Changes in the dielectric relaxations of water in epoxy resin as a function of the extent of water ingress in carbon fibre composites

P. Boinard, W.M. Banks, R.A. Pethrick

Research output: Contribution to journalArticle

41 Citations (Scopus)


Dielectric relaxation measurements are reported over a frequency range from 10-1 to 109 Hz as a function of exposure time for an epoxy resin-carbon fibre composite, ageing at 60C in water. Investigation of the nature of the dipole relaxation of the water molecules, indicates the nature of their interaction with the polymer matrix. Analysis of the dielectric relaxation spectra allow identification of processes that can be attributed to 'free' and 'bonded' water, water in micro-cracking, located in carbon fibre disbonds and plasticizing the polymer matrix. Identification of the various types of location in which water exists was aided by use of the Ng factor from the Kirkwood-Frölich equation, which describes the constraints on free dipole ration nature imposed by the environment in which it is located. These data indicate the power of the dielectric technique for quantitative analysis of water ingress into epoxy composites.
Original languageEnglish
Pages (from-to)2218-2229
Number of pages11
Issue number7
Publication statusPublished - 2005



  • epoxy resin
  • water ingress
  • dielectric relaxation spectroscopy
  • polymer science
  • chemistry
  • mechanical engineering

Cite this