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以轻烧白云灰粉料为原料,采用常压碳化法,在重镁水热解时加入聚乙二醇,制备出不同形貌的氧化镁。考察了聚乙二醇的用量和热解温度对氧化镁形貌和尺寸的影响,探讨了其形成机理。结果表明:聚乙二醇用量为30%(体积分数)时,氧化镁颗粒分散性最好,颗粒粒径主要分布在2~4μm。热解温度从40~95℃时,未添加聚乙二醇的氧化镁形貌由棒状变为花朵状,最后变为规则的球状,其中,棒状氧化镁的长度约为25μm,直径约为5μm,球状氧化镁的直径约为25μm;添加了聚乙二醇后,氧化镁形貌由棒状变为无规则片状,其中,棒状氧化镁长度约为15μm,直径约为2.5μm,片状氧化镁的厚度约为30nm,说明聚乙二醇能够抑制氧化镁晶体的生长。 相似文献
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研究了在脉冲酸性电镀铜工艺中,不同相对分子质量的聚乙二醇及聚二硫二丙烷磺酸钠的质量浓度以及搅拌条件对微孔直径为300μm,深径比为7.3:1的通孔填充效果的影响。结果表明,随着聚乙二醇相对分子质量增大,通孔内壁铜沉积的均匀性逐渐增大,当聚乙二醇相对分子质量为8 000和12 000时,通孔的均匀度达到90%以上;当镀液中聚二硫二丙烷磺酸钠的质量浓度为4~6 mg/L、搅拌速率保持在700 r/min时,通孔内壁上可以镀覆一层均匀的铜导电层。 相似文献
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不同热解条件对碱式碳酸镁晶体形貌的影响 总被引:3,自引:0,他引:3
以轻烧白云石粉料为原料,采用常压二次碳化法制备碱式碳酸镁[χMgCO3·Mg(OH)2·yH2O],研究了不同热解温度和不同添加剂对碱式碳酸镁晶体形貌的影响,并对其反应机理进行探讨,且的是提高碱式碳酸镁的填充性和分散性.结果表明:当热解温度为50℃时,制备出长度为36~88μm,直径为2μm的棒状碱式碳酸镁.当热解温度为60℃时,制备出片状和由片状组成的玫瑰花瓣状碱式碳酸镁.当热解温度为70℃时,制备出直径为40μm左右表面光滑的球状碱式碳酸镁.在热解温度为50℃时,添加柠檬酸钠后可使棒状碱式碳酸镁颗粒分布均匀:添加乙醇后可降低棒状碱式碳酸镁的长径比;添加氯化镁后可使棒状碱式碳酸镁晶体长度变为115μm左右,直径为18μm左右. 相似文献
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针状氢氧化镁的研制及其结晶性能研究 总被引:4,自引:0,他引:4
本文介绍了以苦卤和石灰孔等为原料,制备针状氢氧化镁的工艺过程。针状结晶的长度10—100μ,直径0.2—0.5μ,长径比>50,晶体在〈101〉方向的微观内应变<3×10~(-3),比表面积(BET)<20m~2/g。 相似文献
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ZnO超微粉的溶胶-凝胶法制备及晶体生长特征 总被引:11,自引:1,他引:10
利用溶胶-凝胶法以醋酸锌及硝酸铋和醋酸锰制备了纯ZnO以及Bi2O3,MnO掺杂的ZnO超微粉体,通过X射线衍射分析和透射电镜分析,研究了不同温度和不同掺杂条件下ZnO粉体的生长特征,结果表明,ZnO晶体的生长掺杂元素和制备温度的显著影响,未掺杂的纯ZnO晶体生长具有各向同性特征,晶体呈各边近相等的六边形,Bi2O3,MnO掺杂后,ZnO晶体表现出显著的定向生长特征,晶体呈板状、棒状等形态,掺杂量为0.5%-1.0%摩尔分数时,晶体定向生长最为显著,700℃下制备的BiO3,MnO掺杂的ZnO晶体短轴一般为40-180nm,长轴200-600nm,极少数晶体长达2μm以上,而进一步提高杂量时,晶体定向生长则逐渐减弱,700℃下制备的掺杂量为2.0%摩尔分数的ZnO晶体基本上无定向性,表明ZnO晶体的生长受次晶相的显著影响。 相似文献
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采用溶胶-凝胶法,以菱镁矿、盐酸和尿素为原料,加入成胶剂聚乙二醇制备纳米氧化镁。考察了煅烧温度、成胶剂分子量、分散剂及其用量对实验的影响。结果表明,制备纳米氧化镁的适宜条件为:以10 000分子量聚乙二醇为成胶剂,1.5%的PVT-1为分散剂,煅烧温度为650℃。在此条件下,可获得纯度98.5%,平均粒径小于100 nm,呈近球形均匀分布,活性良好的纳米氧化镁。 相似文献
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利用甲基丙烯酸、聚乙二醇单甲醚直接酯化合成甲氧基聚氧化乙烯甲基丙烯酸酯,采用预处理的方法制备了甲基丙烯酸高效阻聚剂,同时研究了相对分子质量、反应温度、反应时间对酯化反应的影响规律。结果表明:预处理制备的TN酚醌混合阻聚剂对甲基丙烯酸具有良好阻聚效果,掺量为0.75%时,120 ℃反应20 h无明显聚合;140 ℃时,聚乙二醇单甲醚开始分解,—OH被氧化,产生了C=O;120 ℃时TN催化剂与MPEG混合物能够稳定存在,基本无副反应发生,该体系酯化率可达到99%;MPEG相对分子质量影响反应速度,酯化反应1~4 h酯化率随相对分子质量的增加而降低;当反应4 h时,转化率已达80%。之后反应速度减慢,酯化率随MPEG相对分子质量的变化较小。 相似文献
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C36二聚脂肪酸聚乙二醇聚酯硫酸酯盐的制备及性能表征 总被引:3,自引:0,他引:3
以C36二聚脂肪酸(简称二聚酸)和聚乙二醇为原料,缩聚后得到聚酯,再用氨基磺酸硫酸化,制备了新型的C36二聚脂肪酸聚乙二醇聚酯硫酸酯盐型两性高分子表面活性剂,并对其性能进行了研究。聚酯适宜的制备工艺条件是:在0.097 MPa下,n(二聚酸)∶n(聚乙二醇)=1∶1.2,催化剂w(SnC l2)=0.3%(相对于反应物总质量),反应温度200℃,反应时间6 h,酯化率达到98.11%。聚酯平均相对分子质量为613 5,相对分子质量分布系数为1.212。优化的C36二聚脂肪酸聚乙二醇聚酯硫酸酯盐的制备条件是:尿素为催化剂,n(二聚酸聚乙二醇聚酯)∶n(NH2SO3H)∶n(尿素)=1∶1.2∶1.2,反应温度130℃,反应时间2.8 h,聚酯端羟基硫酸酯酯化率达81.17%。表面性能分析结果为:产物γCMC(25℃)为3.021 mN/m,与十二烷基硫酸钠(K12)相当;CMC(25℃)为1.07 mmol/L,远低于K12;乳化性能和乳化稳定性与壬基酚聚氧乙烯醚(OP-10)相当。与K12相比,产物起泡性差但表现出很好的抑泡性能。该工作的新颖性已为河南省科学技术情报研究所2005年12月15日出具的第2005 c0006号《论文查新报告》所证实。 相似文献
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Poly(lactic acid–4‐hydroxyproline–polyethylene glycol) (PLA–Hpr–PEG) was synthesized via melt copolymerization with stannous chloride as a catalyst activated by a proton acid. Copolymers with different poly(ethylene glycol) (PEG) concentrations (0.1, 0.5, 1, and 5 wt %) were synthesized and exhibited moderate molecular weights (weight‐average molecular weight = 9705–13,600 g/mol) and reasonable molecular weight distributions (weight‐average molecular weight/number‐average molecular