高疏水纳米二氧化硅薄膜的制备

溶胶凝胶方法制备高疏水薄膜,加入胶体二氧化硅粒子和TMCS控制薄膜表面粗糙度和表面化学性质。薄膜表面具有很大的表面粗糙度,使薄膜体现出很好的疏水性能。同时这种方法能够实现一步法大面积不规则镀制,具有一定实用价值的薄膜。     

纳米SiO_2对酚醛环氧树脂改性研究

以双酚A及甲醛为基本原料,加入纳米SiO2制备了纳米氧化硅改性酚醛树脂预聚体,其与环氧树脂继续共聚得到纳米氧化硅改性酚醛环氧树脂。通过红外光谱、粒径分布仪、X射线衍射、扫描电镜分析及涂膜性能测试对产物进行了研究和表征。结果表明,纳米氧化硅均匀分布在共聚物中,说明纳米氧化硅中的羟基参与了酚醛的共聚;纳米SiO2的加入对酚醛环氧树脂的结构无太大影响。与未改性醛醛环氧树脂比较,纳米SiO2的加入可有效提高涂层的耐水煮、黄变、硬度、吸水率及耐盐水腐蚀性。     

Preparation of fluorinated polyacrylate composite latex with in situ generated nano-silica dispersion and film durability

Nano-silica dispersion was generated in situ through the hydrolysis and condensation of tetraethyl orthosilicate with methyl methacrylate and butyl acrylate in micelles as dispersing media, hydrochloric acid as catalyst and methacryloxypropyl trimethoxysilane as modifier. Then, the nano-silica/fluorinated polyacrylate composite latexes were prepared via emulsion polymerization directly using the in situ generated nano-silica dispersion as seeds. Dodecafluoroheptyl methacrylate (DFHMA) as functional monomer was incorporated into shell layer of the composite particles by semi-continuous starved condition at the second stage. Fourier transform infrared spectroscopy indicated that silica was generated in situ and DFHMA took part in the copolymerization. Transmission electron microscopy showed uniform composite latex particle morphology and obvious core–shell structure. Dynamic light scattering demonstrated that DNS-86 could control the composite latex particle size ranging from 90 to 180 nm. DFHMA had an important effect on the particle size. Zeta potential (ζ) revealed that the composite latex had good stability. The resulted composite films were characterized by angle-resolved X-ray photoelectron spectroscopy, contact angle measurements and thermo-gravimetric analysis. The well-tailored composite latex particle structure of nano-silica core and fluorinated polyacrylate can effectively improve the hydrophobicity of the resultant films. Water contact angle could reach 123.5° when 6 wt% DFHMA was incorporated in the film. Moreover, water contact angles remained 106° after water immersion in the range of the experimental sample films. In addition, the incorporation of fluorinated monomer and nano-silica contributed to the improvement of thermal stability of the composite film.     

纳米白炭黑的复合改性及性能表征

为使纳米白炭黑具有强疏水性,在传统硅烷偶联剂改性工艺基础上,引入了硬脂酸进行复合改性,制备出了具有高疏水性能的纳米白炭黑。采用红外光谱(FTIR)、X射线光电子能谱(XPS)、接触角测试和沉降实验等研究了改性后试样的结构和性能,并讨论分析了复合改性的机理。结果表明:通过硅烷偶联剂改性,白炭黑表面接枝了氨基(—NH2)基团;硬脂酸改性后,—NH2基团与硬脂酸的羧基基团(—COOH)形成酰胺键(—CONH—),白炭黑最终表面形成了疏水性能优异的—(CH2)3COHN—(CH2)16CH3基团。复合改性后的纳米白炭黑表面通过化学键接枝了硬脂酸分子,与水的接触角达到了140°,具有优异的疏水性能。     

Novel surfactant-free waterborne acrylic-silicone modified alkyd hybrid resin coatings containing nano-silica for the corrosion protection of carbon steel

We report a novel waterborne acrylic-silicone modified alkyd nanocomposite latex containing nano-silica prepared by the surfactant-free miniemulsion polymerization. The influences of γ-methacryloxy-propyltrimethoxysilane- (MPS-) modified nano-silica particle contents to the thermal, mechanical and anti-corrosion performance of hybrid latex coatings were studied. The results revealed that the incorporation of nano-silica particles into latex films could directly increase the thermal stability and mechanical properties. Electrochemical corrosion studies revealed that these nanocomposite coatings exhibited superior corrosion resistance performance (inhibition efficiency 99.36% and corrosion rate 1.09 × 10 ^?3 mm per year) than that of the control system (without SiO₂ NPs).     

