共查询到20条相似文献,搜索用时 171 毫秒
1.
利用直流电弧等离子体蒸发冷凝法制备纳米银粉,采用X射线衍射分析对纳米银粉的结构进行表征,采用纳米激光粒度仪研究不同超声分散工艺与不同离子类型的分散剂聚乙烯吡咯烷酮、十六烷基三甲基溴化氨、十二烷基硫酸钠对纳米银粉在水溶液中分散性能的影响,获得纳米银粉的最佳分散工艺与激光粒径分布,对比研究纳米银粉的激光粒径与透射电镜统计的粒径的差异。结果表明:纳米银颗粒为立方晶系多晶体,颗粒的结晶性良好;以十六烷基三甲基溴化氨为分散剂的效果最理想,最佳超声波功率为600 W;当十六烷基三甲基溴化氨的质量浓度为0.5 g/L时,纳米银颗粒的分散稳定性较好;激光粒径反映的纳米颗粒的动态二次粒径略大于从透射电镜图像统计得到的粒径。 相似文献
2.
采用直流电弧等离子体蒸发法制备高纯度纳米级硅粉,利用X射线衍射、X射线荧光分析、氮氧分析仪、透射电子显微镜和相应的选区电子衍射等测试手段对样品物理化学性质进行表征。采用紫外分光光度计法研究超声时间和不同的分散剂及其加入量对纳米硅粉在水介质中分散效果的影响。结果表明:制备出近球形、立方晶型结构的纳米硅粉,粒径分布窄,其纯度达到99.93%(质量比)。随着超声时间和分散剂浓度的增加,分散效果呈现先增大后趋向平稳的趋势,十六烷基三甲基溴化铵(CTAB)对纳米硅粉在水介质中的分散效果最好。纳米硅粉在水介质中较好的分散工艺为:在pH=6、超声功率为560 W的情况下,CTAB加入量为4%,超声时间为80 min。分散后的硅粉比未分散的硅粉首次放电比容量提升14.93%,达到了2640 m Ah/g,首次库伦效率达到34.92%。 相似文献
3.
针对含纳米红色硒粉抗菌保健不锈钢餐具的开发问题,为制备高分散性和悬浮稳定性的纳米硒粉,本文在测定纳米硒粉在乙二醇介质中pH-zeta电位图的基础上,选用CTAB、PVP、PEG-2000和Span80四种表面活性剂,采用吸光度测试、沉降实验研究了纳米硒粉在乙二醇介质中的分散工艺及其悬浮稳定性,并探讨了不同表面活性剂的分散机理。结果表明,在最佳配比下的CTAB与具有空间位阻稳定机理PVP和PEG-2000的复合分散体系的分散效果明显好于单分散剂,其中,PVP与CTAB的复合分散比最佳单分散剂CTAB的分散效果提升了105%;推荐纳米硒粉在乙二醇中的分散工艺为:在pH=6、3%(质量比)CTAB+3%PVP复配分散,分散时间为10 min,该工艺下分散的纳米硒粒子静置60天的沉降率仅为0.7%。红外测试表明,CTAB在纳米硒粉表面为物理吸附,PVP、PEG-2000和Span80则为化学吸附。 相似文献
4.
《真空科学与技术学报》2019,(10)
针对含纳米红色硒粉抗菌保健不锈钢餐具的开发问题,为制备高分散性和悬浮稳定性的纳米硒粉,本文在测定纳米硒粉在乙二醇介质中pH-zeta电位图的基础上,选用CTAB、PVP、PEG-2000和Span80四种表面活性剂,采用吸光度测试、沉降实验研究了纳米硒粉在乙二醇介质中的分散工艺及其悬浮稳定性,并探讨了不同表面活性剂的分散机理。结果表明,在最佳配比下的CTAB与具有空间位阻稳定机理PVP和PEG-2000的复合分散体系的分散效果明显好于单分散剂,其中,PVP与CTAB的复合分散比最佳单分散剂CTAB的分散效果提升了105%;推荐纳米硒粉在乙二醇中的分散工艺为:在pH=6、3%(质量比)CTAB+3%PVP复配分散,分散时间为10 min,该工艺下分散的纳米硒粒子静置60天的沉降率仅为0.7%。红外测试表明,CTAB在纳米硒粉表面为物理吸附,PVP、PEG-2000和Span80则为化学吸附。 相似文献
5.
6.
7.
