Rheological behavior of novel polyamide 6/silica nanocomposites containing epoxy resins

A novel polyamide 6/silica nanocomposite containing epoxy resins(EPA6N) was prepared via in situ polymerization using tetraethoxysilane(TEOS) as the precursor of silica.The dynamic rheological properties of pure PA6 and EPA6N at temperatures of 225 and 235 ℃ were investigated.The results of transmission electron microscopy(TEM) and atomic force microscopy(AFM) indicate that the silica particles are well dispersed in the polyamide 6 matrix on about 30 nm in diameter,which demonstrates that this method can effectively avoid agglomeration of the inorganic particles.The rheological results suggest that pure PA6 shows Newtonian behavior.However,the novel EPA6N exhibits a solid-like rheological behavior,which is due to the small size,large surface of silica particles and the stronger polyamide 6-silica chemical bond formed through the reactions of epoxy resins with end groups of PA6 molecular chains.The EPA6N also exhibits higher melt viscosity,storage modulus and loss modulus than those of pure PA6.

Preparation and Properties of Phenolic Resin/Montmorillonite Intercalation Nanocomposites

Phenolic resin/montmorillonite intercalation composites were prepared by using the methods of pressing intercalation and melt intercalation.Properties and structure of the composites were investigated by using XRD,TG and test of softening point.It is indicated that both the pressing intercalation and melt intercalation can be used to prepare the phenolic resin/organo-montmorillonite intercalation nanocomposites.Compared with phenolic resin,the intercalation nanocomposites have better heat-resistance,higher decomposition temperatures and less thermal weight-loss.However,these two intercalation methods have different effects on the softening point of the intercalation nanocomposites.Pressing intercalation almost does not affect the softening point of the intercalation nanocomposites,while melt intercalation significantly increases the softening point of the intercalation nanocomposites, probably due to the chemical actions happening in the process of melt intercalation.

ZnS/Bacterial Cellulose/Epoxy Resin(ZnS/BC/E56) Nanocomposites with Good Transparency and Flexibility

ZnS/bacterial cellulose/epoxy resin （ZnS/BC/E56） nanocomposites with good transparency and flexibil-ity were prepared and characterized. When the precursor Zn^2＋ concentrations were not more than I wt%, the size of the introduced ZnS nanoparticles was smaller than 50 nm and the distribution was homo-geneous within the composites. Under the condition, outstanding transmittance more than 70g in the visible light was obtained. By incorporation of ZnS nanoparticles with excellent thermo-optic stability to the composites, the thermo-optic coefficient was obviously increased from -361 × 10^-6 to -310 × 10^-6K^-1. The good flexibility, optical and mechanical properties endow the nanocomposites potential applica- tions in the flexible optoelectronic materials.

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.

Influences of POSS-E-GO Content on Mechanical Properties of Bio-based Epoxy/DOPO-POSS Nanocomposites

The bio-based epoxy nanocomposite(GAER/DOPO-POSS)was prepared from gallic epoxy resin(GAER)and polyhedral oligomeric silsesquioxane(which containing 9,10-dihydrogen-9-oxo-10-phosphorus-phenanthrene-10-oxide groups,called DOPO-POSS).The polyhedral oligomeric silsesquioxane containing epoxy groups(E-POSS)was grafted onto aminated graphene oxide(E-GO),then the novel POSS-E-GO was obtained.The POSS-E-GO was used as modifier for GAER/DOPO-POSS nanocomposite.The influences of POSS-E-GO content on mechanical properties,dynamic mechanical properties and thermal stability of GAER/DOPO-POSS nanocomposites were determined.The experimental results show that POSS-E-GO can significantly improve the toughness of the GAER/DOPO-POSS nanocomposite.When 0.5wt% POSS-E-GO was added in GAER/DOPO-POSS nanocomposite,the impact strength of the nanocomposite was 4.74 kJ/m^(2) higher than that in the absence of POSS-E-GO,meantime the initial thermal degradation temperature was 277℃.

Study on Morphology and Mechanical Properties of High-functional Epoxy Based Clay Nanocomposites

Morphology and mechanical properties of clay/high-functional epoxy nanocomposites are investigated. An intercalated morphology is always observed for clay loadings ≤5 wt %. The glass transition temperature （Tg） of the composites decreases with the clay loading, and the impact strength increases first by 10% at 2 wt% clay loading, and is followed by a dramatic decline, while the flexural strength decreases in all cases.

