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.

PPy/SiO_2纳米复合材料的合成与导电性能

以乙醚为反应介质，用化学方法合成了聚吡咯（ＰＰｙ／ＳｉＯ２）纳米复合材料。利用红外光谱、四探针技术和透射电镜表征了这些材料的组成、结构和导电性能。结果表明，载流子在ＰＰｙ分子链之间和ＰＰｙ聚集体之间有显著的传导性。

SiO2气凝胶常压干燥工艺与隔热应用进展

综述了SiO2气凝胶常压制备技术及其复合隔热材料的最新研究进展。着重介绍了提高凝胶网络基架强度、添加干燥控制化学添加剂、表面改性、降低毛细管力等几种SiO2气凝胶常压干燥工艺,并回顾了几种SiO2气凝胶复合隔热材料的应用现状。

纳米SiO_2与硅粉的火山灰活性的比较

本文应用XRD物相分析和强度试验对纳米SiO2 与硅粉的火山灰活性进行了比较性研究。研究得到纳米SiO2 与硅粉均为无定形的物质 ,纳米SiO2 与氢氧化钙的反应速度远大于硅粉与氢氧化钙的反应速度 ,纳米SiO2 与氢氧化钙反应形成水化硅酸钙凝胶的速度远大于硅粉的速度 ,由纳米SiO2 与氢氧化钙制成浆体的强度发展速度远大于硅粉的速度。总之 ,纳米SiO2 的火山灰活性远大于硅粉的火山灰活性。本研究的目的在于应用少量的纳米SiO2 来有效地吸收高性能水泥混凝土界面早期形成的氢氧化钙。

PMVS/SiO_2复合体系中粒子表面处理对动态粘弹特性的影响

The dynamic viscoelastic behavior of polysiloxanes filled with ultrafine SiO 2 has become ever-lasting important due to its unique properties. In present article, the influence of SiO 2 treated with silane coupling agent bis(3-triethoxysilyl)tetrasulfane(TESPT) on dynamic viscoelastic properties of uncured polymethylvinylsiloxane(PMVS)/ultra fine-silica(SiO 2) composites was investigated by using an advanced rheometric expansion system(ARES) under the conditions of temperature 25 ℃, strain(γ) from 0.01% to 100% and frequency(ω) from 0.01 to 100 rad/s. The results reveal that the treated SiO 2 particles leads to the frequency-dependent storage modulus(G′) which approaches linear viscoelastic behavior in the lower frequency region. Based on an examination of the dynamic viscoelastic behavior and TEM observation, we owe these characteristics to improved dispersion of SiO 2 particles in the polymer matrix due to their surface-treatment as compared with the untreated case. On the other hand, dynamic viscoelastic behavior sensitively reflects the dispersion of SiO 2 particles with diameters from 100 to 500 nm, which further evidence the promotion of filler dispersion induced by the incorporation of TESPT.

电工级高纯超细SiO_2粉研究

高纯超细石英粉生产工艺系统和产品研究的成果介绍 ,目前已经进入工业化生产的主要品种规格和产品的主要性能指标。主要产品的各项主要指标达到国内领先 ,国际先进水平。其中最主要的指标与实际达到的值为 :SiO2 ≥ 99 9% ,Na+ 1ppm ,Cl-≤ 1ppm ,Fe3 + ≤ 1ppm ,电那里率≤ 3μs/cm。

层层自组装SiO2阻燃棉织物的制备及其性能

以SiO 2为阻燃剂,通过层层自组装(LBL)的方法对棉织物进行阻燃整理。研究制备过程中SiO 2浓度、反应温度和pH值等参数对处理后棉织物阻燃性能的影响,对整理前后织物的结构、阻燃性能、力学性能和透气性进行了表征。结果表明,经SiO 2阻燃整理的棉织物具备较好的阻燃性能、力学性能和透气性。

