustion reaction, and HO-Si can produce a special insulating SiO layer to improve the thermo oxidative stability. The synergistic effects of these factors contribute to the designable flammability of the WPU coating. Further investigation revealed that Si units can efficiently balance the other properties of the WPU, and the cold resistance and mechanical properties of FR/Si-WPU were found to increase instead of decrease. In this work, a flame retardant WPU coating with good comprehensive performance was fabricated via a simple and efficient method.

Ecofriendly Microencapsulated Phase-Change Materials with Hybrid Core Materials for Thermal Energy Storage and Flame Retardancy.

Microencapsulated phase-change material (ME-PCM) employing octadecane as a core material has been practiced for thermal-energy-storage (TES) applications in buildings. However, octadecane as a hydrocarbon-based PCM is flammable. Herein, silica-shelled microcapsules (SiO2-MCs) and poly(urea-formaldehyde)-shelled microcapsules (PUF-MCs) were successfully prepared, loaded with octadecane/tributyl phosphate (TBP) as hybrid core materials, which not only exhibited good TES properties but also high-effective flame retardancy. SiO2-MC (ΔHm = 124.6 J g-1 and ΔHc = 124.1 J g-1) showed weaker TES capacity than PUF-MC (ΔHm = 186.8 J g-1, ΔHc = 188.5 J g-1) but better flame retardancy with a lower peak heat-release rate (HRRpeak) of 460.9 W g-1 (556.9 W g-1 for PUF-MCs). As compared with octadecane (38.7 kJ g-1), the reduction in total heat release (THR) for SiO2-MC was up to 22% (30.1 kJ g-1) with combustion time shortened by 1/6. SiO2-MC had a typical diameter of 150-210 μm, shell thickness of ∼6.5 μm, and a core fraction of 84 wt %. SiO2-MC showed better thermal stability with a higher initial evaporation/pyrolysis temperature than PUF-MC. The thermal decomposition of MCs with its mechanism of flame retardancy was significantly studied using thermogravimetric analysis/infrared spectrometry (TG-IR). The strategy presented in this study should inspire the development of microcapsules with PCMs/flame retardants as hybrid core materials for structural applications.

A novel phosphorus‐nitrogen flame retardant for improving the flame retardancy of polyamide 6: Preparation, properties, and flame retardancy mechanism

In this work, a novel phosphorus–nitrogen flame retardant (CN‐DOPO), which was successfully prepared via a facile method of graphitic carbon nitride (g‐C3N4) and 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO). Polyamide 6 (PA6) composites were then prepared through melt blending with different ratios of g‐C3N4/DOPO and different contents of CN‐DOPO. CN‐DOPO was characterized and confirmed using X‐ray diffraction (XRD), Fourier transform infrared spectra (FTIR), and scanning electron microscopy (SEM). PA6/CN‐DOPO composites were investigated by limiting oxygen index (LOI), vertical combustion (UL‐94), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), and thermogravimetric analysis‐infrared spectrometry (TGA‐IR). The results indicated LOI value was increased from 23.4% to 29.2% and successfully passed UL‐94 V‐0 rating when the presence of CN‐DOPO increased to 15 wt%. Moreover, mechanical properties of PA6/CN‐DOPO composites had not deteriorated significantly due to CN‐DOPO having better dispersion and compatibility in PA6. The morphological of char layer revealed that CN‐DOPO formed a highly integrated char layer surface during the combustion process, as compared to that of pure PA6. Meanwhile, CN‐DOPO decomposed to release gases could inhibit decomposition by diluting flammable volatiles. Accordingly, the special gas‐condensed phase synergistic flame‐retardant mechanism of PA6/CN‐DOPO was proposed. This work indicated that CN‐DOPO could endow PA6 with highly effective flame‐retardant and good mechanical performance.

Inhibiting effect of inhibitors on ignition sensitivity of wood dust

Wood products are easy to produce dust in the production and processing process, and have a serious explosion risk. In order to improve the safety of wood products production, the inhibiting effects of magnesium hydroxide (MTH), SiO2, melamine polyphosphate (MPP) on the minimum ignition energy (MIE) and minimum ignition temperature (MIT) of wood dust were experimentally studied. The results showed that the inhibiting effects of inhibitors on the MIE of wood dust show the order of MPP > SiO2>MTH. The order of the inhibiting effects on the MIT of wood dust was MPP > MTH > SiO2. When 10% MPP was added to wood dust, the time when the flame appears (Tappear) and the time when the flame reaches the top of the glass tube (Ttop) obviously rose to 80, 140 ms. Therefore, MPP had the best inhibiting effect on the ignition sensitivity of wood dust.According to thermogravimetry (TG), differential scanning calorimetry (DSC) tests, the introduction of MPP leaded to lower maximum mass loss rate (MMLR), higher temperature corresponding to mass loss of 90% (T0.1), residual mass and heat absorption. In addition, thermogravimetric analysis/infrared spectrometry (TG-IR) results showed that MPP produced H2O (g) and NH3 (g) during the thermal decomposition process, which diluted the oxygen.