纳米二氧化硅改性聚丙烯复合材料研究进展

介绍了近年来纳米二氧化硅改性聚丙烯复合材料的研究进展,综述了纳米二氧化硅粒子表面处理和添加增容剂改性的主要方法,阐述了纳米粒子与聚合物相容性的提高对复合材料各项性能的改善作用,并讨论了不同纳米二氧化硅颗粒结构对复合材料性能的影响,最后展望了其在改善聚合物渗透性、阻燃性、导电性等方面的发展前景。     

液相沉淀法制备超疏水纳米白炭黑

以水玻璃为原料,采用硫酸制备纳米白炭黑,并利用硅烷偶联剂S i-75对纳米白炭黑进行疏水改性。通过X射线衍射、透射电镜、红外光谱和热重分析对纳米白炭黑进行表征。粉末X射线衍射（XRD）分析结果显示,纳米白炭黑为非晶态二氧化硅;通过透射电镜（TEM）分析可知,改性后的纳米白炭黑分散性更好,团聚降低,白炭黑一次粒径在20 nm-40 nm,粒子之间相互连接形成链枝结构附聚体;红外光谱（FT-IR）和热重分析（TG）显示,硅烷偶联剂S i-75成功地接枝到纳米白炭黑。活化指数（99.6%）的测定表明,合成的纳米白炭黑具有超疏水性。     

聚丙烯／弹性体／纳米SiO2复合材料性能研究

以聚丙烯（PP）为基体,以弹性体（POE、TPU）和纳米SiO2为改性剂,采用熔融共混法制备了PP／弹性体／纳米SiO2复合材料,研究了材料的力学性能、动态力学性能、结晶性能与流变性能。结果表明,弹性体和纳米粒子的加入具有明显的协同增韧效应;弹性体和纳米SiO2促进PP的结晶,TPU和纳米SiO2有更好的结晶成核作用;弹性体和纳米粒子使复合材料的模量、复合粘度增大。     

Scratch resistance of nano-silica reinforced acrylic coatings

Organic–inorganic hybrid coatings were obtained by a dual-curing process combining the sol–gel reaction with the UV-induced polymerization technique by starting from bisphenol A ethoxylate (15 EO/phenol) dimethacrylate (BEMA, as organic network former), methacryloyloxypropyl-trimethoxysilane (MEMO, as coupling agent) and tetraethoxysilane (TEOS, as inorganic silica network precursor). For comparison, TEOS was also substituted with preformed silica nanoparticles. Scratch test was carried out in order to study the scratch resistance of that silica reinforced acrylic resins. Excellent scratch resistant coatings were obtained by UV and sol–gel dual curing process. On the contrary, coatings with very poor scratch resistance were obtained by dispersing preformed nano-silica into the acrylic resin indicating the key role played by the morphology of the inorganic filler and its interaction with the organic matrix.     

Vulcanization kinetics of nano-silica filled styrene butadiene rubber

It was shown that the physical filler-polymer and filler–filler interactions, apart from the filler surface chemistry, has a substantial role in controlling the vulcanization kinetics of styrene butadiene rubber filled with nano-silica in a sulfur vulcanization system. Kinetic studies by the oscillating disc rheometer, differential scanning calorimeter, and swelling tests revealed that the vulcanization rate goes through a maximum as loading of silica increases, but conversion in crosslinking continuously decreases as the amount of silica increases. The effect of silica loadings on the vulcanization reactions was linked to the immobilization of rubber chains around particles as well as in a polymer-mediated filler network, which were differentiated by the nonlinear viscoelastic behavior of rubber vulcanizates. By surface modification of nano-silica, the accelerating/decelerating effects of nano-silica on the vulcanization reactions were altered corresponding to the non-linear viscoelastic behavior of the vulcanizates. Therefore, a mechanism was proposed which correlates vulcanization kinetics of rubber to the dynamics of chains influenced by the reinforcing fillers.     

非水解溶胶-凝胶反应制备功能化纳米二氧化硅

以正硅酸乙酯和甲酸为原料,硅烷偶联剂KH-570为改性剂制备了功能化纳米二氧化硅溶胶,通过紫外-可见分光光度计表征反应体系溶胶-凝胶反应的程度,研究了甲酸浓度、反应温度、微量水、醇类共溶剂以及硅烷偶联剂KH-570用量等对溶胶-凝胶反应的影响,并利用红外光谱对反应产物进行了表征.结果表明,增大甲酸浓度、加入微量水,提高...     

