Effect of different zeolitic imidazolate frameworks nanoparticle-modified β-FeOOH rods on flame retardancy and smoke suppression of epoxy resin

A simple method was used to load zeolitic imidazolate frameworks (ZIFs) onto β-FeOOH nanorods to ameliorate the flame retardancy and smoke suppression of epoxy resin (EP). The morphology and structure of ZIF-8-β-FeOOH (Z8Fe) and ZIF-67-β-FeOOH (Z67Fe) nano hybrids were systematically characterized by field emission scanning electron microscope, Fourier transform infrared and X-ray diffraction (XRD) spectra, which proved the successful preparation of the hybrids. 3 wt% of Z8Fe and Z67Fe were added to the EP matrix, and their combustion properties were studied, respectively. The results showed that the composites' limiting oxygen index values were ameliorated to 27.3% and 28.1%, respectively. Their UL94 flame retardant rating was improved, their peak heat release rate and total heat release were reduced, their flame retardant performance was considerably improved, and their generation of toxic smoke was significantly suppressed. Further, through X-ray photoelectron spectroscopy, XRD and laser Raman spectroscopy analysis of the char residue, their potential mechanism of flame retardancy and smoke suppression were studied.     

Synergistic effect of expandable graphite and α‐type zirconium phosphate on flame retardancy of polyurethane elastomer

Organically modified zirconium phosphate (OZrP) was prepared by cation exchange of natural counterions with hexadecyltri‐n‐butylphosphonium bromide. Subsequently, OZrP and expandable graphite (EG) were incorporated into polyurethane elastomer (PUE), and the thermal stability and flame retardancy of PUE composites were investigated. The thermogravimetric analysis indicated that partial substitution of EG with OZrP could improve both the thermal stability and char yield of PUE composites. The cone calorimetry and limiting oxygen index test showed that partial substitution of EG with OZrP could further enhance the flame retardancy of PUE composites and presented an excellent synergistic effect. Moreover, the char residue of PUE composites was analyzed by X‐ray photoelectron spectroscopy and laser Raman spectroscopy. Their results indicated that the synergistic effect of the physical barrier to prevent transmission of heat and mass between condensed and gas phases. Therefore, the further combustion of the nether material could be inhibited, which created better flame retardancy. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45188.     

Influence of expandable graphite on flame retardancy and thermal stability property of unsaturated polyester resins/organic magnesium hydroxide composites

An eco-friendly flame retardant unsaturated polyester resin (UPR) material was prepared by combination organic magnesium hydroxide (OMH) and expandable graphite (EG). Different from direct addition of magnesium hydroxide (MH) in UPR matrix-like traditional method, OMH as a reactive monomer participates in the polycondensation reaction of UPR was more effective in improving the compatibility of flame retardant with matrix. Interestingly, the flame retardant UPR composites exhibited a more satisfactory flame retardant effect when a certain amount of 8 wt % EG was added into UPR/OMH matrix because of the synergistic effect between OMH and EG, resulted in the limited oxygen index from 21.7 to 28.5% and UL-94 test passed V-0 rating. Moreover, the peak heat release rate, total heat release, and smoke production rate of flame retardant UPR composites significantly reduced. The excellent flame retardancy was due to the formation of a dense and continuous carbon layer in the later stages of combustion. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 47881.     

壳聚糖/聚磷酸铵膨胀阻燃PP的阻燃及抑烟性能

为了提高聚丙烯(PP)的阻燃和抑烟性能,将壳聚糖(CS)作为膨胀型阻燃剂的碳源、聚磷酸铵(APP)作为膨胀型阻燃剂的酸源和气源,在此基础上通过熔融共混的方法制备了PP/CS/APP复合材料。采用极限氧指数仪、锥形量热仪等仪器研究了PP/CS/APP复合材料的的抑烟性及阻燃性。研究结果表明:CS/APP添加量为30%时,复合材料的极限氧指数值最大可达28.1%;且复合材料在烟气释放总量、CO和CO_2排放上明显降低,抑烟性得到了提升;热释放速率峰值、平均热释放速率值、平均有效燃烧热值、总热释放量值降低,成炭率升高,PP/CS/APP复合材料更难点燃;火灾性能指数明显提高,阻燃性能得到了大幅度提升,火灾蔓延指数显著减小,同时火灾危险性也相应降低。     

