Dispersion and roles of montmorillonite on structural,flammability, thermal and mechanical behaviours of electron beam irradiated flame retarded nanocomposite

In this work, the effects of montmorillonite (MMT) dispersion and electron beam irradiation on intercalation and flammability-thermal behaviours of alumina trihydrate (ATH) added low density polyethylene and ethylene vinyl acetate (LDPE–EVA) blends were investigated. MMT and ATH added LDPE–EVA blends were compounded using Brabender mixer and compression moulded into sheets. The samples sheets were electron beam irradiated in the dosage range of 0 to 250 kGy. The dispersion and intercalation of nano-MMT in LDPE–EVA matrix were investigated through X-ray diffraction (XRD) analysis. The d-spacing measurements revealed that the addition of nano-MMT has effectively intercalated into polymer matrix and this has enhanced the compatibility of ATH particles and LDPE–EVA matrix. Limiting oxygen index test (LOI) revealed that the incorporation of MMT into ATH added LDPE–EVA blends as improved the flame retardancy up to 26.5 LOI%. Besides, the application of electron beam irradiation were also improved the flame retardancy of the blends by increasing the LOI% for about 2% compared to non-irradiated samples. The application of irradiation dosage up to 250 kGy has rapidly improved the thermal stability of blends by delaying decomposition temperature and also promoting formation of char. The increasing of MMT loading level and irradiation dosage has effectively enhanced tensile strength and Young’s modulus by intercalating polymer matrix into interlayer galleries of MMT particles. Beside, the formation of crosslinking networks in polymer matrix also could further enhance the tensile strength and Young’s modulus. The intercalation effect of MMT particles and formation of crosslinking networks in polymer matrix could improve the thermal and mechanical properties. Consequently, this study has demonstrated that addition of MMT and electron beam irradiation into ATH added LDPE–EVA blends could produce better flammability, thermal and physical properties of ATH added LDPE–EVA blends.     

硅丙乳液包覆Mg(OH)2核壳结构纳米粒子的制备与表征

为有效提高Mg(OH)_2纳米粒子在硅丙乳液中的相容性与分散稳定性,在油酸修饰Mg(OH)_2纳米粒子的基础上,以甲基丙烯酸甲酯、丙烯酸丁酯、丙烯酸与乙烯基三乙氧基硅烷为共聚单体,通过乳液聚合法制备出具有核壳结构的硅丙乳液包覆Mg(OH)_2复合材料。利用傅里叶变换红外光谱仪(FTIR)、X射线衍射仪(XRD)、透射电子显微镜(TEM)等测试手段对样品结构、形貌进行了表征。通过燃烧实验,研究了硅丙乳液包覆Mg(OH)_2纳米粒子对水性防火涂料阻燃性能的影响。结果表明,油酸通过酯化作用修饰在Mg(OH)_2纳米粒子表面,借助油酸分子中双键结构,丙烯酸类混合单体在纳米Mg(OH)_2表面完成聚合过程,形成以Mg(OH)_2纳米粒子为核、硅丙乳液为壳的复合材料。XRD与热分析表明经硅丙乳液包覆的纳米Mg(OH)_2晶体结构与热稳定性能未受影响。此外,掺杂0.1%(质量分数)的硅丙乳液包覆Mg(OH)_2可使水性防火涂料阻燃时间延长至113 min,较未掺杂水性涂料阻燃时间(91min)提高约23%。     

阻燃剂协同复配对热固性酚醛树脂阻燃性能的影响

通过阻燃剂氢氧化镁(MH)、三水氢氧化铝(ATH)、膨胀型阻燃剂(IFR)、硼酸锌(ZB)等以单一或协同复配的形式对酚醛树脂体系阻燃性能的影响进行了研究。利用差热分析(DTA)对体系的曲线形貌、放热量等热行为进行研究,并对体系的氧指数、垂直燃烧等级及产烟率等燃烧性能进行了测定。结果表明,燃烧放出热量最小的体系为MH/ATH/IFR/ZB/PF,较纯酚醛树脂体系降低了65%,氧指数最大的体系为MH/ATH/IFR/ZB/PF,数值为93.4,较纯酚醛树脂体系的氧指数43.6提高了1.2倍。添加阻燃剂后,体系的垂直燃烧等级由UL94V-1级均提高至UL94V-0级,产烟率最低的体系为MH/ATH/PF,数值为72%。     

