A flame‐retardant composite foam: foaming polyurethane in melamine formaldehyde foam skeleton

A composite foam, polyurethane–melamine formaldehyde (PU/MF) foam, was prepared through foaming PU resins in the three‐dimensional netlike skeleton of MF foam. The chemical structure, morphology, cell size and distribution, flame retardancy, thermal properties and mechanical properties of such composite foam were systematically investigated. It was found that the PU/MF foam possessed better fire retardancy than pristine PU foam and achieved self‐extinguishment. Moreover, no melt dripping occurred due to the contribution of the carbonized MF skeleton network. In order to further improve the flame retardancy of the composite foam, a small amount of a phosphorus flame retardant (ammonium polyphosphate) and a char‐forming agent (pentaerythritol) were incorporated into the foam, together with the nitrogen‐rich MF, thus constituting an intumescent flame‐retardant (IFR) system. Owing to the IFR system, the flame‐retardant PU/MF foam can generate a large bulk of expanded char acting as an efficient shielding layer to hold back the diffusion of heat and oxygen. As a result, the flame‐retardant PU/MF foam achieved a higher limiting oxygen index of 31.2% and exhibited immediate self‐extinguishment. It exhibited significantly reduced peak heat release rate and total heat release, as well as higher char residual ratio compared to PU foam. Furthermore, the composite foam also showed obviously improved mechanical performance in comparison with PU foam. Overall, the present investigation provided a new approach for fabricating a polymer composite foam with satisfactory flame retardancy and good comprehensive properties. © 2018 Society of Chemical Industry     

Flame‐retarding mechanism of organically modified montmorillonite and phosphorous‐Nitrogen flame retardants for the preparation of a halogen‐free,flame‐retarding thermoplastic poly(ester ether) elastomer

In this study, thermoplastic poly(ester ether) elastomer (TPEE) nanocomposites with phosphorus–nitrogen (P–N) flame retardants and montmorillonite (MMT) were prepared by melt blending. The fire resistance of the nanocomposites was analyzed by limiting oxygen index (LOI) and vertical burning (UL 94) tests. The results show that the addition of the P–N flame retardants increased the LOI of the material from 17.3 to 27%. However, TPEE containing P–N flame retardants only obtained a UL 94 V‐2 ranking; this resulted in a flame dripping phenomenon. On the other hand, TPEE containing the P–N flame retardant and organically modified montmorillonite (o‐MMT) achieved better thermal stability and good flame retardancy; this was ascribed to its partially intercalated structure. The synergistic effect and synergism were investigated by Fourier transform infrared spectroscopy and thermogravimetry. The introduction of o‐MMT decreased the inhibition action of the P–N flame retardant and increased the amount of residues. The catalytic decomposition effect of MMT and the barrier effect of the layer silicates are discussed in this article. The residues after heating in the muffle furnace were analyzed by scanning electron microscopy, energy‐dispersive X‐ray spectroscopy and laser Raman spectroscopy. It was shown that the intercalated layer silicate structure facilitated the crosslinking interaction and promoted the formation of additional carbonaceous char residues in the formation of the compact, dense, folded‐structure surface char. The combination of the P–N flame retardant and o‐MMT in TPEE resulted in a better thermal stability and fire resistance because of the synergistic effect of the mixture. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41094.     

阻燃聚苯乙烯板的力学性能

以阻燃涂料对可发性聚苯乙烯板(EPS)进行内部包覆和外部涂刷,制备阻燃EPS板。对涂覆涂料的阻燃EPS板进行抗弯压缩、高低温尺寸稳定性以及吸水率的测试结果表明,在阻燃EPS板极限氧指数达34.7%、垂直燃烧达UL94 V–0级及水平燃烧达HF–1级标准时,其力学性能及其它性能均能达到国家要求的保温材料标准,由此表明,阻燃涂料在改善EPS板的阻燃性能的同时,也能保证阻燃EPS板的力学性能。     

