Date of Award
Master of Science
Madhu S. Madhukar
Kevin M. Kit, Mancil W. Milligan
During the cure of polymer matrix composites, induced stresses develop due to shrinkage of the matrix material. Consequences of this can lead to shifting of the reinforcement, adversely affecting final properties of the material, or the induced stresses can alter the final geometry of the part. With the use of a new closed loop feedback program developed, residual stresses built up during cure were minimized. Experiments were performed using the EPON 828 resin with two types of reinforcement, carbon and glass fiber. The residual stress built up during the optimized cure cycle was compared with that produced during the lPanufacturer recommended 2-step cure cycle and isothermal cure cycles. Results for both fibers show a large reduction in stresses endured during cure for the optimized cure compared to typical stresses seen under isothermal and standard cure cycles. Static and dynamic testing were done on specimens and showed that the modulus and the glass transition temperatures of cured specimens were not significantly affected by the optimized cure cycles. Results also show that optimized cure cycles were of shorter duration compared to the standard cure cycles.
Burgess, Richard W., "Cure-Induced Stress Control in Thermosetting Polymer Composites. " Master's Thesis, University of Tennessee, 2005.