RESUMO
Dimethylnorbornene ester (DNE) is successfully used as a noncovalent adhesion promoter. DNE was confirmed to copolymerize with dicyclopentadiene (DCPD) to yield a copolymer with better adhesion to an EPON 828 epoxy matrix relative to poly(DCPD) alone. The mechanical properties of the copolymer were comparable to that of poly(DCPD) alone. An optimized blend of the monomers was encapsulated using a urea-formaldheyde microencapsulation procedure and the resulting capsules were used for in situ self-healing experiments. Improved healing efficiency was observed for samples containing the DCPD/DNE capsules under conditions in which the monomers were efficiently polymerized.
Assuntos
Adesivos/química , Polímeros/química , Cápsulas/química , Compostos de Epóxi/química , Ésteres , Formaldeído/química , Indenos/química , Temperatura de Transição , Ureia/químicaRESUMO
Double-walled polyurethane/poly(urea-formaldehyde) microcapsules (PU/UF) are prepared for use in self-healing materials. This modified encapsulation procedure combines two chemistries to form more robust capsule shell walls in a single operation. Robust capsules are formed by this procedure as long as the aromatic polyisocyanate prepolymer is soluble in the core liquid and the core liquid is compatible with isocyanates. Compared to a standard UF encapsulation, the modified procedure results in capsules with an increase in shell wall thickness from 200 to 675 nm as a function of the amount of PU added to the core liquid. Thermal stability of PU/UF microcapsules prepared with varying amounts of PU is compared to UF microcapsules. Mechanical properties of the PU/UF microcapsules are assessed from single-capsule compression testing.