粉体流动性及喷流性测量方法及其应用

使用以Carr指数法为理论基础研发的、唯一符合美国材料试验协会(ASTM)标准的细川综合测粉仪器——粉体流动性-喷流性测量仪的最新型号PT-X型,采用3种粒度不同的日本工业标准(JIS)试验用粉体,综合分析评价该仪器自动测量的先进性与可靠性,并将其发展应用于纳米复合颗粒的物性评价,探讨该测量法在生产与研发中的实用价值。结果表明,通过改进Carr指数法测粉仪器的自动化水平,可以提高粉体流动性及喷流性的测量精度与再现性,并能将其应用在纳米粉体的物性评价。     

卡尔指数法在评价煤粉粉体特性中的应用

以卡尔指数原理为理论基础 ,使用MT - 10 0 0型多功能粉体物性测定仪 ,成功测定了 3种煤粉材料的粉体流动特性和喷流性特性 ,并结合该测定结果 ,探讨了煤粉加工生产中的注意事项及具体应用     

医药粉体流动性评价方法研究进展

综述医药粉体流动性评价方法的研究进展,介绍休止角法、流出速度法、压缩度测定法和剪切实验法等4种流动性评价方法的原理及特点,以及利用Carr流动性指数进行流动性综合性评价的方法,重点介绍旋转式、环形、Jenike、平行平板型等剪切实验法的特点;提出剪切实验法可以直接、定量地反映粉体粒子的力学特性,从微观的粒子间摩擦力的角度对粉体粒子受不同外力作用时的流动特性进行评价,判断粉体之间流动性的微小差别,尤其能顺利进行测定超微粉体的流动性;要对粉体流动性进行正确、全面地评价和表征,必须根据需要选择合适的评级方法,甚至综合运用几种流动性测定方法进行全面评价。以期为医药粉体流动性测定方法的选择以及流动性测定方法学的研究提供参考。     

超微粉碎对苦荞物化性质的影响

目的实验探究超微粉碎对苦荞全粉物化性质的影响,为苦荞精深加工提供参考依据。方法以苦荞全粉为实验对象,研究剪切粉碎、气流粉碎和纳米研磨对苦荞基本化学成分、物理性质和抗氧化性的影响。结果通过测定不同方法处理所得苦荞全粉的流动性、含水量、持水力、蛋白质、黄酮等理化指标,发现粉体体积密度显著降低(P0.05),纳米粉体的流动性差异不显著(P0.05);脂肪含量和水分含量分别为5.00 g/kg和79.20 g/kg,下降趋势明显(P0.05)。纳米粉体的总酚含量与粗粉相比增加了19.46%,黄酮的含量增加了7.70%。经剪切粉碎和气流粉碎的粉体,其基本化学成分无较大变化。结论经纳米研磨所得苦荞粉具有较优的功能特性、营养品质,适合于苦荞的精深加工,是一种极具潜力的苦荞超微化方式。     

有机硅表面活性剂改性牡蛎贝壳粉填充尼龙6复合材料的制备

采用氨基型有机硅表面活性剂对气流粉碎的牡蛎贝壳粉体进行表面改性,并与尼龙6熔融共混制备复合材料。通过激光粒度、表面元素分析、热失重分析、高压毛细管流变仪等分别研究了贝壳粉体的粒径分布、元素构成、热稳定性及相应复合材料的加工流变性和力学性能。实验结果表明,经气流粉碎和表面改性后的贝壳粉体具有粒子尺寸小(D50为5.1μm)、粒径分布窄(1~10μm)的特点。贝壳粉残留有机质和主体无机物热分解温度分别在300℃和600℃以上,表现出较好热稳定性。改性贝壳粉较未改性粉体具有更好的分散性及与树脂的界面结合,相应复合材料的熔体流动性和力学性能也明显优于后者。另外,贝壳粉因含有机质而具有一定极性,其尼龙树脂基复合材料较商品化碳酸钙填充尼龙的性能更佳。     

