含磷阻燃剂阻燃环氧树脂热降解动力学

以2-二苯基膦酰基-1,4-苯二酚(DPO-HQ)为阻燃剂制备了阻燃环氧树脂,利用动态热重分析法(TGA)研究了纯环氧树脂(EP)和阻燃环氧树脂(FR-EP)在不同升温速率下的热稳定性,建立了EP和FR-EP体系的动力学模型和非模型动力学(MFK),并对比分析了模型动力学和非模型动力学对于描述EP体系和FR-EP体系的适用性.结果表明:阻燃剂的引入降低了环氧树脂初始降解温度,但增加了残炭率.由Flynn-Wall-Ozawa方法和Coats-Redfern方法建立的模型动力学表征EP和FR-EP体系高温降解过程中误差较大,而非模型动力学能更准确地预测和描述EP和FR-EP体系的高温降解行为.     

聚丙烯/尼龙/纳米蒙脱土膨胀型阻燃材料的研究

用尼龙6(PA6)代替季戊四醇(PT)作为成炭剂组成的膨胀型阻燃聚丙烯(PP)有熔滴、阻燃效果差的缺点，加入纳米蒙脱土(nano-MMT)作为阻燃剂的协效剂后可克服以上缺点。研究结果表明：加入质量分数为4％的nano-MMT不仅克服了阻燃体系熔滴的缺点，还使材料的拉伸强度提高了44．3％；热重分析和燃烧测试表明，nano-MMT的加入提高了材料的热稳定性，使剩炭率增加了12％，从而提高了材料的阻燃性能；由扫描电镜(SEM)观察发现：nano-MMT的加入增强了材料的界面粘结力，提高了材料的韧性，起到了一定的增容作用。     

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.     

Preparation of thermally stable and flame-retardant sugarcane bagasse-ammonium dihydrogen phosphate/epoxy composites and their performance

Epoxy resin was often applied in fiber-reinforced composite materials, adhesives, and encapsulation materials. However, epoxy was easily flammable and limited its usage in certain applications. The study recycled and reused agricultural waste sugarcane bagasse to prepare a halogen-free bio-based intumescent flame retardant and then mixed with epoxy resin to prepare a composite containing polymer with improved thermal properties and flame retardancy of the materials. The work followed the concept of circular economy and sustainability. Bagasse-ammonium dihydrogen phosphate (ADP) flame retardant was added to an epoxy resin to prepare epoxy/bagasse-ADP composites, an effective flame-retarding composite material through hydrothermal method. Adding bagasse-ADP increased the thermal stability and flame retardancy of the composite materials compared with that of pure epoxy. For the material with 30 wt% added bagasse-ADP, the char yield was 32.3 wt%, which was 18.2 wt% higher than that of pure epoxy (14.1 wt%) through thermogravimetric analysis. In addition, the limiting oxygen index increased from 21% to 30%, and the UL-94 classification improved from “Fail” to “V-0.” This performance was attributed to the nitrogen, phosphorus, and silicon content of the flame retardant.     

Preparation,thermal, and flammability of halogen‐free flame retarding thermoplastic poly(ether‐ester) elastomer/montmorillonite nanocomposites

In this article, the nanocomposites thermoplastic polyester‐ether elastomer (TPEE) with phosphorous–nitrogen (P–N) flame retardants and montmorillonite (MMT) was prepared by melt blending.The fire resistance of nanocomposites was analyzed by limiting oxygen index (LOI) and vertical burning (UL94) test. The result shows that the flame retardants containing P–N increased the LOI of the material from 17.3 to 27%. However, TPEE containing P–N flame retardants just got UL94 V‐2 ranking, which resulted in the flaming dripping phenomenon. On the other hand, TPEE containing P–N flame retardant and organic‐modified montmorillonite (o‐MMT) achieved UL94 V‐0 rating for the special microstructure. The XRD and TEM morphology has demonstrated that the formation of multi‐ordered structure regarding restricted segmental motions at the organic–inorganic interface and stronger interactions between the clay mineral layers and the polymer chains. The structure was supported by the results of rheological properties and DSC analysis. The thermal degradation and char residue characterization was studied by thermal gravimetric analysis (TGA) and SEM‐EDX measurements, respectively. The TGA and SEM‐EDX have demonstrated that o‐MMT results in the increase of char yield and the formation of the thermal stable carbonaceous char. POLYM. COMPOS., 37:700–708, 2016. © 2014 Society of Plastics Engineers     

