Abstract
Microencapsulated healing agents that possess adequate strength, long shelf-life and excellent bonding to the host material are required for self-healing materials. Urea-formaldehyde microcapsules containing dicyclopentadiene were prepared by in situ polymerization in an oil-in-water emulsion that meet these requirements for self-healing epoxy. Microcapsules of 10-1000 μm in diameter were produced by appropriate selection of agitation rate in the range of 200-2000 rpm. A linear relation exists between log(mean diameter) and log(agitation rate). Surface morphology and shell wall thickness were investigated by optical and electron microscopy. Microcapsules are composed of a smooth 160-220 nm inner membrane and a rough, porous outer surface of agglomerated urea-formaldehyde nanoparticles. Surface morphology is influenced by pH of the reacting emulsion and interfacial surface area at the core-water interface. High yields (80-90%) of a free flowing powder of spherical microcapsules were produced with a fill content of 83-92 wt% as determined by CHN analysis.
Original language | English (US) |
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Pages (from-to) | 719-730 |
Number of pages | 12 |
Journal | Journal of Microencapsulation |
Volume | 20 |
Issue number | 6 |
DOIs | |
State | Published - Nov 2003 |
Keywords
- Dicyclopentadiene
- In situ polymerization
- Microcapsule
- Self-healing
- Surface morphology
- Urea formaldehyde
ASJC Scopus subject areas
- Chemistry (miscellaneous)
- Pharmaceutical Science
- General Chemical Engineering
- Pharmacology