Mg(OH)2-Al(OH)3-微胶囊红磷/高抗冲聚苯乙烯无卤阻燃复合材料

以氢氧化镁(MH)、氢氧化铝(ATH) 和微胶囊红磷(MRP) 为无卤阻燃剂, 高抗冲聚苯乙烯(HIPS) 树脂为聚合物基体, 通过熔融共混法制备了一系列不同组成的MH-ATH-MRP/HIPS复合材料。采用水平燃烧、垂直燃烧、氧指数、锥形量热分析、高温热分解实验等方法研究了复合材料的阻燃性能。结果表明, 阻燃剂用量相同时, 在HIPS基体中同时引入MH和ATH得到的复合材料比单独加入MH或ATH得到的复合材料具有更好的阻燃性能。当MH-ATH/HIPS的质量比为70:30:100时, 复合材料的水平燃烧级别达到FH-1级, 氧指数为25.2%, 但垂直燃烧无级别。在上述体系中加入极少量的MRP(占复合材料的质量分数为2.9%)就可使复合材料的火灾性能指数(FPI) 提高85%, 燃烧过程中热量释放和质量损失更慢、成炭能力明显增强, 垂直燃烧级别达到FV-0级。当MH-ATH-MRP/HIPS的质量比为21:9:12:100时, 复合材料的各项阻燃性能达到最佳, 可以大幅度减少阻燃剂的用量。MH、ATH和MRP对HIPS具有非常显著的协同阻燃作用。同时加入MH和ATH时不仅可以在更宽的温度范围内抑制HIPS的升温和分解, 而且能够在更宽的温度范围内相继释放出水蒸气稀释氧气和可燃气体的浓度, 从而起到协同阻燃作用。加入MRP后复合材料的成炭能力大大增强, 进一步改善了凝聚相阻燃的效果, 因此阻燃性能显著提高。     

镁盐晶须增强阻燃LDPE/EVA/ATH复合材料的研究

通过拉伸性能、燃烧性能测试及热失重-差示扫描量热分析(TG-DSC),研究了EVA、镁盐晶须和相容剂的用量对LDPE/EVA/ATH复合体系的影响。结果表明,EVA在复合体系中的最佳用量为m(EVA)∶m(LDPE)=6∶4;镁盐晶须的加入不仅提高了复合材料的拉伸强度和断裂伸长率,而且镁盐晶须与纳米氢氧化铝之间存在协效阻燃作用,提高了复合材料的氧指数;相容剂的加入改善了无机粉体与基体树脂间的相容性,提高了复合材料的力学性能和燃烧性能,相容剂的最佳用量为15 phr。     

Cyclodextrin microencapsulated ammonium polyphosphate: Preparation and its performance on the thermal,flame retardancy and mechanical properties of ethylene vinyl acetate copolymer

Cyclodextrin microencapsulated ammonium polyphosphate (MCAPP) was prepared by the reaction between cyclodextrin (CD) and toluene-2,4-diisocyanate (TDI) with the goal of improving the water durability of APP and preparing a novel functional flame retardants. The Fourier transform infrared spectra (FTIR) and X-ray photoelectron spectroscopy (XPS) results indicated MCAPP were successfully prepared, and the water contact angle (WCA) results indicated that cyclodextrin resulted in the transformation of hydrophilic to hydrophobic of the flame retardant surface. The MCAPP was then incorporated into the ethylene vinyl acetate copolymer (EVA) system and the effects of the MCAPP on the mechanical, combustion, thermal, interfacial adhesion and flame-retardant properties of EVA cable were investigated and compared by thermogravimetric analysis (TGA), scanning electron microscopy (SEM), limiting oxygen index (LOI), mechanical test, cone calorimeter and UL-94 test. The characterization for the various properties of EVA composites demonstrated that cyclodextrin microencapsulation technology could enhance the interfacial adhesion, resulting in the improved mechanical, thermal stability, combustion properties and flame-retardant properties compared with those of EVA/APP/CD system. Furthermore, the water resistance experiments results demonstrate that EVA/MCAPP composites have good water durability due to the hydrophobic property of MCAPP. Above all, the microencapsulation of APP with cyclodextrin developed in this study may be a promising formulation for combining the acid source, the carbonization agent and the blowing agent in one flame retardant, and the MCAPP can solve the water resistance and the compatibility problem of the flame retardant during the industrial application.     