用于超纤革PU浆料的无卤阻燃改性

选择了有机磷系和磷氮协同两种不同的无卤阻燃剂与溶剂型PU进行共混制备无卤阻燃PU,对其力学性能、阻燃性能及耐碱性能进行了系统研究。结果发现:相较于磷氮协同阻燃剂(SN-605),采用有机磷系阻燃剂(JL-30)改性PU显示出更好的阻燃性能与耐碱性能;当阻燃剂质量分数为11.1%时,阻燃PU的LOI可以达到29.1%,垂直燃烧测试达到V-0级;并且具有较好的耐碱性能,在90℃、30 g/L NaOH溶液中碱处理40 min后,其LOI仍然可以达到28.7%,垂直燃烧测试等级没有下降;但两种阻燃剂的加入均会使PU的抗张强度出现不同程度的下降。此外,热失重测试(TG)显示,两种阻燃PU的阻燃机制不同,JL阻燃剂的加入使PU的热分解温度降低,并且在800℃时的残炭量没有明显增加,呈现明显的气相阻燃机制;而SN阻燃剂的加入使PU的残炭量明显增加,呈现明显的凝聚相阻燃机制。     

Graphene and poly(ionic liquid) modified polyurethane sponges with enhanced flame‐retardant properties

Graphene (Gr) and poly(ionic liquid) (PIL) modified polyurethane (PU) sponges with enhanced flame‐retardant properties were prepared by the direct dip coating of Gr and ionic liquid (IL) monomers onto a PU sponge followed by the polymerization of IL monomers under thermal initiation. With a content of 1.5% Gr in IL, the limiting oxygen index (LOI) of PU–PIL–Gr was 26.1%, whereas the neat PU sponge showed an LOI of only 17.9%. The horizontal flame test results indicate that PIL–Gr prevented horizontal flame spread and eliminated melt dripping. Compared with that of the neat PU sponge, the peak heat release rate of PU–PIL–Gr decreased about 22.0%. These improvements on flame retardancy might have been due to a hybrid flame retardant originating from Gr (which acted as carbon source) and PIL (which contained the flame‐retardant elements) in the PU sponge and the formation of protective layers, which isolated the oxygen and heat more effectively. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45477.     

消防服用多层织物的热防护性能

研究了消防服用多层织物的热防护性能,对单层织物的热防护性能及十种多层组合织物的热防护性能分别进行了研究分析,得出以下结论:就单层纤维成分相同的阻燃面料而言,热防护系数(TPP)值与织物的厚度、面密度具有显著的正相关性;多层组合织物中,外层及防水透湿层为覆聚四氟乙烯(PTFE)膜的阻燃帆布、隔热层为芳纶1313针刺毡、舒适层为芳纶-阻燃黏胶的8#样品的防护性能最好,就阻燃防护性能方面而言,是最适合用于消防员灭火消防服的面料。     

水性聚合物阻尼涂料性能的研究

以聚合物乳液为基料,以云母、石墨、空心微珠、无机纤维、复合阻燃剂为填料,制备的阻尼涂料涂层具有Tg温域宽、阻尼因子值高、减振降噪、隔热隔音效果明显、力学性能好、阻燃性能优等特性。     

Preparation and application of high sound insulation polyurethane composite film through glass fiber reinforcement

Laminated glasses have been widely used in buildings, physical protections, and vehicles because of their safety, sound insulation, thermal insulation, and other performance. In recent years, the high sound insulation performance of laminated glass intermediate films in the frequency range of low or high frequencies has attracted more and more attentions. In this work, a glass fiber/polyurethane elastomer composite (PU-MGF) film with high transparency and impact resistance has been successfully synthesized, 5 dB of the transmission loss increased at 1600–6000 Hz, and 3.6 dB increased at 63–1600 Hz compared with the control polyurethane film. This is a significant progress in the laminated glass industry. In addition, the transmittance of the composite reaches over 75%. The excellent impact resistance of the laminated glass, based on PU-MGF film, has been confirmed through falling ball impact test, demonstrating its ability to withstand multiple impacts without spattering. The PU-MGF film prepared in this work exhibits great potential for applications in building windows, transportation, and soundproof devices.     

