The Influence of Carbon Nanotubes and Nano-Silica Fume on Enhancing the Damping and Mechanical Properties of Cement-Based Materials

This paper conducted experimental studies on the damping and mechanical properties of carbon nanotube-nanosilica-cement composite materials with different carbon nanotube contents. The damping and mechanical properties enhancement mechanisms were analyzed and compared through the porosity structure test, XRD analysis, and scanning electron microscope observation. The results show that the introduction of nanosilica significantly improves the dispersion of carbon nanotubes in the cement matrix. At the same time, the addition of nanosilica not only effectively reduces the critical pore size and average pore size of the cement composite material, but also exhibits good synergistic effects with carbon nanotubes, which can significantly optimize the pore structure. Finally, a rationalization suggestion for the co-doping of nanosilica and carbon nanotubes was given to achieve a significant increase in the flexural strength, compressive strength and loss factor of cement-based materials.

Nano-SiO_(2)选择性分布对CPE增韧PVC体系的影响

通过改变混合顺序,研究了纳米二氧化硅(nano-SiO_(2))选择性分布对氯化聚乙烯(CPE)增韧聚氯乙烯(PVC)体系力学性能、流变性能、耐热性能的影响。结果表明:当nano-SiO_(2)分布于CPE相时,样品的拉伸强度、弯曲强度、弯曲模量、热变形温度提升更显著,当nano-SiO_(2)分布于PVC相时,样品的缺口冲击强度提升更显著,尤其在CPE用量较低时。nano-SiO_(2)选择性分布对样品的流变性能会产生影响,但对其玻璃化转变温度影响较小。

Nano silica aerogel-induced formation of an organic/alloy biphasic interfacial layer enables construction of stable high-energy lithium metal batteries

Lithium metal batteries represent promising candidates for high-energy-density batteries, however, many challenges must still be overcome,e.g., interface instability and dendrite growth. In this work, nano silica aerogel was employed to generate a hybrid film with high lithium ion conductivity(0.6 mS cm^(-1)at room temperature) via an in situ crosslinking reaction. TOF-SIMS profile analysis has revealed conversion mechanism of hybrid film to Li–Si alloy/Li F biphasic interface layer, suggesting that the Li–Si alloy and Li F-rich interface layer promoted rapid Li+transport and shielded the Li anodes from corrosive reactions with electrolyte-derived products. When coupled with nickel-cobalt-manganese-based cathodes, the batteries achieve outstanding capacity retention over 1000 cycles at 1 C. Additionally the developed film coated on Li enabled high coulombic efficiency(99.5%) after long-term cycling when coupled with S cathodes. Overall, the results presented herein confirm an effective strategy for the development of high-energy batteries.

Silica sol/Nano-Au/PVP修饰金电极电致化学发光测定槐定碱

基于槐定碱对联吡啶钌（Ru（bpy）3^2＋）在电致化学发光中的增敏机理,通过传感器修饰技术,将Silica sol/Nano-Au/PVP修饰到金电极表面,建立了简单、快捷测定槐定碱的新方法。实验表明,最佳实验条件下,在1.6×10^-7-1.6×10^-4mol/L范围内,槐定碱的浓度与其对应的电化学发光强度值呈良好的线性关系,I=4.000×10^7c＋262.2,r^2=0.994 5,检出限（S/N=3）为3.5×10^-9mol/L。连续平行测定浓度为1.6×10^-5mol/L的槐定碱溶液6次,其相对标准偏差（RSD）为2.9%。该方法具有较高的选择性和灵敏度,样品处理简单快速,用于槐定碱的测定,结果满意。

Nano-Au/Silica sol/PVP修饰金电极上电化学发光测定盐酸硫必利

采用溶胶-凝胶法制备了Nano—Au／Silicasol／PVP修饰金电极，并基于盐酸硫必利对联吡啶钌（Ru（bpy）2/3＋）在该修饰电极上弱电化学发光具有较强的增敏作用，建立了电化学发光检测盐酸硫必利的新方法。在最佳实验条件下，盐酸硫必利浓度在1．0×10-7～1．0×0-4mol／L范围内与相对发光强度呈线性关系（r2=0．9978），检出限（S／N-3）为6．7×10-10mol／L。连续平行测定1．0×10-5mol／L盐酸硫必利溶液10次，发光强度的相对标准偏差（RSD）为1．789／6。对样品进行回收率试验，其回收率在97．7％～103．9％之间，RSD为2．62％。该方法具有较高的选择性和灵敏度，样品处理简单快速，用于盐酸硫必利的测定，结果满意。