Epoxy resin nanocomposites reinforced with ionized liquid stabilized carbon nanotubes

Epoxy resin nanocomposites reinforced with three different ionic liquid functionalized carbon nanotubes(f-CNTs)were fabricated by an in situ polymerization method.The influence of the anions on the curing process was studied through differential scanning calorimetry(DSC)and normalized Fourier transform infrared(FTIR)spectroscopy.The composition of the nanocomposites was analyzed by X-ray photoelectron spectroscopy.Two different mechanisms are proposed to explain the curing process of the neat epoxy and its composites.The electric conductivity and mechanical properties of the nanocomposites are also reported.The tensile strength was increased dramatically due to the insertion of f-CNTs.Scanning electron microsopy fracture surface analysis indicates a strong interfacial bonding between the carbon nanotubes and the polymer matrix.

Re-Assembly of Archaeological Massive Limestones Using Epoxy Resin Modified with Nanomaterials—Part 1: Experimental

Massive limestones were used in construction of ancient Egyptian tombs, temples, obelisks and other sculptures. These stones are always exposed to physico-mechanical deterioration and destructive forces, leading to partial or total collapse. The task of reassembling this type of artifacts represents a big challenge for the conservators. Recently, the researchers are turning to new technologies to improve the properties of traditional adhesive materials and techniques used in re-assembly of broken massive stones. The epoxy resins are used extensively in stone conservation and re-assembly of broken stones because of their outstanding mechanical properties. The adding of nanoparticles to polymeric adhesives at low percentages may lead to substantial improvements of their mechanical performances in structural joints and massive objects. The aim of this study is to evaluate the effectiveness of montmorillonite clay, calcium carbonate, and silicon dioxide nanoparticles for enhancing the performances of epoxy adhesives used in re-assembly of archaeological massive limestones. Scanning electron microscopy (SEM) was employed in order to investigate the morphology of the prepared nanocomposites, and the distribution of nanoparticles inside the composites. Artificial aging, tensile, compressive, and elongation strength tests were used to evaluate the efficiency of epoxy-nanocomposites. The results showed that the epoxy-clay nanocomposites exhibited superior tensile, compressive, and elongation strength, in addition to improving the mechanical properties of stone joints.

Modification of Montmorillonite through Intercalative Polymerization

Montmorillonite (MMT) was modified through intercalative polymerization of phenol and formaldehyde catalyzed by oxalic acid. The modified montmorillonite was delaminated at large, as demonstrated by XRD and TEM studies. It can disperse easily in epoxy resin to form exfoliated nanocomposites. The nanoscale silicate platelets dispersed in water can be metallized by silver deposition.

Residual Monomer Content and Its Release into Water from the Denture Base Nanocomposite Using Organic Montmorillonite as Reinforcement

A novel kind of denture base nanocomposite was prepared by polymethyl methyacrylate（PMMA） and cethyltrimethylammonium bromide modified organic montmorillonite （OMMT）. The dispersion of montmorillonite in the polymer matrix was characterized by x-ray diffraction （XRD） and transimission electron microscope （TEM）.The content of residual MMA in nanocomposites and the amount of MMA released to water from nanocomposites were determined by gas chromatography （GC）. The analysis of TEM and XRD showed that exfoliated-intercalated and intercalated nanocomposites were formed when the content of OMMT was 3% and 5% in the PMMA powder respectively. The results of GC showed that the residual MMA increased with the increase of OMMT content in the polymer matrix. After 7 days in water, the amount of MMA released into water from the nanocomposites tended to be stable. The results of one-way ANOVA and t-test showed that OMMT gave a significant increase of residual MMA concentration （p〈0.05） in nanocomposites.

Effect of Functionalized Magnetite Nanoparticles and Diaminoxanthone on the Curing, Thermal Degradation Kinetic and Corrosion Property of Diglycidyl Ether of Bisphenol A-Based Epoxy Resin

To prepare a high-performance epoxy resin with excellent thermal, chemical and corrosion stability, diaminoxanthone（DAX） was used to cure diglycidylether of bisphenol-A（DGEBA）-based epoxy resin and blend of DGEBA with functionalized Fe3O4 nanoparticles. Kinetic parameters of curing and thermal degradation of epoxy resin systems were estimated by differential scanning calorimetry（DSC） and thermogravimetric analysis（TGA）, respectively. The 10% weight loss temperature has been increased from 340 °C to 366 °C and there was an increase in the char yield from 32.6% to 45.3% for the above systems. The corrosion performance of epoxy coated carbon steel was examined by potentiodynamic polarization, along with immersion test in 1.0 mol/L HCl solution. The results showed that epoxy resins cured with DAX had low tendency to corrosion. In addition, the cured epoxy resin containing 10% Fe3O4 had higher anticorrosion activity than bare DGEBA system. The results showed that functionalized Fe3O4 nanoparticles enhanced char formation and improved the thermal stability as well as anticorrosion activity of the resin.

