组合电解质对氧化铁-水悬浮液流变特性的影响

应用LVDV-Ⅲ＋型可编程流变仪测定了组合电解质对氧化铁—水悬浮液的流变特性的影响。实验结果表明,一价、二价组合电解质在改善悬浮液流变性的同时会使悬浮体系粘度有较大降低;三价组合电解质在改善悬浮液流变性的同时不会使悬浮体系粘度有较大增加。凝聚氧化铁—水悬浮液在测定范围内表现出伪塑性流体的特征。     

蒙脱石的湿法机械球磨剥离

以内蒙古钙基蒙脱石为原料,通过湿法改型、改性制备了钠基蒙脱石和有机蒙脱石.分别以钙基蒙脱石、钠基蒙脱石和有机蒙脱石为对象,在乙醇中湿法机械球磨、超声处理蒙脱石,利用XRD、TEM、AFM等手段研究了机械球磨法对不同层间离子的蒙脱石剥离效果.结果表明,内蒙古钙基蒙脱石湿法钠化及有机化效果良好,机械球磨法剥离钠基蒙脱石效果最佳,剥离型蒙脱石片层尺寸小于200 nm,其平均厚度约为15 nm;有机蒙脱石层间有机物具有稳定蒙脱石片层的作用,有机改性不能促进机械球磨法对蒙脱石片层的剥离.     

不同蒙脱石的有机插层及聚合剥离

以成因、类型、性质不同的6种蒙脱石为原料,制备了有机插层和聚酰胺6／蒙脱石纳米复合材料。研究了蒙脱石矿物类型、成分及阳离子交换容量对其有机插层及聚合剥离的影响。结果表明：有机插层蒙脱石层间距随插层剂用量及阳离子交换容量的增加而增加,低阳离子交换容量及高钠含量蒙脱石更有利于插层剥离。钠化对蒙脱石有机插层影响不明显。     

粒度分布与氧化铁凝聚悬浮体系的流变性

应用LVDV-Ⅲ＋型可编程流变仪测定了粒度分布与微米级氧化铁水悬浮液凝聚处理后的流变特性的关系。实验结果表明,在一定的固相体积分数下,悬浮液的表观粘度随悬浮液中颗粒中位径的增大而减小。颗粒半径越小,溶剂化导致的体积增加越多,颗粒在悬浮体系中所占的体积分数也越大,结果是运动阻力增大,悬浮液粘度增加。悬浮液固相体积分数从3...     

聚乙烯醇/蒙脱石纳米复合材料的制备工艺研究

通过正交实验法研究了溶液插层-流延成膜法制备聚乙烯醇/蒙脱石纳米复合材料中制备工艺条件对复合材料结构的影响,确定了最佳的制备方法。对复合材料进行了TEM表征,结果表明:蒙脱石片层均匀的剥离分散在PVA基体中,蒙脱石含量不高于7.5wt%时,形成了剥离型的纳米复合材料;高于10wt%时,形成了剥离型和插层型共存的纳米复合结构。     

蒙脱石层电荷密度对其二维纳米片剥离的影响

以2种典型不同层电荷密度的蒙脱石为研究对象,通过烷基铵法测定了2种蒙脱石的层电荷密度,分别为0.342和0.439。研究了层电荷密度对蒙脱石二维剥离及其剥离后纳米片表面电性的影响。通过分子动力学模拟解释了层电荷密度对蒙脱石剥离二维纳米片和水化膨胀能力的影响机理。结果表明:层电荷密度低的蒙脱石具有更好的水化膨胀能力,更易剥离制备二维纳米片。层电荷密度高的蒙脱石剥离的二维纳米片单位面积的电负性更大。蒙脱石层电荷密度越低,其晶层表面对水分子吸附作用越弱,层间阳离子水化能力更强,水化膨胀能力大,也解释了层电荷密度低的蒙脱石更易剥离成二维纳米片的原因。     