Application of nano silica to improve self-healing of asphalt mixes

Nano silica due to its spherical shape, tiny size and higher density compared to bitumen, may have an inherent potential to improve hot mix asphalt(HMA) self-healing. In this research scanning electron microscopy(SEM) images were used to investigate size, morphology and dispersion of nano silica particles. Additionally, HMA self-healing mechanism was also examined by SEM. Furthermore, dynamic indirect tensile test(IDT) was used to evaluate HMA self-healing index. The SEM results indicated that bitumen mortar flowing into micro cracks may be one of the most important mechanisms of HMA self-healing. The experiment results also showed that modification of bitumen by nano silica promotes the ability of the HMA self-healing.

橡胶-再生骨料保温混凝土热传输机理及微观结构分析

采用橡胶颗粒(RP)、再生骨料(RA)作为保温轻骨料,纳米SiO_(2)(NS)作为辅助胶凝材料,制备橡胶保温混凝土(IRC)。通过自然光照和模拟光照下的环境模拟试验,并结合材料密度、吸水率、导热系数、微观孔结构等指标,研究IRC的热工性能及热传输机理.结果表明:RP的掺加引入了大量孔隙,密度、吸水率和孔容逐渐增大,形成了多孔结构,提高了IRC的保温性能,RP掺量为20%时,导热系数为1.01 W(m·K)^(-1);NS的掺加细化了IRC的孔径,破坏了连通的热流通道,进一步提高了IRC的保温性能,掺入3%的NS后,导热系数进一步降低7.8%~9.4%。

MORPHOLOGY EVOLUTION OF POLY(St-co-BuA)/SILICA NANOCOMPOSITE PARTICLES SYNTHESIZED BY EMULSION POLYMERIZATION

Poly（St-co-BuA）/silica nanocomposite latexes were synthesized via conventional emulsion polymerization in the presence of 3-（trimethoxysilyl）propyl methacrylate modified colloidal nano-silica. The effects of surface property, particle size and content of colloidal nano-silica as well as the concentrations of monomer and surfactant on the morphology of nanocomposite latex particles were investigated by transmission electron microscope （TEM） and scanning electron microscope （SEM） in detail. Various interesting morphologies such as grape-like, Chinese gooseberry-like, pomegranate-like and normal core-shell structures were observed. Droplet nucleation mechanism competing with micelle nucleation mechanism was proposed to explain the morphological evolution of the nanocomposite particles.

纳米SiO_(2)对玄武岩纤维增强煤矸石粉-矿粉基地质聚合物砂浆性能的影响

【目的】为了改善煤矸石粉-矿粉基地质聚合物砂浆的脆性破坏特征,采用纳米SiO_(2)对玄武岩纤维增强煤矸石-矿粉基地质聚合物砂浆(basalt fiber-reinforced coal gangue-mineral powder-based geopolymer mortar,BGSG)进行改性。【方法】采用流动度、流变性、抗压强度、抗折强度、单轴拉伸和断裂试验并结合能量准则和微观手段研究纳米SiO_(2)增强地质聚合物砂浆的增韧机制。【结果】随着纳米SiO_(2)掺量的增加,BGSG的流动度逐渐下降,触变面积、屈服应力和塑性黏度逐渐增大;当纳米SiO_(2)掺量(质量分数)为3%时增韧效果最好,养护龄期为28 d时,纳米SiO_(2)改性BGSG的抗压强度为22.3 MPa,抗折强度为6.8MPa,极限拉伸强度为5.75 MPa,失稳韧度为0.534 MPa·m^(1/2),与未掺加纳米SiO_(2)的对照组相比,其抗压强度、抗折强度、极限拉伸强度和断裂失稳韧度分别增加29.1%、39.5%、36.9%、47.8%;微观分析表明,纳米SiO_(2)掺入并未改变地质聚合物水化产物的类型。【结论】纳米SiO_(2)参与聚合反应,促进地质聚合物凝胶的生成,从而增强BGSG的综合性能。

