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Journal of Materials Science

, Volume 23, Issue 9, pp 3073–3082 | Cite as

Fracture toughness and molecular structure of unfilled epoxy adhesives

  • Jessica A. Schroeder
Article

Abstract

The cohesive, mode I (tensile cleavage) fracture energy (or fracture toughness), GIc, of bulk tapered double cantilevered beam (TDCB) samples of a series of three epoxy thermoset networks was determined using a linear elastic fracture mechanics (LEFM) analysis. Networks of different crosslink density were obtained by mixing various amounts of an aromatic epoxy novolac and an aliphatic epoxy and crosslinking with an imidazole catalyst. Brittle, stick-slip fracture was observed for all formulations, with GIc increasing as the amount of aliphatic epoxy increased. However, fracture surface morphologies exhibited evidence of increasing plastic deformation as GIc increased. In the investigation of structure-property relationships for this series of thermoset networks, GIc was found to be inversely related to both network crosslink density and glass transition temperature (Tg). It was also found that the room temperature frequency of the glassy state transition (β-transition) increased as fracture toughness increased.

Keywords

Epoxy Fracture Toughness Glass Transition Temperature Cantilever Beam Crosslink Density 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Chapman and Hall Ltd 1988

Authors and Affiliations

  • Jessica A. Schroeder
    • 1
  1. 1.Polymers DepartmentGeneral Motors Research LaboratoriesWarrenUSA

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