Layer double hydroxide and sodium montmorillonite multilayer coatings for the flammability reduction of flexible polyurethane foams

Flexible polyurethane foam (PUF) is coated by layer‐by‐layer (LbL) assembly using branched polyethyleneimine (BPEI), poly(acrylic acid) (PAA), and two different charged nanoparticles, such as sodium montmorillonite (Na‐MMT) and layered double hydroxide (LDH). Three different deposition strategies, that is, bilayer, trilayer, and quadlayer, exhibit different coating growth, morphology, and flammability properties. Changing the nanosheet from LDH to MMT dramatically alter the coating mass for the same number of layers. A five bilayer PAA/BPEI+LDH coating reduced the peak heat release rate by 40% and the average heat release rate by 70%, which is two times more effective than commercial fire retardants (FRs) and other LbL‐FR coatings for PUF. MMT and LDH mixed multilayers resulted in effective flame‐retardant coatings with less coating mass by manipulating the deposition strategy. This study manifests the flexibility of LbL to fine‐tune flammability reduction by switching the coating weight gains, which is significant to accelerate the development of other LbL coating regardless of the intended applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41767.     

纳米材料对聚丙烯／八溴醚阻燃体系的影响研究

将碳纳米管、蒙脱土和膨胀石墨分别添加到聚丙烯(PP)/八溴醚(TBAB)阻燃体系中,通过双螺杆挤出并注塑成一定形状的片状样品,用锥形量热仪和热失重分析仪分析其燃烧性能。结果表明:添加碳纳米管、蒙脱土和膨胀石墨后PP/TBAB阻燃体系的燃烧性能均降低,添加了碳纳米管的阻燃体系热释放速率仅是纯PP树脂的八分之一;同时添加了碳纳米管和蒙脱土的:PP/TBAB阻燃体系中阻燃剂TBAB的析出量也有所降低。用透射电镜对这两种阻燃体系的微观结构进行了观察,分析了添加蒙脱土后PP/TBAB体系中TBAB的析出量比添加碳纳米管的体系中TBAB析出量少的原因。     

邻苯二胺基环三磷腈阻燃剂在EVA材料中的性能及机理研究

应用混料设计实验方法研究了邻苯二胺基环三磷腈(HACTP)和聚磷酸铵(APP)、蒙脱土(MMT)复配阻燃剂对乙烯-醋酸乙烯酯共聚物(EVA)材料阻燃和力学性能的影响,并利用锥形量热仪及电子扫描显微镜研究了不同配方下阻燃EVA的热释放性能和燃烧后膨胀炭层的微观形貌,探讨阻燃机理.结果 表明:在HACTP质量分数为32.8...     

A low-density polyethylene composite with phosphorus-nitrogen based flame retardant and multi-walled carbon nanotubes for enhanced electrical conductivity and acceptable flame retardancy

Design and exploitation of flame retardant polymers with high electrical conductivity are desired for polymer applications in electronics. Herein, a novel phosphorus-nitrogen intumescent flame retardant was synthesized from pentaerythritol octahydrogen tetraphosphate, phenylphosphonyl dichloride, and aniline. Low-density polyethylene was combined with the flame retardant and multi-walled carbon nanotubes to form a nanocomposite material via a ball-milling and hot-pressing method. The electrical conductivity, mechanical properties, thermal performance, and flame retardancy of the composites were investigated using a four-point probe instrument, universal tensile machine, thermogravimetric analysis, and cone calorimeter tests, respectively. It was found that the addition of multi-walled carbon nanotubes can significantly improve the electrical conductivity and mechanical properties of the low-density polyethylene composites. Furthermore, the combination of multi-walled carbon nanotubes and phosphorus–nitrogen flame retardant remarkably enhances the flame retardancy of matrixes with an observed decrease of the peak heat release rate and total heat release of 49.8% and 51.9%, respectively. This study provides a new and effective methodology to substantially enhance the electrical conductivity and flame retardancy of polymers with an attractive prospect for polymer applications in electrical equipment.     

