磷杂菲类阻燃剂的合成及其与聚磷酸铵复合膨胀体系对环氧树脂的阻燃性能研究

以9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物(DOPO)、五硫化二磷(P2S5)为原料合成9,10-二氢-9-氧杂-10-磷杂菲-10-硫化物(DOPS),并将DOPS与聚磷酸铵(APP)组成复合阻燃剂,用于环氧树脂(EP)的阻燃改性.通过氧指数(LOI)、垂直燃烧(UL-94)、热失重(TGA)、锥形量热(CONE)和扫描电镜(SEM)等方法对改性后的环氧树脂的阻燃性能和阻燃机理进行了测试和分析.实验结果表明,DOPS/APP阻燃体系对EP具有很好的阻燃性能,且复配阻燃剂的阻燃效果比单一的阻燃剂阻燃效果好;其中,当阻燃剂的总添加量达到30%时即W_(DOPS)=10%、W_(APP)=20%时,阻燃EP复合材料的LOI值可达到29.2%,垂直燃烧等级达到UL-94 V-0级,残炭量可达49.3%.     

聚磷酸酯阻燃剂复配蒙脱土及聚磷酸铵对环氧树脂阻燃性能的影响

本文以二氯化磷酸对甲基苯酯和10-(2,5-二羟基苯基)-10-氢-9-氧杂-10-磷杂菲-10-氧化物(ODOPB)为原料,合成了一种新型聚磷酸酯阻燃剂聚磷酸-2-10-氢-9-氧杂-10-磷杂菲-10-氧化物基对苯二酚对甲苯酯(POTP),并采用傅里叶变换红外光谱(FTIR)和核磁共振(~(31)P-NMR,~1H-NMR和~(13)C-NMR)对其结构进行表征.将POTP与蒙脱土(MMT)及聚磷酸铵(APP)组成复合阻燃剂对环氧树脂(EP)进行阻燃改性,通过垂直燃烧(UL-94)、氧指数(LOI)、热失重(TGA)、锥形量热(CONE)和扫描电镜(SEM)等方法研究其对EP的热性能和阻燃性能的影响.结果表明,当阻燃剂添加量为7%时, EP复合材料UL-94测试等级可达V-0级;当添加阻燃剂为9%时,其LOI值可达到27.6%,最大热释放速率(Pk-HRR)下降了50.1%,热释放总量(THR)下降了27.4%,其残炭量高达29%. CONE测试后的残炭形貌研究显示阻燃EP在高温下形成较稳定的致密膨胀炭层,能有效抑制烟毒性气体释放,隔绝可燃气体与空气的交换,从而提高阻燃EP在高温下的热稳定性和阻燃性能.     

卡拉胶包覆APP微球阻燃水性环氧树脂

以氯化钡提纯k-卡拉胶, 经过氧化氢降解, 通过反相乳液聚合的方式制备了一系列卡拉胶包覆聚磷酸铵(APP)阻燃微球(k-CM/APP); 将其加入到水性环氧树脂(EP)中, 制备了3种钢结构防火涂层EP2, EP3和EP4. 利用红外光谱(IR)、 扫描电子显微镜(SEM)及元素分析(EDS)对k-CM/APP的结构及形貌进行了表征. 利用极限氧指数(LOI)、 垂直燃烧(UL-94)、 背温测试法、 热重分析(TG)、 锥形量热(CONE)、 附着力测试、 IR和SEM等方法分析了涂层的阻燃、 隔热及力学性能. 结果表明, k-CM/APP(3/1)球形结构完整, 800 ℃时的残炭量高达59.5%. 与其它阻燃涂层体系相比, 添加了k-CM/APP(3/1)的EP3防火涂层的极限氧指数达到28.5%, UL-94达到了V-0级, 60 min防火涂层耐火温度为253 ℃. 相比于纯EP涂层, EP3涂层的热释放速率峰值降低了58.26%, 总热释放量降低了20.84%, 附着力达到8.74 MPa.     