Intumescent flame retardant TPO composites: Flame retardant properties and morphology of the charred layer

Intumescent flame retardant thermoplastic polyolefin (TPO) composites were prepared to study the relationships between their structure of charred layer (including of the multicellular intumescent layer and the charry layer) and flame retardant properties. They were characterized using the LOI and UL‐94 test, which indicated that the best fire retardant behavior (V‐0 rating and LOI reach to 28.1%) was obtained at the formulation of TPO/ammonium dihydrogen phosphate/starch (100/60/20). Thermal gravimetric analysis demonstrated that the presence of ammonium dihydrogen phosphate/starch promoted the esterification and carbonization process in lower temperature range while enhancing the thermal stability of intumescent flame retardant TPO in high‐temperature range. Scanning electron microscope and optical microscope were shown that, with combustion time prolonged, the intumescent layers obtained greater number of cells, and the charry layer became more compact while the size of the carbon granules became smaller on the surface. Introduction of starch had an obvious effect on the structure of the intumescent and charry layers. The charry layer of the composites with the content of 20 phr starch was more compact and uniform than that of the composites with 50 phr. The weight ratio of ammonium dihydrogen phosphate to starch in the intumescent flame retardant was fixed as 3 : 1 which cooperated with each other well to promote a compact charry layer and to obtain the better flame retardancy performance. Therefore, the better the charred layers produced, and the better flame retardant properties they obtained. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

阻燃硬质聚氨酯泡沫塑料垂直火蔓延特性研究

通过一步合成法制备了阻燃硬质聚氨酯泡沫,自主搭建保温材料火蔓延实验台,采用中小尺寸实验对比研究了阻燃及非阻燃硬质聚氨酯的垂直火蔓延特性,分析了火焰结构特性、火蔓延速度、火焰温度、质量损失速率等参数的变化规律。结果表明,火蔓延过程中,材料表面均出现了炭化现象,垂直双面燃烧过程中聚氨酯纯样RPUF燃烧最剧烈,阻燃剂膨胀石墨(EG)、次磷酸铝(AHP)和二乙基次膦酸铝(ADP)的加入,抑制了材料的燃烧和蔓延,使材料燃烧的火蔓延速度、质量损失速率及温度等参数都相应降低。RPUF/AHP5垂直双面火蔓延过程中,火焰稳定性差,在20 s后出现熄灭现象,原因是阻燃剂次磷酸铝(RPUF/AHP5)受热挥发出难燃气体。AHP降解后形成的含磷化合物可促进聚氨酯分子链成炭,导致产生熄灭现象。而RPUF/ADP5火蔓延过程中,同样出现了熄灭现象,其熄灭的程度低于阻燃剂次磷酸铝(RPUF/AHP5)试样。RPUF/EG5火蔓延过程中试样表面温度存在两个峰值,由于RPUF/EG5燃烧生成的炭层不稳定所致。当温度高于400℃时炭层被迅速氧化,热量穿透炭层使内部未燃样品热解,生成温度的第二个峰值。     

Synthesis of a phosphorus and sulfur‐containing aromatic diamine curing agent and its application in flame retarded epoxy resins