磷-硅涂层对芳纶1313/聚酰亚胺织物阻燃性能的影响

为进一步提高消防服外层织物的阻燃性能,采用芳纶1313和聚酰亚胺织造3/1斜纹机织物,并配制聚磷酸铵和纳米二氧化硅复合阻燃剂对其进行功能化修饰。测试结果表明,配制的阻燃剂涂料,能够有效提高试样的阻燃性能,LOI值提高到了35.1%,热释放量下降了70.69%,烟释放量降低了98.84%。所制备的涂层织物可应用于消防服外层,提高消防服的热防护性能。

A Comparative Study on the Pozzolanic Activity between Nano-SiO_2 and Silica Fume

The pozzolanic activity of nano-SiO2 and silica fume was comparatirely stndied by X-ray diffraction （ XRD ） , differential scanning calorimetry （DSC）, scanning electron micrascopy （SEM） and the compressive , bond and bending streugths of hardened paste and concrete were also measured. Results indicate that the compressive strength development of the paste made from Ca（OH）2 and nano-SiO2, the reaction rate of Ca（ OH）2 with nano- SiO2 and the velocity of C-S-H gel formation from Ca （ OH）2 with nano-SiO2 showed marked increases over those of Ca（ OH）2 with silica fume. Furthermore, the bond strength at the interface between aggregate and hardened cement paste, and the bending strength of concrete incorporated with 3% .NS increased more than those with SF, especially at early ages. To sum up, the pozzolanic activity of nano-SiO2 was much greater than that of silica fume. The results suggest that with a small amount of nano-SiO2, the Ca（ OH）2 crystal at the interface between hardened cement paste and aggregate at early ages may be effectively absorbed in high performance concrete.

Porous Properties of Nano-fibriform Silica from Natural Chrysotile

With the TEM and physical gas adsorption techniques, porous properties of nano-ribriform silica （MLD： 92.73%） from natural chrysotile are studied in this paper. The results indicate that porous nano-fibriform silica results from brucite octahedral sheets of nature chrysotile dissolved completely and Si-O tetrahedral sheets collapsed by acid leaching. Its length is at a micron or nanometer scale. There are two types of pores： pores among neighboring fibers and pores in nanoriber. These pores （less than 6.5 nm in diameter, mostly 2.1 nm and 3.8 nm） all belong to mesopores. The pores in fibers consist of those among SiO2 particles, those among aggregates, remnant nanotubes and capillary tubes. Nanoribriform silica proves better than the traditional silica as a carrier of catalyzer and a filler for reinforce rubber and plastics.

Road Performances of Mesoporous Nano-silica Modified Asphalt Binders

The objective of this paper was to find new modifier to improve the aging resistance and low temperature cracking resistance of asphalt. To investigate the aging resistance of modified asphalt binders, mesoporous nano-silica（doping Ti^（4＋）） was used as a asphalt modifier. Some physical properties including penetration, ductility, and softening point of asphalt were analyzed with RTFO（Rotating thin film oven） aging and ultraviolet aging. Moreover, the performances of high and low temperature of modified asphalt binders with pressure aging were tested by dynamic shear rheometer（DSR） test and bending beam rheometer（BBR） test. These results showed that the penetration decreased, low temperature ductility, and softening point increased when adding mesoporous nano-silica to base asphalt. After ultraviolet radiation aging, the penetration loss and ductility loss of modified asphalt decreased than that of original asphalt, the increase of softening point was also significantly reduced than that of base asphalt. Furthermore, The test results of DSR and BBR showed that the G＊sinδ and creep modulus‘s＇ of pressure aged asphalt decreased, but the creep rate ‘m＇ increased. It can be concluded that the aging resistance and cracking resistance of modified asphalt are improved by adding mesoporous nano-silica, especially the doping of Ti^（4＋） could improve the aging resistance obviously.

Preparation of Scratch-Resistant Nano-Porous Silica Films Derived by Sol-Gel Process and Their Anti-reflective Properties

Structural strengthening of the nano porous silica films has been reported. The films were prepared with a base/acid two-step catalyzed TEOS-based sol-gel processing and dip-coating, and then baked in the mixed gas of ammonia and water vapor. The silica films were characterized with TEM, AFM, FTIR, spectrophotometer, ellipsometer, and abrasion test, respectively. The experimental results have shown that the films have a nanostructure with a low refractive index and can form an excellent scratch-resistant broadband anti-reflectance. The two-step catalysis noticeably strengthens the films, and the mixed gas treatment further improves mechanical strength of the silica network. Finally the strengthening mechanism has been discussed.