阻燃增效剂对ATH/EVA纳米复合材料性能的影响

采用熔融共混挤出法制备纳米氢氧化铝（ATH）为主体的阻燃乙烯-醋酸乙烯共聚物（EVA）材料，研究了阻燃增效剂纳米有机蒙脱土（OMMT）与硼酸锌（ZnB）对复合材料阻燃、力学与电学性能的影响.TEM、TG与FT-IR检测表明，OMMT在基体中插层状分散，不仅提高了材料的拉伸强度，而且在燃烧过程中具有显著的促进基体成炭作用;少量ZnB的加入有效制止了阴燃，此时材料综合性能达到使用要求。     

硅油对EVA/ATH复合材料的协同阻燃作用

采用氧指数、锥形量热仪等手段,研究了羟基硅油（HSO）在乙烯-醋酸乙烯酯（EVA）/氢氧化铝（ATH）体系中的协效阻燃作用。氧指数结果表明,随着HSO添加量的增加,复合材料的氧指数略有所下降,样品EVA1～EVA5的氧指数从31下降至27.5。锥形量热仪结果表明,随着HSO添加量的增加,复合材料的热释放速率峰值呈明显的...     

Mg(OH)2/聚苯乙烯复合材料的阻燃机制

把Mg(OH)₂ (Magnesium hydroxide, MH) 在不同温度热处理不同时间, 得到一系列不同热分解状态的Mg(OH)₂ (Treated magnesium hydroxide, t-MH)。以MH和t-MH为无卤阻燃剂, 聚苯乙烯(PS)为基体, 采用熔体共混法制备了MH/PS和t-MH/PS复合材料。详细研究了MH热处理对t-MH/PS复合材料燃烧性能的影响, 并以此实验结果为基础提出了复合材料的阻燃机制模型。结果表明, 随着热处理温度升高、热处理时间延长, MH逐渐分解并转化成MgO。在相同条件下t-MH/PS复合材料的阻燃性能较MH/PS复合材料显著降低, 但是仍然比纯PS有明显提高。此外, MH热分解产生的MgO有促进PS成炭的作用。MH/PS复合材料的阻燃机制是以下几种因素协同作用的结果: (1)MH分解吸热的冷却降温作用;(2)MH热分解释放水蒸气的气相稀释作用;(3)MH热分解产物MgO的固相阻隔与防护作用;(4)MgO促进PS成炭阻燃作用。     

PP/PVAc-OMMT纳米复合材料及其阻燃材料的燃烧性能

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)/聚醋酸乙烯酯(PVAc)-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/PVAc-OMMT/氢氧化镁(MH)/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10%(质量分数)PVAc-OMMT可以提高PP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PVAc-OMMT与无卤复配阻燃剂之间可产生阻燃协效作用,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。     

聚合物基蒙脱土纳米复合材料的热稳定性能及协同阻燃研究

综述了近年来国内外聚合物基蒙脱土纳米复合材料热稳定性能及其与磷-氮阻燃剂协同阻燃方面的研究进展及机理,并展望了蒙脱土与其他绿色阻燃剂协同阻燃的前景.     

Core-shell magnesium hydroxide/polystyrene hybrid nanoparticles prepared by ultrasonic wave-assisted in-situ copolymerization

In this paper, vinylated magnesium hydroxide (MH) nanosheets were prepared with 3-(trimethoxysilyl) propyl methacrylate (γ-MPS) and pristine MH nanosheets, then the MH/polystyrene (PS) hybrid nanoparticles were prepared by ultrasonic wave-assisted in-situ copolymerization of vinylated MH nanosheets and styrene (St). The morphology, thermal stability and chemical structure of the final products were investigated in detail with transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and Fourier-transform infrared spectra (FTIR). The TEM and FTIR results showed that the uniformly-dispersed core-shell structure of MH/PS nanocomposites with MH-cores and PS-shell was formed. TGA indicated that the covalent interaction between PS and MH improved the thermal stability of PS. A possible formation mechanism of the MH/PS core-shell nanocomposites was also proposed.     

