Physical Aging of Linear and Network Epoxy Resins.
Abstract
Network and linear epoxy resins principally based on the diglycidyl either of bisphenol-A and its oligomers have been prepared and studied. Both diamine and anhydride crosslinking agents were utilized. In addition some rubber modified epoxies and a carbon fiber reinforced composite was investigated. All of these materials display time-dependent changes in many of their properties when they are stored (following) quenching) at temperatures below their glass transition temperature (sub-T sub g annealing). For example, the degree of stress relaxation for a given time period is observed to decrease in a linear fashion with the logarithm of time during sub-T sub G annealing. Young's modulus and yield stress were also found to increase in physical aging. Solvent sorption experiments initiated after different sub-T sub G annealing times have demonstrated that the rate of solvent uptake can be indirectly related to the free volume of the epoxy resins. Water affecting the physical aging of these epoxy resins was not found to be a significant variable. Residual thermal stresses were also found to have little effect on the physical aging process, although this variable was not studied in detail.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 13, 1981
- Accession Number
- ADA097017
Entities
People
- A. K. Banthia
- Eric Siu-wai Kong
- James E. Mcgrath
- M. R. Tant
- Y. Mohajer
Organizations
- Virginia Tech