卧式行星磨水泥粉磨能耗理论研究

采用小型卧式行星磨粉磨水泥熟料,在不同行星因子和入料粒级的条件下,研究粉磨后粉体的粒度分布和粉磨能耗理论。结果表明:所得产物粉体粒度分布符合RRSB(Rosin-Rammler-Schuhmann-Bennett)分布,粉体的均匀性系数约为0.8;当行星因子为14并且粉磨120 s时,80μm筛余质量分数小于10%,45μm筛余质量分数小于30%,粒度分布符合国家标准GB 175—2007要求,此时单位产量能耗为332 J/g;通过对粒度与能耗的关系进行曲线拟合,得到粉碎功指数为1.999 36,数值接近雷廷格粉碎功指数,比表面积增加量与粉磨能耗呈线性关系;在不同行星因子时的雷廷格粉磨能耗理论均适用于卧式行星磨。     

图像处理方法在粉体粒度分布测量中的应用

为考察图像处理方法在粉体粒度分布测量中的应用,用数码相机和显微镜获取二氧化硅粉和粉煤灰样品的颗粒形貌图像,分别运用图像处理方法中的手动方式和自动方式测算了所选粉体样品的粒度分布。结果表明,二氧化硅粉的微分分布呈双峰特征,其累积分布曲线呈近似"S"型;粉煤灰的微分分布呈指数下降,其累积分布曲线为不严格"S"型;图像处理方法是适用于测量粉体粒度分布的方法之一。     

聚乙烯亚胺对β-碳化硅粉体的表面改性研究

采用聚乙烯亚胺(Polyethyleneimine,PEI)作为表面活性剂对工业用β-SiC超细粉体进行表面改性,采用离心式喷雾干燥技术对碳化硅浆料进行干燥。通过扫描电镜、X射线衍射仪、红外光谱仪、粉体综合测试仪测试了改性前后粉体的形貌、表面性质、粒度及流动性。结果表明:PEI在粉体表面形成了包覆层,使粉体团聚现象减少;喷雾干燥大大地提高了粉体的流动性,综合流动性指数由原粉的44增加到88;改性并没有改变粉体内部的物相与结构;PEI仅仅是吸附包覆,通过空间位阻效应使得粉体稳定分散。     

黄芪破壁粉的粉体学性质

为尝试现代高分子材料科学的研究方法和技术,初步明确黄芪破壁粉粉体特性的表征指标及分析方法,以黄芪破壁粉为例,研究黄芪破壁粉粉体特性的表征指标及分析方法。制备10批次黄芪破壁粉,考察其粒径分布、堆密度、比表面积、休止角、色度的影响因素,确定黄芪破壁粉粉体指标测定的方法,建立黄芪破壁粉的粉体学指标。结果表明:建立的测定黄芪破壁粉粒径、比表面积、堆密度、流动性、色度的方法可以用于粉体测定,且最佳粒径分布在16. 417～44. 113μm之间,堆密度为0. 17～0. 28 g/mL,比表面积为1. 644 8～2. 509 8 m~2/g,休止角平均值为48. 87°,色度为87. 22～89. 57。     

硬脂酸对W型六角晶系铁氧体粉体的表面改性

采用硬脂酸对W型六角晶系铁氧体粉体进行表面改性,研究改性剂用量、改性时间和改性温度等因素对铁氧体粉体表面改性的影响,采用红外光谱、差热分析及润湿性实验对改性前后的铁氧体粉体进行表征。结果表明,在硬脂酸质量分数为1.5%,改性时间为30 min,改性温度为80℃的条件下,制备的产品性能优良,活化指数达95.2%;铁氧体粉体经硬脂酸改性后,硬脂酸在铁氧体粉体表面发生化学吸附;改性后的铁氧体粉体表面性质由亲水变为疏水,复合体系黏度降低,从而改善加工流动性以及提高铁氧体-环氧树脂复合材料的力学及热稳定性能。     

