硬聚氯乙烯/蒙脱土纳米复合材料的制备与性能

以蒙脱土为主要原料，通过适宜的有机物插层荆对其改性研制有机蒙脱土。利用高聚物PVC的亲油性，且运用插层技术将聚合物熔融插入有机蒙脱土层间，将蒙脱土片层刺离出来，使之蚋米级地分散在PVC相中，从而制得硬聚氯乙烯（PVC—U）／层状硅酸盐蚋米复合管材，管材的力学性能得到了较大的改善。同时，FT—IR和XRD也证实了蒙脱土已均匀地分散在PVC基体中。此外，文中还用热重分析仪考察了复合材料的热性能，蒙脱土的加入提高了PVC的耐热等级。     

天然橡胶/蒙脱土原土纳米复合材料的制备与性能

用机械混炼反应插层法,通过引入第三组分RH,制备了天然橡胶／蒙脱土原土纳米复合材料,实现了对天然橡胶的补强,在这种复合材料中,蒙脱土原土的层间距显著增大,蒙脱土无机片层在橡胶基体中达到了纳米级分散．蒙脱土原土与天然胶纳米复合保持了较低的滚动阻力,显著地提高了天然胶的抗湿滑性．     

聚氨酯和蒙脱土协同增韧增强环氧树脂

采用聚合物互穿技术与原位插层聚合相结合的方法制备了有机蒙脱土修饰的环氧树脂/聚氨酯互穿网络纳米复合材料.傅立叶红外光谱,X射线衍射及透射电镜分析表明剥离或插层的蒙脱土片层表面羟基能与环氧树脂/聚氨酯基体发生交联反应,并且均匀分散在环氧树脂/聚氨酯基体中.力学性能测试结果表明聚氨酯,蒙脱土的加入同时增加了环氧树脂的拉伸强度和断裂韧性.扫描电镜分析表明聚氨酯和蒙脱土协同增韧增强环氧树脂的主要原因为剪切屈服和微裂纹增韧.     

原位聚合尼龙6／蒙脱土纳米复合材料的结晶行为

本文用原位聚合的方法制备了尼龙6／蒙脱土纳米复合材料,通过高速离心沉降实验和XRD表征了蒙脱土在复合材料中的剥离程度和分散状态;采用解偏振光强度法研究了复舍材料的等温结晶过程,并用偏光显微镜观察了其结晶形态;通过DSC研究了复舍材料的非等温结晶动力学,并用Kissinger法计算了复舍材料的结晶活化能。结果表明,蒙脱土在复合材料中完全剥离,以纳米片层的形式均匀分散在基体尼龙6中,蒙脱土的纳米片层对基体的结晶过程起异相成核作用;在蒙脱土的含量较低时,复合材料的结晶速率明显提高,但当蒙脱土的含量较高时,由于蒙脱土纳米片层对结晶生长的阻碍作用占主导地位,复舍材料的结晶速率有所下降,复合材料的结晶活化能也表现出类似的行为。     

蒙脱土填充相对蒙脱土/淀粉复合材料结构和性能的影响

利用XRD和DMTA分析手段对填充不同类型蒙脱土的蒙脱土／淀粉复合材料的结构、性能及其相互关系进行了初步研究。结果表明，蒙脱土／淀粉复合材料的性能与蒙脱土片层的无序分散程度相关。通过对有机化蒙脱土的溶胀处理，有机化蒙脱土的片层趋向于无规分散，从而也令蒙脱土／淀粉复合材料的性能大为改观。     

天然橡胶/固相改性蒙脱土纳米复合材料的制备与表征

在固相对蒙脱土进行有机改性,并与天然橡胶机械混炼插层制备了纳米复合材料。利用X射线衍射仪(XRD)、橡胶加工分析仪(RPA)和透射电镜(TEM)等研究了天然橡胶/固相改性蒙脱土纳米复合材料的结构,同时考察了材料的力学性能和耐老化性能。结果表明:固相改性蒙脱土在天然橡胶中可以实现纳米级分散,得到天然橡胶/蒙脱土纳米复合材料。固相改性蒙脱土对天然橡胶不但具有明显的补强效果,大幅度提高材料的力学性能和耐热氧老化性能,而且还具有很好的促进硫化作用。     

