大粒径硅溶胶粒径增长及其控制工艺的研究

大粒径硅溶胶在涂料、化学机械抛光、催化剂载体等工业领域中都有着极其广泛的应用。在添加适量催化剂的条件下,采用单质硅粉氧化法制备了大粒径溶胶。重点介绍了大粒径硅溶胶的分类、性质及应用,通过研究不同条件下大粒径硅溶胶的粒径增长过程分析了大粒径硅溶胶制备过程中的粒径增长机理。在添加阴离子表面活性剂的条件下,采用浓缩蒸馏实验研究了大粒径硅溶胶粒径增长与其浓度的关系,结果表明：随着大粒径硅溶胶浓度的增大,大粒径硅溶胶的粒径呈先减小后增大的趋势。最后提出了制备大粒径硅溶胶的粒径控制工艺。     

激光粒度仪测定PTA粒径分布

介绍了激光粒度仪测定PTA粒径分布的分析方法 ,通过试验确定了分析条件 ,并与筛分法分析结果进行了对比。该方法简捷、快速、重现性好 ,适用于PTA产品的粒度分析。     

高岭土浆液粒度影响因素的研究

高岭土是半合成FCC催化剂的重要载体,其浆液粒度对催化剂性能有较大影响。高岭土作为载体是半合成FCC催化剂的重要组成部分,其浆液粒度的性能已引起广泛重视。考察了打浆时间对高岭土浆液粒度性能的影响,发现粒度随打浆时间的增加而减小,但是达到一定的时间后高岭土的粒度基本不变。进一步研究了分散剂对高岭土浆液粒度的影响,结果表明,加入分散剂有利于降低高岭土的粒度,提高打浆效率,有利于打浆过程,但加入一定量后,降低粒度的效果不明显。工业生产过程中,可以考虑加入适量的分散剂提高打浆效率,降低浆液粒度。     

激光测量二氧化钛粒径的影响因素探讨

探讨了激光粒度仪在测量聚酯生产用二氧化钛粒径的过程中，对测定结果产生影响的因素。     

现代颗粒粒度测量技术

颗粒粒度的测定已成为现代测量学的一个重要分支。介绍了筛分法、显微镜法、沉降分析法、电感应法等传统颗粒粒度测量技术的方法和原理 ,并着重介绍了光散射法、质谱法、基于布朗运动的粒度测量法等近年来发展起来的颗粒粒度测量新方法     

PTA质量对浆料性能的影响

浆料是影响聚酯切片质量的直接因素,而PTA作为浆料的主要成分又影响浆料的性能,从PTA3项质量指标入手,详细论述其与浆料性能的关系。     

激光粒度仪测量PVC树脂粒径的影响因素

通过激光粒度仪仪器参数设置和不同样品加入量的对比试验,确定了测量PVC树脂粒径分布的Mastersizer 3000型激光粒度仪最佳仪器参数:搅拌速度2 700 r/min、超声时间60 s、遮光度7.0％～9.0％.     

PTA粒度分布对其浆料性能的影响

浆料的稳定性和浆料性是影响聚酯产品质量的重要因素 ,PTA作为浆料的主要成份 ,又直接影响到浆料的性能。本文论述了平均粒径和粒度分布情况对浆料性能的影响     

激光粒度仪测定纳米磷酸铁粉体粒度的研究

采用Zetasizer Nano S90型激光粒度分析仪对纳米磷酸铁粉体进行粒度测定的实验研究。主要考察了分散剂及其用量、超声时间、磷酸铁在测定液中的含量等因素对粉体分散性能及粒径测定的影响,确定了纳米磷酸铁粉体粒度分析的最佳条件,即以蒸馏水为分散介质,质量浓度为1 g/L的十二烷基硫酸钠为分散剂,纳米磷酸铁质量浓度为0.2 g/L,超声时间为15 min时,激光粒度仪测得的结果与扫描电镜表征结果基本一致。     

影响苯丙乳液黏度与粒径的因素分析

采用种子乳液聚合法,以苯乙烯、丙烯酸丁酯、丙烯酸异辛酯、甲基丙烯酸甲酯等为主要原料合成了用于制备胶粘剂的苯丙乳液。重点研究了引发剂、乳化剂及种子单体的用量及硬软单体不同配比对苯丙乳波黏度和粒径的影响。实验结果表明,当引发剂用量为0.5％（占单体总质量,后同）、乳化剂用量为1％、种子单体用量为8％、硬软单体配比为30／46的条件下,合成的笨丙乳液黏度较高、粒径小、粒度分布宽,用该乳液制备的胶粘剂具有优良的施工性能.     

