ELASTIC PROPERTIES OF POLYMER-FILMS .1. ELASTIC-CONSTANTS OF A POLYIMIDE FILM DETERMINED BY BRILLOUIN-SCATTERING AND MECHANICAL TECHNIQUES

We discuss here the complete determination of the elastic properties o f polymeric film using two experimental techniques. One technique empl oys the polymer film as a vibrating membrane and allows a direct deter mination of the ''macroscopic'' biaxial modulus, which serves as a fig ure of merit of polymer performance in applications such as packaging. Brillouin scattering, which measures the elastic properties on a appr oximately 100-mum scale, allows for a complete characterization of the elastic behavior. Both techniques have been applied to polyimide film s. The results obtained by the two techniques are in agreement within the reported error bars.