Studies on the oxygen barrier and mechanical properties of low density polyethylene/organoclay nanocomposite films in the presence of ethylene vinyl acetate copolymer as a new type of compatibilizer

Nanocomposite films based on low density polyethylene (LDPE), containing of 2, 3, and 4 wt.% organoclay (OC) and ethylene vinyl acetate (EVA) copolymer as a new compatibilizer were prepared and characterized using rheological tests, X-ray diffraction, differential scanning calorimetry, oxygen permeation measurements, and tensile tests. There was no exfoliation or intercalation of the clay layers in the absence of EVA, while an obvious increase in d-spacing was observed when the samples were prepared with EVA present. This issue was reflected in the properties of nanocomposites. The oxygen barrier properties of the LDPE/EVA/OC film were significantly better than those of the LDPE/OC film. The average aspect ratio of clay platelets in nanocomposites was determined from permeability measurements and using Lape–Cussler model. In addition to barrier properties, the LDPE/EVA/OC film also had better elastic modulus than their counterparts without EVA. The modulus reinforcement of nanocomposites was studied using Halpin–Tsai equations, which are universally used for composites reinforced by flake-like or rod-like fillers.     

熔体插层制备EVA/粘土纳米复合材料

通过熔体插层制备了乙烯-乙酸乙烯酯共聚物(EVA)／粘土纳米复合材料。采用FT-IR、XRD、TG分析和力学性能测试研究了有机改性粘土和EVA/粘土复合材料的结构与性能。实验结果表明，通过离子交换反应，可使长链十八胺阳离子嵌入粘土片层间，增大了粘土的片层间距；对于EVA／有机化粘土体系，通过熔体插层可使EVA分子链插层于粘土片层中，使粘土片层被进一步撑开；EVA／粘土纳米复合材料具有较好的力学性能。     

表面改性纳米氢氧化铝及复合体系阻燃聚丙烯的研究

通过不同偶联剂改性纳米氢氧化铝(ATH)及ATH/红磷复合体系填充阻燃PP,研究了表面改性剂的种类及用量和体系配比对体系阻燃性和力学性能的影响。结果显示:表面改性可有效提高ATH/PP体系的阻燃性和力学性能,硅烷偶联剂较油酸钠和钛酸酯改性效果更好;在PP体系中,其最佳添加用量为ATH质量的2%,体系中PP/ATH质量比为100:50时,改性可使体系氧指数提高14%～30.3%,垂直燃烧等级达FV-1级,且力学性能有较大提高。少量红磷加入可与纳米ATH形成协同阻燃,体系中PP,ATH与红磷质量配比为100:45:5时比单独ATH阻燃效果更好。     

水镁石基复合阻燃剂的制备及在EVA材料中的应用

采用化学复合方法制备出水镁石基复合阻燃剂,SEM、XRD和EDS测试表明复合阻燃剂颗粒表面粗糙,水镁石表面包覆着许多超细氧化锌粒子,通过BET测定,比表面积由包覆前的10.1499 m2/g提高到13.6762 m2/g。由复合阻燃剂填充的EVA材料,氧指数可达41.8,拉伸强度达13.4 MPa,断裂伸长率达193%,较水镁石原料及水镁石和氧化锌机械混合样的阻燃性能和力学性能有显著提高。TG和DTA热分析表明,复合阻燃剂可提高复合材料的分解温度和燃烧残留率,能有效抑制聚乙烯主链裂解,增强复合材料的热稳定性。     