A novel curing agent of epoxy resins (EPO), bis(3‐amino‐2‐thienyl) phenylphosphine oxide (ABTPPO), was synthesized and characterized by Fourier transform infrared spectroscopy, ¹H nuclear magnetic resonance (NMR), ¹³C NMR, and ³¹P NMR. ABTPPO was used as a flame retardant curing agent, and a novel halogen‐free flame retardant EPO composite was prepared. The flame retardant properties of ABTPPO‐cured EPO were evaluated in terms of limiting oxygen index and vertical burning test (UL‐94), while the combustion and thermal degradation behaviors were investigated by cone calorimeter test (CONE) and thermogravimetric analysis, respectively. The cured EPO composite passed the UL‐94 V‐1 and V‐2 rating when the sample thickness is 3.0 and 1.6 mm, respectively, and the limiting oxygen index value reached 38.3%. The morphological structures of char residue tested by scanning electron microscopy demonstrated that ABTPPO benefited to the formation of a more compact and homogeneous char layer on the materials' surface during burning, which protected the underlying matrix from decomposition and enhanced the flame retardancy of materials. The cured EPO showed excellent fire performance after the water resistance test because of the low water uptake (0.6 wt%), which demonstrated that the flame retardant EPO composite possessed excellent water resistance property. Copyright © 2014 John Wiley & Sons, Ltd.     

Modification of ramie fabric with a metal‐ion‐doped flame‐retardant coating

Transition‐metal‐ion‐doped flame‐retardant coatings were constructed on the surface of ramie fabrics by a layer‐by‐layer (LbL) assembly technique to investigate possible cooperative actions that could improve the fabric's flame‐retardant efficiency. We found that these functional coatings, consisting of poly(vinylphosphonic acid) (the anionic layer) and branched polyethylenimine/cupric or zinc ions (the cationic layer), improved the fire retardancy of the ramie fabrics remarkably. Attenuated total reflectance–Fourier transform infrared (FTIR) spectroscopy and energy dispersive X‐ray spectroscopy demonstrated the successful LbL assembly process and the incorporation of metal ions into the coating. Thermogravimetric analysis coupled with FTIR spectrometry, vertical flame testing, and microscale combustion calorimetry confirmed the improved thermal stability and reduced flammability of the coated ramie fabrics. All of the results show that the metal‐ion‐doped flame‐retardant coatings not only dramatically increased the residues but also retained the original weave structure and fiber morphology of ramie fabrics well. The enhanced flame‐retardant efficiency may have been caused by the lower decomposition temperature of the flame‐retardant coating, as promoted by cupric and zinc ions, and as a result, may have helped the flame‐retardant activity to take place earlier. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and investigation of efficient flame retardant TPE composites with piperazine pyrophosphate/aluminum diethylphosphinate system

The piperazine pyrophosphate (PPAP) combined with aluminum diethylphosphinate (AlPi) with a certain mass fraction and then incorporated into thermoplastic elastomer (TPE) composites composed of oil extended styrene–ethylene–butadiene–styrene block copolymer and polypropylene. The fire retardancy, thermal behavior, mechanical performance, and flame retardant mechanism of TPE materials were investigated in detail. The results demonstrated that 1.6 mm TPE composites reached UL-94 V-0 grade during vertical burning tests and the limiting oxygen index value was 28.5% when 25 wt % PPAP/AlPi with the mass ratio of 4:1 was incorporated. The introduction of PPAP/AlPi improved the residual mass and thermal stability, and stimulated to produce the char layer with high quality. The formed char layer exerted shielding effect and AlPi could inhibit the flame in gas phase. Consequently, the PPAP/AlPi system evoked fire retardant effects in condensed and gas phase simultaneously, and the fire resistance of the TPE composites was enhanced. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 47711.     

Study of the electrical properties of flame retardant poly(vinylchloride) using positron annihilation lifetime spectroscopy

