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1.
王少华  张淑芬 《精细化工》2019,36(10):2046-2051
通过硅氧烷单体在碱性条件下的水解-聚合反应,制备出了单分散乳液,研究了乳化剂HLB、反应时间、乳化剂用量、单体用量等因素对乳液的影响。然后以该乳液为模板、有机硅为壳层进行包覆,得到了中空微球。采用纳米粒度及Zeta电位分析仪、SEM、TEM、EDS、FTIR对乳液及中空微球进行表征。结果表明,在室温条件下,反应时间为6h时能够制备出单分散性较好的乳液,通过改变乳化剂用量、单体用量,能够实现对乳液粒径的调控,调控范围346~472 nm。以该乳液为模板进行缓慢包覆,当乳化剂质量分数低于0.003%时,能够得到形貌规整的单分散中空微球,中空微球的主要成分为有机硅。与硬模板法相比,该模板通过乙醇洗涤即可除去,制备过程较为简单。  相似文献   

2.
以脂肪醇聚氧乙烯醚(AEO-9)和十二烷基硫酸钠(SDS)复配为乳化剂,通过相反转技术乳化秸秆基环氧树脂,考察了复配乳化剂的HLB值、用量以及乳化温度和搅拌速率对乳液临界含水量Rf值、粒径及稳定性的影响,获得了如下较佳的乳化工艺条件:HLB值17,复合乳化剂用量8%,乳化温度35°C,搅拌速率800 r/min。以此工艺制得的乳液稳定性较好,平均粒径为1.57μm。以水性聚酰胺为固化剂,将此乳液制成清漆,固化后所得漆膜综合性能良好。  相似文献   

3.
Needlelike mullite, which shows high aspect ratios, has been synthesized by coprecipitation from aluminum nitrate enneahydrate and colloidal silica sols. The effects of precursor pH and sintering temperature on the synthesizing behavior and the morphology of the needlelike mullite have been investigated. The equilibrium mullite phase appeared in the samples, which had been sintered at and above 1200 °C for each precursor pH. Crystallization of cristobalite from excessive SiO2 occurred during sintering from 1200 °C, and the amount of cristobalite increased with sintering temperature up to 1400 °C. However, resorption of cristobalite into mullite decreased the amount of the phase from 1500 °C. The mullite synthesized with precursor pH2 (acidic sample) displayed high aspect ratios at high sintering temperature. However, morphology of the mullite synthesized with precursor pH8 (basic sample) transformed to rodlike or granular shape with increasing sintering temperature.  相似文献   

4.
The perovskite proton conductor BaZr0.9Y0.1O2.95 (BZY10) shows better chemical stability but lower conductivity than BaCe0.9Y0.1O2.95 (BCY10). In this paper we attempted to synthesize BCY10:BZY10 core–shell materials in which BCY10 particles prepared by solid reaction were wrapped by a sol–gel deposited thin layer of BZY10 with ZnO as sintering aid to improve the sinterability of the materials. The effects of the BCY10/BZY10 ratios on the phase purity, microstructure, chemical stability and electrical conductivity of the samples were characterized by XRD, TEM, SEM, TGA and electrochemical impedance spectroscopy. A dense core–shell structure was formed after being sintered at 1300 °C for 10 h. The core–shell samples displayed improved stability against CO2 and water vapor at high temperature. With BCY10/BZY10 ratio varying from 9:1 to 7:3, the core–shell samples became more stable, and the total conductivities decreased.  相似文献   

5.
The formation of porous glass ceramic via core/shell-structured poly(methyl methacrylate)(PMMA)/powder glass was investigated. Core/shell structures were prepared via ultrasonic irradiation in high-pressure liquid carbon dioxide (CO2) using PMMA microspheres as the core material and glass powder as the shell material. The mean particles sizes of PMMA template microspheres and glass powder were 9.8 μm and 0.9 μm, respectively. After removal of the PMMA template by calcination in air, porous glass was obtained. The products were characterized by scanning electronic microscopy (SEM) and thermogravimetric-differential thermal analysis (TG-DTA). The average pore diameter of porous glass was 4.3 μm. Compared with porous glass prepared by the other method, the porous glass prepared by ultrasonic irradiation of liquid CO2 was achieved the narrow pore size distribution (CV = 35%) and the higher porosity (89%). The pores are not isolated and connected each other. Furthermore, the effects of experimental conditions, such as coating method, crosslink density of the template PMMA microspheres, ultrasonic intensity and calcination temperature, on the product morphology were investigated. The higher ultrasound intensity achieved the uniform coating of PMMA templates with powder glass. The calcination temperature and crosslinked density of PMMA template microspheres affect the pore structure.  相似文献   

