The mechanical properties of epoxy resins

Abstract

The yield stress, σ_y, and Young's modulus, E, of a series of triethylenetetramine-cured epoxy resins have been measured as a function of resin composition and testing rate and temperature. It is found that for a given composition, both σ_y and E increase as the testing rate is increased and as the temperature is decreased. It is also found that under the same testing conditions, σ_y and E both decrease as the amount of curing agent in the resin is increased. The relationship between σ_y and E has been analysed using the theories of plastic deformation in glassy polymers of Argon and Bowden. Good agreement has been found with the Argon theory at low temperatures whereas the agreement with the Bowden theory is found to be good at all temperatures up to T _g. It appears therefore that the plastic deformation of epoxy resins which are thermosets is similar to that of glassy thermoplastics. The significance of the parameters derived from the two theories has been discussed in terms of the molecular structure of the resins.