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。     

六苯氧基环三磷腈的热解及其对环氧树脂的阻燃机理

采用极限氧指数仪和锥形量热仪测试了以六苯氧基环三磷腈(HPCP)阻燃环氧树脂的燃烧性能,结果显示,与纯环氧树脂相比,阻燃环氧树脂的极限氧指数值(LOI)明显提高、热释放速率峰值(pk-HRR)和总热释放量(THR)明显下降、环氧树脂的点燃时间提前以及分解速度加快.采用热失重(TGA)、热重红外联用(TGA-FTIR)、X射线光电子能谱(XPS)和热裂解气相色谱质谱联用(Py-GC/MS)研究了HPCP及其阻燃环氧树脂的热解路线和阻燃机理.结果表明,在阻燃环氧树脂过程中,一方面,HPCP分子中的苯氧基团首先解离并发生歧化反应,由此产生的苯氧基及其歧化产物的焠灭效应在环氧树脂中发挥气相阻燃作用,剩余的磷腈环和苯环基团会进一步裂解产生小分子碎片;另一方面,环氧树脂基体在HPCP的作用下提前分解,产生了基于双酚A结构的大分子碎片并在HPCP裂解产物作用下加速炭化,从而使更多的基体组分以残炭的形式被固定在凝聚相中,提高了阻燃环氧树脂的残炭产率,发挥了凝聚相阻燃作用.     

聚苯氧基磷酸联苯二酚酯/聚磷酸铵膨胀阻燃剂对环氧树脂阻燃性能影响研究

以聚苯氧基磷酸联苯二酚酯(PBPP)与聚磷酸铵(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)等方法研究改性环氧树脂的阻燃性能和阻燃机理.结果表明,PBPP/APP体系对EP具有较好的阻燃性能,阻燃剂添加量为10%时能使环氧树脂的氧指数提高到29.6%,垂直燃烧等级达到UL94 V-0级,残炭量大大增加;平均热释放速率下降45.7%,热释放速率峰值下降51.0%,有效燃烧热平均值下降21.1%;TGA、CONE、SEM等综合分析显示了PBPP/APP改性后的环氧树脂比纯环氧树脂具有更高的热稳定性,燃烧后能够形成连续、致密、封闭、坚硬的焦化炭层,在聚合物表面产生有效覆盖、隔绝了氧气,改善了环氧树脂的燃烧性能.     

OMMT-NC-膨胀型阻燃剂三元协同阻燃LLDPE的效果

采用有机蒙脱土(OMMT)和碳酸镍(NC)为阻燃协效剂,与膨胀型阻燃剂(IFR)三元体系协同阻燃线性低密度聚乙烯(LLDPE).采用热重分析(TGA)、氧指数(LOI)测试、UL-94燃烧测试和锥形量热测试(CONE)研究了LLDPE阻燃体系的热稳定性和燃烧性能;采用红外光谱分析(FT-IR)、数码相机和扫描电子显微镜(SEM)对燃烧残余物的结构和形貌进行了分析.结果表明:固定mnLLDPE/mIFR=7/3,当moMMT/m(LLDPE+IFR)=0.04时,阻燃体系的LOI为31.5％,通过UL-94 V-0级测试,LLDPE-IFR-OMMT的残炭率为15.09％,最大热释放速率(PHRR)相比于纯LLDPE降低了50％;向LLDPE-IFR-OMMT体系中添加NC,少量的NC就能显著增加体系的阻燃性能,当mNC/m(LLDPE+IFR)=0.02时,阻燃体系的LOI为32.7％,LLDPE-IFR-OMMT-NC的残炭率达到19.04％,PHRR相比于纯LLDPE降低了57％.OMMT和NC的加入能催化LLDPE-IFR成炭,形成致密的炭层,增加炭层的强度,从而提高复合材料的阻燃性能.     

含磷/氮/硫环交联磷腈微纳米管的合成及对环氧树脂的阻燃作用

采用原位模板法,以六氯环三磷腈(HCCP)和二羟基二苯砜(BPS)为原料合成了一种环状交联型不溶不熔的磷腈大分子——聚环三磷腈-二羟基二苯砜(PZS)微纳米管,研究了PZS对环氧树脂(EP)的阻燃作用及阻燃机理.利用红外光谱(FTIR)、扫描电子显微镜(SEM)及透射电子显微镜(TEM)对PZS微纳米管进行了表征;采用热重分析(TG)考察了EP/PZS阻燃材料的热稳定性,并通过极限氧指数(LOI)和微型量热分析(MCC)测试了EP/PZS的阻燃性能.热降解实验结果表明,PZS微纳米管的加入使环氧树脂热降解温度降低,但残炭率显著提高.PZS微纳米管可以显著提高环氧树脂的阻燃性能,当阻燃剂添加量为5%时,环氧树脂的残炭率提高了46%,热释放速率峰值降低了约40%;LOI值从纯环氧树脂的26.0%提高到了30.6%.PZS微纳米管的加入还增强了环氧树脂的力学强度.阻燃性能的显著提高和力学性能的改善归因于PZS微纳米管在环氧树脂基体中的良好分散,以及燃烧炭化过程中生成的石墨化程度较高的类石墨烯结构的残炭,具有较高的抗氧化能力.研究结果表明,PZS微纳米管是一种优良、高效的具有潜在应用价值的阻燃剂.     