6.
We present the preparation of advanced antistatic and anticorrosion coatings of polystyrene (PS) incorporating a suitable amount of dodecylbenzenesulfonic acid (DBSA)‐doped SiO2@polyaniline (SP) core–shell microspheres. First, aniline‐anchored SiO2 (AS) microspheres that were about 850 nm in diameter were synthesized using the conventional base‐catalyzed sol–gel process with tetraethyl orthosilicate in the presence of N‐[3‐(trimethoxysilyl)propyl]aniline. SP core–shell microspheres were then synthesized by chemical oxidative polymerization of aniline monomers with ammonium persulfate as an oxidizing agent in the presence of the AS microspheres. The polyaniline shell thickness of the as‐prepared core–shell microspheres was estimated to be about 120 nm. The AS and SP microspheres were further characterized using Fourier transform infrared spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy. The as‐synthesized DBSA‐doped SP core–shell microspheres were then blended into PS using N‐methyl‐2‐pyrrolidone as solvent and then cast onto a cold–rolled steel (CRS) electrode to obtain antistatic and anticorrosion coatings with a thickness of about 10 µm. The corrosion protection efficiency of the as‐prepared coating materials on the CRS electrode was investigated using a series of systematic electrochemical measurements under saline conditions. The enhanced corrosion protection ability of the PS/SP composite coatings may be attributed to the formation of a dense passive metal oxide layer induced by the redox catalytic effect of the polyaniline shell of the as‐synthesized core–shell microspheres, as evidenced by electron spectroscopy for chemical analysis and SEM observations. Moreover, the PS composite coating containing 10 wt% of the SP core–shell microspheres showed an electrical resistance of about 3.65 × 109Ω cm?2, which meets the requirements for antistatic applications. Copyright © 2012 Society of Chemical Industry  相似文献   

7.
大颗粒吸水树脂的制备工艺及其性能   总被引:2,自引:0,他引:2  
采用反相悬浮聚合制备了大颗粒聚丙烯酰胺-丙烯酸-丙烯酸钠[P(AM-AA-SA)]树脂微球,考察了搅拌速率与乳化剂对树脂微球粒径的影响,交联剂用量、单体配比和丙烯酸中和度对330μm树脂微球吸水倍率的影响,丙烯酸丁酯的用量对树脂吸水速率的影响以及树脂微球在80℃下的保水性能.结果表明:制备的树脂吸去离子水量达983.0 g/g,对NaCl和CaCl2溶液的吸水倍率最大值分别为91 3,15.6 g/g,在80℃下有良好的保水性能,丙烯酸丁酯的加入可将吸水饱和时间延长2倍.  相似文献   

8.
Core–shell composite magnetic polymer microspheres, containing a magnetic core and a polymer shell, were synthesized by dispersion copolymerization of styrene (St) and 2-hydroxyethyl methacrylate (HEMA) in the presence of magnetic oxide (Fe3O4) powder. The Fe3O4 powder was ultrasonically disperesed in poly(ethylene glycol) (PEG) and the affinity between the obtained superfine powder and the monomer and initator was improved. It shows that the dispersion medium and stabilizer system have a great effect on the diameter and dispersion parameter of microspheres. In the condition of controlling polymerization, the magnetic polymer microspheres containing surface ? OH groups, having 50–500 μm diameter and with better magnetic induction, were synthesized. The proteinase of Balillus sublitis was immobilized on magnetic polymer microspheres with an average diameter of 50–60 μm by covalent coupling. The magnetic immobilized proteinase shows an enzyme activity of 1000 U/g, the enzyme yields are usually 20–30 mg/g of carriers, and the activity retention is about 40%. The stability of the immobilized enzyme was obviously improved. © 1995 John Wiley & Sons, Inc.  相似文献   

9.
Polyaniline (PANI) hollow microspheres constructed with their own nanofibers were prepared by inversed microemulsion polymerization associated with a template‐free method in the presence of β‐naphthalene sulfonic acid (β‐NSA) as the dopant. The hollow microspheres were 4.0–6.0 μm in outer diameter and 150–250 nm in shell thickness; they consisted of the nanofibers (20–30 nm in diameter and 150–250 nm in length). We propose that the coordination effect of the reversed emulsion and the dopant or dopant/aniline micelle might have been a driving force in the formation of the special microstructures/nanostructures, where the reversed microemulsion acted as a soft template in the formation of the microspheres and where NSA or the aniline/NSA micelle was regarded as a soft template in the formation of the nanofibers. The molar ratio of water to the aniline/NSA salt and ultrasonic irradiation were critical in the control of the formation yield and the diameter of the uniform microspheres. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3050–3054, 2006  相似文献   