粉粒体三次物性的分析与测量

综述了粉粒体几种主要三次物性的分析测量方法 ,包括粉粒体流动性、流化特性、喷流性和流变性 ,总结了这些测量方法的共同特点 ,并对粉粒体基础研究发展前景做了分析。     

小麦和小麦粉湿面筋含量测定影响因素的研究

湿面筋含量是小麦和小麦粉品质的一项重要指标.本文首先比较了手洗法与仪器洗涤法对小麦粉湿面筋含量测定,表明此二法对于小麦粉中湿面筋含星测定影响差异较小;再者研究了不同温度、pH值、和面时间及NaCI浓度对硬质小麦、混合小麦和软质小麦湿面筋含量测定的影响,结果表明22℃±2℃、中性至微弱咸性、35s和面时间及2%的NaCl...     

高效液相色谱法快速测定小麦粉中过氧化苯甲酰

目的:用高效液相色谱准确、快速测定小麦粉中过氧化苯甲酰。方法:小麦粉直接以水溶解,经振荡及超声提取,滤膜过滤后上高效液相色谱进行测定。结果:苯甲酸在0.2μg/ml～100μg/ml范围内呈良好线性,检出限为0.3mg/kg。平均回收率在94.1%～99.0%范围内。相对标准偏差小于2%。经检验,本法对CNCA能力验证剩余样品的检测结果与CNCA公布结果基本一致。结论:本法简单快捷,结果准确,重现性好,适用于小麦粉中过氧化苯甲酰的测定。     

Predicting the flowability of alumina powder during batch grinding through the establishment of a grinding kinetic model

Grinding is one of the main unit operation in industrial processes handling powders. The particle size reduction that takes place during grinding tests, usually results in a significant change in the flow behavior of the ground powder. Up to now, a model predicting the evolution of powder flowability with grinding time, according to the operating conditions is still missing. In this paper, a methodology combining a grinding kinetic model and a flowability model involving the population-dependent granular Bond number is developed. The methodology has been applied to an alumina powder, ground in a batch ball mill. The flow function coefficient of the ground samples is measured after various grinding times in a powder shear tester. The comparison between model predictions and experimental data shows that this method allows an accurate prediction of the powder flow behavior over the first sixteen minutes of grinding.     

Effect of particle morphology on the flowability of HDH Ti powders treated by high temperature ball milling

The metal powder flowability determined by powder characteristics significantly influences on the final parts manufactured by additive manufacturing (AM). Among the characteristics, the individually effect of morphology on its flowability still is not comprehensively evaluated. In this study, the effect of morphology on the flowability of hydride-dehydrate titanium (HDH Ti) powder treated by high temperature ball milling (HTBM) was investigated systematically using the fractal dimension and shape factors, i.e., circularity, elongation, compactness and convexity. The results of HTBM show that the modified HDH Ti powder with a mass flow rate of 48.1 ± 0.3 s/50 g and the angle of repose (AOR) of 38.88 ± 0.5°. The fractal dimension of powder plays a main role on the flowability, which increase in the decrease of it. The box plot and Pearson correlation coefficient of shape factors indicate that only circularity is strong correlation with flowability, which increases with it. The regression model of flowability expressed with fractal dimension and circularity shows the adjusted R² value of 0.991, which is good agreement with the experiment. Taken together, this study provides a general guide to evaluate the powder flowability based on the morphology.     

Effect of Compressibility and Powder Flow Properties on Tablet Weight Variation

A powder flowmeter has been designed to provide both quantitative and qualitative data relating to powder flowability. Three directly compressible powders, Emdex, Emcompress and magnesium oxide as well as a three component powder mixture was assessed for flowability, angle of repose and particle size. Compressibility indices were determined for all the above materials as well as for the fractions of each which consisted of a particle size below 315 μm. Sieve analysis was performed on the above powders in order to establish groups consisting of cohesive, mildly cohesive and non-cohesive fractions and their respective flow-time profiles were subsequently determined. Scanning electron microscopic analysis was performed to obtain information on the particle size, shape and size distribution. The interrelationships between flow rate, angle of repose, compressibility index and coefficient of tablet weight variation were established using both a single punch and a high-speed rotary tabletting machine.