Preparation of aluminum diethyl hypophosphite intercalation-modified montmorillonite AlPi-MMT and its effect on the flame retardancy and smoke suppression of thermoplastic polyester elastomer

An aluminum diethyl hypophosphite intercalation-modified montmorillonite flame retardant (AlPi-MMT) is successfully prepared and characterized by FT-IR, SEM, and X-ray diffraction. It is found that thermoplastic polyester elastomer (TPEE) composites incorporating 15 wt% AlPi-MMT flame retardant exhibited better char formation and flame retardant properties compared to those incorporating 15 wt% (4:1, w:w) AlPi and MMT. And the char residual of TPEE/AlPi-MMT at 700°C is 16.17%, which is higher than that of TPEE/AlPi-MMT at 13.94%. and the former can pass UL-94 V-0 rating test while the latter can only pass UL-94 V-1 rating test. Afterwards, the combustion performance of TPEE composites is characterized, and it is found that the heat release and smoke release of TPEE/AlPi-MMT are greatly reduced compared with those of pure TPEE and TPEE/AlPi/MMT, which is a flame retardant and smoke suppressant TPEE composite. Finally, by analyzing the residual char morphology and elements of TPEE composites after combustion, the mechanism of the flame retardant AlPi-MMT to promote char formation and flame retardancy is demonstrated.     

LDH@MMT/MZBMSO的制备及其在皮革中的阻燃性能

采用水热法在蒙脱土（MMT）表面原位生长层状双氢氧化物（LDH），获得了层状双氢氧化物@蒙脱土（LDH@MMT）。通过XRD、SEM、FTIR对LDH@MMT进行了表征。结果表明，LDH和MMT通过氢键复合在一起，呈花状结构。将其引入花椒籽油（ZBMSO）中制得层状双氢氧化物@蒙脱土/改性花椒籽油（LDH@MMT/MZBMSO），TEM结果表明：LDH@MMT均匀分散在MZBMSO中。将其应用于皮革加脂工艺，结果表明：与MZBMSO加脂坯革相比，当LDH@MMT的质量占ZBMSO的12%时，LDH@MMT/MZBMSO加脂坯革阻燃性能明显提高，加脂坯革氧指数由22.8%提升至28.3%，有焰燃烧时间由87 s减少到43 s，热释放速率降低了43.6%，总热释放速率降低了73.6%，产烟速率降低了63.5%；LDH@MMT包裹在坯革纤维表面，形成的“曲折路径”可减缓热量及烟气的释放，燃烧后在纤维表面形成致密碳层进一步阻隔坯革燃烧过程中释放的热量、烟气，并隔绝氧气，从而提升了加脂坯革的阻燃抑烟性能。     

O–VMT和二乙基次磷酸铝对PBT/GF的阻燃作用

研究了有机蛭石(O–VMT)和二乙基次磷酸铝(ADP)对玻纤(GF)增强聚对苯二甲酸丁二酯(PBT)(PBT/GF)的阻燃作用,对复合材料的极限氧指数(LOI)和UL94阻燃等级进行测试,并用热失重和锥形量热仪进行分析。结果发现,ADP可以很好阻燃PBT/GF,加入19%的ADP,复合材料的LOI为33.5%,阻燃达到UL941.6 mm V–0级,相对PBT/GF,其点燃时间、火灾性能指数(FPI)有所提高,热释放速率峰值(PHRR)、平均热释放速率(AHRR)、总热释放量(THR)及总生烟量(TSR)有所降低。同时加入15%的ADP和2%的O–VMT,复合材料的PHRR,AHRR,THR和TSR相对单独添加17%ADP的材料,分别降低12.8%,9.5%,4.5%和15.9%,FPI提高15.4%,LOI和UL94阻燃也对应提高,O–VMT和ADP在PBT/GF中有协同阻燃作用。     

茶皂素基膨胀型阻燃剂的制备及其在涂料中的应用

采用多羟基、多羧基的活性天然产物茶皂素为原料,与聚磷酸铵和季戊四醇在一定条件下反应,制备一种聚磷酸酯类茶皂素基三位一体新型环保膨胀型阻燃剂。采用傅里叶红外分析技术对阻燃剂进行了结构表征,采用综合热分析仪对阻燃剂的热降解性能进行了研究。结果表明,茶皂素与聚磷酸铵、季戊四醇发生反应,生成聚磷酸酯类茶皂素基膨胀型阻燃剂,且该阻燃剂具有良好的热稳定性,降解热释放较小,高温残留率高,最终的质量残留率高达30.77%。将制备阻燃剂用于阻燃涂料中,并采用氧指数测试仪和锥形量热仪研究了阻燃涂料的阻燃性能和热解性能。研究表明,茶皂素基三位一体膨胀型阻燃剂能显著提高涂料的阻燃性能,阻燃涂料的氧指数值高达34.2%,耐火时间为11.1 min,且锥形量热实验中,该阻燃涂料试样的平均热释放速率（m-HRR）为36.18 kW/m2,总热释放量（THR）为5.25 kJ/m2,平均有效燃烧热（m-EHC）为5.11 kJ/kg,与含复合型阻燃剂的阻燃涂料试样相比,阻燃性能得到极大提高。该制备阻燃剂不含卤素,集三源一体,具有阻燃性能优越,相容性能良好,高效环保等优点。     