为了提高锡掺杂的氧化铟纳米粉体在有机单体甲基丙烯酸甲酯(MMA)中的分散效果,采用球磨、辅助超声等方法,选用PEG4000、KH570、油酸和十八醇等作为分散剂,对纳米粉体进行表面修饰和改性.研究了分散剂种类、添加量及球磨时间对纳米粉体分散稳定性的影响.找出了在MMA单体中分散最好的纳米粉体改性工艺条件:以乙二醇为分散介质、锡掺杂氧化铟纳米粉体摩尔分数为0.1%的KH570和0.016%的一缩二乙二醇为分散剂,球磨10 h,辅助超声30 min,红外干燥.采用高分辨透射电镜(HRTEM)和红外光谱(FT-IR)等对其结构和包裹性能进行了表征,结果显示粉体粒径约为50 nm,表面被无定形分散剂所包裹,颗粒之间无明显团聚现象,分散性好. 相似文献
8.
纳米TiN粉体在无水乙醇中的分散研究 总被引:1,自引:0,他引:1
应用超声、球磨等分散方法,分别以非离子型表面活性剂吐温-80、聚乙二醇1000、聚乙二醇1500及硅烷偶联剂A-1230为分散剂对纳米TiN粉末在无水乙醇中的分散性能进行了研究。分析了分散剂类型、分散剂用量、体系pH值、超声时间、球磨时间、球磨转速等因素对粉体分散效果的影响。采用分散相的沉降高度和沉降速率表征分散稳定性,试验结果表明硅烷偶联剂A-1230是纳米TiN粉体在无水乙醇中较为理想的分散剂,pH值和分散剂的用量存在一个最佳值,超声分散与球磨分散相结合是合适的分散工艺。当pH值为4、A-1230添加量为粉体质量的23%时,经10min超声处理、4h球磨后所得纳米浆料的分散效果最好,稳定时间可达6个月。对分散后的纳米TiN颗粒进行了TEM、SEM观察,纳米TiN均匀分散在无水乙醇中,颗粒平均粒径在20nm以下,纳米TiN在无水乙醇中的分散遵循空间位阻稳定机制和静电稳定机制。 相似文献
9.
有机分散介质中纳米SiC粉体稳定悬浊液的制备 总被引:2,自引:0,他引:2
纳米粉体的稳定分散是制备微观结构均匀、缺陷少的纳米复相陶瓷坯体的关键。本文中采用Zeta电位、粒度分析、SEM等测试技术分析了超声震荡和HF酸洗对SiC纳米粉体的影响;对比研究了乙醇、乙二醇以及75%乙醇和25%乙二醇混合液作为分散介质,聚乙二醇为分散剂时纳米SiC粉体在不同pH下的分散稳定性,确定了粉体最佳超声震荡的最佳时间;探讨了酸洗的作用;并在乙二醇中,以1%PEG为分散剂,pH=10条件下获得了纳米碳化硅粉体的高稳定分散悬浮液。 相似文献
10.
11.
以十二烷基硫酸钠(SDS)、聚丙烯酸(PAA)复合曲拉通(Tx100)、分散助剂DISPERBYK-180(D-180)和十二炕基苯磺酸钠(SDBS)等4种表面活性剂作为分散剂,采用多种表面活性剂超声分散法分散纳米碳纤维(CNFs).结合紫外/可见分光光度计法、透射电镜(TEM)及场发射扫描电镜(FESEM)观察、Zeta电位法、表面张力测试、静置及离心分离等测试方法,全面地表征了采用不同表面活性剂的CNFs悬浮液的分散状态,探讨了表面活性剂对CNFs在水性体系中分散性的影响.实验结果表明:4种表面活性剂中,SDS对CNFs的分散效果最好,其最佳掺量为1.6g/L:SDBS的分散效果次之,D.180效果再次,而PAA复合Tx100的分散效果最差. 相似文献
12.
13.
Kang Zhang Xiaohua Zhang Hengxiang Li Xiaohan Xing Li’e Jin Qing Cao Ping Li 《Journal of Materials Science》2018,53(4):2484-2496
Large-scale production of high-quality graphene is very critical for practical applications of graphene materials and devices. Exfoliation of graphite in an aqueous solution of surfactants is one of the most promising approaches to produce graphene. In this study, a novel anionic surfactant [sulfonated used engine oil (SUEO)], which was prepared from used engine oil, was employed to exfoliate the graphite nanoplatelets into graphene sheets in an aqueous solution under sonication to form a stable dispersion. The efficiency of SUEO for exfoliating and dispersing graphene was investigated and compared with that of traditional surfactants, such as sodium dodecyl sulfate, sodium dodecyl benzene sulfate, cetyl trimethyl ammonium bromide, and polyvinylpyrrolidone. Result showed that the graphene dispersion with excellent stability had a higher concentration (0.477 mg/mL) than others at 0.5 g/L optimal SUEO dosage in 4 h sonication time. The superior performance of SUEO can be attributed to its special molecular structures, whose hydrophobic moieties contain cycloalkanes/aromatics with different molecular weights and/or side chain –R with different lengths. Structural diversities are very helpful to the “jigsaw-puzzle” process on the graphene surface, where the total interfacial energy of the mixture system was minimized. Microscopic (SEM, TEM, and AFM) and spectroscopic (XRD, XPS, and Raman) measurements revealed that the dispersion consisted of few-layer graphene sheets with lower levels of defects or oxidation. This study presents a new class of dispersing agents for graphene that assists in the exfoliation process in water with high concentration and the stabilization of the graphene sheets against reaggregation. 相似文献
14.