Flame‐retardant properties of acrylonitrile–butadiene–styrene/wood flour composites filled with expandable graphite and ammonium polyphosphate

Expandable graphite (EG) and ammonium polyphosphate (APP) were used to improve the flame retardancy of acrylonitrile–butadiene–styrene based wood–plastic composites (WPCs). A synergistic effect between EG and APP on the flame retardancy of the WPCs was proposed. The results show that the highest limited oxygen index (LOI) of 34.2% and a V‐0 rating were achieved when the ratio of EG to APP 12.5:7.5; this comprised 20 wt % of the total amount. However, LOI values of the samples with EG and APP alone were only 30.5 and 24.5%, respectively. Thermogravimetric analysis indicated that the flame retardants improved the amount of residue. The EG and EG/APP additives greatly decreased the peak heat release rate and suppressed smoke according to cone calorimetry testing. The scanning electron microscopy analysis indicated that the surface of the wormlike char was covered with a granular substance, which may have been the viscous phosphoric acid or poly(phosphoric acid) decomposed from APP. The flame‐retardant additives worsened the mechanical properties of the WPCs. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40281.     

An efficient approach to improving fire retardancy and smoke suppression for intumescent flame‐retardant polypropylene composites via incorporating organo‐modified sepiolite

In this work, an efficient approach to improving the fire retardancy and smoke suppression for intumescent flame‐retardant polypropylene (PP) composites is developed via incorporating functionalized sepiolite (organo‐modified sepiolite [ONSep]). The PP composites with different amounts of intumescent flame retardants and ONSep were prepared by melt compounding. The morphology, thermal behavior, fire retardancy, smoke suppression, and mechanical property of flame‐retardant PP composites were studied. The results indicate an appropriate amount of ONSep in the flame‐retardant PP composites can increase thermal degradation temperature and char formation as well as a reduction of the peak heat release rate and total heat release; moreover, the addition of ONSep significantly decreases the CO production, total smoke production, smoke production rate, and smoke temperature. Simultaneously, the impact strength of intumescent flame‐retardant PP composite is also maintained by introducing an appropriate amount of ONSep as compared with that without ONSep.     

Mechanical performance and flame retardancy of polypropylene composites containing zeolite and multiwalled carbon nanotubes

Intumescent‐flame‐retarded polypropylene (PP‐IFR) composites were prepared by the incorporation of methyl hydrogen siloxane treated ammonium polyphosphate and dipentaerythritol in a twin‐screw extruder. The effects of zeolite (Z), multiwalled carbon nanotubes (CNTs), and maleic anhydride grafted polypropylene on the flame retardancy, mechanical properties, and thermal stability of PP‐IFR were investigated. The addition of Z and CNT promoted the flame retardancy of PP‐IFR, and the highest limited oxygen index was 35.6%, obtained on PP‐M‐IFR‐2–Z, for which the heat‐release rate, total heat release, and smoke production rate based on cone calorimetry analyses decreased by 45.0, 51.0, and 66.3%, respectively, in comparison with those values of the PP‐IFR composites. Additionally, scanning electron microscopy analyses showed that there was a good interface interaction between the polypropylene matrix and additives. The flexural, tensile, and impact strengths of the PP‐IFR composites were improved significantly with the incorporation of CNT. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42875.     