Pulmonary Toxicity in Rats Caused by Exposure to Intratracheal Instillation of SiO2 Nanoparticles

Objective The effect of the silica nanoparticles（SNs） on lungs injury in rats was investigated to evaluate the toxicity and possible mechanisms for SNs.Methods Male Wistar rats were instilled intratracheally with 1 mL of saline containing 6.25,12.5,and 25.0 mg of SNs or 25.0 mg of microscale SiO_2 particles suspensions for 30 d,were then sacrificed.Histopathological and ultrastructural change in lungs,and chemical components in the urine excretions were investigated by light microscope,TEM and EDS.MDA,NO and hydroxyproline（Hyp） in lung homogenates were quantified by spectrophotometry.Contents of TNF-α,TGF-β1,IL-1β,and MMP-2 in lung tissue were determined by immunohistochemistry staining.Results There is massive excretion of Si substance in urine.The SNs lead pulmonary lesions of rise in lung/body coefficients,lung inflammation,damaged alveoli,granuloma nodules formation,and collagen metabolized perturbation,and lung tissue damage is milder than those of microscale SiO_2 particles.The SNs also cause increase lipid peroxidation and high expression of cytokines.Conclusion The SNs result into pulmonary fibrosis by means of increase lipid peroxidation and high expression of cytokines.Milder effect of the SNs on pulmonary fibrosis comparing to microscale SiO_2 particles is contributed to its elimination from urine due to their ultrafine particle size.

改性剂对旋转法SiO2减反膜均匀性的影响

分析了采用旋转涂膜法制备溶胶-凝胶SiO2减反膜过程中条纹缺陷产生的机理,利用含氟醇类试剂对减反膜溶胶进行改性,使溶胶链段柔顺性及流动性得到改善。在光学显微镜下对改性前后的膜层进行了对比和分析,对膜层的表面形貌、表面粗糙度以及透射比等特性进行了表征。结果表明:溶胶改性之后的膜层未出现条纹缺陷,表面粗糙度均方根值从4.55 nm下降到小于1.00 nm,膜层表面质量有了较大提高;改性前后膜层的增透性能相当,在熔石英基片上制备的膜层峰值透射比为99.60%～99.89%,膜层激光损伤阈值为21.0～25.3 J/cm2。

Preparation of Organic/Inorganic Hybrid Polymer Emulsions with High Silicon Content and Sol-gel-derived Thin Films

A novel polymer/SiO2 hybrid emulsion(PAES)was prepared by directly mixing colloidal silica with polyacrylate emulsion(PAE)modified by a saline coupling agent.The sol-gel-derived thin films were obtained by addition of co-solvents into the PAES.The effects ofγ-methacryloxypropyltrimethoxysilane(KH-570)content and co-solvent on the properties of PAES films were investigated.Dynamic laser scattering(DLS)data indicate that the average diameter of PAES(96 nm)is slightly larger than that of PAE(89 nm).Transmission electron microscopy (TEM)photo discloses that colloidal silica particles are dispersed uniformly around polyacrylate particles and some of the colloidal silica particles are adsorbed on the surface of PAE particles.The crosslinking degree data and Fourier transform infrared(FT-IR)spectra confirm that the chemical structure of the PAES is changed to form Si-O-Si-polymer crosslinking networks during the film formation.Atomic force microscope(AFM)photos show the solvent induced sol-gel process of colloidal silica and the Si-based polymer distribution on the film surface of the dried PAES.Thermogravimetric analysis(TGA)curves demonstrate that the PAES films display much better thermal stability than PAE.