DOPO基膦酸铝盐的制备及其阻燃环氧树脂的性能研究

以10-羟基-9-氧杂-10-磷杂菲-10-氧化物(DOPO-OH)和六水合氯化铝为原料合成了一种DOPO基膦酸铝盐(DOPO-Al)阻燃剂,通过红外光谱、扫描电镜、能谱、核磁共振磷谱和热失重表征了其结构,并制备了DOPO-Al阻燃的环氧树脂,通过极限氧指数、锥形量热、热失重和差示扫描量热测试分析了该树脂的阻燃和热性能。结果表明,DOPO-Al为高温阻燃剂,其初始热分解温度(T_(5%))高达595.5℃。DOPO-Al能提高环氧树脂的阻燃性能和耐热性。当DOPO-Al添加量为7.5%(wt)时,环氧树脂的LOI值由24.1%提高至31.3%;在燃烧过程中,使其热释放速率峰值、平均热释放速率、总热释放、总烟释放和总烟产量均降低,使残留物增加幅度高达135%。炭层分析表明DOPO-Al存在凝聚相阻燃机理。环氧树脂的T_(5%)和玻璃化转变温度分别高达368.9℃和161.8℃,所制备阻燃环氧树脂具有较好的热性能。     

高抗冲聚苯乙烯/蒙脱土复合材料的阻燃性研究

用经十六烷基三甲基溴化铵有机化改性的蒙脱土 (OMMT)与高抗冲聚苯乙烯 (HIPS)通过熔融插层法制备了HIPS OMMT复合材料 ,用X ray衍射技术对材料结构进行了表征 ,发现钠基蒙脱土 (Na+ MMT)和有机蒙脱土的层间距分别为 1 5 1nm和 2 18nm ,HIPS OMMT(5phr)复合材料中蒙脱土的层间距因聚合物大分子的插入扩大为 3 4 4nm ;而HIPS与Na+ MMT形成的复合材料的层间距与Na+ MMT的层间距相比却没有变化 ,表明未有机化处理土没有形成插层结构 .锥形量热仪的研究结果表明HIPS OMMT复合材料的热释放速率、质量损失速率以及生烟速率等燃烧特性参数均显著降低 ,具有较明显的阻燃性和抑烟性 ,而HIPS Na+ MMT非插层型复合材料只有在Na+ MMT很高填充量下 (>2 0phr)才有一定阻燃效果 .比较了铵盐对HIPS阻燃性的影响 ,结果表明铵盐自身的阻燃作用很小 ,主要是插层复合结构起阻燃作用 .     

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.     

三聚氰胺聚磷酸盐/季戊四醇配比、协效剂组及表面改性对聚丙烯基木塑复合材料的膨胀阻燃影响

通过极限氧指数(LOI)、线性燃烧速率(LBR)、热重分析和锥形量热分析等技术手段研究膨胀型阻燃剂(IFRs)中三聚氰胺聚磷酸盐(MPP)和季戊四醇(PER)的质量比、组成为m(MgO):m(可膨胀石墨,EG):m(SiO₂)=1:5:5的协效剂组(MgO/EG/SiO₂)和硅烷偶联剂(KH550)对聚丙烯基木塑复合材料(WPC)阻燃性能的影响。 结果表明,当IFRs中m(MPP):m(PER)=23:2(IFRs-M1)、质量分数为25%时的阻燃性能最佳,膨胀阻燃复合材料WPC/IFRs-M1的LOI和LBR分别为27.1%和3.89 mm/min,较未添加的WPC分别提高48.1%和下降89.79%,燃烧时的热释放速率、总热释放量、总烟释放量和CO₂释放量分别降低了76.2%、50.1%、6.9%和65.4%,600 ℃时的残炭率提高了498.3%。 协效剂组和KH550表面处理均可进一步改善WPC/IFRs-M1的阻燃性能,均对IFRs-M1具有良好的阻燃增效作用。 相比于WPC/IFRs-M1,同时用这两种阻燃增效手段的WPC/IFRs-M1/MgO/EG/SiO₂/KH550,其LOI提高了3.7%,LBR降低了20.3%;材料的热稳定性明显提高,热失重降低;燃烧时的热释放速率、总热释放量、总烟释放量和CO₂释放量分别降低了36.5%、37.6%、57.5%和33.33%,600 ℃时的残炭率提高了84.02%,显示出二者更好的协同效应。     

