复合氟化改性制备EP-ZnO纳米超疏水涂层的研究

风力发电机叶片覆冰严重影响风机安全经济运行,高质量的超疏水防冰涂层是当前研究的热点之一.本实验采用复合氟化改性的方法分别对环氧树脂(EP)和固化剂进行氟化改性,同时通过ZnO纳米颗粒对涂层表面结构进行修饰制备EP?ZnO纳米复合超疏水涂层,并研究了涂层的疏水性、耐磨性和抗冲击性能.研究结果表明,复合氟化改性能有效提高涂层的疏水性能,其接触角为150°,滚动角为6°;经过ZnO纳米颗粒对涂层表面结构修饰后涂层的接触角达158°,滚动角为3°.涂层具有良好的粘附力、稳定的抗冲击能力和耐磨性能,在磨损实验过后,涂层仍能保持较高的疏水性能.     

硬脂酸改性纳米ZnO的研究

采用酯化反应法,以水为溶剂,采用硬脂酸对纳米ZnO的表面进行改性,对改性效果进行测试表征。其最佳工艺条件为:硬脂酸质量分数为6%,反应温度为90℃,反应时间为90 min。结果表明,改性后的ZnO粒子呈纳米级的分散,亲油化度值达到72.31%,吸水率达到3.04%;经表面改性的纳米ZnO表现了很好的亲油疏水性;改性后的纳米ZnO表面引入了硬脂酸的官能团,使其表面羟基的数目明显减少,其改性机理为纳米ZnO表面羟基与硬脂酸分子中的羧基发生了类似醇和酸的酯化反应。     

纳米SiO_2/有机硅聚丙烯酸复合防冰涂层的制备及性能研究

以有机硅聚丙烯酸为成膜物质,经γ-(甲基丙烯酰氧)丙基三甲氧基硅烷(KH-570)表面化学改性后的纳米SiO_2粒子(经甲苯-2,4-二异氰酸酯活化)为无机填料,制备纳米SiO_2/有机硅聚丙烯酸复合防冰涂层。利用红外测试(FT-IR)、热失重(TGA)、扫描电镜(SEM)等研究了纳米SiO_2表面化学改性的机制,探讨了纳米SiO_2用量对涂层表面形貌、浸润性及涂层与冰层之间粘附性能的影响。结果表明,KH-570化学改性提高了纳米SiO_2在涂层中的分散性并有效地提高了涂层表面的疏水性能,当KH-570化学改性后的纳米SiO_2用量为8%时,涂层表面水的接触角为150°,呈现超疏水特性;涂层与冰层之间粘附力随纳米SiO_2用量增加呈现下降趋势,当纳米SiO_2用量为8%时,涂层与冰层之间的粘附力仅为树脂涂膜的30%左右。KH-570化学改性后的纳米SiO_2与低表面能有机硅聚丙烯酸树脂的协同效应使涂层具有了良好的疏水防冰性能。     

纳米SiO2对聚丙烯酸酯复合涂层在水润滑下摩擦学性能的影响

考察了纳米SiO₂对聚丙烯酸酯复合涂层在水润滑下摩擦磨损性能的影响。利用FTIR分析纳米SiO₂与聚丙烯酸酯的界面结合;利用SEM观察复合涂层磨损表面,并结合FTIR和摩擦磨损实验分析其磨损机理。结果表明:水润滑时,聚丙烯酸酯在摩擦过程中会发生摩擦化学反应,引起涂层摩擦腐蚀磨损;而纳米SiO₂能与聚丙烯酸酯以化学键的形式结合,它的加入有助于摩擦界面在水介质中形成具有较好减摩作用的表面膜和水分子膜,提高聚丙烯酸酯复合涂层的耐磨性。在水润滑下,当纳米SiO₂的含量较低时,涂层表面的磨损形式为摩擦腐蚀磨损和磨粒磨损;当纳米SiO₂的含量达到5wt% 时,涂层表面形成完整的表面膜和水分子膜,此时涂层具有良好的摩擦学性能。      

