凹凸棒／烷基糖苷悬浮液流变行为研究

以烷基糖苷（APG）为分散剂,系统研究分散剂的用量对凹凸棒悬浮液流变性的影响,运用等温吸附和Zeta电位测定技术对流变作用机制进行分析,并用六种流变模式对悬浮液的流变曲线进行了拟合,结果表明,随烷基糖苷浓度的增大,悬浮液的塑性粘度出现减小、增加再减小的趋势,其中,烷基糖苷浓度为200mg／L时凹凸棒悬浮液塑性粘度最大,该浓度也是悬浮液由“剪切变稀”向“剪切变稠”的转变点。凹凸棒／烷基糖苷悬浮液的流变曲线符合Herschel Buikley流变模型。     

纳米SiO2/聚乙二醇复合体系剪切增稠特性与机制

为分析纳米固体颗粒在剪切增稠液体(STF)稠化过程中的影响及其在中低速稳态剪切和高速动态冲击环境下发挥的作用,以纳米SiO2和聚乙二醇(PEG 200)作为分散相和连续相,以不同含量的纳米石墨和纳米金刚石颗粒为添加剂,制备STF.研究样品的摩擦系数曲线和不同温度下的流变特性,以临界剪切速率、稠化区间长度和增稠比为指标依...     

羧甲基纤维素对铜版纸涂料流变行为的影响

通过在铜版纸面涂涂料中增加羧甲基纤维素用量来改善涂料流变性和保水性,对涂料的稳态剪切流变行为进行了研究。结果表明,随着剪切速率的增加,涂料表现出剪切稀化,呈现假塑性流体特性;另外,在同一剪切速率下,增加羧甲基纤维素加入量,涂料的表观粘度变大。采用两参数的Bingham,三参数的Herschel-Bulkley及四参数的Carreau方程对涂料的流变曲线进行了数学拟合。结果表明,Carreau方程能够准确地描述涂料的流变曲线,Herschel-Bulkley方程次之,而Bingham方程拟合效果较差。根据Carreau方程拟合结果,羧甲基纤维素加入量为0.5%,0.8%和1.0%时,涂料的零剪切粘度分别为100.8,155.7,161.8 Pa·s,极限粘度相应为0.03170,0.03934和0.05764 Pa·s,这说明羧甲基纤维素对铜版纸涂料具有明显的增稠作用。另外,涂料流动特性指数均小于1.0,呈现明显的假塑性流体特性,这与剪切稀化的实验流变结果吻合。     

氧化铝黑瓷浆料流变性能的研究

通过对氧化铝黑瓷粉料进行预烧技术处理,增大颗粒尺寸、降低粉体比表面能、改善其团聚现象,制备出固相体积分数达55%的氧化铝黑瓷稳定料浆,并研究了分散剂用量、体系固相体积分数、R值(塑性剂/粘结剂)对料浆流变性的影响.结果表明:浆料的粘度随剪切速率增加而下降,呈剪切稀化的流变学特性,随着固相体积分数的增加,浆料的最佳分散剂用量也相应增加;浆料的粘度随着R值的增加而急剧降低,流变性能得到明显改善.     

超细二氧化钛在水溶液中分散性研究

采用沉降法研究了不同分散剂对超细二氧化钛粉末在水溶液中分散性的影响。结果表明:SDS、TPB、聚丙烯酸钠、乙二醇是超细二氧化钛粉末的有效分散剂。通过测定颗粒表面Zeta电位、悬浮体系粘度,分析了分散剂的作用机理。实验结果表明:SDS、TPB、聚丙烯酸钠能显著提高水溶液中二氧化钛表面Zeta电位绝对值,增大了颗粒间静电排斥力,改善了悬浮液稳定性,降低了体系的粘度。而乙二醇能在颗粒表面形成良好的溶剂化层,提高了二氧化钛在水溶液中的分散稳定性。     

D-山梨醇对聚丙烯酸-水基氧化铝悬浮液流变性能的影响

研究了D-山梨醇(D-sorbitol)对聚丙烯酸(poly(acrylic acid))(PAA)稳定的水基氧化铝(Al₂O₃)悬浮液流变性能的影响. 实验发现: 在pH为9.0时, 对于固含量为30vol% ~ 40vol%的Al₂O₃悬浮液, 少量D-山梨醇的加入皆能明显提高其分散稳定性. 当D-山梨醇的添加量占分散剂总量(0.5wt%)的20%时, 悬浮液粘度最低. 且添加二元分散剂PAA/D-山梨醇的悬浮液具有更好的抗电解质性能. 分别对单一PAA分散的Al₂O₃及二元分散剂分散的Al₂O₃进行了红外光谱表征. 结合流变与红外实验结果, 分析了山梨醇的作用机理: 部分山梨醇吸附在Al₂O₃颗粒表面, 部分山梨醇与PAA以氢键形式结合, 增大了颗粒间的空间位阻, 提高了悬浮液的流变性能.     

