Glass transition and viscoelastic behaviour of partially cured composites

For this study, two tests were conducted in order to investigate the cure monitoring of composite parts utilizing XMTM-49 (carbon/epoxy composite) as the specimen. The first test involved the use of a dynamic mechanical thermal analyzer to investigate the nature of the loss modulus while the second test incorporated a differential scanning calorimeter to evaluate the degree of cure of the composite. From the results of the research, it was found that the loss modulus is an extremely sensitive cure monitoring indicator for composites beyond 70% cured. This is a significant finding since traditional ultrasonic procedures could only be effective in monitoring the cure of composite structures when the degree of cure reaches approximately 70% but decreases when the cure reaches 80% or more. Therefore, it is recommended that future developments should focus attention on a non-contact technique for measuring loss modulus for cure monitoring.