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101.
102.
A new method is presented for preparing highly monodispersed silica particles using a two-stage semibatch/batch hydrolysis reaction of Si(OC2 H5 )4 . The slower rate of hydrolysis of the tetraethylorthosilicate (TEOS) that occurred during the semibatch process resulted in larger silica particles with a higher yield and narrower size distribution. This was in direct contrast to the batch process. In addition, the ability of four different mixed processes to produce silica particles with good packing density, narrower particle-size distribution, and higher yield were evaluated. These were batch/batch (B-B), batch/semibatch (B-S), semibatch/batch (S-B), and semibatch/semibatch (S-S) processes. The S-S system produced the largest particles with the highest yields. The size of the silica particles obtained by the S-B method decreased with increasing reaction time, while the particles obtained by the B-S process had the best particle-size distribution and packing density. In conclusion, a mixed batch/semibatch system was the best way to produce an extremely narrow particle-size distribution and a good packing density. 相似文献
103.
Richard Kotek Dong‐Wook Jung Joon Ho Kim Brent Smith Patricia Guzman Benjamin Schmidt 《应用聚合物科学杂志》2004,92(3):1724-1730
The surface alkaline hydrolysis of fibers made from poly(trimethylene terephthalate) (PTT) was studied after extruding the polymer at high spinning speeds from 2000 to 6000 m/min and heat setting in the range of temperatures from 100 to 180°C. Fiber weight loss increased with an increasing heat‐setting temperature but it was also dependent on the spinning speed. Some of the partially hydrolyzed fibers had a well‐developed, hydrophilic surface, and pore size in the range of 0.69 to 1.20 μm. The optimum reaction and morphological conditions for increasing porosity in PTT fibers depends on spinning speed and heat‐setting temperature. A temperature of 180°C is the upper limit for heat‐setting PTT filaments but seems to be the most effective for making porous fibers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1724–1730, 2004 相似文献
104.
不同分散剂对细粒高硫煤及煤系黄铁矿的选择性分散 总被引:1,自引:0,他引:1
主要研究六偏磷酸钠和腐植酸纳2种分散剂分别对细粒高硫煤、煤系黄铁矿悬浮液的分散作用,考察了分散剂用量、介质pH值对细粒煤与煤系黄铁矿选择性分散的影响。 相似文献
105.
In this study, poly(ethylene terephthalate) (PET)/SiO2 nanocomposites were synthesized by in situ polymerization and melt‐spun to fibers. The superfine structure, physical properties, and dyeability of alkaline hydrolyzed PET/SiO2 nanocomposite fibers were studied. According to the TEM, SiO2 nanoparticles were well dispersed in the PET matrix at a size level of 10–20 nm. PET/SiO2 nanocomposite fibers were treated with aqueous solution of sodium hydroxide and cetyltrimethyl ammonium bromide at 100°C for different time. The differences in the alkaline hydrolysis mechanism between pure PET and PET/SiO2 nanocomposite fibers were preliminarily investigated, which were evaluated in terms of the weight loss, tensile strength, specific surface area, as well as disperse dye uptake. PET/SiO2 nanocomposite fibers showed a greater degree of weight loss as compared with that of pure PET fibers. More and tougher superfine structures, such as cracks, craters, and cavities, were introduced, which would facilitate the certain application like deep dyeing. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3691–3697, 2006 相似文献
106.
Chengyun Yue J. Milton Harris Per-Erik Hellberg Karin Bergstrom 《Journal of the American Oil Chemists' Society》1996,73(7):841-845
A series of noncyclic acetal-linked cleavable surfactants were simply prepared by condensation of aldehydes with poly(ethylene
glycol) monomethyl ethers. All of the products were characterized by1H nuclear magnetic resonance. Their hydrophile-lipophile balance, surface tension, cloud point, critical micelle concentration,
and foam height were determined. Hydrolysis kinetic studies, followed by gas chromatography, showed that they had higher hydrolytic
reactivity in acidic solution than cyclic acetal-linked cleavable surfactants. 相似文献
107.
Polycrystalline Ag treated with O2 at pressures up to 1 bar and at temperatures up to 920 K was examined by TDS. It was found that the peak commonly observed at 595±25 K and assigned to adsorbed atomic oxygen (Oa) is shifted to higher desorption temperatures with rising dosing temperatures. Since saturation of the uptake was not possible either, this peak was identified as dissolved atomic oxygen (Od). The existence of a maximum for the O2 uptake after exposure at 820 K was found. Hence, under conditions of formaldehyde synthesis ( 920 K) the ability of the catalyst to dissolve oxygen is near its maximum. 相似文献
108.
考察了Pd/Al2O3、In/Al2O3和Co/Al2O3对甲烷选择性还原NO的催化活性。结果表明,采用浸渍法制备的Pd/Al2O3、In/Al2O3和Co/Al2O3三种催化剂,在有氧气氛下,用CH4作还原剂催化还原NO时,Pd/Al2O3催化剂的活性最佳,热稳定性好,在550 ℃,用CH4选择还原NO,Pd/Al2O3催化剂表现出较强的催化能力,NO的转化率达到100%。在高空速实验中,该催化剂亦表现出较高的活性,其活性顺序为Pd/Al2O3>In/Al2O3>Co/Al2O3。实验研究了助催化剂、氧含量以及空速对Pd/Al2O3催化剂活性的影响。 相似文献
109.
The influence of various fillers on sizing efficiency, adsorption and hydrolysis of alkyl ketene dimer (AKD) has been investigated. Results indicated that the precipitated calcium carbonate (PCC) improved AKD retention, both bound and unbound. The sizing efficiency was reduced as PCC contents increased, which might be attributed to the decrease in the relative AKD dosage to fibres and AKD hydrolysis promoted by PCC. Less amount of AKD was adsorbed on PCC, compared with calcined clay and TiO2 fillers under the same conditions. Hydrolysis studies indicated that PCC had a more detrimental effect on AKD hydrolysis than clay and TiO2. 相似文献
110.
以城市污水处理厂剩余污泥为原料制备了一种新型碳质催化剂。通过试验考察了催化剂在NH3选择催化还原NO中的应用效果。结果表明,催化性能较好,最佳的制备和催化反应条件为:锌铁物质的量比1∶0.5,热解温度750 ℃,反应温度400 ℃,O2浓度15%。在此条件下,NOx的最大转化率达98.3%。通过考察证明催化剂自身具有一定的还原性能。对催化剂进行了FTIR、TG、SEM和BET分析,结果表明,催化剂具有很丰富的孔结构、活性粒子和表面官能团,比表面积较大,最大可达307 m2·g-1,分析结果显示具有良好的催化条件。 相似文献