Depth profiles and free volume in aircraft primer films

11th International Workshop on Positron and Positronium Chemistry

物理学;化学

Van Horn, J.D.^1 ; Chen, H.^1 ; Jean, Y.C.^1 ; Zhang, W.^2 ; Jaworowski, M.R.^2

Department of Chemistry, University of Missouri-Kansas City, 5110 Rockhill Road, Kansas City

MO

64110, United States^1

Physical Sciences Department, United Technologies Research Center, 411 Silver Lane, East Hartford

CT

06108, United States^2

关键词: Anisotropic behaviours;    Energy spectroscopy;    Layered Structures;    Nondestructive methods;    Positron annihilation lifetime spectroscopy;    Positron beams;    Study materials;    Water-vapour transport rates;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/618/1/012023/pdf
DOI  :  10.1088/1742-6596/618/1/012023

来源: IOP

【 摘 要 】

Positron annihilation lifetime spectroscopy (PALS) and associated techniques provide non-destructive methods to study the free volume inside polymeric materials, and to study material characteristics over a depth profile. Cast free films of organic-or aqueous-based, non-chromated aerospace primers, when cured for about one week, had very different water vapour transport (through-plane) behaviour. In addition, both types of primer films showed strong anisotropic behaviour in in-plane versus through-plane water vapour transport rates. We report the differences between the organic-and aqueous-based aircraft primer films samples and their surface depth profiles. In bulk PALS measurements, an aged, organic-based film exhibited typical lifetimes and intensities for a particulate-containing polymer film on both faces. In contrast, aqueous-based films exhibited face oriented-dependent differences. In all aqueous-based samples, the I3 value of the back of the sample was smaller. The primer film samples were also evaluated with mono-energetic positron beam techniques to generate depth profile information. The heterogeneity in the samples was verified by Doppler broadening of energy spectroscopy (DBES). A model for the differences in the faces of the films, and their layered structure is discussed.