10.
A silica cellular structure was synthesized as a novel means of enhancing the geometrical surface area of a silicon microchannel with cell diameter of ∼10 μm and cell interconnectivity of ∼0.4. Surface-selective infiltration, assembly, and partial sintering of polystyrene microspheres in the microchannel were used as mechanisms to create a sacrificial template. The polymer template was infiltrated with a silica precursor, and the infiltrated structure was dried and calcined at 500°C to remove the polymer phase and subsequently sintered at 1100°C to form dense silica skeleton. Volume shrinkage and crack formation during calcining and sintering of the infiltrated silica structure were strongly influenced by silica particle size in the precursor. In comparison with free-standing cellular specimens prepared by similar template methods, the shrinkage and cracking issues offered an interesting challenge for synthesizing the cellular structure which could be net-shaped into the spatial confinement of the microchannel geometry.  相似文献   

11.
Textured (Na0.85K0.15)0.5Bi0.5TiO3 (NKBT) ceramics with a relative density of >94% were fabricated by reactive-templated grain growth. Plated-like Bi4Ti3O12 template particles synthesized by the NaCl–KCl molten salt process were aligned by tape casting in a mixture of original oxide powders. The effect of sintering temperature on the grain orientation and electrical properties of textured NKBT ceramics were investigated. The results show that the textured ceramics have a microstructure with plated-like grains aligning in the direction parallel to the casting plane. The degree of grain orientation increased at increasing sintering temperature. The textured ceramics show anisotropic electrical properties in the directions parallel and perpendicular to the casting plane. The dielectric constant parallel to {h 0 0} plane is three times higher than that of the perpendicular direction in textured NKBT ceramics. The optimized sintering temperature is 1150 °C where the maximum dielectric constant is 2041, the remnant polarization is 68.7 μC/cm2, the electromechanical coupling factor (k31) and the piezoelectric constant (d33) amount to 0.31 and 134 pC/N, respectively.  相似文献   

12.
水热法制备二硫化钴空心微球   总被引:2,自引:0,他引:2  
以CoCl2.6H2O和Na2S2O3.5H2O为原料,在150℃的水热条件下反应12 h制备了CoS2空心微球。利用X射线粉末衍射仪(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)对产物进行了表征,探索了不同反应条件对合成产物的影响。结果表明,所得产物为立方晶系的CoS2单相,呈空心球状,其直径约为2μm,壁厚约为100 nm。此外,反应物的量、反应温度和反应时间均对产物的形成有较大影响。  相似文献   

13.
以双甘氨肽(Gly-Gly)为模板分子、丙烯酰胺为单体、乙二醇二甲基丙烯酸酯为交联剂,采用乳液聚合法制备了双甘氨肽分子印迹聚合物微球(Gly-Gly-MIPMs),讨论了水相制备条件对其平均粒径及粒径分布的影响及聚合物微球的吸附特性.较优的制备工艺条件为:乳化剂Tween-80与Span-80质量比3:1,用量为单体用...  相似文献   

14.
Fe_3O_4/P(St-CBA)核壳磁性复合微球的制备及性质   总被引:1,自引:0,他引:1  
运用分散聚合法制备出Fe3O4 /P(St -CBA)核壳磁性复合微球。该微球粒径为 0 .0 75~0 .70 0 μm、w(Fe3O4 ) =0 .0 5 %~ 0 .90 % ,呈规整球型 ,表面光滑 ,在 0 .0 5T磁场中的磁响应性为3.0cm/min。制备微球的最佳条件为 :w(磁流体 ) =0 .5 %~ 3 .0 %、w(马来酸酐 ) =0 .0 %~2 .0 %、w(无水乙醇 ) =30 .0 %~ 70 .0 %。  相似文献   

15.
Pure monoclinic lithium zirconate (Li2ZrO3) powder was synthesized by solution combustion route using glycine as fuel and nitrates as oxidants. Effect of fuel-to-oxidizer ratio (φ = 0.5–1.25) on synthesis condition, phase, powder morphology, sintering and thermodynamic aspects was systematically investigated. Thermodynamic analysis reveals; mode of combustion, adiabatic flame temperature, amount of gases and powder characteristics can be controlled by adjusting φ. The crystallite size of Li2ZrO3 powder was in the range of 18–40 nm. The powders consist of micrometric soft-agglomerates of irregular flake shape particles. The residual Li2O in Li2ZrO3 powder was found to be in the range 155–469 μg/g. The Li2ZrO3 powder synthesized by present method shows significantly enhanced sinter-ability as compared to conventional solid-state method. The Li2ZrO3 pellets were sintered close to 98% of T.D. at 1000 °C with grain size 1–2 μm. Increase of sintering temperature to 1050 °C results abnormal grain growth with large number of closed pores.  相似文献   