Enhanced flame-retardant performance of rigid polyurethane foam by using APTES-MMT and ATH mixed intumescent coatings

The design of environment-friendly fireproof rigid polyurethane foams (RPUFs) that completely prevent ignition or the spread of fires is important for energy conservation and emission reductions. In this paper, an intumescent flame-retardant coating was prepared and coated onto the surface of a RPUF to improve its flame retardancy. Vertical combustion experiments (UL-94) showed that, compared with the pure RPUF, a RPUF coated with the expansion coating successfully self-extinguished without a droplet formed after ignitor removal. Thermogravimetric analyses showed that the expanded coating effectively increased the rate of carbon residue formation. Cone calorimetry showed that when the pigment-to-binder ratio was 3.5:1, with 5% modified montmorillonite, 6% aluminum hydroxide, and 4% titanium dioxide, the intumescent coating effectively reduced the heat release rate and total heat release of the RPUF. Remarkably, the smoke release rate and total exhaust gas volume showed that the expanded coating provided obviously enhanced smoke suppression. Therefore, the flame retardancy and toxic smoke suppression provided by the RPUF thermal insulation material is essential and very useful for healthy development of human society and the environment.     

Synergistic effects of aluminum hydroxide on improving the flame retardancy and smoke suppression properties of transparent intumescent fire-retardant coatings

A series of novel aluminum phosphate ester (APEA) flame retardants were synthesized by the salification of cyclic phosphate ester acid (PEA) with different mass ratios of aluminum hydroxide (ATH) and thoroughly characterized by Fourier transform infrared (FTIR) spectroscopy and ¹H nuclear magnetic resonance spectroscopy. The PEA and APEAs were thoroughly mixed with melamine formaldehyde resin to produce five kinds of transparent fire-retardant coatings. The synergistic effects of ATH on the thermal stability, flame retardancy, and smoke suppression properties of the coatings were investigated by different analytical instruments. The results show that the incorporation of ATH greatly decreases the weight loss, char index, flame spread rating, heat release rate, total heat release, smoke production rate, total smoke release and specific optical density in the coatings applied to plywood boards, which is ascribed to a more compact and intumescent char formed during burning, as determined from digital photographs and scanning electron microscopy images. The synergistic effects of ATH in the coatings depend on the content of ATH, and an excessive amount of ATH diminishes the synergistic effects on the flame retardancy and smoke suppression properties based on fire protection tests and cone calorimeter test. Thermo-gravimetric analysis reveals that the thermal stability and char-forming ability of the coatings gradually improve with increasing loading of ATH. FTIR analysis demonstrates that the incorporation of ATH forms a more phosphorus-rich crosslinked char and aromatic char during burning, thus effectively reducing the mass loss, heat release, and smoke production and exhibiting excellent synergistic flame retardant and smoke suppression effects in the coatings.     

Preparation and smoke suppression mechanism of flame-retardant PBS composites with BNNS@DOPA

Currently, the flame-retardant modification of polybutylene succinate (PBS) is mainly focused on improving flame-retardant efficiency, ignoring the negative impact of the smoke produced by combustion on the human respiratory tract. To address this problem, PBS composites were prepared by melt blending method in this study. The effect of boron nitride-grafted DOPO flame retardant (BNNS@DOPA) on flame retardancy and smoke suppression of PBS composites was investigated. Incorporating 3% BNNS@DOPA into PBS composites results in a 90% improvement in thermal conductivity. This resulted in a reduction of the peak heat release rate, total heat release rate, and actual smoke rate to 453.7 kW m⁻², 86.3 MJ m⁻², and 1035.9 m², respectively, compared with pure PBS. The latter indicated a decrease of 34.0%, 37.6%, and 51.2%, respectively. Furthermore, the ignition time was extended by 45 s and the limiting oxygen index value increased by 12.5%. This functionalization approach presents a new way to study PBS flame retardancy improvement, consequently boosting its application in fire safety for polymer materials.     