Effect of Fumed SiO_2 on Pore Formation Mechanism and Various Performances of β-iPP Microporous Membrane Used for Lithium-ion Battery Separator

In this work, four samples containing different contents of fumed SiO_2 were prepared to improve the pore size distribution and various properties of b nucleated isotatic polypropylene（b-i PP） biaxial membrane used for lithium-ion battery separator. The wide-angle X-ray diffraction（WAXD） and differential scanning calorimetry（DSC） results show that the fumed SiO_2 promotes the formation of b-crystal slightly and narrows down the thickness distribution of b-lamellae; meanwhile, evenly distributed SiO_2 within b-i PP can be inspected by scanning electron microscopy（SEM）. Moreover, further detailed characterization of morphological evolutions during biaxial stretching by tensile testing and SEM manifests that SiO_2 can strengthen b-i PP and make the samples deform more homogeneously, resulting in a gradually elaborate and finer oriented microfibril structure after longitudinal stretching, in which more uniform defects distribute between fibrils and restrain the formation of coarse fibrils effectively. Therefore, more superior microporous structure emerges with the addition of SiO_2, accompanied by narrower pore size distribution and better connectivity between microvoids, which is confirmed by mercury porosimeter and diminished Gurley value. Moreover, the lower thermal shrinkage, decreased shrinkage rate and suppressed porosity reduction indicate that fumed SiO_2 improves thermal and dimensional stability of membrane dramatically. Furthermore, due to the excellent wettability of SiO_2 with electrolyte, the microporous membranes doped with SiO_2 have higher electrolyte uptake, even after heat treatment at elevated temperature.

Distinguished discriminatory separation of CO2 from its methane-containing gas mixture via PEBAX mixed matrix membrane

Highly selective separation of CO_2 from its methane-containing binary gas mixture can be achieved by using Poly(ether-block-amide)(PEBAX)mixed matrix membranes(MMMs).According to FESEM and AFM analyses,silica-based nanoparticles were homogenously integrated within the polymer matrix,facilitating penetration of CO_2 through the membrane while acting as barrier for methane gas.The membrane containing 4.6 wt% fumed silica(FS)(PEBAX/4.6 wt%FS)exhibits astonishing selectivity results where binary gas mixture of CO_2/CH_4 was used as feed gas.As detected by gas chromatography,in the permeate side,data showed a significant increase of CO_2 permeance,while CH_4 transport through the mixed matrix membrane was not detectable.Moreover,PEBAX/4.6 wt%FS greatly exceeds the Robeson limit.According to data reported on CO_2/CH_4 gas pair separation in the literature,the results achieved in this work are beyond those data reported in the literature,particularly when PEBAX/4.6 wt%FS membrane was utilized.

Carboxylic Acids and Esters as Scaffold for Cavities in Porous Single Layer Anti-Reflective Coatings of Silica-Titania with Excellent Optical and Mechanical Properties

Anti-reflective (AR) single layer of silica-titania (SiO2-TiO2) coatings were obtained from sols containing pyromellitic dianhydride (PMDA) derivatives and Ti and Si precursors on glass substrate by dip-coating method. The coatings showed very high optical quality and the transmission was improved to up to 98.5%. Furthermore, the coatings also presented good mechanical stability.

Postprocessing treatments to improve the laser damage resistance of fused silica optical surfaces and SiO_2 coatings

The combination of deep wet etching and a magneto-rheological finishing （MRF） process is investigated to simultaneously improve laser damage resistance of a fused-silica surface at 355 nm. The subsequently deposited SiO2 coatings are researched to clarify the impact of substrate finishing technology on the coatings. It is revealed that a deep removal proceeding from the single side or double side had a significant impact on the laser-induced damage threshold （LIDT） of the fused silica, especially for the rear surface. After the deep etching, the MRF process that followed does not actually increase the LIDT, but it does ameliorate the surface qualities without additional LIDT degradation. The combination guarantee both the integrity of the surface＇s finish and the laser damage resistance of the fused silica and subsequent SiO2 coatings.

