THERMAL-DEGRADATION OF A DIGLYCIDYL ETHER OF BISPHENOL-A 1,3-BISAMINOMETHYLCYCLOHEXANE (DGEBA 1,3-BAC) EPOXY-RESIN SYSTEM/

The thermal degradation for a system containing a diglycidyl ether of bisphenol A (DGEBA) and 1,3-bisaminomethylcyclohexane (1,3-BAC) has be en studied using dynamic mechanical analysis (DMA) and differential sc anning calorimetry (DSC). The DMA results showed that the peak value o f the dynamic loss factor (tan delta), the glass transition temperatur e (T-g), and the dynamic storage modulus (E') above T-g changed consid erably with increasing thermal degradation, while E' below T-g only un derwent a moderate change with increased thermal degradation. There wa s no appreciable change in the beta transition temperature (T-beta) wi th thermal aging time. DSC results showed the same trend for T-g as wi th DMA. A shift of T-g to higher temperature with increasing aging tim es was found, but a decrease in T-g for longer aging times was also ob served. This could be attributed to thermooxidative degradation in the oven. From these results it can be argued that thermal degradation du ring the stage prior to the onset of the severe degradation involves s tructural changes in the epoxy system, such as further crosslinking an d loss of dangling chains in the crosslinked network.