核壳型纳米粒子填充PP-EVA及阻燃材料的动态燃烧行为

利用锥形量热仪(CONE)和热重分析(TGA),并结合极限氧指数(LOI)和UL-94垂直燃烧测试方法对核(PSt/OMMT)-壳(PBA)结构纳米复合粒子(CSN)填充聚丙烯(PP)-乙烯-醋酸乙烯酯共聚物(EVA)复合材料及加入无卤复配阻燃剂制备的PP-EVA/CSN/聚磷酸铵(APP)/层状氢氧化镁铝(LDH)复合阻燃材料的阻燃性能及热降解行为进行了研究。结果表明,添加10%(wt)CSN可以提高PP-EVA复合材料的阻燃性能,且PP-EVA复合体系燃烧时的热释放速率、有效燃烧热减少,热稳定性增强。CSN与APP/LDH产生阻燃协同作用,使复合阻燃材料的阻燃性能、热稳定性能进一步提高。     

聚磷酸铵-苯并噁嗪微胶囊的制备及其对环氧树脂燃烧性能影响

以多聚甲醛、丙烯胺、苯酚为原料,通过Mannich反应合成烯丙基型苯并噁嗪单体(Bala),并通过核磁共振氢谱(~1H-NMR)确定了其化学结构.将Bala在聚磷酸铵(APP)原位开环聚合后,制备APP微胶囊(BMAPP).傅里叶变换红外(FTIR)和静态接触角测试表明,Bala在APP表面成功聚合,并有效提高APP的疏水性,与纯APP相比,BMAPP的接触角从10.8°提高到了71.3°.将BMAPP添加到环氧树脂(EP)中,制备EP/BMAPP复合材料.通过热重分析仪(TGA)、垂直燃烧(UL-94)、极限氧指数(LOI)、锥型量热仪(CONE)和动态热机械分析仪(DMA)对EP和EP/BMAPP的热性能以及燃烧性能进行对比分析.结果显示,10%的BMAPP的成炭效果最佳,有良好的阻燃性能,可使EP的LOI值从22.6%提高到33.6%,并通过UL-94 V-0级,600°C下残炭率达26.3%.同时,BMAPP可大幅度降低EP燃烧过程中烟密度和热释放速率,提高EP的玻璃化转变温度(T_g).BMAPP/EP-10%中,PBala和APP协同后使EP热释放速率峰值(PHRR)由1247 kW·m~(-2)降低到434 kW·m~(-2),生烟速率(SPR)降低67%左右,T_g从169°C提高到了173°C.     

星型绿色磷腈阻燃剂的制备及阻燃环氧树脂性能

从分子结构设计出发,以六氯环三磷腈、对羟基苯甲醛、三氯氧磷及新戊二醇等为原料,制备了一种新型阻燃剂六[4-(5,5-二甲基-1,3,2-二氧杂己内磷酰基)苯氧基]环三磷腈(HDDCPPCP),并将其与聚磷酸铵(APP)和多壁碳纳米管(MWCNT)复配,应用于环氧树脂(EP)中,制备了HDDCPPCP/APP/MWCNT/EP阻燃复合材料.利用极限氧指数(LOI)、水平燃烧(UL-94)、锥形量热(CONE)、拉伸、弯曲和冲击等方法研究该阻燃复合材料的燃烧性能、热性能及力学性能.实验结果表明,保持阻燃体系总质量分数为30%,当MWCNT质量分数为2%时,EP2(HDDCPPCP/APP/MWCNT/EP)的各项燃烧参数综合表现较好,其LOI值达到42. 8%,热释放速率峰值(pk-HRR)、热释放速率平均值(av-HRR)、有效燃烧热平均值(av-EHC)及一氧化碳释放率平均值(av-CO)相对EP0分别降低92. 5%,93. 0%,65. 2%和66. 6%,呈现出良好的阻燃、抑烟和抑毒性能; EP2的拉伸强度、断裂伸长率、弯曲强度和弯曲模量较好,分别为110. 46 MPa,6. 24%,1259. 99 MPa,377. 72 MPa.     

氧化石墨烯与Si-P低聚物在环氧树脂中的协同阻燃作用

采用Hummers方法制备了氧化石墨烯(GO),并通过扫描电镜(SEM)和原子力显微镜(AFM)对GO微观形貌进行了表征.详细研究了GO与硅磷低聚物(DMS-DOPO)在环氧树脂(EP)力学性能和阻燃性能中的协同作用.万能材料试验测试结果表明,GO和DMS-DOPO分别对拉伸强度和断裂伸长率提高效果明显,二者协同后,可使EP拉伸强度和断裂伸长率分别提高17.1%和42.2%.采用热重分析(TG)、极限氧指数(LOI)、垂直燃烧(UL-94)、锥型量热(CONE)和SEM对EP及其阻燃材料的热性能、燃烧性能以及炭层微观形貌进行了表征.EP/DMS-DOPO/GO在600℃残留量为EP的5.2倍,比EP/DMS-DOPO和EP/GO分别提高4.4%和208.6%.EP/DMS-DOPO/GO的LOI值大于30,并能通过UL-94 V-0级别,燃烧过程中可形成内部结构疏松多孔、外表面致密的膨胀炭层.DMS-DOPO和GO协同后使EP热释放速率峰值由1154 k W·m-2降低到710 k W·m-2,总烟释放量降低30%.     

