Microcapsule induced toughening in a self-healing polymer composite

Microencapsulated dicyclopentadiene (DCPD) healing agent and Grubbs' Ru catalyst are incorporated into an epoxy matrix to produce a polymer composite capable of self-healing. The fracture toughness and healing efficiency of this composite are measured using a tapered double-cantilever beam (TDC...

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Bibliographic Details
Published in:Journal of materials science 2004-03, Vol.39 (5), p.1703-1710
Main Authors: BROWN, E. N, WHITE, S. R, SOTTOS, N. R
Format: Article
Language:English
Subjects:
Applied sciences
Cantilever beams
Crack initiation
Exact sciences and technology
Fillers
Fracture mechanics
Fracture surfaces
Fracture toughness
Heat treating
Materials science
Mechanical properties
Microcracks
Microspheres
Morphology
Physical properties
Polymer industry, paints, wood
Polymer matrix composites
Polymers
Properties and testing
Self healing materials
Silicon dioxide
Technology of polymers
Toughening
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Summary:Microencapsulated dicyclopentadiene (DCPD) healing agent and Grubbs' Ru catalyst are incorporated into an epoxy matrix to produce a polymer composite capable of self-healing. The fracture toughness and healing efficiency of this composite are measured using a tapered double-cantilever beam (TDCB) specimen. Both the virgin and healed fracture toughness depend strongly on the size and concentration of microcapsules added to the epoxy. Fracture of the neat epoxy is brittle, exhibiting a mirror fracture surface. Addition of DCPD-filled urea-formaldehyde (UF) microcapsules yields up to 127% increase in fracture toughness and induces a change in the fracture plane morphology to hackle markings. The fracture toughness of epoxy with embedded microcapsules is much greater than epoxy samples with similar concentrations of silica microspheres or solid UF polymer particles. The increased toughening associated with fluid-filled microcapsules is attributed to increased hackle markings as well as subsurface microcracking not observed for solid particle fillers. Overall the embedded microcapsules provide two independent effects: the increase in virgin fracture toughness from general toughening and the ability to self-heal the virgin fracture event.
ISSN:0022-2461
1573-4803
DOI:10.1023/b:jmsc.0000016173.73733.dc