硅锡协同阻燃尼龙6

采用氯化亚锡(SnCl2)/聚氨丙基苯基倍半硅氧烷(PAPSQ)复合阻燃剂阻燃改性尼龙6(PA6)。测定了阻燃PA6的氧指数(LOI),利用锥形量热仪测定了阻燃PA6的释热速率、总释热量、有效燃烧热等多种阻燃参数,并用扫描电镜(SEM)观察了阻燃PA6残炭的形貌。实验表明,当SnCl2用量为4%,PAPSQ用量为1%时,PA6的LOI为31%,PA6的释热速率、总释热量和有效燃烧热均明显下降,PAPSQ对SnCl2有协同阻燃效果。     

In-situ growth of layered double hydroxide on montmorillonite nanosheets to improve the flame retardant performance of ABS resin

Layered double hydroxide (LDH) is a widely used flame retardant in polymer materials; however, the poor dispersion due to its high hydrophilic nature results in disappointing thermal stability and fire safety. In this work, LDH was in-situ grown on the disordered montmorillonite (MMT) nanosheets to obtain the hybrid of LDH and MMT nanosheets (LDH@MMT, simplified as LM). Various techniques, including X-ray diffraction, Fourier-transform infrared spectroscopy, field emission scanning electron microscopy, and transmission electron microscope were used to characterize the microstructure of LM. In addition, the acrylonitrile-butadiene-styrene (ABS) composite containing LM and intumescent flame retardant (IFR) was prepared, and its mechanical and flame-retardant properties were also measured. The characterization results demonstrate that the LM exhibits a periodically alternating layered structure. The Limiting Oxygen Index (LOI) of the ABS composite reaches 27.2% with a V-0 rating in the UL-94 vertical burning test, while its flexural strength and tensile strength decrease by only 17.82% and 13.45%, respectively. Furthermore, the heat release rate, total heat release, smoke production rate, and carbon monoxide production rate of the ABS composite present a significant decline in cone calorimeter tests compared with those of pure ABS. The results further indicate that the hybridization could effectively improve the flame-retardant performance of ABS composites and perform lesser impacts on their mechanical properties.     

Filler blend of carbon nanotubes and organoclays with improved char as a new flame retardant system for polymers and cable applications

Multi wall carbon nanotubes (MWCNTs) or single wall carbon nanotubes (SWCNTs) were used as fillers in polyethylene (PE). Only MWCNTs reduced the heat release rates caused by polymer degradation. MWCNTs can be more effective in heat release reduction than organoclays. The char generated by the filler blend ‘MWCNTs and organoclays’ as a synergistic flame retardant system in an ethylene vinylacetate (EVA) based polymer blend was improved compared with the char generated by the only organoclay based nanocomposite. Initial results indicated that there was a strengthening effect of the char by MWCNTs. The synergistic improvement for heat release reduction by a blend of the two fillers ‘MWCNTs and organoclays’ was used for the development of a flame retardant cable compound. 1.5 kg of MWCNTs was compounded on a Buss ko‐kneader to generate 60 kg of a nanocomposite based on the filler blend. The flame retardant properties of insulated wires made either by the filler blend or by ‘classical’ organoclays were measured. Copyright © 2004 John Wiley & Sons, Ltd.     

海泡石与APP对PVC/竹粉复合材料的阻燃抑烟机理

将海泡石(SEP)和聚磷酸铵(APP)同时加到聚氯乙烯(PVC)/竹粉复合材料中,考察SEP和APP对复合材料的协效阻燃抑烟作用及力学性能的影响。结果表明,在锥形量热实验中,热释放速率峰值相对减少42.8%,平均热释放速率和总热释放量相对减少29.5%和25.7%,总烟释放量相对降低了12.2%,一氧化碳平均产率相对降低了42.0%;扫描电子显微镜分析发现,APP具有催化成炭并形成膨胀泡沫炭层的作用,而SEP具有吸附聚集诱导成炭的作用;APP的阻燃机理主要属于气相阻燃机理,SEP的阻燃机理主要属于凝聚相阻燃机理;弯曲性能测试结果表明,SEP与APP对PVC/竹粉复合材料具有协同颗粒增强作用;拉伸性能测试结果表明,SEP对PVC/竹粉复合材料的塑性变形能力的损害比APP小。因此,SEP与APP联用能够对PVC/竹粉复合材料进行有效的阻燃抑烟,同时也能增强复合材料的力学性能。     