15.
The crystallization of strontium carbonate is performed in aqueous solution or alcohol/water solution in the presence of mixed nonionic/anionic surfactants Pluronic F127/sodium dodecyl sulfate. With an increase of the volume ratio of ethanol/water, SrCO3 pancakes transform into flowers, and then to irregular flakes. X-ray diffraction (XRD) pattern reveals that both of pancake-like and flower-like SrCO3 particles are orthorhombic phases. Larger pancakes with porous structure are produced when the content of ethylene glycol reaches a relatively high value. Results indicate that -OH groups of alcohol play an important role in morphological controlling of SrCO3. 相似文献
16.
17.
Strano MS Moore VC Miller MK Allen MJ Haroz EH Kittrell C Hauge RH Smalley RE 《Journal of nanoscience and nanotechnology》2003,3(1-2):81-86
The ionic surfactant-assisted dispersion of single-walled carbon nanotubes in aqueous solution has been studied by Raman and fluorescent spectroscopy during ultrasonic processing. During the process, an equilibrium is established between free individuals and aggregates or bundles that limits the concentration of the former that is possible. This equilibrium is a function of free sodium dodecyl sulfate concentration. At surfactant concentrations below this value, fluorescence is shifted to a lower energy due to an increase in micropolarity from water association at the nanotube surface. The mechanism of dispersion is postulated as the formation of gaps or spaces at the bundle ends in the high shear environment of the ultrasonicated solution. Surfactant adsorption and diffusion then propagate this space along the bundle length, thereby separating the individual nanotube. The former is found to be controlling, with the use of a derived kinetic model for the dispersion process and extraction of the characteristic rate of nanotube isolation. 相似文献
18.
Molecular dynamics simulations are used to compute the potential of mean force (PMF) governing the interactions between carbon nanotubes (CNTs) in water/surfactant systems. The effects of CNT length, diameter, chirality (armchair and zigzag) and surfactant structures on CNT interaction and dispersion in water/surfactant systems are investigated for (5, 5), (5, 0), and (10, 10) single walled CNTs with two commonly used surfactants [viz., sodium dodecyl sulfate (SDS) and sodium dodecylbenzene sulfonate (SDBS)] at room conditions. An adaptive biasing force method was used to speed up the calculations. Simulations revealed that CNT length and diameter as well as optimum amount of surfactant addition and its structures can significantly affect CNT interactions (i.e., PMFs vary significantly). Surfactant molecules were found to adsorb at the CNT surface and reduced interaction strength between CNTs. SDBS surfactant contributed weaker interactions between CNTs as compared with that of SDS surfactant by a factor of about 10 indicating that SDBS is better than SDS for dispersing CNTs in an aqueous suspension. This phenomenon agrees qualitatively with the experimental results reported in the literature. The understanding of detailed atomic arrangements and atomic interactions between CNTs and surrounding molecules reported in this study is significantly helpful to computationally screening different surfactants and improving the CNT dispersion in aqueous solution. The method will also facilitate the reduction of time and cost required to produce CNT reinforced nanocomposite materials as well as homogeneous CNT dispersed solutions for many biological applications. 相似文献
19.
20.
Measurements of the surface tension have been carried out to determine the effects of both temperature and concentration on the surface tension of aqueous solutions of sodium chloride, propylene glycol, and ethylene glycol. A differential capillary-rise method was employed for the measurements. The results show that the surface tension of the ethylene glycol solution and the propylene glycol solution increases as the concentration of the solution decreases, while for the sodium chloride solution the surface tension increases monotonically as the concentration increases. The surface tension of the liquids was found to be an almost-linear function of temperature from 20°C to just above the freezing temperature. Equations for the surface tension of the three binary aqueous solutions as a function of temperature and concentration are presented. 相似文献