化学助剂在造纸过程中的应用

主要介绍了造纸过程中,为了提高纸页的质量,提高填料和细小纤维的留着率,提高生产效率,降低成本所用的一些化学助剂具体应用。     

染料分散剂的研究现状及发展趋势

介绍了木质素类分散剂、萘磺酸甲醛缩合物和聚羧酸系分散剂．简述了溶胶稳定性理论（包括经典的DLVO理论、空间稳定理论及空缺稳定理论）指出了稳定性领域存在的不确定因素，并对染料分散剂的研究开发与工业应用前景作了展望．     

分散剂对超细α-Al2O3浆料流变性的影响

以66％丁酮(质量分数,下同)和34％乙醇的共沸混合物为溶剂,测定了α-Al_2O_3超细粉体在该溶剂系统中所得浆料的流变性。研究了三油酸甘油酯(GTO)、蓖麻油(CTO)以及它们的混合物对α-Al_2O_3粉体在该溶剂中的稳定性的影响。实验发现,在0～300 s~(-1)的剪切区,不同条件下测得的流变曲线均符合Casson模型。实验结果显示,同时加入GTO与CTO的浆料,当GTO所占比例在2/3到5/6的范围内时,其流变性明显优于由单种分散剂分散的浆料。     

Preparation of Hydroxyapatite Lathlike Particles Using High-Speed Dispersing Equipment

Hydroxyapatite lathlike monocrystalline particles were prepared using high-energy dispersing equipment in combination with a pH shock-wave method. The Ca/P atomic ratios were very close to theoretical, and the acidic group content was very small. The particles were nonporous, with anisotropic crystal growth and average grain size ∼140–1300 nm in length, ∼20–100 nm in width, and ∼10–40 nm in thickness. The high-speed dispersing equipment created the proper hydrodynamic conditions for lathlike particle growth in the [001] direction. The hydroxyapatite particles formed aggregates of 1–5 μm average diameter.     

Probing Polymeric Stabilization in Nonaqueous Media by Direct Measurements

The steric repulsion induced by adsorbed layers of the commercial dispersant Hypermer KD3 has been probed by direct measurements in decalin. The forces are long range (commencing at 30–40 nm) and repulsive, and the distance dependence can be modeled with a simple scaling theory expression valid for polymer brushes. We obtain layer thicknesses of ∼9–15 nm for the compressed layers, depending on KD3 concentration, whereas the undisturbed layers have a thickness of ∼23–24 nm, independent of polymer concentration. Comparison of the measured interaction lengths with previous layer thickness estimates based on rheological studies shows that the polymer layers are compressed in dense suspensions.     

Weakly Flocculated Aqueous Alumina Suspensions Prepared by the Addition of Mg(II) Ions

Well-dispersed aqueous alumina suspensions were prepared at an inherent pH via the addition of an anionic dispersant. With the addition of an appropriate amount of magnesium acetate to such a suspension, the surface charge of the particles was neutralized, which was reflected in the destabilization of the slurry. Because of the formation of coordinative bonds between the Mg ion and the two dissociated carboxylic groups of the dispersant, a thin neutral layer was formed on the surface of the particles, which established a nontouching particle network and resulted in a weakly flocculated suspension.     

分散剂浓度、遮光度、超声分散时间对钼粉粒度分布测试结果影响的分析研究

本文通过研究Mastersizer2000型激光粒度分析仪，在不同浓度的分散剂，不同的遮光度，以及不同的超声波分散时间3个方面，对测定钼粉的粒度分布测试结果所造成的影响，从而找出钼粉粒度分布测试的最佳条件，为钼粉性能的判定提供准确的数据。     

分散剂对钛白粉分散性能及机理的研究

研究了3种分散剂对钛白粉的分散性能,结果表明硅酸钠、六偏磷酸钠和 DA1705都有分散效果,且DA1705的分散效果最好。并从表面电位方面分析了分散机理,3种分撒及都是通过水解成离子状态,吸附在颗粒表面,使颗粒表面带电,增加了彼此的排斥力,阻止了颗粒之间的团聚。     

Effects of Organic Dispersants on the Dispersion, Packing, and Sintering of Alumina

The effects of water-soluble polymers and benzoic acid derivatives on green and sintered Al₂0₃ compacts were studied for two types of alumina powder. The percent of theoretical density achieved by each Al₂0₃ sediment was dependent primarily on the concentration of water-soluble polymeric dispersant rather than on the pH. Aromatic acids, such as 4-hydroxy- and 4-aminobenzoic acid, were also effective dispersants. The final density and grain size of sintered compacts depended on the green microstructure of the compacts and on differences in the concentration of trace elements in the two powders.     

The application of lateral force microscopy to particle removal in aqueous polymer solutions

Abstraet-An atomic force microscope (AFM) has been used to examine the effect of a typical polymeric dispersant on the adhesion between an iron oxide sphere and a silicon wafer in the presence and absence of shear. Two separate methods for the determination of the lateral spring constant (k₁) of AFM cantilevers were employed. Determination of k₁ allows the absolute, rather than relative, shear force to be extracted from the lateral force output of the AFM. A comparison is made between the pull-off force (no shear) and the lateral force as the dispersant concentration and loading force are varied. While in both cases the magnitude of the forces decrease with increasing dispersant concentration, the effect is much less marked for the lateral force. A linear increase in removal forces with increasing loading force was observed. For a given load, the removal force is typically an order of magnitude smaller in the presence of shear.