插层聚合制备粘土/环氧树脂纳米复合材料过程中粘土剥离行为的研究

用ＸＲＤ、ＤＳＣ 等手段研究了有机蒙脱土在环氧树脂中的插层与剥离行为,证明环氧树脂容易插层到粘土片层间,形成稳定的插层混合物,加入胺固化剂固化后,粘土被剥离而得到剥离型纳米复合材料,剥离程度与所采用的固化温度关系不大,主要取决于固化程度,全部剥离的时间与环氧树脂凝胶的时间接近．     

4,4'-二氨基二苯醚二苯酮固化环氧树脂/粘土纳米复合材料的研究

采用离子交换法, 用十六烷基三甲基溴化铵处理钙基蒙脱土(MMT), 使蒙脱土的层间距由1.49 nm扩大到2.21 nm, 制备了环氧树脂/ BADK/MMT纳米复合材料, 并用XRD等手段研究了有机蒙脱土在环氧树脂中的插层及剥离行为. 研究结果表明, 蒙脱土含量及环氧树脂与有机土的混合温度和时间均对固化后复合材料的剥离产生影响, 只有在特定条件下才能得到剥离型纳米复合材料.     

不同有机化蒙脱土对聚丙烯/蒙脱土纳米复合材料结构和性能的影响

采用不同的有机改性剂制备了三种含羟基极性基团、环氧基和不含极性基团的有机化蒙脱土, 并与混有少量马来酸酐接枝聚丙烯的聚丙烯基体进行复合, 制备了聚丙烯粘土纳米复合材料. 采用X射线衍射仪、透射电子显微镜、热分析仪、示差扫描热分析仪和力学测试仪对样品进行结构表征和力学性能测试. 探讨和比较了不同有机化蒙脱土对聚丙烯/蒙脱土纳米复合材料结构和性能的影响. 结果表明, 携带极性基团的有机改性剂和马来酸酐接枝聚丙烯的强烈相互作用有利于有机化蒙脱土在复合材料中的插层、剥离和稳定性, 由此形成的聚丙烯粘土纳米复合材料具有更高的结晶度, 其力学性能的提高也更为显著.     

丙烯酸树脂／蒙脱土纳米复合材料的制备研究

采用离子交换法,用十六烷基三甲基溴化铵对钠基蒙脱土(Na-MMT)进行改性制备了有机蒙脱土(OMMT).用丙烯酸(AA)、硫酸化蓖麻油、乳化剂OP-10、过硫酸钾为原料进行水溶液聚合制得丙烯酸树脂.将丙烯酸树脂与改性蒙脱土通过聚合插层制备了丙烯酸树脂/ 蒙脱土纳米复合材料.通过傅立叶变换红外(FTIR)和X-射线衍射 (XRD)等手段对复合材料的结构进行了表征,结果表明:丙烯酸树脂插层进入有机蒙脱土内可形成插层型或剥离型的纳米复合材料.蒙脱土含量及蒙脱土与丙烯酸树脂的反应温度、反应时间均对复合材料的剥离行为产生影响,在蒙脱土含量为树脂固含量的7%、温度为70℃、反应4h的条件下可得到完全剥离的纳米复合材料.     

辐照法制备PVAc/蒙脱土纳米复合材料及其表征

蒙脱土有机化后 ,片层结构间距离增大 ,对有机物的亲和性有所增强 .采用VAc单体渗入有机化蒙脱土层间 .经γ 射线辐照引发原位插层聚合 ,使蒙脱土片层结构发生剥离 ,形成无机 有机纳米复合材料 .并用X衍射、红外光谱、扫描电镜以及透射电镜等现代测试手段对复合材料进行了表征     

三元乙丙橡胶/蒙脱土纳米复合材料制备中硫化体系的比较

采用了熔融插层和两种硫化体系硫磺 促进剂和过氧化物体系制备了三元乙丙橡胶 蒙脱土纳米复合材料 ,并将这两种体系形成的纳米复合材料进行了形态、力学性能和光学性能的比较 ,同时采用Flory Rehner方程对它们的硫化行为进行了评价 .X射线衍射 (XRD)、透射电镜 (TEM)、力学性能和光学性能的测试结果表明 ,由硫磺硫化体系制备的纳米复合材料为不透明和剥离型 .其原有的d0 0 1 衍射峰消失 ,有序层被剥离成 10 0～ 2 0 0nm的片层均匀分散在EPDM基体中 ,其力学性能有了极大的提高 ;而过氧化物体系制备的纳米复合材料为半透明和插层型 .对两种体系的硫化行为的评价结果表明 ,随着有机蒙脱土加入量的增加 ,硫磺 促进剂硫化体系的t90 延长 ,交联密度减小 ,最大 最小转矩也变小 ;而过氧化物硫化体系的相应值却变化不大     