16.
Fe3O4/poly(styrene‐co‐maleic anhydride) core–shell composite microspheres, suitable for binding enzymes, were prepared using magnetite particles as seeds by copolymerization of styrene and maleic anhydride. The magnetite particles were encapsulated by polyethylene glycol, which improved the affinity between the magnetite particles and the monomers, thus showing that the size of the microspheres, the amount of the surface anhydrides, and the magnetite content in the composite are highly dependent on magnetite particles, comonomer ratio, and dispersion medium used in the polymerization. The composite microspheres, having 0.08–0.8 μm diameter and containing 100–800 μg magnetite/g microspheres and 0–18 mmol surface‐anhydride groups/g microsphere, were obtained. Free α‐amylase was immobilized on the microspheres containing reactive surface‐anhydride groups by covalent binding. The effects of immobilization on the properties of the immobilized α‐amylase [magnetic immobilized enzyme (MIE)] were studied. The activity of MIE and protein binding capacity reached 113,800 U and 544.3 mg/g dry microspheres, respectively. The activity recovery was 47.2%. The MIE had higher optimum temperature and pH compared with those of free α‐amylase and showed excellent thermal, storage, pH, and operational stability. Furthermore, it can be easily separated in a magnetic field and reused repeatedly. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 328–335, 2005  相似文献   

17.
Citrate–nitrate combustion synthesis was used for the preparation of NiO–YSZ. The main advantage of the preparation method used was reflected in the fact that after the synthesis both phases NiO and YSZ were randomly distributed on a nanometre level. The prepared NiO–YSZ powder composites were shaped, sintered and reduced to Ni–YSZ and subsequently submitted to microstructure investigations. Relative sintered densities higher than 90% were obtained at sintering temperatures as low as 1200 °C. A sintering temperature 1200 °C was also recognized as the preparation temperature that provided the smallest Ni grains in the final Ni–YSZ cermet with an average Ni-particle diameter as low as 0.27 μm.  相似文献   

18.
Eran Partouche 《Carbon》2008,46(5):796-805
Micrometer-sized polystyrene/poly(styrene-divinylbenzene) and polystyrene/polydivinylbenzene composite particles of narrow size distribution were formed by a single-step swelling process of uniform polystyrene template particles with emulsion droplets of dibutyl phthalate containing benzoyl peroxide and divinylbenzene in the presence or absence of styrene, followed by polymerization of the monomer(s) within the swollen template particles at 70 °C. Porous poly(styrene-divinylbenzene) and polydivinylbenzene uniform microspheres were formed by dissolution of the polystyrene part of the former composite particles. Hydroperoxide conjugated microspheres were formed by ozonolysis of the former porous microspheres. Uniform poly(styrene-divinylbenzene)/PAN and polydivinylbenzene/PAN core/shell microspheres were prepared by room temperature redox graft polymerization of AN onto the hydroperoxide conjugated particles. Uniform carbon microspheres were prepared by carbonization of the core/shell particles at 800 and 1100 °C under dynamic N2 atmosphere. On the other hand, a similar treatment of the core particles only resulted in destruction of the particle shape. Carbon microspheres of increasing surface area (up to ca. 1000 m2/g) were prepared by activation of the former carbon microspheres with CO2 at 850 °C. The influence of the carbonization temperature of the core/shell particles and the activation time of the carbon particles on the carbon yield and surface area has been elucidated.  相似文献   

19.
中国黄金尾矿资源量大,作为二次资源在建筑材料领域的综合利用有着重要的经济价值和环境意义。以黄金尾矿为主要原料,SiC为发泡剂,通过高温制备发泡陶瓷,用激光共聚焦显微镜、XRD等手段,研究了烧结温度、黄金尾矿掺入量、原料粒度对材料的容重、真气孔率和孔径等性能的影响。研究表明:随着烧结温度的升高,发泡陶瓷材料的真气孔率和孔径增大,容重减小;材料的真气孔率和容重随着黄金尾矿掺入量的增大分别降低和提高,随着原料粒度的减小分别提高和降低,气孔孔径随着黄金尾矿掺量的增大和原料粒度的减小均呈下降趋势。优化后,在烧成温度1 050 ℃,黄金尾矿掺入量50%(质量分数),黄金尾矿平均粒度D(50)=5.6 μm,SiC平均粒度D(50)=3.0 μm的条件下可制备出性能良好的发泡陶瓷。  相似文献   

20.
The polymeric microspheres were synthesized by the precipitation copolymerization of glycidyl methacrylate (GMA) with methacrylic acid(MAA) or 2‐hydoxyethyl methacrylate (2‐HEMA) containing styrene (ST) in SC‐CO2. Scanning electron microscopy (SEM) showed that the products were spherical microparticles, with the addition of MAA and/or 2‐HEMA as the monomer, with diameter of 0.2–2 μm. The effects of copolymerization pressure, temperature, and ratios of GMA/MAA, ST, and/or GMA/2‐HEMA, on the particle size and morphology were investigated in detail. A new experiment setup is proposed for the large amount of production, based on the rule of lower monomer concentration, more stable system, and better use of the present polymerization apparatus. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2425–2431, 2007  相似文献   

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