(203b) Determination of the Viscoelastic Shear Modulus of Poly(Isobutylene)/Solvent Systems Using Thickness-Shear Mode Quartz Resonators

Characterization of the storage modulus, G', loss modulus, G", and, consequently, the shear moduli, G (G = G' + jG" ), of polymer and polymer/solvent systems was conducted in this study using a thickness-shear mode (TSM) quartz resonator. The polymeric substance polyisobutylene was spin-coated as a film of a few microns thickness on the surface of the TSM device and, upon inducing oscillation of the device at its resonance frequency (several mega-Hertz), the impedance characteristics were measured. In addition, the polyisobutylene was exposed to known weight concentrations, up to 20%, of benzene, toluene, cyclohexane, and chloroform vapors diluted in nitrogen gas, and the impedance characteristics were measured. These data sets collected from the impedance analyzer were then examined by modeling the polymer and polymer/solvent loaded TSM device with an electrical equivalent circuit model to yield the shear moduli, which enters as a parameter in the mathematical theory describing this circuit model.

Reference: J. Hossenlopp, L. Jiang, R. Cernosek, F. Josse, Characterization of Epoxy Resin (SU-8) Film Using Thickness-Shear Mode (TSM) Resonator Under Various Conditions, J. Polymer Science 42 (2004) 2373-2384.