β-羟基丁酸与β-羟基戊酸共聚物 (PHBV)/蒙脱土纳米复合材料的结构与性能

用溶液复合法成功地制备了插层型PHBV／蒙脱土纳米复合材料。采用X射线衍射（XRD）和透射电子显微镜（TEM）研究了复合材料的结构，硅酸盐片层间距从1.8nm升至2.4nm左右。同时研究了复合材料的结晶，熔融，动态力学行为和力学性能，发现有机蒙脱土的加入，可以加快PHBV的结晶,降低熔融温度，使基体的玻璃化转变温度升高，提高了材料的力学性能，有机蒙脱土含量在3％时，其综合性能最佳。     

环氧/粘土纳米复合材料的形成机理与性能

粘土／聚合物纳米复合材料由于具有优良的物理力学性能和特殊功能而倍受关注。实验证明,粘土也很容易被环氧树脂插层,并在固化过程中剥离,得到纳米复合材料。本文重点综述了粘土／环氧纳米复合材料的形成机理,结构形态和力学性能,并对该类材料的应用前景进行了展望。     

木质纤维素-蒙脱土纳米复合材料的制备

采用插层复合方法在碱性水溶液中制备了木质纤维素-蒙脱土纳米复合材料,并分析了反应温度、反应时间、木质纤维素与蒙脱土的质量比等因素对纳米复合材料有机化程度的影响,用FT-IR、XRD、TEM、SEM等方法对纳米复合材料的结构进行了表征。结果表明:蒙脱土片层结构在反应过程中被撑开,木质纤维素分散在其中,形成插层-剥离型纳米复合材料,其热稳定性较木质纤维素有了较大提高。     

酚醛树脂/蒙脱土纳米复合材料的制备及固化反应动力学研究

利用自制的有机蒙脱土 ,采用浇模固化成型法制备酚醛树脂 /六次甲基四胺 /蒙脱土纳米复合材料 ,并用XRD观察有机蒙脱土分别在热塑性和热固性酚醛树脂中复合行为 .研究发现 ,由于两种树脂的固化反应机理不同 ,热固性酚醛树脂与蒙脱土复合 ,可得插层型纳米复合材料 ;而采用热塑性酚醛树脂进行固化 ,则得到部分剥离的纳米复合材料 .通过DSC进一步研究热塑性酚醛树脂 /蒙脱土复合体系的固化反应动力学 .运用Kissinger ,Flynn Wall Ozawa ,Crane方法求出活化能和反应级数等动力学参数 .结果发现 ,加入蒙脱土使固化反应活化能下降 ,反应级数减小 ,从而有利于固化工艺的实现 ,便于纳米复合材料实际应用 .     

Influence of Mixing Conditions on Morphologies and Properties of MMT/Epoxy Resin Composite Materials

Montmorillonite(MMT) was directly modified with hexadecyl trimethyl ammonium bromide. The interlayer spacing of the organophilic montmorillonite(organo-MMT) corresponding to the d(001) plane peak was 2.21 nm. The influences of the content of organo-MMT and mixing conditions including mixing temperature and mixing time on the intercalation and exfoliation structures of MMT/epoxy resin composites were investigated by wide X-ray diffraction(WXRD). The X-ray patterns reveal that organo-MMT was intercalated by the epoxy resin during mixing process. Only under certain mixing conditions, could the exfoliation nanocomposites be formed. The mechanical and thermal properties of the composites were measured. The results indicate that the composites have better mechanical properties and higher Tg than those of the pristine epoxy resin.     

Exploitation of introducing of catalytic centers into layer galleries of layered silicates and related epoxy nanocomposites. I. Epoxy nanocomposites derived from montmorillonite modified with catalytic surfactant‐bearing carboxyl groups

Montmorillonite (MMT) was modified with the acidified cocamidopropyl betaine (CAB) and the resulting organo‐montmorillonite (O‐MMT) was dispersed in an epoxy/methyl tetrahydrophthalic anhydride system to form epoxy nanocomposites. The intercalation and exfoliation behavior of the epoxy nanocomposites were examined by X‐ray diffraction and transmission electron microscopy. The curing behavior and thermal property were investigated by in situ Fourier transform infrared spectroscopy and DSC, respectively. The results showed that MMT could be highly intercalated by acidified CAB, and O‐MMT could be easily dispersed in epoxy resin to form intercalated/exfoliated epoxy nanocomposites. When the O‐MMT loading was lower than 8 phr (relative to 100 phr resin), exfoliated nanocomposites were achieved. The glass‐transition temperatures (T_g's) of the exfoliated nanocomposite were 20 °C higher than that of the neat resin. At higher O‐MMT loading, partial exfoliation was achieved, and those samples possessed moderately higher T_g's as compared with the neat resin. O‐MMT showed an obviously catalytic nature toward the curing of epoxy resin. The curing rate of the epoxy compound increased with O‐MMT loading. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1192–1198, 2004     