有机磷氮系蒙脱土/LDPE纳米复合材料的制备及阻燃性能

以三氯氧磷和新戊二醇等为原料, 合成了一种新型磷氮型季铵盐(PAHAC), 通过红外光谱(FTIR)、 核磁共振氢谱(1H-NMR)和高分辨质谱(HRMS)表征化合物结构。利用PAHAC与钠基蒙脱土(Na-MMT)离子交换反应制备有机磷氮系蒙脱土阻燃剂(PAHACMMT)。FTIR和X射线衍射(XRD)研究表明: PAHAC通过离子交换对蒙脱土进行了有机化改性, 经20%质量分数的PAHAC改性后的MMT(20%PAHAC-MMT)层间距增至1.87nm, 20%PAHACMMT的热分解温度在310℃以上。透射电镜(TEM)分析结果表明, 20%PAHACMMT经LDPE熔融插层, 形成了插层剥离型纳米复合材料。锥形量热测试结果表明有机磷氮系蒙脱土/LDPE纳米复合材料具有良好的阻燃性能, 其中20%PAHACMMT(7%)/LDPE的热释放速率峰值(PHRR)比LDPE降低了21%, 热释放总量(THR)下降了9.5%。炭层的扫描电镜(SEM)分析结果表明, 20%PAHACMMT/LDPE燃烧后能形成致密的炭层, 起到良好的阻燃作用。      

Preparation of silane precursor microencapsulated intumescent flame retardant and its enhancement on the properties of ethylene–vinyl acetate copolymer cable

Silane precursor microencapsulated intumescent flame retardant (IFR) was prepared by sol–gel process and then modified with vinyltrimethoxysilane (A-171) with the goal of that the vinyl group functionalized silica microcapsule could be introduced into EVA matrix through crosslinking, which will enhance the compatibility and dispersion between EVA matrix and microencapsulated IFR. The effects of silane precursor microencapsulation technology on the mechanical, electrical, thermal, interfacial adhesion and flame retardant properties of intumescent flame-retardant EVA cable were investigated by mechanical test, resistance meter, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), limiting oxygen index (LOI) and UL-94 test. The Fourier transform infrared (FTIR) results indicated silane precursor microencapsulated IFR were successfully prepared, and the water contact angle (WCA) results indicated that silane precursor results in the transformation of hydrophilic to hydrophobic of IFR surface. The characterization for the various properties of EVA composites demonstrated that silane precursor microencapsulation technology enhanced the interfacial adhesion, mechanical, electrical, thermal stability and flame retardancy of EVA/MCAPP/MCPER system. Furthermore, the water resistance test results demonstrate that EVA/MCAPP/MCPER composites have good water durability. This investigation provides a formulation for the industrial application as insulated materials of EVA cable with excellent properties.     

纳米OMMT/EVA-g-PU复合材料

采用熔融接枝与熔融插层相结合的方法,成功制备了纳米OMMT/EVA-g-PU复合材料。通过FTIR及13C NMR测试表明,端—NCO的聚氨酯(PU)预聚体与皂化乙烯-醋酸乙烯酯共聚物(EVA)间发生接枝反应。采用X射线衍射仪(XRD)与透射电镜(TEM)观察了蒙脱土(OMMT)在基体中的分散状态,用电子万能试验机、动态力学分析仪(DMA)和热重分析仪(TG)分析了复合材料的力学性能、储能模量和热性能。结果表明：OMMT主要以插层型分布在基体中;当OMMT的质量分数为3%时,复合材料的断裂强度、杨氏模量和撕裂强度分别为7.96 MPa、7.12 MPa和49.97 MPa;复合材料的储能模量随 OMMT含量的增加而升高,当OMMT的质量分数为7%时,复合材料的储能模量相对于纯EVA 提高了2 倍多;复合材料的热稳定性能也要优于纯EVA,并随OMMT含量的增加而升高。     

三聚氰胺磷酸盐和季戊四醇在EVA中的阻燃研究

研究了三聚氰胺磷酸盐(M P)和季戊四醇(PER)作为膨胀型阻燃剂(IFR)在乙烯-醋酸乙烯酯共聚物(EVA)中的阻燃作用。采用氧指数法和垂直燃烧法研究了M P和PER不同配比对EVA阻燃效果的影响。实验结果表明,M P和PER的配比不同对体系的阻燃有很大影响。在M P和PER总添加量为50%时,M P/PER质量比为2∶1时显示出最好的阻燃效果,阻燃EVA体系氧指数最高,垂直燃烧达到V-0级。采用热分析研究了膨胀型阻燃EVA体系的热分解特性,以及采用激光拉曼光谱等手段对材料燃烧后形成的膨胀炭层进行了表征。