Effects of Polyelectrolyte as a Dispersant on Slip Casting of Ceramic Slurries

聚电解质作为分散剂对陶瓷浆料注浆成型的影响

基本信息

批准号：
07651016
负责人：
HASHIBA Minoru
金额：
$ 1.28万
依托单位：
Gifu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

It is desirable in slip casting to prepare concentrated slurries whilst retaining fluidity. A polyelectrolyte as a dispersant is effective for thickening of the slurries and that polymer have a characteristic function in fluidizing slurries, other than that dispersion and stabilization. The flow point refers to the least amount of a medium (the thickening limit) required for a definite amount of powder of a start to flow. The fluidity of the slurries in the vicinity of the thickening limit was affected by a kind of dispersant, the concentration and molecular weight of dispersants and the solid loading in the slurries. The dispersion accompanied by fluidization and the limit of thickening should be related to the structure of the length extension of dispersant (the conformation of dispersant) in the adsorption layr on the ceramic particles and also to the interaction among such solid particles in the concentrated slurry. A polyelectrolyte dispersant has electrostatic effect and an addit … More ional steric effect since the polymer expands in the adsorption layr thereby exceeding the effective distance that the van der Waals attraction force operates over.An average shell volume occupied in the adsorption layr on alumina by a polyacrylic acid ammonium salts molecule (PAA) defined as the average area occupied by an adsorped PAA on alumina multiplied by the average thickness of the water layr at the limit of thickening, has been calculated from the adsorbed amount of PAA and from the flow points of alumina in the presence of PAA of different molecular weights. A steric effect of the PAA dispersant on the dispersion of alumina resulted in a flow with no yield stress. This was due to the change of the extension of PAA in the adsorption shell from a sphere to an ellopsoid with a long axis which exceeded the effective distance that the van der Waals attraction force reaches at a molecular weight for the PAA of between 10,000-20,000.It was also developed the determination method of polyelectrolyte and discussed the effects of pH changes on the conformation changes for polymers in the slurries, the adsorbed amount of polymers and the dispersion accompanied by fluidization in the presence of dispersant. Less

在注浆浇铸中期望制备浓缩浆料，同时保持流动性，作为分散剂的聚电解质对于浆料的增稠是有效的，并且除了分散和稳定之外，聚合物还具有使浆料流化的特征功能。一定量的粉末开始流动所需的最少介质量（稠化限度）稠化限度附近浆料的流动性受到一种分散剂的影响。分散剂的浓度和分子量以及浆料中的固体负载量，伴随流化的分散和增稠的极限应与陶瓷颗粒吸附层中分散剂的长度延伸结构（分散剂的构象）有关。以及浓缩浆料中此类固体颗粒之间的相互作用，聚电解质分散剂具有静电效应和附加离子空间效应，因为聚合物在吸附层中膨胀，从而超过了吸附层。范德华吸引力起作用的有效距离。聚丙烯酸铵盐分子（PAA）在氧化铝吸附层中占据的平均壳体积定义为氧化铝上吸附的PAA占据的平均面积乘以平均厚度稠化极限时水层的厚度，是根据 PAA 的吸附量和不同分子量的 PAA 存在下氧化铝的流点计算得出的。 PAA分散剂对氧化铝分散的空间效应导致无屈服应力的流动，这是由于PAA在吸附壳中的延伸从球体变为长轴的椭球体，超过了有效距离。 PAA的分子量在10,000-20,000之间时范德华吸引力达到。还建立了聚电解质的测定方法并讨论了聚电解质的影响。 pH变化对浆料中聚合物的构象变化、聚合物的吸附量以及分散剂存在下伴随流化的分散体的影响较小。