超细粉体粒度测试方法浅析

介绍了超细粉体粒度测试的几种主要方法(激光衍射散射法、离心沉降法、颗粒图像处理仪和库尔特颗粒计数器)的测试原理及性能特点，并进行了比较。讨论了粒度测试中应注意的几个问题，重点分析了测试条件不同对粒度测定的影响，得出分散介质、分散剂、超声功率及超声时间等是影响粒度测定的最主要的因素；指出了重复性、真实性、易操作性、量程和动态范围是评价粒度仪测试性能的几个重要指标。     

弹性微球通过油层孔隙的临界粒径

根据微球在孔隙中的受力情况,建立简化的力学模型,计算出通过孔喉的微球的临界粒径。结果表明,当微球物性参数不变时,微球临界粒径随孔隙孔径线性增大;当孔隙孔径不变,只改变微球物性参数中的弹性模量时,微球临界粒径随微球弹性模量的增大而减小;当孔隙孔径不变,只改变微球物性参数中的极限应力时,微球临界粒径随极限应力的增大而增大。     

Simultaneous effect of particle size and solid concentration on the hydrodynamics of slurry bubble column reactors

The simultaneous effect of particle size and concentration on the total gas holdup of slurry bubble column reactors was investigated in this work. The total gas holdup was measured for air–water–glass beads systems. Three solid concentrations and three particle diameters were used. It was found that increasing particle size at high constant concentration decreases gas holdup. Moreover, increasing solid concentration decreases gas holdup and this decreasing effect is higher for larger particles. Also, solid particles have two effects on hydrodynamics, namely, changing the viscosity and density of the liquid phase as well as hindering the bubbles from rising within the column by the collision phenomenon. Therefore, a novel correcting factor was introduced to correct the gas holdup. The hindering factor considers both the collision efficiency affected by the particle size as well as the solid concentration. A novel correlation was developed to predict the experimental data of the three-phase gas holdup.     

The influence of particle size and density on the radial gas mixing in the dilute region of the circulating fluidized bed

A cold model of a CFB, having a 0.120m ID, 5.75m high riser, was operated at a superficial gas velocity of 6m/s and at average solids mass fluxes varying in the range between 16 and 55kg/sm². A stream of carbon dioxide was injected continuously at a fixed position along the riser axis and used as tracer gas. Three solids, belonging to groups A and B of Geldart's classification, were selected in order to investigate separately, the effect of particle size and density on the radial mixing of the gas phase. The intensity of radial gas dispersion reduced when larger or heavier particles were used. The differences in the values of radial dispersion coefficient and Peclet number were explained, taking into account the role of the particle size with respect to the scale of gas turbulence.     

超声法在线测量烟气脱硫浆液粒度分布、密度方法和装置

针对烟气脱硫工艺中石灰石/石膏浆液粒度、密度（浓度）在线测量需求,研究了基于超声衰减法的浆料多参数在线测量方法和装置。改进了一种自适应控制参数的差分进化算法用于颗粒粒径反演,模拟算例显示,改进差分进化算法求解精度更高;设计了非接触式测量管段,采用换能器一发一收模式,实现非接触式无损测量;开展了温度变化对声衰减影响实验,提出了声衰减量的温度修正方法。通过实验室结果验证,文中方法浓度测量结果与取样法浓度分析结果最大偏差为1.75%,最小偏差为0.59%。通过电厂测试结果验证,文中方法的粒度测量结果与显微镜图像法、激光粒度仪三者测量结果具有较好的一致性,最大偏差小于17%;密度测量结果与取样法吻合度高,最大重复性偏差仅为0.23%,单次测量结果与取样法最大偏差为0.26%,两项指标均优于差压密度计测量结果,可满足烟气脱硫工艺中石灰石/石膏浆液粒度、密度（浓度）在线测量需求。     

