Natural aging and dynamic mechanical properties of polymer matrices
The influence of natural six-month aging at 293 K of two kinds of epoxy resins with different network density on their dynamical properties was studied. All the samples were examined by forced resonance oscillations at a frequency of 200 Hz in the range of 120–520 K. The components of the complex Young's modulus E′, E″, tan δ, and low-frequency velocity of sound were measured. The basic temperature transitions including Tg and the network density ν were determined from the experimental data. It was established that after aging of epoxy resins cured by the cross-linking agent meta-phenylenediamine their network density ν decreased (“cold” degradation). By using the cross-linking agent 2,6-diaminopyridine, ν and Tg increased. An attempt is made to explain the nature of this phenomenon.
KeywordsPolymer Experimental Data Mechanical Property Epoxy Temperature Transition
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