酚氧基环磷腈阻燃环氧树脂的热解过程研究

用自制六氯环三磷腈通过亲核取代反应制备了六（酚氧基）环三磷腈（HPCP）,并将HPCP与环氧树脂（EP）以不同比例共混,固化成型,采用氧指数仪和热质联用仪对其热性能和降解机理进行分析。结果表明,在EP中加入HPCP可提高材料的热解残炭率;当添加10份HPCP时,阻燃EP的极限氧指数可达27.0 %;HPCP的阻燃机理是其所含的氮磷2种元素的协效作用与自缩合放出H2O分子2种阻燃机理的共同作用。     

Using PA6 as a charring agent in intumescent polypropylene formulations based on carboxylated polypropylene compatibilizer and nano‐montmorillonite synergistic agent

The intumescent fire retardant polypropylene (IFP/PP) filled with ammonium polyphosphate (APP), melamine (M), and PA6 (charring agent) is discussed. Intumescing degree (ID) and the char yield were determined. Only when the three main components of IFR coexist at appropriate proportions, it has optimal ID and higher char yield. The appropriate proportion is PA6 : APP : M = 10 : 10 : 5. A new compatibilizer, carboxylated polypropylene (EPP), was added to PP/PA‐6 blend. Flow tests indicated that the apparent viscosity increased with the addition of EPP, thermal characterization suggested that EPP has reacted with PA6, PA6‐g‐EPP cocrystallized with PA6, and EPP‐g‐PA6 cocrystallized with PP; SEM micrographs illustrated that the presence of EPP improved the compatibility of PP and PA6. All the investigations showed that EPP was an excellent compatibilizer, and it was a true coupling agent for PP/PA6 blends. Using PA6 as a charring agent resulted in the IFR/PP dripping, which deteriorated the flammability properties. The addition of nano‐montmorillonite (nano‐MMT) as a synergistic agent of IFR enabled to overcome the shortcoming. The tensile test testified that the addition of nano‐MMT enhanced the mechanical strength by 44.3%. SEM showed that nano‐MMT improved the compatibility of the composites. It was concluded that the intumescent system with nano‐MMT was an effective flame retardant in improving combustion properties of polypropylene. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 739–746, 2006     

室温固化含磷膨胀型阻燃环氧树脂清漆

室温条件下以酸式磷酸酯固化环氧树脂,制得了含磷膨胀型阻燃清漆。涂膜的理化和燃烧性能测试表明,酸式磷酸酯具有较好的固化和阻燃效果。当酸式磷酸辛酯(m(双酯)/m(单酯)/m(磷酸)=44.38/54.73/0.89))与E-51按质量比6.5/8.7混合时效果最佳,表干时间230 min,烧穿时间76.5 min,残炭膨胀高度5.92mm。而市售G-03胺类固化剂固化的E-51,表干时间240 min,烧穿时间2.3 min,无残炭膨胀。FTIR检测结果显示,室温下酸式磷酸酯可使E-51固化;热分析以及SEM照片显示,酸式磷酸酯提高了炭层密度和残炭量。     

Synthesis and Properties of a Novel Flame-Retardant Epoxy Resin Containing Biphenylyl/Phenyl Phosphonic Moieties

A novel reactive diol, bis-biphenyloxy (4-hydroxy) phenyl phosphine oxide (BBPHPPO) which contains both biphenylyl and phenyl phosphonic groups was synthesized. Flame retardant advanced epoxy resin was obtained by chain extension of diglycidyl ether of bisphenol-A (DGEBA) with the phosphorus-containing diol (BBPHPPO). The thermal properties and flame retardancy of cured epoxy resin were studied. The resulting BBPHPPO containing epoxy system exhibited higher glass transition temperature than that of advanced epoxy resins prepared from bisphenol-A (BA) and tetrabromobisphenol-A (TBBA). The high char yield and the high LOI value were observed to prove the excellent flame retardancy of this phosphorus-containing epoxy resin.     

