Sorption of water and organic solutes in polyimide films and its effects on dielectric properties

Abstract

The effect of structure on the sorption kinetics of water and of various organic solutes into polyimide (PMDA‐ODA) thin films was studied. The major techniques employed include measurements of sorption kinetics, density, and dielectric relaxation. More solute uptake, lower densities and higher diffusivities were observed for films cured at lower temperatures. By measuring both changes of mass and of density, the volume expansion of the polymer due to each solute was obtained; this was found to be proportional to the molar volume of the solute. The two dielectric relaxation peaks (denoted by γ1 and γ2) due to water (and other solutes) were studied in detail to obtain the relevant activation energies and the separate dipole moments. While water and methylene chloride appear in both γ1 and γ2 configurations, methyl and ethyl alcohol appear mainly as γ2, while acetic acid is primarily γ1. It was concluded that the γ1 configurations are relatively homogeneously distributed throughout the polymer, involving loose bonding to the polymer structure, while the γ2 configurations involve small clusters, probably chains of molecules. © 1993 John Wiley & Sons, Inc.

On the mode II popcorn effect in thin packages

“…It was observed, in accordance with earlier publications [10], [11], that the popcorn effect began with a delamination, which occurred after a certain time measured after the package had been immersed into the hot liquid, followed by doming and ending with package cracking at the time . Fig.…”

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Effect of water on the relaxation spectrum of poly(methylmethacrylate)

“…Interactions of water with the polymer segments may hinder the local motions characteristic of the dry macromolecule and give rise to bulkier units that can relax only at higher temperatures [5][6][7][8]. Alternatively, addition of water can intensify a pre-existing secondary relaxation [9][10] or induce new low-temperature loss processes in polymers that exhibit no secondary absorptions in the dry state in the range from 80 to 250 K [3,11]. Among polymers with a hydrophobic main chain, Polymethylmethacrylate is considered an example of the last behavior.…”

Water‐sorption behaviors of poly(3,4′‐oxydiphenylene pyromellitimide) films depending on the thickness variation

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