磷系阻燃环氧电子封装材料研究进展

磷系阻燃环氧树脂具有阻燃效率高、制备成本低、环境危害小等显著优点,成为5G通讯、智能电子和半导体等领域的重要封装材料。基于高效磷系阻燃环氧封装材料的性能要求,介绍了磷系阻燃环氧树脂的种类和阻燃机理,总结了当前磷系阻燃环氧树脂在电子封装领域的应用研究进展并对其未来发展趋势进行了展望,指出本征型(反应型)磷系阻燃环氧树脂存在制备困难、有效磷含量低等问题,需要进一步优化工艺并提升封装体系中的磷含量。相比之下,填充型磷系阻燃环氧树脂的制备工艺简单、阻燃剂种类多、磷含量较高,在电子封装领域应用最为广泛。     

Preparation of phosphorus‐containing phenolic resin and its application in epoxy resin as a curing agent and flame retardant

For the sake of improving the flame retardancy of epoxy resin (EP), a novel phosphorus‐containing phenolic resin (PPR) synthesized in our group instead of conventional phenolic resin (PR) was used to cure EP in the present research. The curing processes and the corresponding crosslinking structure and mechanical performance were investigated by differential scanning calorimeter and dynamic mechanical thermal analysis. Because of the introduction of flame‐retarding elements including P and Si, PPR exhibited higher charring capacity in the condensed phase, which is helpful to construct a char layer of higher quality. Correspondingly, PPR‐cured EP displayed remarkably improved flame retardance as compared to conventional PR‐cured EP through the related evaluations including limiting oxygen index, vertical burning test, and microscale combustion colorimeter. As a multifunction agent, it is believable that PPR possesses potential commercial value to prepare flame‐retardant EP with high performance.     

Preparation of urea formaldehyde microsphere and its effect on flame retardant ethylene vinyl acetate composites

Urea formaldehyde microsphere (UFM) was prepared and used with organic montmorillonite (OMMT) to modify the flame retardant efficiency of ethylene vinyl acetate copolymer (EVA)/intumescent flame retardant (IFR) composites. The results show that single IFR may modify the flame retardancy of EVA, but its efficiency is not good enough. The EVA composite containing 21 wt% IFR is just classified the UL_94 V2 and has a limiting oxygen index (LOI) 24.7 vol%. Combining UFM with IFR does not improve the flame retardancy of EVA/IFR composites, and blending OMMT with IFR only improves its LOI. Adding 2 wt% UFM, 2 wt% OMMT, and 17 wt% IFR into EVA, it obtains the UL_94 V0 without melt dripping and a LOI 29.0 vol%. Also, the peak heat release rate and total heat release decrease a lot. Good synergistic effects among IFR, UFM, and OMMT improve the char residues and modify the char micromorphology of EVA composites, which provide better protect for the underlying resin.     

Organically modified montmorillonite as a synergist for intumescent flame retardant against the flammable polypropylene

Low flame retardant efficiency is a key bottleneck for currently available retardants against the flammable polypropylene (PP). Herein, the organically modified montmorillonite (OMMT) was utilized as a synergist for our previously reported intumescent flame retardant (IFR) that was constructed from ammonium polyphosphate (APP) and hyperbranched charring foaming agent (HCFA) to further enhance the retardant efficiency against PP. The resultant's combustion behavior was thoroughly investigated by cone calorimetry, limiting oxygen index (LOI), vertical burning test (UL‐94), and scanning electron microscopy (SEM). The results showed that 20% addition of IFR with OMMT showed a positive effect and improved the flame retardancy of the PP systems. Especially, addition of 2 wt% OMMT obviously increased the LOI values of PP systems with 20% total loading flame retardants from 29% to 31.5% and the samples meet V‐0 rating as well as the reduction of the heat release rate (HRR), total heat release (THR), CO₂, and CO production occurred. On the other hand, the SEM images were also revealed that OMMT initiated a dense and strong char on the surface of the material, which resulted in efficient flame retardancy of PP matrix during combustion. In addition, thermal degradation behavior discussed by thermogravimetric analysis (TGA) indicated that OMMT could improve the thermal stability of PP systems under high temperature, and promoted char residues of PP/IFR systems. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis and application of a dual functional P/N/S‐containing microsphere with enhanced flame retardancy and mechanical strength on EP resin