Synergistic flame retardant effects of activated carbon and molybdenum oxide in poly(vinyl chloride)

The synergistic effects of activated carbon (AC) and molybdenum oxide (MoO₃) in improving the flame retardancy of poly(vinyl chloride) (PVC) were investigated. The effects of AC, MoO₃ and their mixture with a mass ratio of 1:1 on the flame retardancy and smoke suppression properties of PVC were studied using the limiting oxygen index and cone calorimeter tests. It was found that the flame retardancy of the relatively cheaper AC was slightly weaker than that of MoO₃. In addition, the incorporation of AC and MoO₃ greatly reduced the total heat release and improved smoke suppressant property of PVC composites. When the total content of AC and MoO₃ was 10 phr, PVC/AC/MoO₃ had the lowest peak heat release rate and peak smoke production rate values of 173.80 kW m^?2 and 0.1472 m² s^?1, which represented reductions of 47.3 and 59.9%, respectively, compared with those of PVC. Furthermore, thermogravimetric analysis and gel content tests were used to analyze the flame retardant mechanism of AC and MoO₃, with results showing that AC could promote early crosslinking in PVC. Char residue left after heating at 500 °C was analyzed using scanning electron microscopy and Raman spectroscopy, and the results showed that MoO₃ produced the most compact char, with the smallest and most organized carbonaceous microstructures. © 2017 Society of Chemical Industry     

基于磷杂菲衍生物多组分无卤阻燃天然橡胶的制备及性能

将磷杂菲/三嗪双基协同阻燃剂（TGD）、甲基膦酸二甲酯（DMMP）、可膨胀石墨（EG）及氢氧化铝（ATH）复配添加到天然橡胶（NR）中制备阻燃NR硫化胶,考察了TGD/DMMP/EG/ATH复配阻燃剂对NR硫化胶的阻燃性能、热稳定性及物理机械性能的影响。结果表明,TGD/DMMP/EG/ATH复配阻燃剂可有效提升NR硫化胶的阻燃性能和热稳定性,并降低燃烧过程中的热释放速率。当TGD/DMMP/EG/ATH复配阻燃剂的用量为60份（质量）时,NR硫化胶的极限氧指数可达28.4%,残炭质量分数可达25.61%,热释放速率可降低95%,总热释放量可降低21%。TGD/DMMP/EG/ATH复配阻燃剂对NR硫化胶的物理机械性能影响不大。     

Preparation and investigation of flame‐retardant epoxy resin modified with a novel halogen‐free flame retardant containing phosphaphenanthrene,triazine‐trione,and organoboron units

In this article, a novel flame retardant (coded as BNP) was successfully synthesized through the addition reaction between triglycidyl isocyanurate, 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide and phenylboronic acid. BNP was blended with diglycidyl ether of bisphenol‐A to prepare flame‐retardant epoxy resin (EP). Thermal properties, flame retardancy, and combustion behavior of the cured EP were studied by thermogravimetric analysis, limited oxygen index (LOI) measurement, UL94 vertical burning test, and cone calorimeter test. The results indicated that the flame retardancy and smoke suppressing properties of EP/BNP thermosets were significantly enhanced. The LOI value of EP/BNP‐3 thermoset was increased to 32.5% and the sample achieved UL94 V‐0 rating. Compared with the neat EP sample, the peak of heat release rate, average of heat release rate, total heat release, and total smoke production of EP/BNP thermosets were decreased by 58.2%–66.9%, 27.1%–37.9%, 25.8%–41.8%, and 21.3%–41.7%, respectively. The char yields of EP/BNP thermosets were increased by 46.8%–88.4%. The BNP decomposed to produce free radicals with quenching effect and enhanced the charring ability of EP matrix. The multifunctional groups of BNP with flame retardant effects in both gaseous and condensed phases were responsible for the excellent flame retardancy of the EP/BNP thermosets. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45291.     