Evaluating the potential of surface-modified silica nanoparticles using internal olefin sulfonate for enhanced oil recovery

Recently,nanoparticles have proven to enhance oil recovery on the core-flood scale in challenging high-pressure high-temperature reservoirs.Nanomaterials generally appear to improve oil production through wettability alteration and reduction in interfacial tension between oil and water phases.Besides,they are environmentally friendly and cost-effective enhanced oil recovery techniques.Studying the rheological properties of nanoparticles is critical for field applications.The instability of nanoparticle dispersion due to aggregation is considered as an unfavorable phenomenon in nanofluid flooding while conducting an EOR process.In this study,wettability behavior and rheological properties of surface-treated silica nanoparticles using internal olefins sulfonates(IOS20–24 and IOS19–23),anionic surfactants were investigated.Surface modification effect on the stability of the colloidal solution in porous media and oil recovery was inspected.The rheology of pure and surfacetreated silica nanoparticles was investigated using a HPHT rheometer.Morphology and particle size distributions of pure and coated silica nanoparticles were studied using a field emission scanning electron microscope.A series of core-flood runs was conducted to evaluate the oil recovery factor.The coated silica nanoparticles were found to alter rheological properties and exhibited a shear-thinning behavior as the stability of the coated silica nanoparticles could be improved considerably.At low shear rates,the viscosity slightly increases,and the opposite happens at higher shear rates.Furthermore,the surfacemodified silica nanoparticles were found to alter the wettability of the aqueous phase into strongly water-wet by changing the contact angle from 80°to 3°measured against glass slides representing sandstone rocks.Oil–water IFT results showed that the surface treatment by surfactant lowered the oil–water IFT by 30%.Also,the viscosity of brine increased from 0.001 to 0.008 Pa s by introducing SiO2 nanoparticles to the aqueous phase for better displacement efficiency during chemicalassisted EOR.The core-flood experiments revealed that the ultimate oil recovery is increased by approximately 13%with a surfactant-coated silica nanofluid flood after the conventional waterflooding that proves the potential of smart nanofluids for enhancing oil recovery.The experimental results imply that the use of surfactant-coated nanoparticles in tertiary oil recovery could facilitate the displacement efficiency,alter the wettability toward more water-wet and avoid viscous fingering for stable flood front and additional oil recovery.

Synthesis of a Green Nano-Silica Material Using Beneficiated Waste Dunites and Its Application in Concrete

Nano-silica, one of the substances boosting the field of nanomaterials, can be produced by dissolving olivine in acid. The dissolution of olivine is a convenient alternative route to the existing methods of nano-silica production (neutralization of sodium silicate and flame hydrolysis) because the olivine dissolution is a low temperature process making this method cheaper and greener. Furthermore, this process can use waste olivine materials for the production of nano-silica. The produced nano-silica has a specific surface area between 100 and 400 m2/g;a primary particle size between 10 and 25 nm, which is agglomerated in clusters;and an impurity content below 5 wt.%. In addition, olivine nano-silica can be classified as a pozzolanic material with an activity index of 101%. The optimum replacement level of olivine nano-silica in conventional vibrated concrete is around 5% by volume resulting in: 1) a compressive strength increase of 20%;2) a CO2 emission reduction of 3%. Therefore, the use of the olivine nano-silica in CVC does not only improve the compressive strength but also reduce the CO2 emissions.