微波辅助原位熔融缩聚法制备聚乳酸/有机蒙脱土纳米复合材料

以微波为热源替代传统加热方式,采用原位熔融缩聚法制备出聚乳酸/有机蒙脱土纳米复合材料。有机蒙脱土的加入有利于聚乳酸分子链进入蒙脱土片层,当蒙脱土用量为1.5%时,微波辐射60 min所制得的聚乳酸/有机蒙脱土纳米复合材料与纯聚乳酸相比,拉伸强度提高近2倍,热失重中心温度提高7.3℃,对紫外线的屏蔽波段扩展了50nm以上。透射电镜(TEM)结果表明,有机蒙脱土以剥离态均匀分散于聚乳酸基体中。     

MC尼龙蒙脱土纳米复合材料的制备与表征

在超声条件下以KH550硅烷偶联剂插层蒙脱土,采用阴离子聚合反应制备MC尼龙蒙脱土纳米复合材料(MMT/PA),并对改性蒙脱土和纳米复合材料的结构进行表征与性能测试。结果表明,在超声分散条件下KH-550硅烷偶联剂进入蒙脱土的片层间,增大层间距;聚合过程中己内酰胺进入蒙脱土的片层间,实现蒙脱土与己内酰胺的键性结合,并使得最终尼龙分子插层进入蒙脱土的片层间形成纳米复合材料。蒙脱土以部分剥离的多片层聚集体均匀地分散在尼龙基体中,起到增强增韧作用,当蒙脱土含量在3%左右时纳米复合材料的力学性能达到最优。     

超声波原位插层制备硅树脂/蒙脱土纳米复合材料

采用超声波技术,原位插层聚合法制备了甲基苯基硅树脂/有机蒙脱土(OMMT)纳米复合材料。利用X射线衍射(XRD),透射电镜(TEM)研究了复合材料内部结构以及超声波时间对蒙脱土分散性影响。结果表明,蒙脱土片层间距随着超声波时间延长而增加,当超声波时间短于20min时,有机蒙脱土片层以有序的插层型存在,形成插层型的聚合物/蒙脱土纳米复合材料(PLSN);超声波时间长于30min时,有机蒙脱土片层被剥离,无序地分散在硅树脂基体中,形成剥离型的聚合物/蒙脱土纳米复合材料。     

高度剥离型环氧树脂/蒙脱土纳米复合材料的制备与性能

以丙酮为溶剂,采用超声波分散和高速搅拌混合相结合的方法制备了高度剥离型环氧树脂/蒙脱土纳米复合材料。XRD与TEM测试结果表明,蒙脱土在环氧树脂中得到了高度剥离,大部分蒙脱土被剥离成独立片层,均匀分散于基体树脂中。对材料的力学性能、热机械性能研究表明,蒙脱土能显著提高材料的冲击强度、弹性模量,但降低了材料的拉伸强度与断裂伸长率。蒙脱土使材料的储存模量显著提高,储存模量在材料的橡胶态比在其玻璃态提高的更加明显。     

Poly(ethylene naphthalate)/clay nanocomposites based on thermally stable trialkylimidazolium-treated montmorillonite: thermal and dynamic mechanical properties

Thermally stable organically modified clays based on 1,3-didecyl-2-methylimidazolium (IM2C10) and 1-hexadecyl-2,3-dimethyl-imidazolium (IMC16) were used to prepare poly(ethylene naphthalate) (PEN)/montmorillonite (MMT) nanocomposites via a melt intercalation process. Examination by X-ray diffraction and transmission electron microscopy indicates that an intercalated nanocomposite was formed with IMC16-MMT, while unmodified MMT (Na-MMT) and IM2C10-MMT are generally incompatible with PEN. Thermogravimetric analysis reveals that the peak derivative weight loss temperature of the intercalated PEN/IMC16-MMT was more than 10 "C higher compared to neat PEN, PEN/Na-MMT, or PEN/IM2C10-MMT. Dynamic mechanical analysis also showed that a more significant improvement of the storage modulus was achieved in the better dispersed PEN/IMC16-MMT. The effect of annealing on the dynamic storage modulus of the hybrids is also investigated.     

聚丙烯腈/钠基蒙脱土纳米复合材料的结构和性能研究

采用乳液聚合法制备了聚丙烯腈/钠基蒙脱土(Na-MMT)纳米复合材料,并通过湿法纺丝得到了Na-MMT纳米复合腈纶纤维.用X射线衍射仪表征了纳米蒙脱土在腈纶基体中的分散情况,并用热重分析法和电子单纱强力仪对纤维的热稳定性能和力学性能进行了表征.结果表明,通过乳液分散聚合法,层状蒙脱土剥离,并均匀分散在聚丙烯腈基体中,与不舍蒙脱土的腈纶纤维相比,Na-MMT纳米复合腈纶纤维的热稳定性能和力学性能得到明显提高.     