Synthesis of a novel cross‐linked organophosphorus‐nitrogen containing polymer and its application in flame retardant epoxy resins

A novel cross‐linked organophosphorus–nitrogen polymetric flame retardant additive poly(urea tetramethylene phosphonium sulfate) defined as PUTMPS was synthesized by the condensation polymerization between urea and tetrahydroxymethyl phosphonium sulfate. Its chemical structure was well characterized by Fourier transform infrared (FTIR) spectroscopy, ¹³C and ³¹P solid‐state nuclear magnetic resonance. The synthesized PUTMPS and curing agent m‐phenylenediamine were blended into epoxy resins to prepare flame retardant epoxy resin thermosets. The effects of PUTMPS on fire retardancy and thermal degradation behavior of EP/PUTMPS thermosets were investigated by limiting oxygen index (LOI), vertical burning test (UL‐94), cone calorimeter measurement, and thermalgravimetric analysis (TGA) tests. The surface morphologies and chemical compositions of char residues for cured epoxy resins were investigated by scanning electron microscopy and X‐ray photoelectron spectroscopy (XPS), respectively. Water resistant properties of epoxy resin thermosets were evaluated by putting the samples into distilled water at 70°C for 168 h. The results demonstrated that the EP/12 wt% PUTMPS thermosets successfully passed UL‐94 V‐0 flammability rating and the LOI value reached 31.3%. The TGA results indicated that the incorporation of PUTMPS promoted epoxy resin matrix decomposed and char forming ahead of time, which led to a higher char yield and thermal stability for epoxy resin thermosets at high temperature. The morphological structures and analysis of XPS for the char residues of the epoxy resin thermosets shown that PUTMPS benefited to the formation of a sufficient, more compact, and homogeneous char layer with rich flame retardant elements on the materials surface during burning, which prevented the heat transmission and diffusion, limited the production of combustible gases, inhibited the emission of smoke, and then led to the reduction of the heat release rate and smoke produce rate. After water resistance tests, EP/12 wt% PUTMPS thermosets still remained excellent flame retardancy. Copyright © 2015 John Wiley & Sons, Ltd.     

Polyamide‐enhanced flame retardancy of ammonium polyphosphate on epoxy resin

An attractive intumescent flame retardant epoxy system was prepared from epoxy resin (diglycidyl ether of bisphenol A), low molecular weight polyamide (cure agent, LWPA), and ammonium polyphosphate (APP). The cured epoxy resin was served as carbonization agent as well as blowing agent itself in the intumescent flame retardant formulation. Flammability and thermal stability of the cured epoxy resins with different contents of APP and LWPA were investigated by limited oxygen index (LOI), UL‐94 test, and thermogravimetric analysis (TGA). The results of LOI and UL‐94 indicate that APP can improve the flame retardancy of LWPA‐cured epoxy resins. Only 5 wt % of APP can increase the LOI value of epoxy resins from 19.6 to 27.1, and improve the UL‐94 ratings, reaching V‐0 rating from no rating when the mass ratio of epoxy resin to LWPA is 100/40. It is much interesting that LOI values of flame retardant cured epoxy resins (FR‐CEP) increase with decreasing LWPA. The results of TGA, FTIR, and X‐ray photoelectron spectroscopy (XPS) indicate that the process of thermal degradation of FR‐CEP consists of two main stages: the first stage is that a phosphorus rich char is formed on the surface of the material under 500°C, and then a compact char yields over 500°C; the second stage is that the char residue layer can give more effective protection for the materials than the char formed at the first stage do. The flame retardant mechanism also has been discussed according to the results of TGA, FTIR, and XPS for FR‐CEP. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Strengthen flame retardancy of epoxy thermoset by montmorillonite particles adhering phosphorus-containing fragments

Phosphaphenanthrene derivative tri-(3-DOPO-2-hydroxypropan-1-yl)-1,3,5-triazine-2,4,6-trione (TGD) and organo-modified montmorillonite (OMMT) were jointly introduced into the diglycidyl ether of bisphenol A cured by 4,4-diamino-diphenylmethane (EP) to investigate their flame retardant behaviors. With only addition of 0.5%OMMT and 2.5%TGD, epoxy thermoset achieved a limiting oxygen index value of 33.7% and passed UL 94 V-0 rating test. Compared with the combustion behaviors of 3%OMMT/EP and 3%TGD/EP, an obvious synergistic flame retardant effect between OMMT and TGD can be concluded in OMMT/TGD/EP. Meanwhile, the FTIR spectra of gas-phase and condensed-phase products further proved this synergistic effect working in a physical way. On one hand, the co-existence of hydroxyl-containing TGD enabled montmorillonite (MMT) particles to filtrate and adhere more smoke fragments. On the other hand, the co-action of MMT help the polar phosphorus-containing fragments from TGD better strengthened char layer, enhancing the barrier and protective effect of residue. The synergistic flame retardant effect from OMMT/TGD system endowed themselves with higher flame retardant efficiency, and epoxy thermoset with better flame retardant performance. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 47500.     