锐钛型二氧化钛/水悬浮体的流变性研究

本文用流变学的方法在Ｂｒａｂｅｎｄｅｒ流变仪上研究了不同因素对二氧化钛悬浮体流变性的影响。在同一体积分率下,与粒度分布宽的颗粒形成的悬浮体相比,粒度分布窄的颗粒形成的悬浮体其屈服和稳态剪切粘度较大;在二氧化钛体积分率很小时,悬浮体呈牛顿性;当体积分率大于一定值时,悬浮体具有零切粘度的剪切稀化特征;当其大于一临界值时,存在屈服应力并有强的剪切稀化行为。悬浮全粘度服从广义Ｑｕｅｍａｄａ流变方程。在温度     

氧化铝-水纳米流体的制备及其分散性研究

通过在水介质中添加纳米氧化铝粒子,研制了一种新型传热冷却工质Al2O3-H2O纳米流体,给出的纳米流体沉降照片和粒径分布显示了加入分散剂的悬浮液具有较高的分散性、稳定性.同时还测定了纳米Al2O3-H2O悬浮液的zeta电位和吸光度,探讨了不同pH值和SDBS分散剂加入量对纳米氧化铝粉体在水相体系分散稳定性的影响.结果表明:zeta电位的绝对值与吸光度有良好的对应关系,zeta电位绝对值越高,吸光度越大,粉体体系的分散性能越好;pH值约在8.0时,溶液的zeta电位绝对值较高,吸光度较大,说明此时有较好的分散效果;SDBS能显著提高水溶液中Al2O3表面zeta电位绝对值,增大了颗粒问静电排斥力,改善了悬浮液稳定性.在0.1%纳米Al2O3-H2O悬浮液中,SDBS分散剂最佳加入量(质量分数)为0.10%时,能得到分散稳定的悬浮液体系.     

氧化铝-水纳米流体的分散性研究

通过在水介质中添加纳米氧化铝粒子，研制了一种新型传热冷却工质-氧化铝-水纳米流体，给出的纳米流体沉降照片和粒径分布显示了加入分散剂的悬浮液具有较高的分散性、稳定性．同时还测定了纳米Al2O3-水悬浮液的zeta电位和吸光度，探讨了不同pH值和SDBS分散剂加入量对纳米氧化铝粉体在水相体系分散稳定性的影响。结果表明：zeta电位的绝对值与吸光度有良好的对应关系，zeta电位绝对值越高，吸光度越大，粉体体系的分散性能越好；pH值约在8.0时，溶液的zeta电位绝对值较高，吸光度较大，说明此时有较好的分散效果．SDBS能显著提高水溶液中舢203表面zeta电位绝对值，增大了颗粒间静电排斥力，改善了悬浮液稳定性。在0．1％纳米Al2O3-水悬浮液中，SDBS分散剂最佳加入量（质量分数）为0．10％时，能得到分散稳定的悬浮液体系。     

石墨烯对剪切增稠液挤压流动力学性能的影响

含有剪切增稠液的振动控制装置在服役阶段涉及挤压过程,研究剪切增稠液的挤压力学性能有着重要的意义.采用石墨烯增强纯二氧化硅纳米颗粒剪切增稠液,并利用旋转流变仪开展了挤压流动实验,测试了不同剪切增稠液的流变性能和挤压流动力学性能,得到了黏度曲线以及不同挤压速度下法向应力和临界间隙的变化规律,分析了石墨烯对剪切增稠液流变性能...     