聚氨酯改性有机硅含氟涂层表面能的研究

研究聚氨酯改性有机硅涂层表面与液体的润滑性能,探讨了表面结构对表面能的影响。发现基料与填料复合制成的涂层,表面粗糙会极大地影响涂层的表面能各分量,基料和填料复相构成的表面,使表面能各分量不再是一个简单的加和。     

镁合金表面耐磨涂层研究进展

镁及其合金具有优异的物理及机械性能,从而在许多领域得到应用.但其不耐磨性限制了镁合金在汽车和航空工业中的应用.最简单且有效的解决办法是在镁合金表面施加耐磨涂层.综述了几种新的表面耐磨涂层技术,即激光表面改性涂层(激光表面重熔/激光表面合金化/激光表面熔敷)、表面纳米陶瓷涂层和微弧氧化陶瓷基涂层,并分析了它们的研究和应用前景.     

纳米TiO2的改性及其制备的TiO2/环氧树脂涂层的性能

过去,采用偶联剂等对纳米TiO2粉体改性的效果不好,影响了其制备的环氧树脂复合涂层的性能.以多羟基化合物三乙醇胺(TEA)对纳米TiO2预处理,再用硅烷偶联剂KH560或硬脂酸对其改性,并用其制备含2.0％TiO2的环氧树脂复合涂层.利用傅里叶红外变换光谱仪、激光粒度仪和紫外/可见分光光度计对改性结果进行表征,并用扫描电子显微镜(SEM)观察含2.0％改性纳米粉体的复合环氧涂层的表面形貌,通过电化学工作站、准动态高温高压釜测定其阻抗、耐高温高压性能.结果表明:通过三乙醇胺预处理后,改性纳米TiO2粉体的有效粒径有所减小,透过率有所增加;含改性纳米粉体的复合涂层阻抗性能、高温高压性能有一定的提升,经TEA预处理再有机改性的纳米TiO2制备的复合涂层性能可进一步提高.     

离子注入表面摩擦学改性及其应用

离子注入可以改善材料表面的各种性质,而常温离子注入改性层太薄,工件表面的耐磨性及承载能力均较差,随着各种新的离子注入工艺的出现,摩擦学性能有较大的改善.本文从分析离子注入技术的特点着手,综述了离子注入对材料表面硬度、摩擦系数和耐磨性的影响及其作为表面摩擦学改性手段在航空航天、军事和机械等领域中的应用.     

纳米氧化锆粉体的表面改性研究

本文初步研究了己二酸，硬脂酸对纳米氧化锆陶瓷粉体的表面改性作用及其对粉体的极性和流动性的影响。实验结果表明，己二酸，硬脂酸中的羧基与纳米氧化锆粉体颗粒表面的羟基发生类似于酸和醇的酯化反应，并在其表面形成单分子膜。经过表面改性的纳米氧化锆粉体由极性转化为非极性，同时表现出良好的流动性能。     

纳米TiO2改性丙烯酸涂层的抗紫外光作用

对两种不同晶型的纳米TiO2进行紫外可见光谱的测试,结果表明在波长300～330nm的范围内,金红石型结构的纳米TiO2对紫外光有强的吸收.利用十二烷基苯磺酸钠对纳米TiO2进行改性,提高其表面的亲油性,使之对有机基团有比较好的亲和性.在丙烯酸树脂中加入改性的纳米TiO2,并进行超声波分散和成膜,获得含不同比例纳米TiO2的丙烯酸树脂复合薄膜,对不同的纳米TiO2复合薄膜进行紫外可见吸收光谱分析.结果表明,在一定范围内,随着纳米TiO2含量的增加,纳米复合涂层对紫外光的吸收率呈上升趋势,抗紫外线性能增强.     