聚磷酸酯阻燃剂复配聚磷酸铵对环氧树脂阻燃性能的影响

合成了一种9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物(DOPO)的衍生物——聚苯氧基磷酸-2-10-氢-9-氧杂-磷杂菲基对苯二酚酯(POPP), 以间苯二胺(m-PDA)为固化剂, 环氧树脂(EP)为基料, POPP为阻燃剂, 复配聚磷酸铵(APP), 制备了不同磷含量的阻燃环氧树脂. 利用极限氧指数(LOI)和垂直燃烧(UL94)实验表征了环氧树脂的阻燃性能; 以热重分析、 锥型量热和扫描电镜分析了阻燃环氧树脂的热性能和表面形态. 研究结果表明, 阻燃剂总加入量(质量分数)为5%时即可达到UL94 V-0级, 同时LOI值为27.7%; 当总加入量为15%, 即w_POPP=5%, w_APP=10 %时, 其LOI值可达到33.8%. 随着磷含量的增加, 阻燃环氧树脂的初始降解温度略有降低, 但高温下的残炭率明显增加. POPP/APP的加入在很大程度上降低了环氧树脂的热释放速率、 有效燃烧热、 烟释放量和有毒气体释放量. 阻燃环氧树脂在高温下形成比较稳定的致密膨胀炭层, 为底层的环氧树脂主体隔绝了分解产物及热量和氧气交换, 增强了高温下的热稳定性.     

双层包裹聚磷酸铵微胶囊合成及其在环氧树脂中阻燃研究

采用原位聚合法制备了蜜胺树脂(MF)和环氧树脂(EP)双层包裹聚磷酸铵(APP),得到一种新型核壳结构的微胶囊阻燃剂(EMFAPP).用傅里叶红外光谱(FTIR)和扫描电镜(SEM)对微胶囊的核壳结构进行了表征;用极限氧指数(LOI)、垂直燃烧等级测试(UL 94)对EMFAPP在EP中的阻燃性能进行了研究.EMFAPP在EP基体中阻燃性能优异,当其添加量大于7%时EP/EMFAPP均通过UL 94 V-0级,LOI值达27.0%以上.与未包裹APP相比,EMFAPP耐水性明显提高;经水处理(75℃,6天)后,EMFAPP/EP仍可保持良好的阻燃性能.采用热重分析对EMFAPP及其阻燃复合物的热降解行为进行了研究,EMFAPP能够促进成炭,EP/EMFAPP(8 wt%)在700℃残炭率达16.2%,但其低温稳定性有所下降.此外,利用热失重-红外联用对EMFAPP/EP的热降解行为进行了研究,探讨相关阻燃机理.     

PP/EVA/OMMT纳米复合材料及其阻燃材料的动态燃烧行为

利用锥形量热仪(CONE)在35kW/m2热辐照条件下,并结合极限氧指数(LOI)和UL-94垂直燃烧测试方法对聚丙烯(PP)/乙烯-醋酸乙烯酯共聚物(EVA)/有机蒙脱土(OMMT)纳米复合材料和加入无卤复配阻燃剂制备的PP/EVA/OMMT/氢氧化铝(ATH)/三氧化二锑(AO)纳米复合阻燃材料的热释放速率、烟释放及材料在燃烧时的质量损失行为进行了研究。结果表明,添加5%(质量分数)OMMT可以提高PP/EVA复合材料的阻燃性能,燃烧时的热释放速率、质量损失率以及烟释放量减少,且OMMT与无卤复配阻燃剂之间可产生阻燃协同作用,使纳米复合阻燃材料的阻燃性能、热稳定性和抑烟性进一步增强。     

Preparation of Poly(phosphoric acid piperazine) and Its Application as an Effective Flame Retardant for Epoxy Resin