The influences of particle–particle interaction and viscosity of carrier fluid on characteristics of silica and calcium carbonate suspensions-coated Twaron® composite

The effects of particle–particle interaction and viscosity of carrier fluid on steady and dynamic rheological responses and quasi-static penetration resistance of Twaron® fabrics treated with shear thickening and shear thinning suspensions have been investigated. The suspensions have been made by mechanically dispersing 60 nm silica (SiO₂) and calcium carbonate (CaCO₃) nanoparticles in poly ethylene glycol (PEG) with molecular weights of 200 and 400 g/mol. The CaCO₃ suspensions display shear thinning behaviour along with the total dominance of the elastic state over the viscous state while the SiO₂ suspensions exhibit shear thickening behaviour with the emergence of both the elastic and viscous states. With the increase of molecular weight of PEG, viscosity, viscoelastic modules and instability of the suspensions increase and critical shear rate and frequency of transition to elastic state diminish. The PEG200 and PEG400-contained SiO₂ suspensions-treated Twaron® composites at 35 wt.% have quasi-static penetration resistances which are nearly 2.63 and 2.48 times and maximum absorbed energies which are about 1.54 and 1.55 times higher, respectively, than those of the corresponding CaCO₃ ones. However, the influence of increasing the PEG's molecular weight is not as considerable as the effect of particle–particle interaction on the enhancement of penetration resistance performance.     

碱性水基氧化铝陶瓷料浆的流变学研究

采用流变的方法在RV－20型流变仪上研究了不同条件对碱性氧化铝悬浮体的流变性的影响，重点研究了固含量，分散剂加入量，球磨工艺对料浆流变性的影响，结果表明：分散剂的加入量对料浆的临界剪切速率具有显著的影响，随着球磨时间的延长，料浆的“剪切增厚”临界剪切速率增大。     

Dispersion and Rheological Properties of Alumina/Zirconia Slurries with Methyl Isobutyl Ketone/Ethanol Solvents

The dispersion and rheological behavior of alumina, zirconia, and alumina/zirconia mixed slurries were investigated using various solvent ratios of methyl isobutyl ketone (MIBK)/ethanol (EtOH), by measuring sedimentation bulk density, particle size distribution, and viscosity. Well-dispersed suspensions were obtained in MIBK-rich solvents with additional dispersant and in EtOH-rich without dispersant. The shear viscosity of the slurries was dependent on both the Al₂O₃/ZrO₂ ratio and MIBK/EtOH ratio. At a constant solvent ratio, however, similar rheological behavior was shown regardless of the relative amounts of the two solids. At low shear rate, a Newtonian plateau was absent in the Al₂O₃/ZrO₂ slurries. With increasing shear rate (>600 s^–1), Al₂O₃ slurries exhibited a Newtonian plateau while ZrO₂ demonstrated continuous shear thinning.     

SiO2粉体粒径对STF/Kevlar复合材料防刺性能的影响

采用自制的不同粒径的SiO₂粉体, 利用球磨分散技术配制具有剪切增稠特性的SiO₂/PEG200悬浮液流体(STF), 并利用静态浸渍方法制备STF/Kevlar复合材料, 研究了粉体粒径对流体体系流变性能和复合材料防刺性能的影响。结果表明, 不同粒径SiO₂粉体配制的悬浮液均具有明显的剪切增稠性能, 当SiO₂粉体质量分数相同时, 流体体系的起始黏度、 临界剪切速率、 最大黏度均随着粒径的增大而减小。16层STF/Kevlar试样能承受24.0 J锥体冲击, 远远优于相同面密度的纯Kevlar试样, 随着粒径的增加, 试样的防锥刺性能提高。刀体冲击能量为13.0 J时, STF/Kevlar试样的防刀刺性能优于相同面密度的纯Kevlar试样, 随着粒径的增大, 试样的被刺穿深度减小, 主要表现为剪切断裂破坏。      

SiO2粉体粒径对Kevlar/STF复合材料防刺性能的影响

采用自制的不同粒径的SiO2粉体,利用球磨分散技术配制具有剪切增稠特性的SiO2/PEG200悬浮液流体(STF),并利用静态浸渍方法制备Kevlar/STF复合材料,研究了粉体粒径对流体体系流变性能和复合材料防刺性能的影响。结果表明,不同粒径SiO2粉体配制的悬浮液均具有明显的剪切增稠性能,当SiO2粉体质量分数相同时,流体体系的起始黏度、临界剪切速率、最大黏度均随着粒径的增大而减小。16层Kevlar/STF试样能防住24.0J锥体冲击,远远优于相同面密度的纯Kevlar试样,随着粒径的增加试样防锥刺性能提高。刀体冲击能量为13.0J时,Kevlar/STF试样的防刀刺性能优于相同面密度的纯Kevlar试样,随着粒径的增大试样被刺穿深度减小,主要表现为剪切断裂破坏。     

