Structure-property relations of polyether triamine-cured DGEBA epoxies
The effects of chemical and physical structure on the deformation and failure processes as well as the mechanical properties of polyether triamine cured bisphenol - A - diglycidyl ether (DGEBA) epoxies were studied. Several stoichiometries, ranging from 12% excess epoxy to 11% excess amine by weight, were investigated. Near ir spectroscopy, Tg and swelling ratio observations as a function of amine content indicate that these epoxy networks form exclusively from epoxide-amine addition reactions. Density and Young's modulus measurements indicate that the free volume of these epoxies exhibits a maximum at the highest crosslink density. Photoelastic studies reveal that these glasses initially deform by homogeneous plastic flow followed by inhomogeneous plastic flow in the form of shear bands. Failure occurs via coarse craze formation. Off-stoichiometric networks fail at lower strains because such networks inherently contain more defects in the form of unreacted ends. The mechanical properties of these epoxies are discussed in relation to their crosslink density and free volume, and the plasticizing effect of unreacted monomers.
- Research Organization:
- Lawrence Livermore National Lab., CA (USA)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 5681519
- Report Number(s):
- UCRL-86778; CONF-820304-5; ON: DE82002057
- Resource Relation:
- Conference: 183. American Chemical Society annual meeting, Las Vegas, NV, USA, 27 Mar 1982
- Country of Publication:
- United States
- Language:
- English
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