A study of the mechanism of adsorption of ethyl cellulose on silver powder

Abstract

The mechanism of adsorption and desorption of ethyl cellulose (EC) on and from silver powder was studied. After analysis with DSC, XPS and dynamic FT-IR, which could be heated by a program-controlled heater, applied to observe the states of pure EC and of EC adsorbed on silver powder, and also the thermal decomposition of EC from silver powder, the chemisorption bonding bridge between the 0xygen atoms of EC and the silver atoms investigated. The differences in thermal decomposition between pure EC and EC adsorbed in silver powder were also studied. It was concluded that the ehemisorption bonding between the oxygen atoms of EC and the silver atoms mainly involved the lone-pair electrons of the oxygen atoms on the EC chain and the outer empty 5 sp a hybrid orbital of the silver. Because of the formation of this bridge, the bonds between neighboring carbon and oxygen atoms are weakened. As a result of this effect, the C-O bonds in the EC chain are broken more easily than the C-H bonds, which leads to the observation of--C-H-fragments in the upper space when EC adsorbed on silver is heated. When the same experiments were carried out on pure EC, almost all kinds of broken fragments of the EC molecule, including --C-H-, -C = O-and --C-O--appeared simultaneously.

Direct‐Write Fabrication of Pb(Nb,Zr,Ti)O3 Devices: Influence of Paste Rheology on Print Morphology and Component Properties

“…31 In related work, Tohver et al 23 studied the aging behavior of ZnO varistor thick film pastes and found that the low shear apparent viscosity of samples stored at elevated temperatures (40°-50°C) decreased to its steady state value more rapidly than samples aged equivalent times at room temperature (22°C). Such behavior suggests that the kinetics of dispersant diffusion/adsorption may be accelerated by heating, thereby reducing the aging time required to achieve steady-state rheological behavior.…”

“…These observations suggest that aging phenomena in pastes prepared from as-received powders results from slow diffusion of dispersant molecules to the particle surface in the high-viscosity vehicles utilized, thereby retarding dispersant adsorption and, hence, particle stabilization. 31 In related work, Tohver et al 23 studied the aging behavior of ZnO varistor thick film pastes and found that the low shear apparent viscosity of samples stored at elevated temperatures (40°-50°C) decreased to its steady state value more rapidly than samples aged equivalent times at room temperature (22°C). Such behavior suggests that the kinetics of dispersant diffusion/adsorption may be accelerated by heating, thereby reducing the aging time required to achieve steady-state rheological behavior.…”