层状双氢氧化物和蒙脱石的剥离及其自组装

以钙基蒙脱石为原料,氟化钠为钠化剂,十六烷基三甲基溴化铵为有机改性剂采用离子交换法制备了有机蒙脱石(CTA-MMT);以硝酸镁、硝酸铝、氢氧化钠和十二烷基磺酸钠为原料,采用水热法制备了有机型镁铝层状双氢氧化物(Mg Al-SDS-LDH);以氯仿为剥离介质,采用超声法剥离CTA-MMT和MgAl-SDS-LDH,分别获得了两种剥离型矿物溶胶,将其混合自组装制备了蒙脱石/层状双氢氧化物(MMT/LDH)组装材料。用XRD和AFM表征了CTA-MMT和MgAl-SDS-LDH及其剥离产物,并分析了组装材料的热稳定性。结果表明,CTA-MMT和MgAl-SDS-LDH在氯仿介质中剥离仅需20 min,剥离型CTA-MMT和MgAl-SDS-LDH片层平均厚度分别约为9和8 nm。MMT/LDH由剥离型CTA-MMT和MgAl-SDS-LDH片层有序组装而成,组装材料结构与MgAl-SDS-LDH和CTA-MMT的含量有关,其结构单元层间距2.59 nm(CTA-MMT含量较低时)随着组装材料中CTA-MMT含量的升高而转变为1.82 nm。MMT/LDH组装材料具有较单一的CTA-MMT或MgAl-SDS-LDH更高的热稳定性。     

十二烷基三甲基氯化铵/纳米凹土悬浮体系流变学行为研究

将十二烷基三甲基氯化铵添加到纳米凹土水悬浮液体系,研究其对流变性的影响,考察因素为固含量、分散剂量和离子强度。当体系中未添加十二烷基三甲基氯化铵时,流变曲线为牛顿型流体,随着分散剂的添加,流变学行为符合塑性流体特征。剪切速率一定时,悬浮液的黏度随着分散剂的增加而变大。当离子强度达到0.20mol/L,悬浮液的流变曲线为牛顿型流体,体系黏度不随剪切速率的增加而变化。     

蒙脱石的电导性能和结构

应用固体电解质电导测量技术研究了蒙脱石及其脱水过程中电导率的变化。结合XRD分析,电导测量可以给出重要的结构变化信息。在天然钙蒙脱石和改型镁蒙脱石的情况下它都明显表明了脱水过程中层间非结合阳离子水和结合阳离子水的分步脱除过程,再次证实阳离子嵌入层结构生成不可复水的新相。对各种条件下电导测量结果的物理意义进行了讨论。     

蒙脱石和凹凸棒石纳米复合材料制备、表征和潜在应用

由于晶体结构的制约,蒙脱石和凹凸棒石具有不同的形态和物理化学性质,在水悬浮体系中必定存在蒙脱石和凹凸棒石的互相作用.但这种互相作用的形式和材料科学意义未曾被人认知.本文通过对蒙脱石样品化学剥片和对凹凸棒石样品的分散处理,悬浮液混合和蒙脱石-凹凸棒石颗粒之间的互相作用,实现凹凸棒石和蒙脱石矿物纳米复合,X射线粉末衍射分析、高分辨透射电镜以及比表面积分析证实这种互相作用的存在和颗粒之间的缔合形式.剥片后的蒙脱石纳米晶片和分散的凹凸棒石纳米纤维发生面-面互相作用.2种矿物复合的结果,使得固体产物产生特殊纳米孔结构.此种材料在催化剂制备、吸附脱色、废水废气处理等方面具有潜在的应用价值.     

SINGULAR BEHAVIOR OF THE EFFECTIVE VISCOSITY IN A CONCENTRATED SUSPENSION MEDIUM

The purpose of this paper is to evaluate the effective viscosity of a concentrated Newtonian suspension via spatially periodic approximation and to clarify the results from previously published articies. It is found that singular characteristic of the effective viscosity expression does not disappear. This approximation is then extended to investigate the system of a concentrated non-Newtonian suspension fluid. The results obtained by using the spatially periodic approximation are similar to that of a quasi-steady approximation in terms of the first order of e-¹urthermore, the singular behavior also appears in the expression of the effective viscosity both for a second-order-Rivlin-Ericksen fluid at low shear rate and a Harnoy fluid at high shear rate, except that the viscoelastic effect in the low shear rate is depressed by spatially periodic approximation as compared with those orders obtained by quasi-steady approximation.     

悬浮法成型UP微粒粒径及其分布的控制

以不饱和聚酯树脂（UP）为原料，采用悬浮成型方法制备了粒径为120～250μm的UP球形微粒，从工艺控制的角度考察了搅拌速度、搅拌器形式及反应嚣形式对UP微粒平均粒径及粒径分布的影响。结果表明，将搅拌速度控制在500～1000r／min，以4口圆柱形烧瓶为反应器，采用双层平桨、且桨叶间距为4．5cm时，所制UP微粒的粒径最小、且粒径分布最窄。     