Synergistic Flame Retardant Effects of Carbon Nanotube-Based Multilayer Nanocoatings

In an effort to develop highly functionalized flame retardant materials, hybrid nanocoatings are prepared by alternately depositing a positively charged polyaniline (PANi) and negatively charged montmorillonite (MMT) using the layer-by-layer (LbL) assembly technique. Carbon nanotubes (CNTs) are employed in polymer nanocomposites as effective reinforcement, where nanotubes are stabilized in MMT aqueous solution. The 3D structure and high density of CNTs deposited in the PANi/CNTs-MMT multilayers produce thicker and heavier coatings in comparison to the LbL assemblies without CNTs. Vertical and horizontal flame testing show that the incorporation of CNTs improves fire resistance. Additionally, cone calorimetry reveals that stacking two nanomaterials (MMT and CNTs) in a single coating shows a significant reduction in peak heat release rate (up to 51%), total smoke release (up to 47%), and total heat release (up to 37%) for the polyurethane foam. The enhancement of flame retardancy is attributed to a synergistic effect; MMT serves as a physical barrier that retards the diffusion of heat and gas. The addition of CNTs strengthens the thermal stability and high char yield. These results, coupled with the simplicity with which the LbL deposition is applied, present a viable alternative to halogen-free flame retardant nanocoatings to natural and synthetic fibers.     

新型磷／氮协同阻燃环氧树脂的合成与性能

以双酚A环氧树脂E－51与DOPO（9,10-dihydrooxa-20－phosph henanthrene－10-oxide）合成含磷环氧树脂（ED）,以三聚氰胺与苯酚反应制备含氮的酚醛固化剂MFP。采用红外光谱对产物进行分析表征,采用热失重分析和UL94V垂直燃烧测试考查树脂的热性能和阻燃性能,同时探讨了阻燃环氧树脂的力学性能。结果表明,随着含磷量的增加,环氧树脂的热稳定性和阻燃性能得到改善,当含磷量为3％时,环氧树脂的初始分解温度高达330℃以上,在700℃下的残炭率达到30％以上,阻燃性能均达到了UL－94 V—0级。而试样的力学性能则随含磷量的增加而降低。     

Synthesis and properties of a phosphate ester as curing agent in an epoxy resin system

Phosphate ester compounds display good flame retardancy effect in epoxy resin systems. In this paper, several novel phosphate esters, used as curing agents for epoxy resins, were synthesized based on P₂O₅, phosphoric acid, and different types of alcohol. The structures of phosphate esters were characterized by ³¹P nuclear magnetic resonance (³¹P NMR). Then, a series of flame retardant epoxy composites were prepared by curing the epoxy resins (E-44) with the phosphate esters. The flame retardancy and thermal degradation behaviors of flame retardant epoxy composites were investigated by cone calorimeter test (CCT) and thermogravimetric analysis (TGA), respectively. The results of CCT indicated that phosphate esters can significantly decrease heat release rate, total heat release (THR), and smoke production rate. The sample cured by butyl phosphate ester from phosphorus pentoxide, phosphoric acid and butanol showed the best flame retardant performance among all samples. The TGA results showed that phosphate esters could enhance char residues of flame retardant epoxy composites when compared with those of a composite using T31 as a curing agent at high temperature. It may be concluded that good flame retardant properties of flame retardant epoxy composites are related to the formation of a protective phosphorus-rich char layer. These phosphate esters have a good future on flame retardant epoxy composites.     

Phosphorus‐containing epoxy resin for an electronic application

A phosphorus‐containing epoxy resin, 6‐H‐dibenz[c,e][1,2] oxaphosphorin‐6‐[2,5‐bis(oxiranylmethoxy)phenyl]‐6‐oxide (DOPO epoxy resin), was synthesized and cured with phenolic novolac (Ph Nov), 4,4′‐diaminodiphenylsulfone (DDS), or dicyandiamide (DICY). The reactivity of these three curing agents toward DOPO epoxy resin was found in the order of DICY > DDS > Ph Nov. Thermal stability and the weight loss behavior of the cured polymers were studied by TGA. The phosphorus‐containing epoxy resin showed lower weight loss temperature and higher char yield than that of bisphenol‐A based epoxy resin. The high char yields and limiting oxygen index (LOI) values as well as excellent UL‐94 vertical burn test results of DOPO epoxy resin indicated the flame‐retardant effectiveness of phosphorus‐containing epoxy resins. The DOPO epoxy resin was investigated as a reactive flame‐retardant additive in an electronic encapsulation application. Owing to the rigid structure of DOPO and the pendant P group, the resulting phosphorus‐containing encapsulant exhibited better flame retardancy, higher glass transition temperature, and thermal stability than the regular encapsulant containing a brominated epoxy resin. High LOI value and UL‐94 V‐0 rating could be achieved with a phosphorus content of as low as 1.03% (comparable to bromine content of 7.24%) in the cured epoxy, and no fume and toxic gas emission were observed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 353–361, 1999     