聚萘并噁嗪/蒙脱土纳米复合材料的制备与表征

用原位插层反应法地制备了聚萘并嗪 蒙脱土纳米复合材料 .采用X ray衍射 (XRD)及透射电镜(TEM)研究复合材料中蒙脱土硅酸盐片层间距 ,发现硅酸盐片层间距由 1 2 6nm扩增至 5 88nm以上 .同时研究了该复合材料的耐热性 ,并探讨了复合材料的结晶行为     

Effect of ZnO nanoparticles on the thermal and mechanical properties of epoxy-based nanocomposite

Effect of ZnO nanoparticles particles on the mechanical properties and the curing behavior of an epoxy nanocomposite were studied. Nanocomposites were prepared using different loadings of pre-dispersed ZnO nanoparticles having an average size of 40 nm. The surface topography and morphology of the nanocomposites were studied using atomic force microscope (AFM). The mechanical properties of nanocomposites were studied using analytical techniques including dynamic mechanical thermal analysis and micro-Vickers hardness. Effects of ZnO nanoparticles on the curing behavior of these nanocomposites were investigated utilizing isothermal and non-isothermal differential scanning calorimeter techniques. In addition, chemical compositions of coatings containing different ZnO nanoparticles contents were studied using a Fourier transform inferred. It was found that, ZnO nanoparticles can effectively influence the mechanical properties of epoxy coating. In addition, lower curing degrees, and therefore crosslinking density of epoxy coating including higher ZnO nanoparticles were obtained. This effect was completely different at low and high loadings of the particles.     

Enhancement of Nanoclay Dispersion and Exfoliation in Epoxy Using Aminic Hardener Treated Clay

Exfoliation and dispersion of nanoclays in epoxy matrices plays an important role in achieving better physical and mechanical properties of resultant nanocomposites. In this article, modification of clay with an aminic hardener for the increment of dispersion and exfoliation into the epoxy matrix has been investigated. In the solvent media, a slurry of hydrophilic Na-Montmorrilonite was mixed and treated with isophoronediamine (IPDA). The nanocomposites containing epoxy and IPDA-modified clay were produced through a recently developed “slurry compounding” method. Dispersion and exfoliation of the modified clay and the microstructure of the resultant nanocomposite were studied by optical microscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier-transform infrared (FTIR) spectroscopy. The samples were then compared with the high shear mixed and sonicated nanocomposites containing commonly used quaternary ammonium modified clays. The comparison showed that dispersion and exfoliation of hardener-modified organoclays in epoxy have been improved due to the treatment of clay and the compounding method.     

Layered silicate/epoxy nanocomposites: synthesis,characterization and properties

Novel epoxy‐clay nanocomposites have been prepared by epoxy and organoclays. Polyoxypropylene triamine (Jeffamine T‐403), primary polyethertriamine (Jeffamine T‐5000) and three types of polyoxypropylene diamine (Jeffamine D‐230, D‐400, D‐2000) with different molecular weight were used to treat Na‐montmorillonite (MMT) to form organoclays. The preparation involves the ion exchange of Na⁺ in MMT with the organic ammonium group in Jeffamine compounds. X‐ray diffraction (XRD) confirms the intercalation of these organic moieties to form Jeffamine‐MMT intercalates. Jeffamine D‐230 was used as a swelling agent for the organoclay and curing agent. It was established that the d₀₀₁ spacing of MMT in epoxy‐clay nanocomposites depends on the silicate modification. Although XRD data did not show any apparent order of the clay layers in the T5000‐MMT/epoxy nanocomposite, transmission electron microscopy (TEM) revealed the presence of multiplets with an average size of 5 nm and the average spacing between multiplets falls in the range of 100 Å. The multiplets clustered into mineral rich domains with an average size of 140 nm. Scanning electron microscopy (SEM) reveals the absence of mineral aggregate. Nanocomposites exhibit significant increase in thermal stability in comparison to the original epoxy. The effect of the organoclay on the hardness and toughness properties of crosslinked polymer matrix was studied. The hardness of all the resulting materials was enhanced with the inclusion of organoclay. A three‐fold increase in the energy required for breaking the test specimen was found for T5000‐MMT/epoxy containing 7 wt% of organoclay as compared to that of pure epoxy. Copyright © 2004 John Wiley & Sons, Ltd.