Microintumescent mechanism of flame‐retardant water‐based chitosan–ammonium polyphosphate multilayer nanocoating on cotton fabric

Layer‐by‐layer (LbL) assembly of nanocoatings on fabric substrates has been very successful in terms of reduction of flammability. In particular, an LbL system comprised ammonium polyphosphate as the polyanion and chitosan as the polycation, applied to cotton fabric, dramatically reduced cotton flammability. At this point, the fire‐retardant (FR) mechanism of action of this system has never been fully elucidated. Sonicated and nonsonicated coated cotton fabrics were evaluated using a vertical flame test and mass loss calorimeter. Coating morphology was investigated before and after burning. Thermal analyses and chemical analyses in the condensed phase (and in the gas phase) were conducted to reveal the FR mechanism of action. At the cotton surface, a combination of both condensed (formation of aromatic char) and gas phase (release of water and highly flammable gases) mechanisms impart the FR behavior, promoting a kind of “microintumescence” phenomenon. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43783.     

用锥形量热仪研究无卤阻燃HDPE体系的燃烧性

在35kW／m^2热辐照条件下,利用锥形量热仪研究了膨胀型阻燃剂／Mg(OH)2阻燃高密度聚乙烯(HDPE)体系的燃烧性。结果表明：膨胀型阻燃剂／Mg(OH)2能明显降低HDPE的热释放速率、总热释放量、最大生烟速率及总烟释放量。与膨胀型阻燃剂单独使用相比,Mg(OH)2与膨胀型阻燃剂复合使用的阻燃效果明显,总烟释放量减少了38％,总热释放量减少了10％,达到了低发炯、高效阻燃的目的。     

Effect of nanofillers on the flame retardant properties of a polyethylene–calcium carbonate–silicone elastomer system

This study shows the effects of three different nanofillers on the viscosity properties and fire behavior of a halogen‐free flame retardant system. The original system, based on ethylene‐acrylate copolymer, calcium carbonate, and a silicone elastomer, shows good flame retardant properties. One of the nanofillers, montmorillonite (MMT), significantly increases the viscosity above 250^°C, resulting in reduced dripping and decreased heat release rate. The ash residue, however, is very brittle, indicating poor interactions between the MMT and other components of the system. The second nanofiller, sepiolite, shows no improvement on the flame retardant properties of the system. Reduced dripping is observed when a small amount of the third nanofiller, polyhedral oligomeric silsesquioxane, POSS, is incorporated into the system. In this case, high silica content on the surface indicates char formation originating from the POSS. However, an increased heat release is observed when POSS is used in the system. Copyright © 2010 John Wiley & Sons, Ltd.     

Green DNA-based flame retardant coatings assembled through Layer by Layer

For the first time, DNA and chitosan are employed using the Layer by Layer technique in order to build green coatings exhibiting efficient flame retardant properties. DNA by its chemical structure can be considered as an intrinsically intumescent compound, since it contains precursor of phosphoric-polyphosphoric acid, a polyhydric char source (deoxyribose) and the nitrogen-containing bases that may release ammonia, acting as a blowing agent. When combined with chitosan, DNA layers promote the char formation of the former, by releasing phosphoric and polyphosphoric acid. Such bioarchitectures show an exponential growth as assessed by infrared spectroscopy and scanning electron microscopy. Very interestingly, these LbL assemblies are capable of i) reaching the self-extinguishment of cotton during horizontal flammability tests, ii) increasing the limit oxygen index up to 24% and iii) reducing the heat release rate by 40% during cone calorimetry tests.     

Development of layer-by-layer assembled carbon nanofiber-filled coatings to reduce polyurethane foam flammability

Layer-by-layer (LbL) assemblies made with carbon nanofibers (CNFs) are shown to reduce the flammability of polyurethane foam. The 359 ± 36 nm thick four bilayer coating of polyethyleneimine/CNF (cationic layer) and poly(acrylic acid) (anionic layer) contains 51 ± 1 mass fraction % CNF. This coating completely covers the entire internal and external surfaces of the porous foam. Even though the microscopic CNF distribution was non-uniform, the macroscopic CNF network armor that was generated from this LbL process significantly reduced the flammability of the foam (e.g., 40% ± 3% reduction in peak heat release rate). Normalized by flame retardant concentration, the reduction in foam peak heat release due to these CNF coatings is 38% larger than CNF embedded in the foam and as high as 1138% greater than other commercial technologies used to reduce foam flammability.     