Effect of synthesized zinc stearate on the properties of natural rubber vulcanizates in the absence and presence of some fillers

Zinc stearate was synthesized by precipitation method through two steps; neutralization of stearic acid by sodium hydroxide then double decomposition using zinc sulphate to precipitate zinc stearate. Mass balances of the two steps were calculated and the physical properties of the prepared zinc stearate were measured and compared to standard. It was characterized and incorporated it into natural rubber in the absence and presence of some filler through mixing process of rubber. The vulcanization process was carried out at 142 °C. The rheological properties of natural rubber mixes were measured using oscillating disc rheometer. The plysico-mechanical properties of the vulcanizates were determined using tensile testing machine. It was found that, partial and complete replacement of synthesized zinc stearate instead of the conventional zinc oxide and stearic acid; enhanced the physico-mechanical properties of natural rubber. The measured reinforcing parameter value α_f can be arranged according to the type of filler as follows:     

Characterisation of stearatestearic acid coated fillers

Abstract

Selected magnesium hydroxide and calcium carbonate fillers were dry coated with stearic acid and calcium, magnesium, and zinc stearates. The course of the coating reaction was monitored using a quantitative diffuse reflectance Fourier transform infrared spectroscopy method and by thermal analysis. The coated fillers were also examined by wide angle X-ray diffraction and by X-ray photoelectron spectroscopy. These techniques were shown to produce complementary information. When the dry coating process was useded, complex reactions occurred. Stearic acid reacted to produce stearate, while the stearates melted and formed coatings, but in some cases they also appeared to form polymorphic metal stearates. Stearic acid produced the best coverage on calcium carbonate, but the poorest on magnesium hydroxide. Of the metal stearates, the best filler coverage was produced when zinc stearate was used, while calcium stearate was the least effective coating.     

纳米氧化锌负载氧化石墨烯/环氧树脂复合材料性能研究

氧化石墨烯(GO)和纳米氧化锌(ZnO)具有优异的性能,但在环氧树脂中容易出现团聚现象,为解决这一问题,必须对其进行表面改性。以七水合硫酸锌为原料,将ZnO负载到GO表面,通过FT-IR,XRD,SEM,EDS,TG和接触角测试,纳米ZnO均匀分散在GO基体上,并可以在不改变GO片层结构的条件下,改善GO的团聚问题的同时降低GO的亲水性。然后将ZnO负载GO与环氧树脂制备纳米ZnO负载GO/环氧复合材料。结果表明:纳米ZnO负载GO/环氧复合材料力学性能和热稳定性明显提高,当ZnO/GO加入量为0.250%(质量分数)时复合材料综合性能最佳,拉伸强度、拉伸模量、断裂伸长率和冲击强度分别比纯环氧树脂提高了99.87%,12.09%,98.35%和151.48%,吸水率比纯环氧树脂降低了81.48%。     

The kinetics of Langmuir–Blodgett ZnO nano-film deposition for sensing electrodes

The kinetics of the monolayer formation of zinc oxide nanoparticles on water subphase was studied at different sample concentrations and barrier speeds. The recorded isotherms indicate that stearic acid can act as a suitable microenvironment for the deposition of zinc oxide when the spreading solution contains ~ 50% sample. The AFM image of the double layer shows that the film is nearly homogeneous with average thickness ~ 15 nm. The sensing ability of the nano-films was studied by cyclic voltammetry using ITO substrates, coated with zinc oxide nanoparticles as working electrode. It gave different reduction peaks for different pH electrolytes.     

机械化学法一步合成表面改性氧化锌纳米粉体

以醋酸锌、氢氧化钠、硬脂酸为原料,采用机械化学法,一步制备出具有表面亲油性能的氧化锌粉体。借助XRD、FTIR、TEM、纳米粒度测试等方法对粉体进行了表征,研究了硬脂酸对氧化锌粉体表面改性的机理。结果表明,硬脂酸中的羧基与氧化锌颗粒表面的羟基发生了酯化反应,并在表面形成有机膜,氧化锌粉末由亲水性转化为亲油性。当球磨时间为50 min、硬脂酸加入量为氧化锌质量的4.5%时,可以得到平均粒度为90 nm的亲油性氧化锌粉体。     

Enhancing mechanical properties of styrene–butadiene rubber/silica nanocomposites by in situ interfacial modification with a novel rare-earth complex

