Understanding the role of internal microstructure in capsule-based healing of polymeric composites

摘要

The efficacy of microcapsules possessing varied internal microstructure toward introducing extrinsic self-healing functionality in epoxy has been compared. Unsaturated polyester was encapsulated in microcapsules by adopting different methodologies. Microcapsules formed using dispersion polymerization exhibited reservoir microstructure while solvent evaporation led to the formation of monolithic microcapsules. Theoretical model was developed to predict the amount of healant released in the event of microcapsule rupture, which clearly highlighted the benefits associated with reservoir type microcapsules, especially at lower core contents. At larger core contents (50% vol/vol), all the micro-droplets within the monolithic structure coalesced to form a healant reservoir. Self-healing composites were prepared by introducing both types of microcapsules in an epoxy matrix and the healing efficiency was quantified. In line with the theoretical predictions, reservoir type microcapsules led to much higher healing efficiencies in comparison to monolithic microcapsules. (c) 2017 Wiley Periodicals, Inc.