NS-VAE泡沫混凝土微观分析与宏观性能研究

首先分别探究了VAE乳液(Ethylene-vinylacetatecopolymer,乙烯-醋酸乙烯共聚物)和纳米二氧化硅(NS)对泡沫混凝土干密度和抗压强度等宏观性能的影响,然后对VAE与NS复合改性泡沫混凝土的改性机理进行了微观分析。研究证明当NS掺入比例在0%~1%,VAE掺入比例在2%时,NS-VAE泡沫混凝土较普通泡沫混凝土改善了孔隙率和平均孔径,提高了3 d和28 d抗压强度,减小了0~7 d干缩值。微观分析表明NS形成的晶核附着在水化产物表面,并在水化产物表面与VAE一同形成致密的凝胶网膜结构,这些致密的凝胶网膜结构减小了泡沫混凝土内部的孔隙孔径,提高了复合改性泡沫混凝土的干密度与抗压强度。总体来看,NS-VAE泡沫混凝土同时具备VAE泡沫混凝土和NS泡沫混凝土的优点,早期干缩值小,不易开裂,早期抗压强度高,具备更优秀的力学性能。

纳米二氧化硅对高流态矿渣-脱硫石膏复合碱激发材料早期强度的影响机理

以矿渣和脱硫石膏为前驱体的高流态复合碱激发材料(high-fluidity slag and desulfurization gypsum composite alkali activated material,HSD-AAM)是目前构筑物修复与加固工程中常用的新型建筑材料之一。为了保证流动性,HSD-AAM通常采用较高的水胶比,影响了其早期强度,从而限制了HSD-AAM的应用。针对这一问题,通过室内试验研究了纳米二氧化硅(nano-silica,NS)掺量对HSD-AAM凝结时间、流动性、抗折和抗压强度(1、3、7 d)的影响,以期在不影响HSD-AAM流动性的前提下提升其早期强度;进而,通过扫描电子显微镜(scanning electronic microscopy,SEM)、X射线衍射(X-ray diffraction,XRD)和热重-差示扫描量热仪(thermogravimetric analysis and differential scanning calorimetry,TG-DSC)等方法分析了不同类型HSD-AAM的水化产物和微观结构,揭示了NS掺量对HSD-AAM早期强度的增强机理。结果表明:随着NS掺量的增加,HSD-AAM流动性降低且凝结时间缩短,而早期强度明显提升。NS掺量在0~3%之间时,每提升1%,HSD-AAM流动性平均降低6.0%;初凝和终凝时间平均缩短13.7%和10.0%;1 d抗折强度和抗压强度平均提升10.7%和20.2%;3 d抗折强度和抗压强度平均提升23.3%和12.4%;7 d抗折强度和抗压强度平均提升11.1%和32.9%。这是由于NS具有较高的火山灰活性,在早期与浆体内的Ca(OH)2发生水化反应,促进其水化进程,生成大量的C-S-H凝胶,改善了浆体结构疏松的特点,使浆体早期微观结构更加致密。

RHEOLOGICAL MODIFICATION OF EPOXY RESINS WITH NANO SILICA PREPARED BY THE SOL-GEL PROCESS

Nano silica-modified epoxy resins were synthesized by the sol-gel process, The materials have the morphological structure of nano particales dispersed in the epoxy matrix. The dispersed phase formed a physical network in the resin and thus influenced the rheological behavior greatly. However, the nano silica did not show a significant influence on the mechanical properties of the cured resins.

纳米薄片状高硅ZSM-5分子筛的制备及其甲苯脱除性能研究

以四丙基氢氧化铵(TPAOH)为模板剂、NH4F为矿化剂,运用水热晶化法制备厚度为10~100 nm的纳米薄片状高硅ZSM-5分子筛,考察TPAOH/SiO_(2)摩尔比、晶化温度对纳米薄片状高硅ZSM-5分子筛制备的影响,并对其甲苯动态吸附性能进行评价。结果表明,晶化温度为90℃时,随着TPAOH/SiO_(2)摩尔比的增加,纳米薄片状高硅ZSM-5分子筛的尺寸与厚度减小,孔容与平均孔径增大。TPAOH/SiO_(2)摩尔比为0.35时,晶化温度的升高不影响纳米薄片状高硅ZSM-5分子筛的形貌、结晶度与孔结构。相比市售高硅ZSM-5分子筛,厚度10~20 nm、SiO_(2)/Al_(2)O_(3)摩尔比为305的纳米薄片状高硅ZSM-5分子筛对甲苯的动态穿透吸附容量增加约22.5%、饱和吸附容量增加约26.8%,且吸附曲线符合Yoon-Nelson模型。经20次重复再生后,该纳米薄片状高硅ZSM-5分子筛的甲苯吸附容量衰减低于0.5%,展现出良好的再生使用性能。