Combination effects of carbon nanotubes,MMT and phosphorus flame retardant on fire and thermal resistance of fiber-reinforced epoxy composites

The present work aims to enhance thermal stability and flame retardancy of the epoxy/glass composites containing carbon nanotubes (CNTs). To achieve this purpose ammonium polyphosphate (APP) as a micro filler and montmorillonite (MMT) as nanofiller have been used. Since good dispersion is necessary to achieve thermal and flame resistivity in nanocomposites, it was found that combination of ultrasonication and high shear flow can result in a good dispersion of nanoparticles in polymer matrix. Thus, all samples were prepared according to this method. In order to study thermal resistance and flame retardancy of the samples, thermal gravimetric analysis (TGA) and limiting oxygen index (LOI) have been employed, respectively. TGA results showed that combination of 0.5 wt% CNTs with either 5 wt% MMT or 15 wt% APP can increase the initial thermal decomposition temperature up to 62 °C for the former polymer composite and 47 °C for the latter one. Overall stabilization effect (OSE) and integral procedure decomposition temperature (IPDT) parameters have also been calculated from TGA data. These results showed that the sample containing a combination of APP and CNT has the highest value of OSE. Moreover, IPDT of this sample has increased about 9 % compared with the neat epoxy. LOI of the samples showed that the addition of MMT and CNTs together could increase LOI about 8 % and introduction of APP to these samples increased LOI about 10 %, as well.     

Layer-by-layer assembled bagasse to enhance the fire safety of epoxy resin: A renewable environmental friendly flame retardant

In an effort to make rational use of resources, wasted bagasse were collected, and then fabricated by layer-by-layer (LbL) assembly to prepare an environmentally benign flame retardant for epoxy resin (EP). Six chitosan/ammonum polyphosphate bilayers were successfully deposited on the surface of bagasse, which endows EP/6BL@BF composites with a limiting oxygen index value of 24.1% and V-1 rating in UL-94 test. Compared with untreated bagasse, cone calorimetry test reveals that the incorporation of 6BL@BF reduces the peak heat release rate and total heat release by 64.6% and 13.2%, respectively. Besides, expandable graphite (EG) was combined with 6BL@BF to further enhance the fire safety and thermal stability of EP composites. Furthermore, the gas and condensed phase analysis of EP/6BL@BF/EG-3 composite was investigated by TG-IR, scanning electronic microscopy, Laser Raman spectroscopy, and X-ray photoelectron spectroscopy, and the flame retardant mechanism of 6BL@BF/EG was proposed. Finally, the mechanical properties of EP composites were investigated systematically.     

The flame retardant behaviors and synergistic effect of expandable graphite and dimethyl methylphosphonate in rigid polyurethane foams

A series of flame‐retardant rigid polyurethane foams (RPUFs) containing dimethyl methylphosphonate (DMMP) and expandable graphite (EG) were prepared by box‐foaming. The RPUFs were characterized by thermogravimetric analysis (TGA), the limiting oxygen index (LOI), cone calorimeter, and scanning electron microscope (SEM). The decomposition process of DMMP was investigated by Pyrolysis‐Gas Chromatography/Mass Spectroscopy (Py‐GC/MS). Accordingly, their flame retardant behaviors and mechanism were also discussed. The results show that the DMMP/EG system can linearly enhance the LOI value from 19.2% of the pure RPUF to 33.0% of RPUFs containing 16 wt% flame retardant. In addition, the DMMP/EG system also remarkably increases yields of the residual char and drastically decreases the peak value of heat release rate (PHRR), heat release rate (HRR), total heat release (THR), total smoke release (TSR), and the yields of CO (COY). In the flame retardant RPUFs, when the matrix is ignited, the flame retardant DMMP should be decomposed to gaseous PO₂ fragments, which can inhibit free radical chain reaction of flammable alkyl free radical from the decomposed matrix; whereas the flame retardant EG can rapidly expand and form loose and worm‐like expanding graphite char layer accordingly, which can hinder the heat transmission to the inner matrix and reduce decomposing velocity of matrix. After the combination of the two flame retardant effects, the DMMP/EG flame retardant system provides the matrix with better flame retardant effects than one of them does. Namely, it shows excellent gas‐condensed bi‐phase synergistic effect. POLYM. COMPOS., 35:301–309, 2014. © 2013 Society of Plastics Engineers