Accession Number:

ADA426943

Title:

Dielectric Non-Destructive Analysis of Adhesive Bonded Structures

Descriptive Note:

Final rept. 1 Apr 2001-30 Jun 2004

Corporate Author:

POLYTECHNIC UNIV BROOKLYN NY

Personal Author(s):

Report Date:

2004-09-28

Pagination or Media Count:

148.0

Abstract:

An investigation was conducted aimed at developing dielectric spectroscopy as a non-destructive inspection tool to assess aging of adhesive bonded structures. Dielectric spectroscopy was found to be a sensitive tool capable of detecting defects and absorbed moisture in adhesive bonded structures. The highlights of the research performed are l The defects in adhesive joints decrease the real and imaginary dielectric permittivity in the frequency domain and induce additional peaks in the time domain spectra 2 The dielectric spectra of dry epoxy-amine networks are characterized by two Arrhenius-like local relaxations the beta process, associated with hydroxyl groups and the gamma process, associated with primary and secondary amine, and glycidyl ether groups 3 Dynamics of beta and gamma processes are affected by short time aging. New relaxation processes appear in both model and commercial epoxy-amine adhesives after long term exposure to moisture. 4 Time domain reflectometry TDR traces shift to longer time with water ingress in the early stages of aging, but this trend is reversed at some critical time, which is possibly a signature of disbonding.

Subject Categories:

  • Adhesives, Seals and Binders
  • Atomic and Molecular Physics and Spectroscopy

Distribution Statement:

APPROVED FOR PUBLIC RELEASE