UP/Na-MMT纳米复合材料的制备与性能

研究了UP／Na-MMT纳米复合材料的制备与性能，并考察了插层剂种类、有机蒙脱土加入量及离子交换量对复合材料性能的影响。结果表明，UP／Na-MMT纳米复合材料的XRD曲线中蒙脱土晶体结构的布拉格衍射峰已经消失，说明其晶层已被树脂撑开，达到纳米级分散；复合材料的耐热性能得到明显改善，其冲击强度和拉伸强度均有较大提高。     

Preparation and properties of nitrile rubber/montmorillonite nanocomposites via latex blending

The nitrile rubber (NBR)/unmodified montmorillonite (Na-MMT) clay nanocomposites were prepared by latex blending method followed by melt mixing of compounding ingredients by using two-roll mill. The X-ray diffraction (XRD) studies showed an increase in the basal spacing and broadening of peak corresponding to crystal structure of Na-MMT indicating the formation of intercalated/exfoliated clay layers in the NBR matrix. Increase in clay content of nanocomposite increased the XRD peak height due to the formation of many of clay tactoids at higher loading. The transmission electron microscopy (TEM) strengthened the XRD finding by showing the presence of intercalated/exfoliated morphology of clay platelets having good dispersion. The modulus and tensile properties of the nanocomposites were improved with addition of Na-MMT which is proportional to clay concentration. The retention of tensile properties of aged nanocomposites, with all clay concentration, was superior to either pure NBR and carbon black filled NBR composite. The dynamic mechanical analysis showed proportional increase in storage modulus analogous to Na-MMT loading at all the temperature ranges due to the confinement of polymer chains between the clay layers. Nanocomposites with different proportions of clay showed a decrease in tan δ_max peak height with a shift towards higher temperature indicating the reduction in the segmental mobility of polymer chain. A linear model was proposed to correlate the influence of Na-MMT content on storage modulus of nanocomposites. Differential scanning calorimetry indicated a linear increase in glass transition of nanocomposites which is proportional to clay loading. Thermogravimetric analysis revealed a small improvement in the thermal stability of nitrile rubber/clay nanocomposites.     

蒙脱土插层纳米复合材料改性涂料研究

采用双子季铵盐（GeminiC1）6表面活性剂和十六烷基三甲基溴化铵（CTAB）表面活性剂分别与钠基蒙脱土（Na-MMT）进行阳离子交换后,制备了新的有机蒙脱土（GeminiC16-MMT和CTAB-MMT）,通过X射线衍射（XRD）、透射电镜（TEM）等对有机蒙脱土进行表征并对其分散性做了测试。又用蒙脱土插层纳米复合材料改性水性涂料,并进行了性能测试表征,结果显示,经改性涂料的性能均有不同程度的提高。     

Effect of montmorillonite on carboxylated styrene butadiene rubber/hindered phenol damping material with improved extraction resistance

Three methods of blending, including direct blending, melt blending and latex blending, were introduced to disperse sodium based montmorillonite (Na-MMT) and N,N′-hexane-1,6-diylbis{3-(5-di-tert-butyl-4-hydroxyphenyl-propionamide)} (HP1098) into the carboxylated styrene butadiene (XSBR) matrix. Small angle X-ray Diffraction testing indicated that melting Na-MMT with HP1098 enlarged the d-spacing of Na-MMT, which was further enlarged by mechanical blending with XSBR, and this led to homogeneous dispersion of Na-MMT and HP1098, which was indicated by Transmission Electronic Microscopy; latex blending was found most advantageous in dispersing HP1098 which was essential for improved damping performance. Dynamic Mechanical Analysis was utilized to characterize damping properties, and enhanced static mechanical properties were presumably originated from molecule chains being intercalated into the enlarged galleries of Na-MMT by mechanical blending. Formation of hydrogen bonds was observed by Fourier Transformation Infrared Spectrum and was supposed to be responsible for exceptional damping performance at elevated temperature. Extraction measurement of XSBR/Na-MMT/HP1098 composite indicated that XSBR and Na-MMT showed synergic effect in protecting HP1098 molecules from being extracted, which is a promising method in preparing rubber/hindered phenol damping materials with improved extraction resistance, whereby increasing the performance stability and lifespan of the composite materials. Additional advantage of this type of materials is better processability and shortened vulcanization process.     

