Concerning voids in polyimide

Small angle X‐ray scattering (SAXS) has been used to evaluate the size and concentration of voids in poly(N,N′‐bis‐(phenoxyphenyl)pyromellitimide), PMDA‐ODA. Analysis of the angular dependence of the scattering indicates the presence of voids ranging from 50 to 150 Å in radius. Integrated SAXS demonstrated that the volume fraction of voids was 7 × 10−4. These results were supported by measurements of the attenuation factor as a function of the sample thickness. Copyright © 1984 Society of Plastics Engineers, Inc.