A description is given of a study of the effects of crosslink density and large mechanical stresses on physical aging of DGEBA/diamine model networks. The aging behavior of different crosslink density epoxies in the linear viscoelastic regime was well described by the aging picture introduced by L.C.E. Struik. The authors observed that both classical time-aging time and time-temperature superposition were valid for our networks. Additionally a time-crosslink density superposition was found to be valid for these networks. At temperatures 10°C and 5°C below Tg, the authors were able to age the materials into structural equilibrium. It was found that the time required to reach equilibrium, t*, increased as crosslink density increased. Consistent with other aging results, the shift rate μ decreased as the applied stress level increased. However the time required to reach equilibrium, t*, was found to be independent of the applied stress level.
|Number of pages||4|
|Journal||Annual Technical Conference - Society of Plastics Engineers|
|State||Published - 1989|
|Event||ANTEC 89 - 47th Annual Technical Conference of SPE - New York, NY, USA|
Duration: May 1 1989 → May 4 1989