Improving Thermal and Flame Retardant Properties of Epoxy Resin with Organic NiFe-Layered Double Hydroxide-Carbon Nanotubes Hybrids

To improve the dispersion of carbon nanotubes （CNTs） and flame retardancy of layered double hydroxide （LDH） in epoxy resin （EP）, organic nickel-iron layered double hydroxide （ONiFe-LDH-CNTs） hybrids were assembled through co-precipitation. These hybrids were further used as reinforcing filler in EP. EP/ONiFe-LDH-CNTs nano- composites containing 4 wt% of ONiFe-LDH-CNTs with different ratios of ONiFe-LDH and CNTs were prepared by ultrasonic dispersion and program temperature curing. The structure and morphology of the obtained hybrids were characterized by different techniques. The dispersion of nanofillers in the EP matrix was observed by transmission electron microscopy （TEM）. The results revealed a coexistence of exfoliated and intercalated ONiFe-LDH- CNTs in polymer matrix. Strong combination of the above nanofillers with the EP matrix provided an efficient thermal and flame retardant improvement for the nanocomposites. It showed that EP/ONiFe-LDH-CNTs nanocomposites exhibited superior flame retardant and thermal properties compared with EP. Such improved thermal properties could be attributed to the better homogeneous dispersion, stronger interfacial interaction, excellent charring performance of ONiFe-LDH and synergistic effect between ONiFe-LDH and CNTs.

Epoxy/Clay有机-无机纳米复合材料

通过插层复合的方法可以制备环氧树脂 /粘土纳米复合材料 ,大幅度提高材料的机械力学性能。制备中 ,插层剂的选择和使用是关键 ,应加强插层剂的合成、筛选及插层工艺以及粘土层内层外插层剂、固化剂、单体、粘土片层之间相互作用即插层机理的研究。此外 ,环氧树脂 /粘土纳米复合体系最佳固化条件 (树脂 /固化剂比例 ,固化时间等 )

Long-term corona behaviour and performance enhancing mechanism of SiC/epoxy nanocomposite in SF6 gas environment

Surface coating technology is an effective way to solve the interface insulation problem of DC GIS/GIL basin insulators, but the performance of the coating will change greatly, and the insulation strength will be completely lost, after long-term use in the extreme conditions of corona erosion. In this research, the multi-needle-plate electrode platform was constructed to explore the long-term use performance of Si C-doped nanocomposite exposed to corona discharge in SF6gas. Samples with a high Si C content have advantages in maintaining physical and chemical properties such as elemental composition, erosion depth, surface roughness and mass loss. The nanocomposite doped with 6 wt.% Si C has prominent surface insulation strength after long term exposure to corona, and the others are close to losing, or have completely lost,their insulating properties. Furthermore, the degradation mechanism of physicochemical properties of composite exposed to corona discharge was investigated with the proposed Reax FF MD model of energetic particles from SF6decomposition bombarding the epoxy surface. The reaction process of SF particles and F particles with the cross-linked epoxy resin, and the Si C nanoparticles providing shelter to the surrounding polymer and mitigating their suffering direct bombardment, have been established. The damage propagation depth, mass loss and surface roughness change of nanocomposite material bombarded by SF6decomposition products is reproduced in this simulation. Finally, the deterioration mechanism of insulation properties for the Si C-doped composite was elucidated with DFT analysis. The band gap of the molecule containing S drops directly from the initial 7.785 e V to 1.875 e V, which causes the deterioration of surface electric properties.