Preparation and characterization of carbon nanotube microcapsule phase change materials for improving thermal comfort level of buildings

The phase change material (PCM) microcapsule is a common high-performance storage technology of thermal energy. However, the organic wall with low thermal conductivity for PCM reduces the efficiency of heat storage and release. In this study, the novel carbon nanotube-doped phase change materials (C-PCMs) were developed. Scanning electron microscope test (SEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and the thermogravimetric analysis/infrared spectrometry (TG-IR) were used to analyse the composite structure and thermal performances. The results indicate that C-PCMs are small and regular in spherical shape. When C-PCMs suffer from heat, the shell can maintain integrity below 165 °C. Furthermore, the carbon nanotubes in the shell play as a channel to connect the inside with the outside and improve the efficiency of heat transfer. The DCS test of the samples showed that the latent heat of C-PCMs and PCMs were 112.25 J/g and 116.18 J/g, respectively. The initial phase transition temperature of C-PCMs is 28.97 °C, which is 0.5 °C lower than that of PCMs. The results of the model room test suggested that the composite filled with C-PCMs reduces indoor temperature fluctuations and exhibits the potential for enhancing energy savings and the thermal comfort of buildings.

A novel intumescent flame retardant imparts high flame retardancy to epoxy resin

Intumescent flame retardant (IFR) has received the considerable attention ascribed to the inherent advantages including non‐halogen, low toxicity, low smoke release and environmentally friendly. In this work, a novel charring agent poly (piperazine phenylaminophosphamide) named as PPTA was successfully synthesized and characterized by Fourier transform infrared spectra (FTIR) and X‐ray photoelectron spectroscopy (XPS). Then, a series of flame‐retardant EP samples were prepared by blending with ammonium polyphosphate (APP) and PPTA. Combustion tests include oxygen Index (LOI), vertical Burning Test (UL‐94) and cone calorimeter testing，these test results showed that PPTA greatly enhances the flame retardancy of EP/APP. According to detailed results, EP containing 10 wt% APP had a LOI value of 30.2%，but had no enhancement on UL‐94 rating. However, after both 7.5 wt% APP and 2.5 wt% PPTA were added, EP‐7 passed UL‐94 V‐0 rating with a LOI value of 33.0%. Moreover, the peak heat release rate (PHRR) and peak of smoke product rate (PSPR) of EP‐7 were greatly decreased. Meanwhile, the flame‐retardant mechanism of EP‐7 was investigated by scanning electron microscopy (SEM), thermogravimetric analysis/infrared spectrometry (TG‐IR) and X‐ray photoelectron spectroscopy (XPS). The corresponding results presented PPTA significantly increased the density of char layer, resulting in the good flame retardancy.

Flame Retardancy, Fire Behavior, and Flame Retardant Mechanism of Intumescent Flame Retardant EPDM Containing Ammonium Polyphosphate/Pentaerythrotol and Expandable Graphite.

The intumescent flame retardant ethylene–propylene–diene rubber (EPDM) was prepared using intumescent flame retardant (IFR), including ammonium polyphosphate (APP) /pentaerythrotol (PER) and expandable graphite (EG), as the flame retardant agent. The effects of IFR and EG on the flame retardancy, fire behavior, and thermal stability of the EPDM were investigated. The results show that IFR and EG have excellent synergistic flame retardant effects. When the mass ratio of IFR to EG is 3:1 and the total addition content is 40 phr, the limiting oxygen index (LOI) value of the EPDM material (EPDM/IFR/EG) can reach 30.4%, and it can pass a V-0 rating in the vertical combustion (UL-94) test. Meanwhile, during the cone calorimetry test, the heat release rate and total heat release of EPDM/IFR/EG are 69.0% and 33.3% lower than that of the pure EPDM, respectively, and the smoke release of the material also decreases significantly, suggesting that the sample shows good fire safety. In addition, the flame retardant mechanism of IFR and EG is systematically investigated by thermogravimetric analysis/infrared spectrometry (TG-IR), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM), and the results indicate that IFR and EG have only physical interaction. Moreover, the reason why IFR exhibits a poor flame retardant effect in EPDM materials is explained.

Synthesis of a novel liquid phosphorus-containing flame retardant for flexible polyurethane foam: Combustion behaviors and thermal properties

To overcome the shortcomings of limited flame retardant efficiency and migration of commercialized dimethyl methylphosphonate (DMMP) in flexible polyurethane foams (FPUFs), a novel liquid phosphorus-containing flame retardant named bis((dimethoxyphosphoryl)methyl) phenyl phosphate (BDMPP) was synthesized via dimethyl (hydroxymethyl)phosphonate and phenyl dichlorophosphate and applied into FPUFs. Compared with DMMP, BDMPP contains two kinds of phosphorus with higher molecular weight and one kind of its phosphorus is very similar with that of DMMP. The flame retardancy of FPUFs was evaluated by limiting oxygen index (LOI), vertical burning test and cone calorimetry test. In contrast with DMMP, BDMPP showed better flame retardancy. When 20 wt% BDMPP (relative to polyether polyol) was incorporated, the foam composite obtained an LOI value of 23.0% and passed the vertical burning test. Thermogravimetric analysis (TGA) demonstrated that BDMPP containing FPUFs had better thermal stability and more char yield than those of DMMP containing FPUFs. Moreover, accelerated heat ageing test revealed that BDMPP exhibited better resistance to migration than DMMP. The flame retardant mechanisms were investigated by FTIR, thermogravimetric analysis/infrared spectrometry (TG-IR), scanning electron microscopy and Raman spectroscopy. Compared with DMMP, the increase in the flame retardancy of BDMMP in FPUFs is possibly due to its different structure.