weight = 1.35– 1.66). The structure of the polymers was verified with infrared spectroscopy and proton nuclear magnetic resonance spectroscopy. The nanoparticles were made by the nanoprecipitation method with PLA–Hpr–PEG. The size and size distribution of the nanoparticles were investigated with laser light scattering, and the surface morphology of the nanoparticles was investigated with transmission electron microscopy. The drug encapsulation efficiency and drug loading content were measured with ultraviolet absorption spectroscopy. The effects of various formulation parameters were evaluated. The prepared nanoparticles were spherical and greater than 100 nm in size. The drug loading content and encapsulation efficiency were greatly influenced by the amount of the copolymer and the volume of the solvent. The PEG content in the polymer could affect the release of drugs from the PLA–Hpr–PEG nanoparticles. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2654–2659, 2007 相似文献
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Hideto Tsuji Yoshito Ikada Suong-Hyu Hyon Yoshiharu Kimura Toshio Kitao 《应用聚合物科学杂志》1994,51(2):337-344
To obtain poly(lactic acid) (PLA) complex fibers, spinning was performed by wet and dry methods from 5–10 g/dL chloroform solutions of poly(D-lactic acid) (PDLA) and poly(L-lactic), both with a viscosity-average molecular weight of 3 × 105. The dope was extruded from a monohole nozzle into coagulation baths from ethanol and chloroform for wet spinning and into a drying column kept at 60°C for dry spinning. Scanning electron microscopic observation of the as-spun fibers showed that the surface of the wet-spun fiber had large basins with diameters of 50–100 μm and many pores with diameters from sub μm to 10 μm, whereas the surface of dry-spun fiber had a microporous structure with the pore diameter of 1–3 μm. The tensile strength of the wet-spun complex fiber was very low and could not be drawn at high temperatures, in contrast to the dry-spun fiber. The tensile strength of dry-spun complex fiber increased upon hot drawing and showed the tensile strength of 94 kg/mm2 by drawing at 160°C to the draw ratio of 13. Differential scanning calorimetry revealed that the complex fibers contained both the stereocomplex crystallites (racemic crystallites) and the crystallites of the single polymers, PDLA and PLLA, regardless of the spinning methods. The ratio of the racemic crystallites to the single-polymer crystallites increased with the draw ratio of the complex fiber. © 1994 John Wiley & Sons, Inc. 相似文献
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Synthesis of Aluminum Oxide Platelets 总被引:1,自引:0,他引:1
Richard F. Hill Robert Danzer Robert T. Paine 《Journal of the American Ceramic Society》2001,84(3):514-520
Aqueous solutions of boehmite and hydrofluoric acid (HF) were used to prepare homogeneous mixtures of alumina and aluminum fluoride. Calcination at temperatures as low as 1000°C resulted in the formation of well-defined hexagonal-shaped α-alumina platelets. Containment of the aluminum fluoride by covering the calcination crucible promoted crystal growth presumably by a reaction of continuous evaporation–condensation of aluminum fluoride. Hexagonal-shaped platelet α-alumina was observed with average diameters ranging from 7 to 33 μm. Large platelets with a narrow size distribution and average diameter of over 25 μm were prepared by controlling the initial concentration of HF and the calcination time, temperature, and atmosphere. 相似文献