沉淀法白炭黑与纳米级二氧化硅

依据二氧化硅粒子的形成过程 ,指出传统沉淀法白炭黑并不具有科学意义上的纳米实质。研究重点侧重于改进其分散性能。

新型复合聚合物电解质离子导电行为的研究

PEG60 0和CH2 Cl2 通过Williamson缩聚反应 ,生成主链柔顺的PEG共聚物 .1 HNMR测试表明其以 [CH2 O(CH2 CH2 O) 1 3 ]为重复结构单元 .与聚合物质量含量 8%的气相SiO2 及适量的LiN(CF3 SO2 ) 2 掺杂 ,制备一系列新型复合聚合物电解质 .通过AC阻抗研究离子电导率 ,提出适合本体系的等效电路 .该体系具有良好的成膜性能与热稳定性能 ,电导率比传统的PEO/盐体系高 2～ 3个数量级 .离子电导率随着温度的升高而增加 ,低温电导率增加较快 ,高温电导率增加较慢 ,呈非Arrhenius变化 .在EO/Li =13～ 3 4∶1(摩尔比 )范围内 ,离子电导率随着盐浓度的变化出现两个峰值 ,低盐浓度的峰值较高 .在 3 0 3K ,EO/Li =2 8∶1时 ,最大离子电导率接近 10 -4S/cm .

高钨高硅电炉锡渣烟化条件下的特性

针对高钨高硅电炉锡渣，考察炉渣发泡性能，测定其熔点、粘度，分析ＷＯ３等组分对各性质的影响。通过化学分析、化学物相分析、Ｘ射线衍射、电子探针、光学显微镜鉴定等手段，查明高钨高硅电炉锡渣的相组成及化学元素在各相中的分配以及渣中各相相对百分含量、结构构造、各矿物相的嵌布关系等。对在烟化条件下的炉渣成分、发泡性能、粘度、炉渣中的锡相等特性进行研究和分析。指出电炉锡渣可通过适当措施顺利实现烟化作业。它为烟化法处理该复杂物料提供了理论依据，也是完善冶炼工艺和条件的前提和基础。

溶胶-凝胶技术在光学制造中的应用

溶胶－凝胶技术是一种超结构材料处理技术，与浇铸工艺相结合形成了一种全新的光学制造技术。本文简要回顾和比较了基于溶胶－凝胶处理技术制造ＳｉＯ２单片光学元件和玻璃的多种处理方法，重点描述在常压下用水解硅醇盐方法制造ＳｉＯ２单片凝胶七个处理步骤的化学、物理过程。概述了这种方法的特点和制得光学元件的特性，列举和讨论其在制造折射、衍射、微型光学元件和复合系统中的应用及前景。

渣-硅灰水泥蒸压处理含镉钠低放废液

开发了一种矿渣硅灰混合水泥用来处理含多量Cd2 + 、Na+ 的低放射性废液。该水泥净浆经 12 5℃蒸压 14天的抗压强度达 114MPa ,用水银测孔仪测得总孔隙率为 14 .1% ,最可几孔半径 2 .7nm。目前低放废液的处理常用硅酸盐水泥和矿渣水泥 ,从强度和微结构方面看 ,矿渣 -硅灰混合水泥要比上述两种水泥好得多。对于废液中的Cd2 + 和Na+ ,成功地合成了无定形方沸石作为Na+ 的固主相 ,CdS为Cd2 + 的固化相。

STF/Kevlar复合材料的制备与冲击撕裂性能

以纳米SiO_2粉体为分散相、PEG为分散介质,制备剪切增稠液体(STF),采用涂层法制备STF/Kevlar复合材料,并对其在摆锤冲击条件下的冲击撕裂性能进行测试和分析。试验结果表明,PEG的平均相对分子质量增加有利于提高STF/Kevlar复合材料的冲击撕裂性能,但制备STF时纳米SiO_2粉体均匀分散在PEG中的难度增加,极易产生团聚现象,导致STF/Kevlar复合材料的冲击撕裂性能下降。同时,随着纳米SiO_2粉体质量分数及STF质量分数增加,STF/Kevlar复合材料的冲击撕裂性能呈现提升趋势。