Continuous shear thickening and discontinuous shear thickening of concentrated monodispersed silica slurry

Concentrated slurry is known to exhibit shear thickening behavior, in which viscosity increases as the shear rate ascends. However, to identify the differences between this shear thickening behavior and rapid increases in viscosity (such as the dilatancy behavior of starch, sand, and other concentrated slurries) and the smooth increases in viscosity exhibited by concentrated slurries, this research investigated the rheological behavior of a polyethylene glycol suspension containing monodispersed silica particles with a size of 2.5 μm. The results found that the increases in viscosity as the shear rate ascends or the increases in elasticity as the strain ascends change consecutively from smooth and reversible behavior (i.e., continuous shear thickening (CST)) to rapid and irreversible behavior (i.e., discontinuous shear thickening (DST)) simply by increasing the concentration of the slurry, even in the case of concentrated slurries comprising of the same particles. DST is a manifestation of dilatancy in which a jamming transition occurs due to collisions between particles. Because CST transitions successively to DST, and the on-set shear stress of shear thickening of CST is almost the same with that of DST, shear thickening in the CST region may, therefore, also be regarded as the result of friction due to collisions between particles. This supports the research by Seto, Mari, Poon et al., which stated that shear thickening occurs due to friction from particle collisions.     

Mullite-zirconia composites: Effect of citric acid addition on slip and cast properties

Dispersion of mixed suspensions of zircon and α -alumina using citric acid as dispersant followed by pressure filtration produced after sintering (1600^∘C—2 h) dense mullite-zirconia composites. The effect of citric acid addition and pH on the rheological behavior of the mixed suspensions (57 vol%) was examined. Most of flow curves showed a shear thinning behavior at low shear rates reaching the viscosity a plateau at high shear rates. Newtonian viscosity at high shear rates values decreased to a minimum and then increased with increasing the amount of dispersant added. Compacts prepared from well stabilized suspensions achieved a maximum relative density of 72% (theoretical) which is slightly higher than that obtained from suspensions dispersed with a polyelectrolyte. Characteristics of sintered compacts such as density and crystalline phase composition by XRD were determined.     

Rheological characterization of xanthan suspensions of nanoscale iron for injection in porous media

Nanoscale zerovalent iron (NZVI) represents one of the most interesting reagents for the remediation of contaminated aquifers, but its application is hindered by a lack of colloidal stability. Prior studies have shown that nanoscale iron slurries can be successfully stabilized against aggregation and sedimentation through dispersion in xanthan solutions; thus, further research was carried out by focusing on the flow behavior of xanthan-modified NVZI suspensions. This work aims at understanding the rheological properties of NZVI-xanthan suspensions, which have been extensively tested under two different flow conditions: simple shear flow and flow through a porous medium. According to both experimental approaches, the suspensions show a shear thinning behavior that is dependent on iron concentration. These rheological properties are explained by referring to the microstructure of the colloidal system. Flow equations have been formulated and solved in radial coordinates in order to demonstrate the feasibility of such suspensions in field scale applications.     

不同中和度聚苯乙烯-丙烯酸粒子的聚乙二醇悬液剪切增稠特性研究

实验采用无皂乳液聚合法,以NaHCO_3为中和剂,合成了一系列不同中和度的聚苯乙烯-丙烯酸(PS-AA)粒子。分别通过一步法、两步法合成了两种PS-AA粒子,并通过扫描电镜(SEM)观察了两种粒子的微观形貌。采用高能球磨法将粒子分散到聚乙二醇中,制备得到PS-AA/PEG剪切增稠液(STF),并通过动态流变仪稳态扫描测试了其聚乙二醇悬液的剪切增稠特性,结果表明用两步法合成的粒子作分散相可制备出优良的剪切增稠液。通过红外光谱、热重-DSC、扫描电镜、激光粒度分布仪对不同中和度的粒子进行了表征,并通过动态流变仪对其聚乙二醇悬液流变性能进行表征。结果表明,实验成功合成了不同中和度且表面光滑、粒径均一的核壳状的PS-AA粒子,并以此制备出性能优异的剪切增稠液,得出最优中和度为45%和50%。其中50%中和度PS-AA粒子,其质量浓度为64%的聚乙二醇悬液最大粘度高达2 200Pa·s,该性能在抗外力防护领域研究成果内出类拔萃。