Obtaining transparent silica glass from nano-silica hydrosol

Transparent silica glass is widely used in various fields. However, a simple and economical method of synthesis remains to be developed for high-precision device manufacturing. In this study, transparent silica glass is fabricated from low-cost commercial nano-silica hydrosol. To obtain transparent glass, the crystallization temperature of bulk materials must be higher than their densification temperature. Based on XRD analysis, impurity ions such as Na⁺ have a strong influence on the crystallization characteristics of sintered samples. Purification can be performed by soaking preheated samples in boiling water for a given duration. Transparent silica glass was obtained for purified samples from acidic silica hydrosol sintered at 900–950 °C. The optical characteristics of the samples were investigated for the presence of silica glass, and the transparency was enhanced for samples sintered in vacuum. The mechanical and dielectric properties of the sintered samples were also characterized.     

纳米SiO_2改性PET及其性能研究

选用硅烷偶联剂KH-570对SiO2纳米粉体进行表面改性,利用IR,TG等对改性前后SiO2粉体性能进行了表征;并利用IR,DSC对SiO2/PET体系的热性能和结晶性能进行了测试。实验结果表明:经表面改性的SiO2粉体的红外光谱在1 715cm-1,1300 cm-1及1452 cm-1等处出现了KH-570的特征吸收峰;改性后SiO2粉体的TG曲线在350℃出现明显质量减少,表明KH-570与SiO2发生了化学反应,实现了KH-570对SiO2表面包覆改性的目的。含有SiO2的PET结晶温度和玻璃化温度降低,熔点基本保持不变。     

气相法纳米白炭黑的表面疏水改性

以六甲基二硅氮烷为主表面处理剂,二甲基二乙氧基硅烷为助处理剂,研究不同溶剂、反应温度和时间对气相法白炭黑表面疏水改性效果的影响,并对比研究未改性白炭黑和改性白炭黑对硅橡胶复合膜分离因子的影响。结果表明,以甲苯为溶剂、反应温度为110℃、反应时间为90min时白炭黑的改性效果较好;改性白炭黑/硅橡胶复合膜的分离因子较未改性白炭黑/硅橡胶复合膜高。     

盐酸沉淀法制备纳米白炭黑

采用盐酸沉淀法制备纳米白炭黑,通过实验调整盐酸的浓度、添加剂的加入、反应体系的温度、pH值的大小。制得粒径小、品质好的纳米白炭黑。利用X ray衍射仪和扫描电镜分析,研究白炭黑的结构。     

Microstructure and mechanical properties of 3D-printed nano-silica reinforced alumina cores

Ceramic cores are an important component in the preparation of hollow turbine blades for aero-engines. Compared with traditional hot injection technology, 3D printing technology overcomes the disadvantages of a long production cycle and the difficulty in producing highly complex ceramic cores. The ceramic cores of hollow turbine blades require a high bending strength at high temperatures, and nano-mineralizers greatly improve their strength. In this study, nano-silica-reinforced alumina-based ceramic cores were prepared, and the effects of nanopowder content on the microstructure and properties of the ceramic cores were investigated. Alumina-based ceramic cores contained with nano-silica were prepared using the vat photopolymerization 3D printing technique and sintered at 1500 °C. The results showed that the linear shrinkage of ceramic cores first increased and then decreased as the nano-silica powder content increased, and the bending strength showed the same trend. The fracture mode changed from intergranular to transgranular. The open porosity and bulk density fluctuated slightly. The weight loss rate was approximately 20%. When the nano-silica content was 3%, the bending strength reached a maximum of 46.2 MPa and 26.1 MPa at 25 °C and 1500 °C, respectively. The precipitation of the glass phase, change in the fracture mode of the material, pinning crack of nanoparticles, and reduction of fracture energy due to the interlocking of cracks, were the main reasons for material strengthening. The successful preparation of 3D printed nano-silica reinforced alumina-based ceramic cores is expected to promote the preparation of high-performance ceramic cores with complex structures of hollow turbine blades.     

纳米SiO2粉体有机化程度的表征及评价

采用热分析法研究了硅烷偶联剂KH-570、KH-590、KH-792与纳米SiO2粉体间的缩合反应过程,用傅里叶变换红外光谱(FTIR)分析了KH-792用量与纳米SiO2粉体表面硅羟基峰面积之间的关系,考察了KH-570、KH-590、KH-792改性纳米SiO2粉体填充溶聚丁苯橡胶(SSBR)复合材料的性能。结果表明,硅烷偶联剂与纳米SiO2在90℃左右发生缩合反应,用缩合度可表征硅烷偶联剂对纳米SiO2粉体的改性程度;KH-792的用量为1~3份时,改性纳米SiO2粉体表面的硅羟基缩合度显著增加。3种偶联剂改性纳米SiO2均能改善SSBR复合材料的力学性能,其中KH-570的改性效果较差;当KH-590或KH-792用量为3份时,复合材料的力学性能最佳。KH-590或KH-792改性的纳米SiO2粉体在橡胶基体中的分散性明显得到改善,用其填充SSBR复合材料在应变试验范围内的储能模量变化值、损耗模量和损耗因子均低于纯SiO填充SSBR复合材料。     