A phosphorus-nitrogen containing flame retardant additive of poly(phosphoric acid piperazine),defined as PPAP,was synthesized by the salt-forming reaction between anhydrous piperazine and phosphoric acid,and the dehydration polymerization under heating in nitrogen atmosphere.Its chemical structure was well characterized by Fourier transform infrared (FTIR) spectroscopy,13C and 31p solid-state nuclear magnetic resonance measurements.The synthesized PPAP and curing agent m-phenylenediamine were blended into epoxy resin (EP) to prepare flame retardant EP thermosets.The effects of PPAP on the fire retardancy and thermal degradation behavior of cured EP/PPAP composites were investigated by limiting oxygen index (LOI),vertical burning (UL-94),thermogravimetric analysis/infrared spectrometry (TG-IR) and cone calorimeter tests.The morphologies and chemical compositions of char residues for cured epoxy resin were investigated by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS),respectively.The results demonstrated that the flame retardant EP thermosets successfully passed UL-94 V-0 flammability rating and the LOI value was as high as 30.8％ when incorporating 5wt％ PPAP into the EP thermosets.The TGA results indicated that the synthesized PPAP flame retardant additive possessed high thermal stability and excellent charring capability.Meanwhile,the incorporation of PPAP stimulated the epoxy resin matrix to decompose and charring ahead of time due to its catalytic decomposition effect,which led to a higher char yield at high temperature.The morphological structures and the analysis results of XPS for char residues of EP thermosets revealed that the introduction of PPAP benefited the formation of a sufficient,more compact and homogeneous char layer containing phosphorus-nitrogen flame retardant elements on the material surface during combustion.The formed char layer with high quality effectively prevented the heat transmission and diffusion,limited the production of combustible gases,and inhibited the emission of smoke,leading to the reduction of heat and smoke release.     

Synthesis of a novel phosphorus‐containing curing agent and its effects on the flame retardancy,thermal degradation and moisture resistance of epoxy resins

A novel phosphorus‐containing compound diphenyl‐(1, 2‐dicarboxylethyl)‐phosphine oxide defined as DPDCEPO was synthesized and used as a flame retardant curing agent for epoxy resins (EP). The chemical structure of the prepared DPDCEPO was well characterized by Fourier transform infrared spectroscopy, and ¹H, ¹³C and ³¹P nuclear magnetic resonance. The DPDCEPO was mixed with curing agent of phthalic anhydride (PA) with various weight ratios into epoxy resins to prepare flame retardant EP thermosets. The flame retardant properties, combustion behavior and thermal analysis of the EP thermosets were respectively investigated by limiting oxygen index (LOI), vertical burning tests (UL‐94), cone calorimeter measurement, dynamic mechanical thermal analysis and thermogravimetric analysis (TGA) tests. The surface morphologies and chemical compositions of the char residues for EP thermosets were respectively investigated by scanning electron microscopy and X‐ray photoelectron spectroscopy (XPS). The water resistant properties of the cured EP were evaluated by putting the samples into distilled water at 70°C for 168 hr. The results revealed that the EP/20 wt% DPDCEPO/80 wt% PA thermosets successfully passed UL‐94 V‐0 flammability rating and the LOI value was as high as 33.2%. The cone test results revealed that the incorporation of DPDCEPO effectively reduced the combustion parameters of the epoxy resin thermosets, such as heat release rate and total heat release. The dynamic mechanical thermal analysis test demonstrated that the glass transition temperature (Tg) decreased with the increase of DPDCEPO content. The TGA results indicated that the incorporation of DPDCEPO promoted the decomposition of epoxy resin matrix ahead of time and led to a higher char yield and thermal stability at high temperatures. The surface morphological structures and analysis of the XPS of the char residues of EP thermosets revealed that the introduction of DPDCEPO benefited the formation of a sufficient, compact and homogeneous char layer with rich flame retardant elements on the epoxy resin material surface during combustion. The mechanical properties and water resistance of the cured epoxy resins were also measured. After water resistance tests, the EP/20 wt% DPDCEPO/80 wt% PA thermosets retained excellent flame retardancy, and the moisture adsorption of the EP thermosets decreased with the increase of DPDCEPO content in EP thermosets because of the existence of the P–C bonds and the rigid aromatic hydrophobic structure in DPDCEPO. Copyright © 2015 John Wiley & Sons, Ltd.     

Flame‐retardant performance and mechanism of epoxy thermosets modified with a novel reactive flame retardant containing phosphorus,nitrogen, and sulfur

A novel phosphorus‐containing, nitrogen‐containing, and sulfur‐containing reactive flame retardant (BPD) was successfully synthesized by 1‐pot reaction. The intrinsic flame‐retardant epoxy resins were prepared by blending different content of BPD with diglycidyl ether of bisphenol‐A (DGEBA). Thermal stability, flame‐retardant properties, and combustion behaviors of EP/BPD thermosets were investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), limited oxygen index (LOI) measurement, UL94 vertical burning test, and cone calorimeter test. The flame‐retardant mechanism of BPD was studied by TGA/infrared spectrometry (TGA‐FTIR), pyrolysis‐gas chromatography/mass spectrometry (Py‐GC/MS), morphology, and chemical component analysis of the char residues. The results demonstrated that EP/BPD thermosets not only exhibited outstanding flame retardancy but also kept high glass transition temperature. EP/BPD‐1.0 thermoset achieved LOI value of 39.1% and UL94 V‐0 rating. In comparison to pure epoxy thermoset, the average of heat release rate (av‐HRR), total heat release (THR), and total smoke release (TSR) of EP/BPD‐1.0 thermoset were decreased by 35.8%, 36.5% and 16.5%, respectively. Although the phosphorus content of EP/BPD‐0.75 thermoset was lower than that of EP/DOPO thermoset, EP/BPD‐0.75 thermoset exhibited better flame retardancy than EP/DOPO thermoset. The significant improvement of flame retardancy of EP/BPD thermosets was ascribed to the blocking effect of phosphorus‐rich intumescent char in condensed phase, and the quenching and diluting effects of abundant phosphorus‐containing free radicals and nitrogen/sulfur‐containing inert gases in gaseous phase. There was flame‐retardant synergism between phosphorus, nitrogen, and sulfur of BPD.     