Since the large fire at the Brown Ferry cable plant which occurred at noon on March 22, 1975 in Alabama, attention has been given to the use of flame retardant cable in buildings to meet fire safety requirements. Flame retardants are used in wire and cable applications to prevent the conversion of an electric spark into fire and subsequently to prevent the spread of fire throughout a structure along the wiring. There are many substances used as flame retardants in wires and cables. In Egypt, Multi‐Purpose Reactor insulation and jacket cables have been constructed from a flame retardant substance, poly(vinylchloride) (PVC). In the present work, elemental and X‐ray fluorescence analyses have been performed to determine the composition of PVC in the jacket cable samples. In addition, the conductivity (σ), permittivity (?′), and dielectric loss (?″) as well as positron annihilation lifetime (PAL) are measured in the temperature range 30 to 140 °C. It is found that the amount of chlorine in the flame‐retardant PVC (FRPVC) jacket cable is significantly higher (5%) than the conventional PVC jacket cable. Inverse relationships between σ and free volume size and fractions (V, f) through the temperature range are obtained. However, a distinct positive relationship between σ and I₂ above 100°C is found. The results of PAL and electrical measurements indicate that FRPVC has good electrical insulation properties below 100°C. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 638–644, 2005     

Preparation of polyamide resin‐encapsulated melamine cyanurate/melamine phosphate composite flame retardants and the fire‐resistance to glass fiber‐reinforced polyamide 6

In this study, melamine cyanurate (MCA)/melamine phosphate (MP) composite flame retardants were synthesized in the solution of phosphoric acid/polyamide 6 (PA6). Phosphoric acid acted as the solvent of PA6, catalyst of melamine‐cyanurate self‐assembly reaction and reactant of melamine‐phosphoric acid reaction. With the consumption of the acid, the pH value of the system increased, and the solved PA6 precipitated on the surface of the flame retardant particles to form polymeric encapsulation. This technology realized the synthesis and surface modification of the flame retardants in one process. The catalyst and solvent, phosphoric acid, was finally converted into the product MP, and need no an additional removing process. The encapsulated MCA/MP (EMCMP) composite flame retardants were successfully applied in the fire‐resistance to glass fiber (GF)‐reinforced PA6. Because the encapsulated layer of EMCMP was also PA6, good interfacial compatibility and effective dispersion of EMCMP in PA6 resin can be obtained, and the corresponding flame retardant materials showed excellent flame retardancy and mechanical performance. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1773–1779, 2006     

A commercial phosphorous–nitrogen containing intumescent flame retardant for thermoplastic polyurethane

The aim of this work is to develop a halogen‐free thermoplastic polyurethane (TPU) composite with significantly improved fire performance by using a highly commercial phosphorous–nitrogen containing intumescent flame retardant (P–N IFR). Based on the characterizations of thermogravimetric analysis and in situ Fourier transform infrared spectra, P–N IFR powder was proved a desired flame retardant for TPU in theory and the thermal degradation property of PU/PNIFR composites at elevated temperatures was investigated as well. Fire performance was evaluated by limiting oxygen index, underwriters laboratories 94 testing and char residue morphologies. Results showed that the addition of P–N IFR promotes the formation of char residues which were covered on the surface of polymer composites resulting in the improvement of thermal stability and flame retardancy. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39772.     

The damping and flame‐retardant properties of poly(vinyl chloride)/chlorinated butyl rubber multilayered composites

The alternating multilayered damping composites, which were consisted of chlorinated butyl rubber (CIIR) layers and poly(vinyl chloride) (PVC) layers, were first prepared through multilayered coextrusion technology. The multilayered structure was controlled by adjusting the layer number or the thickness ratio of CIIR layer and PVC layer. The damping and flame‐retardant properties of the CIIR/PVC multilayered damping composites were investigated by dynamic mechanical analysis, the limiting oxygen index, and thermogravimetric analyzer, respectively. The results showed that the effective damping temperature range was broadened with increasing the layer number, since multilayered structure resulted in partial overlap of the loss peaks of CIIR and PVC. Meanwhile, the flame‐retardant properties of the multilayered composites were also enhanced with increasing the layer number. Less surface area of CIIR contacting oxygen in the confined burning space, rather than the formation of char residue, could effectively retard the combustion of the material. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41259.     