A phosphazene derivative flame retardant with a highly cross‐linked microsphere structure, named poly(cyclotriphosphazene‐c‐sulfonyldiphenol) (PCPS) microspheres, were synthesized by 1‐pot reaction and then applied on flame retarded epoxy (EP) resin. The microstructure and chemical composition of PCPS microspheres were characterized using scanning electron microscopy, transmission electron microscopy, and element mapping. The thermal stability of PCPS microspheres and PCPS/EP composites was explored through thermogravimetric analysis. Thermogravimetric data showed that the PCPS microspheres have excellent thermal stability, and the char yield is about 43% at the end of 800°C. The incorporation of PCPS microspheres significantly increased the char yield of PCPS/EP composites. The flammability was investigated by limited oxygen index tests and cone calorimeter. The limited oxygen index value of PCPS/EP composite was increased to 29.8 from 26.6 when 3 wt% of PCPS microspheres was added. Compared with neat EP, the flame retardancy was greatly improved. The peak heat release rate and smoke production rate of PCPS/EP composites were reduced by 45.0% and 43.6%, respectively. The mechanical properties including tensile strength and modulus were both improved due to the enhancement of PCPS microspheres. The PCPS microspheres act as a dual function for improving both the flame resistance and mechanical strength of PCPS/EP system.     

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.     

Flame retardant polyoxymethylene with aluminium hydroxide/melamine/novolac resin synergistic system

Polyoxymethylene (POM), having the lowest limiting oxygen index (LOI) (only ∼ 15%), is well known as the most difficult to be flame retarded plastic among all the polymers. In this paper, a novel synergistic flame retardant system composed of aluminium hydroxide (ATH), melamine (ME) and novolac resin was designed and successfully applied to flame retard POM. ATH took effects through heat absorption and water release. Both ME and novolac could react with the decomposition product of POM, formaldehyde, thus improving the flame retardancy. Particularly, novolac resin and ME played the roles of macromolecular charring agent and gas source, enhancing the flame retarding actions in the condensed and gaseous phases, respectively. This ternary synergistic system exhibited fine flame retardancy for POM (UL94 V-1 rating for 1.6 mm bar), and the obtained flame retardant POM also showed good processability and mechanical properties due to the lubrication, compatibilization and aid-dispersion effects of novolac resin.     

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.     

Synthesis of bio‐based poly (cyclotriphosphazene‐resveratrol) microspheres acting as both flame retardant and reinforcing agent to epoxy resin

A highly cross‐linked poly (cyclotriphosphazene‐resveratrol) microsphere (PRV) was synthesized by using hexachlorocyclotriphosphazene (HCCP) and bio‐based resveratrol (REV) as raw materials, and the obtained PRV microspheres were applied to improve the flame retardancy and mechanical property of epoxy resin (EP). The TGA results showed that the PRV microsphere is an excellent charring agent and the char yield is as high as 62% at 800°C. The incorporation of PRV makes the initial degradation earlier yet significantly increases the char residue of EP composites. Moreover, the introduction of PRV microspheres into EP greatly promoted the flame retardancy performance. Under 3% of addition of PRV microspheres, the peak heat release rate (PHRR) and total heat release (THR) were decreased by 58.3% and 29.6%, respectively, the limited oxygen index (LOI) value was increased to 29.7% from 25.3% of pure EP. In addition, because of the uniform distribution in EP matrix and the enhancing effect of PRV microspheres, the mechanical properties including tensile modulus of EP composites were strengthened. PRV microspheres in this paper provide a possibility to synthesize a dual functional filler, which acts as both flame retardant and strengthening agent.     

A novel intumescent flame retardant imparts high flame retardancy to epoxy resin

Intumescent flame retardant (IFR) has received the considerable attention ascribed to the inherent advantages including non‐halogen, low toxicity, low smoke release and environmentally friendly. In this work, a novel charring agent poly (piperazine phenylaminophosphamide) named as PPTA was successfully synthesized and characterized by Fourier transform infrared spectra (FTIR) and X‐ray photoelectron spectroscopy (XPS). Then, a series of flame‐retardant EP samples were prepared by blending with ammonium polyphosphate (APP) and PPTA. Combustion tests include oxygen Index (LOI), vertical Burning Test (UL‐94) and cone calorimeter testing,these test results showed that PPTA greatly enhances the flame retardancy of EP/APP. According to detailed results, EP containing 10 wt% APP had a LOI value of 30.2%,but had no enhancement on UL‐94 rating. However, after both 7.5 wt% APP and 2.5 wt% PPTA were added, EP‐7 passed UL‐94 V‐0 rating with a LOI value of 33.0%. Moreover, the peak heat release rate (PHRR) and peak of smoke product rate (PSPR) of EP‐7 were greatly decreased. Meanwhile, the flame‐retardant mechanism of EP‐7 was investigated by scanning electron microscopy (SEM), thermogravimetric analysis/infrared spectrometry (TG‐IR) and X‐ray photoelectron spectroscopy (XPS). The corresponding results presented PPTA significantly increased the density of char layer, resulting in the good flame retardancy.