卡拉胶包覆APP/MnO2增强水性环氧树脂阻燃抑烟性能

用反相乳液法，以卡拉胶（KC）为壳材，聚磷酸铵（APP）和二氧化锰（MnO2）为芯材，制备了KC包覆APP/MnO2阻燃剂（KC-FR）。通过FTIR、 XRD、 SEM和 EDS对KC-FR进行了表征。结果表明：卡拉胶已成功包覆APP和MnO2，合成的样品具有微胶囊结构。将KC-FR应用于水性环氧树脂（EP）中，考察KC、APP、MnO2 三者质量比对EP阻燃、抑烟性能的影响。用极限氧指数（LOI）、垂直燃烧（UL-94）和锥形量热（CCT）测试了涂层的阻燃、抑烟性能。结果发现，当KC/APP/MnO2的质量比为2∶1∶1，并且在EP中添加量为20%时，制备的阻燃涂层EP2的LOI达到29.1%，UL-94达到V-0级，表现出较好的阻燃性能。EP2相比于其它涂层热释放峰值（pHRR）、热释放总量（THR）和烟释放总量（TSP）最低，相比于EP0分别下降了42%、37%和46%，表现出较好的抑烟性能。另外，热重分析（TGA）测试结果显示EP2在800℃残炭量（W800）为33%，表明KC-FR具有促进EP成炭的功能。通过SEM对残炭表面分析发现，EP2表面炭层更加致密，这表明KC-FR对促进形成稳定并且致密的炭层起到至关重要的作用。     

Novel phosphorus‐based flame retardants containing 4‐tert‐butylcalix[4]arene: Preparation and application for the fire safety of epoxy resins

A novel flame retardant (FR) containing phosphorus and 4‐tert‐butylcalix[4]arene was synthesized and characterized. The FR combined with ammonium polyphosphate (APP) was then incorporated into epoxy resins (EPs) at different ratios. The flame retardancy, thermal stability, and smoke‐releasing properties were investigated. The limiting oxygen index was as high as 30.8% when the mass fraction ratio of the FR to APP was 1:2. The improved FR effect have been due to the combined FR effects between the FR and APP. The char residue content at 800 °C under a nitrogen atmosphere increased notably from 8.22% to 17.6% when the FR APP was incorporated into EP; this indicated an improvement in the thermooxidation resistance. From the cone test, we found that both the total heat‐release and peak heat‐release rate of the FR resins were reduced. Compared to the resins containing no FRs, the smoke‐production rate and total smoke‐production results indicate that the FR resins also exhibited good smoke‐suppression properties. Generally, the stable char layer of the FR APP–EP not only effectively prevented the release of combustion gases but also hindered the propagation of oxygen and heat into the interior substrate. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45105.     

可膨胀石墨阻燃HIPS的结构与阻燃性能

采用熔融插层法制备高抗冲聚苯乙烯/可膨胀石墨(HIPS/EG)复合材料。通过扫描电镜研究其微观结构;利用锥形量热仪测试并分析HIPS/EG复合材料的阻燃性能;讨论了EG用量和粒子结构对阻燃性能的影响。结果表明:与纯的HIPS相比,HIPS/EG的热释放速率及其峰值、质量损失速率均明显降低;且随着EG用量的增加和粒子尺寸的增大,阻燃性能更加显著。通过对复合材料的阻燃性能和微观结构的分析,探讨其阻燃机理。     

Synergism between hydrotalcite and silicate‐modified expandable graphite on ethylene vinyl acetate copolymer combustion behavior

Influence of independent Mg–Al‐layered double hydroxide (LDH), silicate modified expandable graphite (EG), mixture of LDH and EG at various ratios on ethylene vinyl acetate copolymer (EVA) combustion behavior and thermal stability was detected in sequence through the limiting oxygen index (LOI), vertical combustion (UL‐94) level, microscale combustion calorimeter (MCC) tests and thermal gravimetric/differential thermal gravimetric (TG/DTG) analysis. Results show that the 30 wt % LDH can improve the LOI of 70EVA/30LDH to 27.0%, but the combustion accompanies with serious melt‐dropping. While, the same amount of the EG can increase the LOI, UL‐94 level to 28.5%, V‐0 respectively. However, the combination of LDH and EG can further enhance the 70EVA/20LDH/10EG flame retardancy, it presents the LOI of 29.7%, UL‐94 level of V‐0, and total heat release of 29.5 kJ g^?1. The excellent flame retardancy is attributed to its compact residue. Compared with residue mass, the residue compactness plays a more important role in improving flame retardancy. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44634.     