The influence of particle size distribution on rheological properties of fused silica pastes for direct ink writing

Additive manufacturing of ceramics through the direct ink writing method becomes possible when the effective parameters on rheology are optimized accurately. Successful manufacturing first requires the easy flowing of the ink through the nozzle and then a suitable viscoelastic response for the shape retention of the 3D printed structure. In the present study, fused silica pastes with different particle size distributions varying from D₉₀ of 5–50 µm were prepared for direct ink writing of porous structures. The rheological properties of the pastes, including flow behavior and the viscoelastic moduli variations, were investigated to study the influence of particle size and its distribution on fabricating complex structures. Through investigations, it was found that the narrower size distributions were more appropriate for direct ink writing of fused silica pastes. As the distribution became narrow, the shear thinning behavior was intensified, and the pastes showed high elasticity. The sintering procedure was performed using microwave radiation to suggest a fast process for manufacturing fused silica complex parts containing partially crystallized cristobalite phase and providing porosity of about 10% and a relative density of 90%.     

Latex particle size and CPVC

Monodisperse vinyl acetate/butyl acrylate (85/15) latexes were prepared with particle sizes between 200 and 1200 nm. These were used in a simple paint formulation with TiO₂ as the only pigment. Two optical methods were used for determination of the critical pigment volume concentration (CPVC) of these paints. These are specular gloss at an incidence angle of 85 ° and CIE Z (lightness) values of a blue tinted formulation. Both methods gave coincident results for the CPVC as a function of latex particle size. Our data fit the expression X = 1.44Y^2.65 where X = number of latex particles/number of pigment particles, at CPVC and Y = diameter of pigment particles/diameter of latex particles. Earlier, Bowell reported the same exponential relation, with a different pre-exponential factor, for acrylic latexes. The common exponent is explained with a model in which the latex and pigment particles assume a condition close to minimum porosity during packing. CPVC reflects the packing of particles during the initial stages of dryness of the latex. The ‘universal’ relation reported here permits facile prediction of the effects of latex particle size on the CPVC and binding capacity in water-based paints.     

微细物料颗粒大小的测定(续)

4.2 显微镜法 显微镜法包括使用光学显微镜和电子显微镜,是唯一可以观察和测量颗粒的方法。几种显微镜在测定颗粒大小时的性能如表3。     

PTA粒径增大方法的探讨

通过改善结晶器的工艺控制条件以及在结晶器搅拌器上增加变频器来调整转速,降低其搅拌强度,使PTA粒径从84μm提高至110μm左右,提高了离心机分离效果,延长了设备运转周期,同时亦提高了产品气送速度和PTA产品化等品率。     

Ground particle size influence on the swelling of a copolymer of AA/AMPS in water

The influence of the ground particle size on the swelling behavior of a copolymer of AA/AMPS in water was observed to determine the best size considering water absorbency in view of fastest and highest equilibrium swelling. The copolymer gel, from acrylamide and 2‐acrylamido‐2‐methyl‐propanosulfonic acid and synthesized in the presence of N,N‐methylene‐bis‐acrylamide, was obtained by a radical solution technique, and identified by FTIR spectroscopy. By grinding, various particle diameters were obtained, and then separated by sieves. Studies of dynamic and equilibrium swelling in deionized water at 20°C showed the influence of the particle size on the kinetics of swelling and its equilibrium swelling capacity. A mathematical model for the absorption, including diffusion and relaxation modes, permitted to assess the absorption mechanism, and offered quantitative information about water diffusivity in the copolymer. The fastest swelling was obtained with diameters of 22.5–215 μm. Particle sizes ranging from 67.5 to 355 μm yielded the greatest equilibrium swelling, with mass ratios of about 1100. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008