A three-dimensional plot was constructed to illustrate the influences of flow rate, angle of repose and compressibility index on the coefficient of tablet weight variation. Whilst it was established that particle size has a significant effect on uniformity of flow, the data also indicated that when the compressibility index exceeded a value of about 20% a significant increase in tablet weight variation resulted irrespective of the powder flow rate.     

Effect of Compressibility and Powder Flow Properties on Tablet Weight Variation

A powder flowmeter has been designed to provide both quantitative and qualitative data relating to powder flowability. Three directly compressible powders, Emdex, Emcompress and magnesium oxide as well as a three component powder mixture was assessed for flowability, angle of repose and particle size. Compressibility indices were determined for all the above materials as well as for the fractions of each which consisted of a particle size below 315 μm. Sieve analysis was performed on the above powders in order to establish groups consisting of cohesive, mildly cohesive and non-cohesive fractions and their respective flow-time profiles were subsequently determined. Scanning electron microscopic analysis was performed to obtain information on the particle size, shape and size distribution. The interrelationships between flow rate, angle of repose, compressibility index and coefficient of tablet weight variation were established using both a single punch and a high-speed rotary tabletting machine.

A three-dimensional plot was constructed to illustrate the influences of flow rate, angle of repose and compressibility index on the coefficient of tablet weight variation. Whilst it was established that particle size has a significant effect on uniformity of flow, the data also indicated that when the compressibility index exceeded a value of about 20% a significant increase in tablet weight variation resulted irrespective of the powder flow rate.     

Absorption removal of carbon dioxide in the presence of inert solid particles (flour powder)

Abstract

An experimental analysis of the absorption removal of carbon dioxide with the presence of inert solid particles on the surface of the absorbent liquid is presented. A batch absorber with quiescent absorbent liquid has been applied to study the absorption removal of carbon dioxide by water in the isothermal system. The flour powder is introduced as the inert solid particles in the carbon dioxide absorption system. Tests with the flour powder in water are examined. The mass fluxes of carbon dioxide for the cases with and without the flour powder are then compared to elucidate the effects of inert solid particles on isothermal gas absorption. The results indicate a significant difference between these two cases for the concentrations of the flour powder in the absorbent liquid (WF) being in the range of experimental conditions, namely 0.001 to 0.03 g flour in 10 ml liquid. In general, the inert solid particles of the flour powder as the impurities in water with WF in the range of this study tend to decrease the carbon dioxide absorption rates for the experimental absorption system under investigation. Thus, various concentrations of inert solid particles cause various levels of surface resistance and affect the gas absorption rates. This kind of information is very useful for the gaseous pollutants removal that the impurities of inert solid particles contaminate the isothermal gas absorption system, and for the absorption removal of carbon dioxide associated with the control of the green house effect.     

离子聚合物改性木粉/HDPE复合材料流变特性

为了提高木塑复合材料（WPC）的加工流动性能,利用离子聚合物改性WPC,通过HAAKE Minilab微量混合流变仪研究了离子聚合物改性木粉/高密度聚乙烯（HDPE）的毛细管流变特征。结果表明：添加与未添加离子聚合物的木粉/HDPE均为非牛顿流体中的假塑性流体,均呈现出“剪切变稀”的效应;随着钠离子聚合物含量的增加,改性木粉/HDPE的剪切应力和表观黏度均随着剪切速率的增大呈现降低的趋势,表明钠离子聚合物的加入可以显著改善聚合物熔体的流动特性;添加4wt%的钠离子聚合物和4wt%的锌离子聚合物的木粉/HDPE剪切应力和表观黏度均要低于添加4wt%的偶联剂马来酸酐接枝聚乙烯（MAH-g-PE）的WPC的值,表明与MAH-g-PE相比,离子聚合物更能够改善WPC的流动性能,减小熔体流动时HDPE与木粉之间的摩擦阻力;SEM分析表明,添加离子聚合物后HDPE塑料对木粉有很好的包覆效果,没有明显的界面缝隙,且在WPC断面上存在大量的毛刺纤维。