纳米颗粒填充玻璃纤维增强环氧树脂复合材料的力学性能

为探究纳米颗粒[纳米氧化铁(NFe)、纳米二氧化硅(NS)、多壁碳纳米管(MWCNT)]填充玻璃纤维增强环氧树脂复合材料(GFRP)的力学性能,对纳米颗粒质量分数分别为0.1%、0.2%、0.5%、1.0%的纳米颗粒/GFRP材料开展了拉伸、压缩、弯曲及冲击力学性能试验,并结合扫描电镜(SEM)分析了纳米颗粒的种类及质量分数对试件力学性能的影响规律。结果表明,随着纳米颗粒质量分数的增加,试件拉伸强度均先增大后降低,纳米颗粒的良好分散性及与树脂间的黏聚力能够提升试件的拉伸强度,但过量纳米颗粒的掺入会形成积聚现象,使得试件拉伸强度降低。相较于GFRP试件,掺入纳米颗粒的质量分数为0.1%、0.2%、0.5%和1.0%时,MWCNT/GFRP抗压强度的增幅分别为25.31%、36.04%、26.84%和27.25%,弯曲强度的增幅分别为58.74%、63.21%、40.89%及43.11%,纳米颗粒的掺入使得试件抗压强度、弯曲强度、冲击强度均得到改善,颗粒种类及质量分数的不同使得试件力学性能提升效果存在差异。SEM试验结果表明,外荷载作用下纤维出现断裂、分层现象,纤维与纳米颗粒间存在的摩擦效应增强其力学性能,颗粒的积聚使得试件力学性能降低。

咪唑啉季铵盐缓蚀剂改性蒙脱土/水性环氧纳米复合涂料

以油酸、二乙烯三胺和氯化苄为原料,合成了油酸基咪唑啉季铵盐缓蚀剂。通过FTIR、^(1)HNMR对其结构进行了表征,并离子交换至钠基蒙脱土(DK0)层间,制备了缓蚀剂改性蒙脱土(QACDK0)。通过XRD、TGA和UV-Vis对其结构、组成及层间缓蚀剂释放性能进行了表征。结果表明,咪唑啉季铵盐缓蚀剂约占QACDK0质量的38.96%,并将蒙脱土层间距由1.28 nm(DK0)扩大至3.98 nm(QACDK0)。利用DLS及Zeta电位对添加有QACDK0的水性环氧树脂进行了稳定性测试,其Zeta电位为–27.8 mV,具有较高的稳定性。电化学阻抗谱(EIS)测试表明,在腐蚀介质中浸泡30 d后,基于QACDK0制备的清漆漆膜仍具有2.29×10^(8)Ω·cm^(2)的高阻抗,表明涂层具有较好的耐腐蚀性。并且在耐中性盐雾测试中,QACDK0对应的防腐色漆耐盐雾时间最长,验证了该涂层具有良好的耐盐雾性能。

聚N-乙烯基-γ-氨基丁酸修饰的多壁碳纳米管及其环氧树脂纳米复合材料性能

为了改善多壁碳纳米管(MWCNT)在环氧树脂(EP)纳米复合材料中的分散性以及两者的界面结合作用,从而制备性能优良的EP纳米复合材料,本研究通过使包覆在MWCNT表面上的聚乙烯吡咯烷酮(PVP)先后发生水解和置换,制备出聚N-乙烯基-γ-氨基丁酸修饰的MWCNT,研究了不同反应阶段MWCNT的失重率、亲水性以及在水和丙酮中的分散性,并将改性后的MWCNT与EP复合制备纳米复合材料,研究其力学性能。研究结果表明,聚N-乙烯基-γ-氨基丁酸修饰的MWCNT的失重率最小为8.36%,相比于PVP修饰和PVP水解修饰的MWCNT降低了17.2%和3.8%,并且在水和丙酮中的分散效果有了一定程度的提高。MWCNT经过聚N-乙烯基-γ-氨基丁酸修饰后与EP较难剥离,MWCNT外面包覆了较厚的界面层,可以显著提高MWCNT与基体EP的相容性和界面结合作用。改性后MWCNT的加入在提高纳米复合材料韧性的同时表现出对弯曲强度更好的保持能力,当MWCNT的质量分数为0.25%时,纳米复合材料的冲击强度提高了50.1%,弯曲强度提高了6.05%。

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．

插层聚合线性酚醛树脂/有机改性蒙脱土纳米复合材料的研究

采用插层聚合方法制备了线性酚醛树脂 /有机改性蒙脱土纳米复合材料 ,研究了不同的搅拌时间和配比对有机改性蒙脱土分散效果的影响 ,并用X射线小角衍射 (XRD)和透射电子显微镜 (TEM )测得其微观结构。热重分析 (TG)测试表明 。

环氧树脂/蒙脱土纳米复合改性的研究

采用熔融插层法制备了综合力学性能优异的环氧树脂 /蒙脱土复合体系 ,其剪切强度高于 EP/ PA基体 2倍以上 ,并具有良好的耐水及其它介质的性能。经 TGA分析 ,环氧树脂 /蒙脱土复合材料的热稳定性能略有提高。