In this study, a novel rare-earth complex, dithio-aminomethyl-lysine samarium (DALSm), was prepared and then was employed as activator, accelerator, cross-linker and interfacial modifier to improve the mechanical properties of SBR/silica nanocomposites. The results showed that 6 phr DALSm performed a higher vulcanization efficiency than the combination of 5 phr activator zinc oxide (ZnO), 2 phr stearic acid (SA), and 2 phr accelerator diethyl dithiocarbamate zinc (EDCZn). Meanwhile, the XPS and FTIR analysis of DALSm/silica model compounds confirmed that hydrogen bonds and coordination bonds could be formed between DALSm and silica during vulcanization process, which can effectively facilitate the homogenous dispersion of silica particles into SBR matrix and enhance the interface adhesion between rubber matrix and filler. As a consequent, the mechanical properties of SBR/DALSm/silica nanocomposites were substantially improved and much more excellent than those of the SBR/EDCZn/silica nanocomposites containing equivalent filler content. Based on the results of immobilized polymer layer, the reinforcing mechanism of DALSm in SBR/silica nanocomposites was analyzed.     

Functional finishing in cotton fabrics using zinc oxide nanoparticles

Nanotechnology, according to the National Nanotechnology Initiative (NNI), is defined as utilization of structure with at least one dimension of nanometer size for the construction of materials, devices or systems with novel or significantly improved properties due to their nano-size. The nanostructures are capable of enhancing the physical properties of conventional textiles, in areas such as anti-microbial properties, water repellence, soil-resistance, anti-static, anti-infrared and flame-retardant properties, dyeability, colour fastness and strength of textile materials. In the present work, zinc oxide nanoparticles were prepared by wet chemical method using zinc nitrate and sodium hydroxide as precursors and soluble starch as stabilizing agent. These nanoparticles, which have an average size of 40 nm, were coated on the bleached cotton fabrics (plain weave, 30 s count) using acrylic binder and functional properties of coated fabrics were studied. On an average of 75%, UV blocking was recorded for the cotton fabrics treated with 2% ZnO nanoparticles. Air permeability of the nano-ZnO coated fabrics was significantly higher than the control, hence the increased breathability. In case of nano-ZnO coated fabric, due to its nano-size and uniform distribution, friction was significantly lower than the bulk-ZnO coated fabric as studied by Instron® Automated Materials Testing System. Further studies are under way to evaluate wash fastness, antimicrobial properties, abrasion properties and fabric handle properties.     

On the Optical,Thermal, and Vibrational Properties of Nano-ZnO:Mn,A Diluted Magnetic Semiconductor

Nano-zinc oxide and Mn-doped zinc oxide were synthesized by a chemical process, and the average size of the particles observed was 35 nm for nano-ZnO. Optical and thermal characterizations were carried out by means of photoluminescence and photoacoustic spectroscopy. It was found that nano-ZnO has a thermal diffusivity one order of magnitude larger than bulk ZnO. Similarly, a less explored localized defect mode in ZnO:Mn was studied theoretically and experimentally using FTIR spectroscopy. The localized mode was experimentally found to be 514cm⁻¹, compared to its theoretical value of 502cm⁻¹. These values suggest that the current theory of bulk materials can also be extended to nanosystems and they are consistent with our hypothesis that Mn goes substitutionally as an impurity displacing Zn in nano-ZnO.      

The Solubilization of Drug and Excipient Into a Hydroxypropyl Methylcellulose (HPMC)-Based Film Coating as a Function for the Coating Parameters in a 24” Accela-Cota®

During the aqueous film coating of tablets, components of tablets tend to migrate to the film coating. This migration is enhanced if a component is soluble in the coating solution and also depends on the spray condition used during the coating operation. In this study, a 2³ orthogonal factorial design was used to study the migration of drug and stearic acid from a tablet to an aqueous-based cellulose coating solution. The independent variables evaluated were atomization air pressure, inlet air temperature, and spray rate. Differential scanning calorimetry was used to quantitate the presence of guaifenesin and stearic acid in the film coating. In the 24' Accela Cota that was used on our experiment, only spray rate and inlet air temperature influenced the migration of drug and stearic acid the film coating.