Polyvinyl butyral as a dispersant for barium titanate in a non-aqueous suspension

Abstract

Polyvinyl butyral (PVB) was used as a dispersant for BaTi03 in a toluene-methanol system and its efficiency was evaluated by measuring the zeta potential and by a rheological study of the suspension. Addition of only 1.6 vol % Iow-mo ecu ar-weight (50 000) PVB is effective in making a well-dispersed suspension. But a lower concentration (0.6 vol %) of high-molecularweight (200 000) PVB is necessary to stabilize the suspension due to the longer chain length of the polymer, which enhances steric stabilization. Dispersion of BaTiO3 by PVB is better in a reverse azeotropic composition of toluene-methanol (72.4:27.6) than in an azeotropic composition.

Rheological properties of tin oxide suspensions

“…As the concentration increased, the rheological behavior became dilatant, which is characteristic of highly loaded suspensions with a high repulsive force between particles. 19 The suspension having a 25.1 vol.% of solids presented pseudoplastic behavior, indicating poor dispersion. In other words, PVB is not efficient in dispersing concentrated suspensions (> 21 vol.%).…”

“…19 What part of the copolymer is adsorbed on the particle's surface is still a controversial issue. While it is usually assumed that adsorption is due to PVB, Parker and Sacks studied copolymers containing different amounts of PVA and demonstrated that adsorption on the alumina increases as the amount of PVA increases.…”

“…On the other hand, a good solvent results in an increase in deflocculant efficiency owing to the formation of loops and tails extending from the surface of the particle into the liquid. 19 A similar study was also carried out for PAA. The deflocculant used had an average molecular weight (M n ) of 9308 daltons, a maximum molecular weight (M w ) of 63,027 daltons and a polydispersivity (M w /M n ) of 6.77.…”

“…As mentioned earlier, dilatancy is characteristic of highly charged suspensions, where the repulsive force between particles is high. 19 …”

Estudio del proceso de sinterización de componentes cerámicos para pilas de combustible de óxidos sólidos

“…En el colado en banda, se prefiere utilizar una mezcla de dos disolventes a trabajar con un líquido puro, porque la solubilidad de los polímeros es generalmente mayor en un sistema mixto optimizado que en cualquier disolvente 75 . Las características de los disolventes a elegir dependerán de la naturaleza de los aditivos empleados para estabilizar la suspensión y para conferir la resistencia mecánica adecuada a la pieza colada en crudo.…”