Thermal and flame retardant properties of epoxy resin cured by a novel phosphorus-containing 4,4′-bisphenol novolac curing agent

A novel flame retardant curing agent for epoxy resin (EP), i.e., a DOPO (9,10-dihydro-9-oxa-10-phosphaphenan-threne-10-oxide)-containing 4,4'-bisphenol novolac (BIP-DOPO) was synthesized and characterized by Fourier transform infrared (FTIR), ¹H NMR, ³¹P NMR spectroscopy, and gel permeation chromatography. The epoxy resin cured by BIP-DOPO itself or its mixture with a commonly used bisphenol A-formaldehyde novolac resin (NPEH720) was prepared. The flame retardancy of the cured EP thermosets were studied by limiting oxygen index (LOI), UL 94 and cone calorimeter test (CCT), and the thermal properties by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results show that the cured epoxy resin EPNP/BI/3/1, which contains 2.2% phosphorus, possesses a value of 26.2% and achieves the UL 94 V-0 rating. The data from cone calorimeter test demonstrated that the peak release rate, average heat release rate, total heat release decline sharply for the flame retarded epoxy resins, compared with those of pure ones. DSC results show that the glass-transition temperatures of cured epoxy resins decrease with increasing phosphorus content. TGA indicates that the incorporation of BIP-DOPO promotes the decomposition of epoxy resin matrix ahead of time and leads to higher char yield. The surface morphological structures of the char residues reveal that the introduction of BIP-DOPO benefits to the formation of a continuous and solid char layer on the epoxy resin material surface during combustion.     

Preparation and flammability of a novel intumescent flame-retardant poly(ethylene-co-vinyl acetate) system

A phosphorus-containing flame retardant, 4-(5,5-dimethyl-2-oxo-1,3,2-dioxaphosphorinan-2-yloxymethyl)-2,6,7-trioxa-1-phospha-bicyclo[2.2.2]octane-1-oxide (MOPO), was synthesized successfully and characterized. The flame retardancy and thermal behavior of a new intumescent flame-retardant (IFR) system for EVA, which was made of MOPO and ammonium polyphosphate (APP), were investigated by limiting oxygen index (LOI) test, vertical burning test (UL-94), cone calorimeter, and thermogravimetric analysis (TGA). An LOI value of 28.4 and UL-94 V-0 rating can be achieved when the total loading of MOPO and APP was 30 wt.%. The results from cone calorimeter indicate that both the heat release rate (HRR) and the total heat release (THR) of IFR-EVA decreased significantly compared with those of neat EVA. TG curves showed that the amount of residues increased significantly when intumescent additives were added; it also could be found that the LOI values increased with the increase in char residues. Meanwhile, morphology of the residues obtained from burning IFR-EVA in LOI test was studied through the SEM observations and rich compact char layers could explain the excellent flame retardance.     

Synergistic effect between expandable graphite and ammonium polyphosphate on flame retarded polylactide

Synergistic effect was observed between expandable graphite (EG) and ammonium polyphosphate (APP) on flame retarded polylactide (PLA) in this paper using limiting oxygen index (LOI), thermal gravimetric analysis (TGA), scanning electron microscopy (SEM) and X-ray spectroscopy (XPS) and cone calorimeter tests etc. In the experiments, PLA composites with 15 wt% of APP/EG(1:3) combinations showed a LOI value of 36.5 and V-0 rating in UL-94 tests, greatly improved flame retardant properties from composites with APP or EG alone. Results from TGA and cone calorimeter demonstrated that APP/EG combination could retard the degradation of polymeric materials above the temperature of 520 °C by promoting the formation of a compact char layer. This char layer protects the matrix effectively from heat penetrating inside and prevents its further degradation, resulting in lower weight loss rate and better flame retarded performance.