Manufacture of carbon-fiber prepreg with thermoplastic/epoxy resin blends and microencapsulated solvent healing agents

Unidirectional carbon-fiber/thermoplastic/epoxy prepreg is manufactured with embedded microcapsules containing a healing agent for a thermoplastic-toughened epoxy matrix. A laboratory-scale prepreg fabrication line was designed to produce a prepreg fabric of which fiber-interstitial spaces accommodate microcapsules of an average diameter of 2.8 mu m. Microcapsules containing the healing agent, ethyl phenylacetate (EPA), were coated with polydopamine (PDA) to withstand harsh manufacturing conditions. The prepreg fabrics were laminated and hot-pressed to produce composites of a high fiber volume fraction (ca. 62%), exceptional thermal stability (T-g = 170 degrees C) and fracture toughness. The laminated composite achieved a uniform distribution of intact microcapsules with an overall concentration of 3.1 vol% and a 20 wt% thermoplastic-toughened (poly(bisphenol a-co-epichlorohydrin); PBAE) epoxy matrix developed from cure-induced phase separation. The co-existence of intact microcapsules filled with healing agent and the phase-separated PBAE/epoxy matrix has significant potential to mitigate small scale damage in the composite.