Flame retardancy and mechanical properties of a novel intumescent flame‐retardant unsaturated polyester

A novel macromolecular intumescent flame retardant (MIFR) was synthesized. Unsaturated polyester (UP) filled with MIFR as flame‐retardant additive was prepared. The effects of MIFR on properties such as tensile strength, impact strength, flame‐retardant behavior, thermal stability, and morphology of char were studied. Its flammability and burning behavior were characterized by UL 94 and limiting oxygen index. Twenty‐four percent of MIFR were doped into UP to get 30.5% of limiting oxygen index and UL 94 V‐0, whereas its tensile strength and the impact strength were decreased by only 7.2% and 7.0%, respectively. Activation energy for the decomposition of samples was obtained by using the Kissinger equation. The results for UP containing MIFR, compared with UP, show that the weight loss, thermal stability, and the decomposition activation energy decreased, and the char yield increased, showing that MIFR can catalyze decomposition and carbonization of UP to form an effective charring layer to protect the underlying substrate. J. VINYL ADDIT. TECHNOL., 22:350–355, 2016. © 2014 Society of Plastics Engineers     

磷-胺-醛树脂型阻燃剂处理落叶松的热分析及其动力学

将落叶松用一系列磷-胺-醛树脂型阻燃剂进行阻燃处理,所得阻燃落叶松采用热分析、锥形量热研究其热解行为,用氧指数、剩炭率、热释放速率、总热释放量等参数表征它的阻燃性能,并用Broido方程计算落叶松的动力学参数. 结果发现,阻燃落叶松氧指数、剩炭率增加,热释放速率、总热释放量降低,表明经阻燃剂处理的落叶松燃烧性降低. 落叶松经阻燃剂处理后,热解活化能降低很多,表明阻燃剂对落叶松热解具有催化作用,其主要热解阶段在低于300℃进行. 在此温度下,落叶松热解主要发生脱水、重排交联炭化反应,产生水、CO及CO2、固体残渣,可燃性气体大大降低,达到降低落叶松燃烧性的目的.     

阻燃大豆蛋白纤维的热性能研究

为了提高阻燃性,用四溴酞酐(TBPA)加有机二酸体系对大豆蛋白纤维进行了阻燃处理,然后用极限氧指数(LOI)、剩炭率表征了它的阻燃性能,用热分析和扫描电子显微镜研究了它的热性能。结果表明:与纯大豆蛋白纤维相比,阻燃处理后的大豆蛋白纤维的极限氧指数和剩炭率提高,热分解起始温度降低,阻燃性能得到了明显改进。     

Simultaneously Improving the Thermal,Flame‐Retardant and Mechanical Properties of Epoxy Resins Modified by a Novel Multi‐Element Synergistic Flame Retardant

To obtain epoxy resins with satisfactory thermal, flame retardant, and mechanical properties, a novel multi‐element synergistic flame retardant (PPVSZ) is synthesized through the reaction between P? H of 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) and C?C of polysilazane (PVSZ) and utilized as a multi‐element synergistic flame retardant for epoxy resins. The flame retardant mechanism is explored by XPS and SEM, confirming that the excellent flame‐retardance efficiency owes itself to an optimal flame retardant way which jointly exerts the flame‐retardant effects in the gaseous and condensed phase. The thermal properties deduced from DSC, TGA, and DMA, indicate the glass transition temperature, maximum weight loss rate, and char yields at 700 °C for EP‐2 increase by about 5.0 °C, 8.4 °C and 8.8%, respectively. Furthermore, mechanical properties such as impact strength, tensile strength, and flexural strength are also increased by 45.38%, 14.16%, and 17.43%, respectively, which show that the incorporation of PPVSZ does not deteriorate the mechanical properties of modified resin. All the results demonstrate that epoxy resins modified by PPVSZ not only have good effect on the flame retardance, but also have good improvement on thermal and mechanical properties, indicating the potential for applications in many fields requiring fire safety.