Abstract
We report an in situ encapsulation method demonstrating over an order of magnitude size reduction for the preparation of urea-formaldehyde (UF) capsules filled with a healing agent, dicyclopentadiene (DCPD). Capsules with diameters as small as 220 nm are achieved using sonication techniques and an ultrahydrophobe to stabilize the DCPD droplets. The capsules possess a uniform UF shell wall (77 nm average thickness) and display good thermal stability. By controlling the ζ-potential, the capsules are uniformly dispersed in an epoxy matrix and shown to cleave rather than debond upon fracture of the matrix. Mechanical properties of the epoxy/capsule composite, including mode-I fracture toughness, elastic modulus, and ultimate tensile strength are measured and compared to previous data for larger capsules (ca. 180 μm).
Original language | English (US) |
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Pages (from-to) | 978-986 |
Number of pages | 9 |
Journal | Composites Science and Technology |
Volume | 68 |
Issue number | 3-4 |
DOIs | |
State | Published - Mar 2008 |
Keywords
- A. Nanostructures
- A. Polymer-matrix composites
- A. Smart materials
- B. Mechanical properties
- Self-healing materials
ASJC Scopus subject areas
- General Engineering
- Ceramics and Composites