Effect of polyethylene terephthalate fiber reinforced with non-hydrophilic nano-silica on the mechanical,thermic, and chemical shielding characteristics of saturated polyurethane composite

The research investigates the reinforcing effect of scrap polyethylene terephthalate (PET) fiber, non-hydrophilic nano-SiO₂(NS-972) and heat suppressing agents in saturated polyurethane (SPU) composites. PET fiber was obtained through industrial mechanical processing from scraped PET. Thermic and surface morphology of synthesized SPU composites was characterized by using scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). Thermic characteristics of filled PU,NS-PET fiber (1.5%)-APM (1:1) (PU-NF1.5A) composite with (1:1) proportion of additive NS-PET fiber (0.5–2%) and halogen free fire-extinguishing additives APM (0–3%) were determined utilizing UL-94, TGA, critical oxygen index, and smoke density. The tensile properties of the composite improved to 42.27% (4.14 MPa) when the filler content was increased to 1.5%. The WCA, moisture permeability and chemical resistance analysis indicated that fabricated composite films with variable additive content had excellent hydrophobicity and improved resistance to water, humidity, and chemical resistance. TGA data shows the increased thermal resistance of reinforced PU composite is attributed to the increased thermal deterioration temperature, resulted to the higher thermic degradation temperature of the terephthalic and sebacic acids used in the synthesis of PU. Smoke producing capacity of composite PU-NF1.5A (0–3%) reduced from 82% to 52%. The LOI improved from 19 to 23 (−vol.%) at 3% APM additives.     

The influence of nano-silica on the thermal conductivity of polyurethane foam

This study reports the influence of nano-silica particles (0.0–0.45 %wt) on properties of polyurethane foams (PUF) using monoglycerides, sorbitol, and glycerol as components of polyol. The morphology, density, mechanical, thermal stability, and thermal conductivity properties of samples were investigated in this study. When 0.35 %Wt of nano-silica was used to reinforce PUF, the compression strength of PUF achieved the highest value (82.49 kPa). The thermal gravimetric analysis showed that the presence of nano-silica can improve the thermal stability of PUF samples. Scanning electron microscopy studies indicated that PUF samples containing 0.3, 0.35, and 0.45 %Wt of nano-silica had more uniform cell structures than pure PUF sample. Finally, the thermal conductivity of pure PUF and PUF/nano-silica were measured at three different levels of humidity (33% RH, 57% RH and 75% RH) at 25°C. The lowest thermal conductivity value achieved was 0.034 W/mK.     

Thermal stability and abrasion resistance of polyacrylate/nano-silica hybrid coatings

Polyacrylate (PAE)/nano-silica (SiO₂) hybrids were prepared by an in situ sol–gel process of tetraethyl orthosilicate in the presence of PAE toluene solution. The hybrid coatings were fabricated using a PAE/SiO₂ suspension by the traditional casting. Their intermolecular interaction and morphology, as well as thermal, mechanical, and optical properties, were investigated using Fourier transform infrared spectroscopy, field-emission scanning electron microscope, differential scanning calorimetry and TG/DTA thermogravimetric analysis, coating impact testing, and UV–Vis spectroscopy, respectively. At the same time, their abrasive properties were carried out by abrasion resistance and nanoindentation tests. The results indicate that silica nanoparticles, with diameter about 30 nm, can disperse homogeneously in the PAE matrix, where hydrogen bonds between the PAE and nano-silica are formed. Therefore, homogeneous dispersion of nano-silica particles provides high transparency for the PAE/SiO₂ hybrid coating as the size of nano-silica phase is much smaller than the wavelength (390–770 nm) of visible light. PAE/nano-silica hybrid coatings have increased T _g and thermal stability including the onset decomposition temperature, 10 % weight loss temperature, and char at 700 °C. Additionally, the incorporation of nano-silica particles improves the glossiness of the PAE/nano-silica hybrid coatings and enhances their abrasion resistance and surface hardness. The nano-silica content has obvious effect on the thermal, mechanical, optical, and anti-abrasion properties of PAE/SiO₂ hybrid coatings. With the consideration of all the properties of hybrid coatings, the PAE/SiO₂ hybrid containing 10 phr of nano-silica has the optimal composition. These PAE/nano-silica hybrid coatings have potential applications in high-performance hologram image recording.