Local dynamics of adhesives in aggressive environment in the pre-damage stage

Jovan Mijovic, Nobuhiro Miura, Som Soni

Research output: Contribution to journalArticle

Abstract

Molecular aspects of chemical and physical changes in adhesive joints caused by absorbed moisture were investigated. The focus was on the pre-damage stage that precedes the formation of voids and microcracks. A model and a commercial epoxyamine formulation were studied. Local dynamics were monitored by broad-band dielectric relaxation spectroscopy (DRS). One portion of the absorbed water does not form hydrogen bonds with the network and gives rise to a fast relaxation process (termed γ) with activation energy of 28 kJ/mol. The local β dynamics are slowed down by the interactions between water and various sites on the network that include the ether oxygen, the hydroxyl group and the tertiary amine nitrogen. One particularly significant finding is that the average relaxation time for the β process above 20°C is of the order of nanoseconds or less and, hence, the detection and monitoring of this process hinges upon the ability to perform high-precision DRS at frequencies above 1 MHz. This is an important consideration in the ongoing efforts aimed at the implementation of DRS as nondestructive inspection (NDI) tool for adhesive joints.

Original languageEnglish (US)
Pages (from-to)123-150
Number of pages28
JournalJournal of Adhesion
Volume76
Issue number2
StatePublished - 2001

Fingerprint

Dielectric relaxation
adhesives
Adhesives
Adhesive joints
Spectroscopy
damage
Water
Microcracks
Relaxation processes
Hinges
spectroscopy
Hydroxyl Radical
Ether
Relaxation time
Amines
hinges
Ethers
microcracks
Hydrogen bonds
Nitrogen

Keywords

  • Adhesive
  • Dielectric relaxation spectroscopy
  • Environmental exposure
  • Local dynamics

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Computational Mechanics
  • Mechanics of Materials
  • Materials Science(all)

Cite this

Local dynamics of adhesives in aggressive environment in the pre-damage stage. / Mijovic, Jovan; Miura, Nobuhiro; Soni, Som.

In: Journal of Adhesion, Vol. 76, No. 2, 2001, p. 123-150.

Research output: Contribution to journalArticle

Mijovic, Jovan ; Miura, Nobuhiro ; Soni, Som. / Local dynamics of adhesives in aggressive environment in the pre-damage stage. In: Journal of Adhesion. 2001 ; Vol. 76, No. 2. pp. 123-150.
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