title: High frequency rheometry of viscoelastic coatings with the quartz crystal microbalance.
abstract: We describe a quantitative method for using the quartz crystal microbalance (QCM) to characterize the high frequency viscoelastic response of glassy polymer coatings with thicknesses in the 5-10 μm regime. By measuring the frequency and dissipation at the fundamental resonant frequency (5 MHz) and at the third harmonic (15 MHz), we obtain three independent quantities. For coatings with a predominantly elastic response, characterized by relatively low phase angles, these quantities are the mass per unit area of the coating, the density-shear modulus product, and the phase angle itself. The approach was demonstrated with a model polyurethane coating, where the evolution of these properties as a function of cure time was investigated. For fully cured films, data obtained from the QCM are in good agreement with results obtained from traditional dynamic mechanical analysis.
authors.affiliation: Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States.
authors.forename: Garret C
authors.initials: GC
authors.lastname: DeNolf
authors.forename: Larry
authors.initials: L
authors.lastname: Haack
authors.forename: Joe
authors.initials: J
authors.lastname: Holubka
authors.forename: Ann
authors.initials: A
authors.lastname: Straccia
authors.forename: Kay
authors.initials: K
authors.lastname: Blohowiak
authors.forename: Chris
authors.initials: C
authors.lastname: Broadbent
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Shull