GENERATION OF THERMAL STRAINS IN CARBON FIBER-REINFORCED BISMALEIMIDE (PMR-15) COMPOSITES .3. A SIMULTANEOUS THERMOGRAVIMETRIC MASS-SPECTRAL STUDY OF RESIDUAL VOLATILES AND THERMAL MICROCRACKING

Simultaneous thermogravimetric analysis with mass spectrometry demonstrates the entrapment of curing volatiles in PMR-15 laminates which have been post-cured in the presence and absence of bagging films. These volatiles modify the thermomechanical response of the laminate, enhancing the thermal strain and promoting thermal microcracking. Furthermore, differing thermal degradation characteristics above 300-degrees-C suggest that longer poly-(cyclopentadiene) cross-links exist in material post-cured in the autoclave bagging package. Differences in cure chemistry appear to be responsible for the varying thermomechanical and microcrack stability of the laminates.