Flame‐retardant mechanism of expandable polystyrene foam with a macromolecular nitrogen–phosphorus intumescent flame retardant

Expandable polystyrene (EPS) foam is largely used as the thermally insulating external wall in buildings and constructions, but it is extremely flammable because of the presence of almost 98% air into its porous structure, its high surface‐area‐to‐mass ratio, and its elemental composition. Lots of serious fire disasters caused by EPS foam have posed great threats to people's properties and lives in recent years. Thus, a halogen‐free, flame‐retardant EPS is urgently needed, and its preparation is still a global challenge. To solve the problem that it is easy for EPS foam to form melt dripping and difficult for it to generate a char layer during the combustion process, a macromolecular nitrogen–phosphorus intumescent flame retardant (MNP) was selected to prepare flame‐retardant EPS foam and good mechanical and flame‐retardant properties were obtained. The scanning electron microscopy characterization revealed that MNP could penetrate into the gap between the beads, and a thin physical coating layer formed on the surface of the bead. The data from the thermogravimetry–Fourier transform infrared test indicated that a nitrogenous noncombustible gas was generated by the pyrolysis of MNP. When the MNP content increased to 30%, the limiting oxygen index and the smoking density rate of the EPS–MNP foam were 28.8 and 23.6, respectively, and a UL94 V‐0 classification was achieved. In addition, the heat‐release rate, total heat‐release, smoke produce rate, and carbon dioxide production of the EPS–MNP foams all decreased obviously; this was attributed to the flame‐retardant effects of MNP in both the condensed and gas phases. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44356.     

Expandable graphite encapsulated by magnesium hydroxide nanosheets as an intumescent flame retardant for rigid polyurethane foams

Encapsulation of expandable graphite (EG) particles by organic or inorganic shells has been proved to efficiently enhance the expandability of EG, and thus to improve the flame‐retardant efficiency of EG. In this study, magnesium hydroxide (MH) nanosheets were utilized to fabricate core–shell EG@MH flame‐retardant particles through a heterocoagulation method. It was observed that after the encapsulation by MH nanosheets, the edges of the char residue of the EG layer were sealed after combustion, which contributed to the enhancement of expandability. The expansion volume of EG@MH increased dramatically to 456 mL/g, in contrast to 338 mL/g for pure EG. By incorporating 11.5 wt % of flame‐retardant particles, polyurethane foam containing EG@MH (here PU‐EG@MH) displayed excellent flame retardancy. Compared with the physically mixed sample, PU‐EG+MH, the limiting oxygen index value for the PU‐EG@MH sample increased from 29.8% to 32.6%. Furthermore, the shell of MH nanosheets was beneficial for improving the interfacial adherence between EG and the rigid polyurethane foam (RPUF) matrix, due to the reaction between isocyanate functional groups and MH. The cell structure and storage modulus of PU‐EG@MH were improved. In other words, the shell of MH nanosheets successfully improved the flame‐retardant efficiency and enhanced the interface adhesion between EG and the matrix. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46749.     

Study on char reinforcing of different inorganic fillers for expandable fire resistance silicone rubber

Sodium silicate monohydrate (NSH), glass frits (GF) and aluminum hydroxide (ATH) were incorporated into room temperature vulcanized (RTV) silicone rubber (SR) as char reinforcing materials to improve the fire resistance of intumescent flame retardant silicone rubber. SR composites containing only intumescent flame retardant such as phosphorus nitrogen composite flame retardant (NH₂-C) and expandable graphite (EG) were used as comparison samples. Limiting oxygen index (LOI) test, vertical burning test (UL-94), flame resistance test, scanning electron microscopy (SEM) and X-ray diffraction spectroscopy tests, as well as volume variation and compression strength of char residues were used to discuss the effects of the above-mentioned fillers on the fire resistance, char residue strength and char integrity of SR composites. The results showed that SR composite filled with only intumescent flame retardants EG and NH₂-C had excellent flame retardancy. After adding ATH, the char residue was relatively dense and had good compressive strength, but its thermal insulation performance was reduced. GF or NSH reduced the flame retardancy of SR composites, but it obviously played a role in binding combustion residues, forming new crystals and improving the stability of char residues.