悬浮与溶液聚合法合成丙烯腈共聚物的对比

采用水相悬浮聚合法和均相溶液聚合法合成丙烯腈共聚物 (PAN) ,讨论了聚合条件对不同聚合反应的影响 ,对样品的结构和性能进行GPC、IR等分析和表征 ;并对比两种PAN纺出原丝的热性能。结果表明 :水相悬浮聚合法可得到 MW =5 4 .72× 1 0 4,D =2 .71 ,三单元组等规立构分数X =0 .2 89的PAN ;均相溶液聚合法仅得到 MW =8.96× 1 0 4,D =4.1 4,三单元组等规立构分数X =0 .2 4 3的PAN。     

环流反应器的底部构型和环流方向对固相悬浮的影响

气提式环流反应器的应用日趋广泛，但对其中固相悬浮的机理仍不够清楚，反应器传统的锥底是否适合固树悬浮仍有待理论和实验的验证．本文在小型环流反应器中试验了平底瓦两种深浅不同的截头雄底对悬浮离子交换树脂的影响．实验结果表明，对上流式（指中心管内流向）操作，平底优于推底；对下流式操作，深浅适中的雄底效果最好．因此，三相环流反应器的优化还需在理论的指导下继续深入．     

苯与十二烯烷基化反应悬浮床催化精馏非平衡级模型

引　言近年来 ,在传统催化精馏的基础上提出了一种悬浮床催化精馏的新技术[1,2 ] .悬浮床催化精馏不仅继承了传统催化精馏具有的节省投资、提高反应转化率和选择性、操作条件易控制等优点 ,而且克服了催化剂元件的预制、装卸、更换比较麻烦的缺点 .因此 ,悬浮床催化精馏被认为是一种具有研究价值和应用前景的新技术 ,将其应用于负载杂多酸催化的苯与十二烯的烷基化反应已经过小试验证[2 ] .目前 ,催化精馏的模拟研究大都采用非平衡级数学模型[3～ 5] .因为平衡级模型与工业实际精馏塔的运行结果常常不甚相符 ,已经不能准确模拟催化精馏因反…     

SUSPENSION CHARACTERISTICS OF LARGE CYLINDERS IN AGITATED TANKS

Considerable research has been done concerning solid suspension in agitated tanks. Typically, such studies concern slurries or granular material, such as sand, and involve minimum suspension rotational speeds or suspension homogeneity.

The objectives of this work are similar, however we are concerned with rather large cylinders of varying length to diameter ratios. The work involves: 1) the determination of minimum impeller rotational speed for suspension similar to criterion used by Zwietering, 2) the measurement of suspension heights and times, 3) an investigation into whether the correlations by Zwietering, Kolar and Rieger et al., can be used for predicting minimum suspension rotational speed and 4) weight fraction effects on minimum suspension rotational speed.     

单颗粒在浓相悬浮体中的沉降运动

用磁感测量法对颗粒在浓相悬浮体中的沉降过程进行实验研究，得到了悬浮体的表现粘度与悬浮体固体浓度关系及Ars-Lys关系曲线     

SUSPENSION CHARACTERISTICS OF LARGE CYLINDERS IN AGITATED TANKS

Considerable research has been done concerning solid suspension in agitated tanks. Typically, such studies concern slurries or granular material, such as sand, and involve minimum suspension rotational speeds or suspension homogeneity.

The objectives of this work are similar, however we are concerned with rather large cylinders of varying length to diameter ratios. The work involves: 1) the determination of minimum impeller rotational speed for suspension similar to criterion used by Zwietering, 2) the measurement of suspension heights and times, 3) an investigation into whether the correlations by Zwietering, Kolar and Rieger et al., can be used for predicting minimum suspension rotational speed and 4) weight fraction effects on minimum suspension rotational speed.     

POWER CONSUMPTION AND SOLID SUSPENSION IN COMPLETELY FILLED VESSELS

Mixing in a completely filled vessel, designed as a pressure vessel, has been investigated. The power demand of two pitched blade turbines of different sizes, and one high flow impeller was studied. The influence of side-mounted and bottom-mounted baffles, as well as the clearance between the bottom and the impeller was investigated. The experiments were carried out in a plexiglass vessel with a diameter of 288 mm. The Power number was calculated from measured data on the power demand and the impeller speed. Furthermore, preliminary studies on the critical impeller speed and power demand at the off-bottom suspension point for one set of glass particles were carried out. The Power number was mainly influenced by the impeller type, while the power demand at the off-bottom suspension point was more dependent of the impeller size and clearance. For bottom-mounted baffles a minimum in the Power number was noticed with increased clearance. It was found the minimum was located at the transition point between two different How patterns. This study shows that the configuration with the lowest Power number is not necessary the most efficient for suspending solid particles.