POLYMER VISCOELASTICITY: RELATION TO PEEL STRENGTH IN STRUCTURAL ADHESIVES

The two most important tests in evaluating structural adhesives for metals are (1) Lap shear strength and (2) Peel strength. Epoxies perform well in the first due to high tensile and shear strength. They are poor in the second unless modified to reduce brittleness. Details are given of the development of a urethane modified epoxy for this purpose. By taking climbing drum peel data in which both the temperature and the peel rate varied, the time- temperature superposition principle was tested. This principle is most generally applicable to thermoplastic materials between T. and T. + 100 Degrees C (T.= glass transition temperature), and serves as a measure of visceolastic response in the polymer. First, good agreement was found for a thermoplastic adhesive (PE-AA Film). This was done to verify that climbing drum peel data can be used in this manner. Next, data were taken for the urethane modified epoxy. Results showed adherence to the superposition principle only above the heat distortion temperature of the cured polymer. These results indicate, among other things, that the point of failure upon peeling is within the body of the adhesive rather than within a urethane-rich layer at the metal-adhesive interface. This paper was presented at the Symposium On Recent Advances In Adhesion during the 162nd National American Chemical Society Meeting, Spetember, 1971. /TRRL/

  • Corporate Authors:

    GORDON AND BREACH SCIENCE PUB.

    AMSTERDAM:
    ,    
  • Authors:
    • Clarke, J A
  • Publication Date: 1972

Media Info

  • Features: Figures; Photos; References; Tables;
  • Pagination: p. 295-306
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00083430
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Files: ITRD, TRIS
  • Created Date: May 29 1975 12:00AM