The Effect of Different Smoke Suppressants with APP for Enhancing the Flame Retardancy and Smoke Suppression on Vinyl Ester Resin

Flame retarded and smoke suppressed vinyl ester resin (VER) were prepared through ammonium polyphosphate (APP) coupled with different smoke suppressants. The flame retardancy of these composites was tested by the limiting oxygen index and UL-94 tests. The typical combustion parameters including heat release rate (HRR), peak of HRR (p-HRR), total heat release, smoke production rate, and total smoke production were detected using a cone calorimeter. The smoke suppressants CaCO₃, ZnMoO₄, Cu₂O, and Fe₂O₃ show different effect on flame retardancy and smoke suppression of VER composites when they are coupled with APP, the synergistic action of APP and CaCO₃ is more effective on decreasing the HRR and smoke release rate than several other smoke suppressants. This is attributed to the fact that CaCO₃ could promote the formation of a dense carbon layer with high thermal stability and anti-oxidation property, which could act as an effective physical barrier. The flame retardant performances and mechanisms of APP and CaCO₃ were evaluated and analyzed at length by thermogravimetric coupled with a Fourier transform infrared spectrometer (FTIR), scanning electron microscopy, FTIR, and X-ray diffraction. POLYM. ENG. SCI., 60: 314–322, 2019. © 2019 Society of Plastics Engineers     

复合型阻燃剂对聚氯乙烯的阻燃抑烟作用研究

采用微胶囊红磷（MRP）、硼酸锌（ZnBO3）、氢氧化铝(ATH)和氢氧化镁(MH)进行复配对软质聚氯乙烯（PVC）进行阻燃处理,通过极限氧指数、热失重、锥形量热方法研究了不同配比阻燃剂对PVC的阻燃抑烟性能的影响。结果表明,当PVC/MRP/ZnBO3/ATH/MH质量比为100:3:1:20:20时,具有良好的阻燃抑烟效果,极限氧指数可达35.9 %;阻燃体系PVC/ATH/MH、PVC/MRP/ZnBO3/ATH/MH相对于纯PVC具有良好的阻燃抑烟性,PVC/MRP/ZnBO3/ATH/MH比PVC/ATH/MH体系在热释放、烟气、一氧化碳和二氧化碳排放指标上数值更低,热稳定性增加,成炭率更高,火灾性能指数提高,火灾蔓延指数减小,火灾危险性降低。     

氧化铋对环状膦酸酯阻燃棉织物的协效阻燃抑烟作用

通过阻燃性能测试、热重分析、锥形量热分析等研究手段,考察了氧化铋对环状膦酸酯阻燃棉织物的阻燃抑烟协效作用。结果发现,在阻燃整理剂中添加0.4 g/L的氧化铋,可以使阻燃棉布的极限氧指数从43%提高到52%;损毁炭长缩短到5 cm,垂直燃烧达到B1级;而对断裂强度影响不大。热重分析表明,氧化铋的加入进一步降低了阻燃棉织物的初始分解温度和最大热解速率,500℃时的成炭量有所增加;扫描电镜显示,添加氧化铋后,棉织物燃烧成炭更致密;氧化铋具有明显的抗燃烧变形能力;锥形量热测试表明,氧化铋的添加不仅降低了阻燃棉织物的总热释放速率,而且使阻燃棉织物的总烟释放量降低了60%。