Abstract
Epoxy (Ep)-polyethermide (PEI) blends system were employed as a matrix resin for carbon fiber reinforced plastics (CFRP). Microstructure, dynamic mechanical properties and toughness were investigated for bulk and CFRP consisting of Ep and 20wt% PEI blends. Effects of curing reagents and curing temperature were also studied. SEM observation revealed that Ep rich connected globule structure was presented in PEI rich continuous phase, in all the investigated fractured surface of the cured blend. When bulk blend was cured with a particular conditon, microstructure region consisting of PEI rich spherical domains dispersed in Ep rich continuous phase was also present as a mixture in connected-globule structure region. When CFRP was cured with such condition, Ep rich continuous phase localized arround CF. When CFRP was cured with the condition that connected-globule structure was only present, morphology in CFRP matrix was the same as that in the cured bulk blend.
From the results of dynamic mechanical measurements, considerable differences between matrix resin and curing conditions were observed for adhesion between CF and matrix, and adhesion decreased by the addition of PEI. Fracture toughness changed depending on curing conditions, and it increased by the addition of PEI.