Facile fabrication of CdTe/montmorillonite nanocomposite films with stable photoluminescence properties

We report herein the facile synthesis of CdTe/montmorillonite (MMT) nanocomposite films via charge-charge interactions between the CdTe quantum dots (QDs) and MMT platelets. Firstly, negatively charged CdTe QDs were prepared with the use of thioglycolic acid (TGA) as ligand. Then hybrid of the as-prepared TGA-stabilized CdTe QDs with sodium montmorillonite (Na-MMT) and cetyltrimethylammonium-modified montmorillonite (CTA-MMT), respectively, afforded novel CdTe/MMT nanocomposite films. The structure and optical properties of CdTe/MMT nanocomposite films were thoroughly investigated by scanning electron microscope (SEM), ultraviolet transmittance reflection and photoluminescence (PL) measurements. Results showed that CdTe/(CTA-MMT) nanocomposite films exhibited highly enhanced PL intensity compared with CdTe/(Na-MMT) nanocomposite films. More importantly, CdTe QDs in CdTe/(CTA-MMT) nanocomposite films well maintained PL properties even after thermal annealing at 100 °C for 10 h.     

Preparation and properties of the powder SBR composites filled with CNTs by spray drying process

Carbon nanotubes (CNTs) filled powder styrene-butadiene rubber (SBR) composites were prepared by spray drying of the suspension of CNTs in SBR latex. The powder was spherical like and uniform with an average diameter of less than 10 μm. The dispersion of CNTs in the rubber matrix was improved remarkably compared with that in the rubber composites obtained by the conventional mechanical mixing method. Further study about the effect of CNTs on the prepared SBR composites was performed by analyzing the vulcanization process of the SBR powder, thermal and mechanical properties of the vulcanized SBR composites. Differential scanning calorimeter (DSC) analysis indicated that the glass transition temperatures of SBR composites increased with the increasing ratio of CNTs. The vulcanization process showed that CNTs could decelerate the vulcanization of the SBR composites. Dynamic mechanical analysis indicated that the storage modulus of the composites was improved with the CNTs additions, especially when the CNTs addition exceeded 30 phr. Compared with pure SBR composites, the hardness, tensile and tear strengths of the composites filled with 60 phr CNTs enhanced 73.9%, 327.7% and 191.1%, respectively, which should be ascribed to the excellent mechanical properties of CNTs and uniform dispersion of CNTs in the rubber matrix.     

层柱粘土与膨胀阻燃剂在聚乙烯醋酸乙烯酯中的协同作用EI北大核心CSCD

层柱粘土不仅可以发挥粘土本身的阻隔作用,还具有层柱结构的催化作用,从而有望在膨胀阻燃聚乙烯醋酸乙烯酯(EVA)中发挥协同作用。文中以铝、钛、铁聚阳离子交联剂作为柱撑,分别制备具有催化作用的铝、钛、铁层柱粘土(Al-MMT、Ti-MMT、Fe-MMT)。结果发现层柱粘土的层间距明显扩大,其中Al-MMT的层间距为1.82nm,比表面积为250.9m^2/g,均明显大于Ti-MMT、Fe-MMT以及Na-MMT。将它们与膨胀阻燃剂(IFR)协同阻燃EVA。结果表明,在EVA中仅添加质量分数12%IFR和质量分数1%Al-MMT即通过UL-94V0级别的测试,其他体系则无法通过,说明Al-MMT在该体系中具有最好的协同作用。     

The composite of carbon nanotubes and cobalt(II)-intercalated montmorillonite for enhanced electrocatalytic oxygen reduction

Abstract

Due to the rapid development of fuel cells, the fabrication of electrocatalysts for oxygen reduction (ORR) with high performance and low-cost is of great significance. Herein, cobalt cations-intercalated montmorillonite (Co-MMT) was prepared by a simple cation-exchange reaction between Na-MMT and cobalt cations. A detailed ORR investigation indicates that the as-prepared nanocomposite of Co-MMT and multiwalled carbon nanotubes (Co-MMT/MWCNT) exhibits better ORR catalytic activity in aqueous alkaline medium with a 4e-route mechanism than Na-MMT, Co-MMT and MWCNT, suggesting the synergistic effect between Co-MMT and MWCNT. Moreover, further research shows that Co-MMT/MWCNT hybrid demonstrated more positive onset potential for ORR, higher oxygen reduction peak current than commercial 5% Pt/C ORR electrocatalyst.