Synthesis and Characterization of Chitosan/Urea-Formaldehyde Shell Microcapsules Containing Dicyclopentadiene

Microcapsules containing healing agent have been used to develop the self-healing composites. These microcapsules must possess special properties during the use of composites such as stability in surrounding, appropriate mechanical strength, and lower permeability. A new series of microcapsules containing dicyclopentadiene with chitosan/urea-formaldehyde copolymer as shell materials were synthesized by in situ copolymerization technology. The microencapsulating mechanism was discussed and the process was explained. Also, the factors influencing the preparation of microcapsules were analyzed. The morphology and shell wall thickness of microcapsules were observed by using scanning electron microscopy. The size of microcapsules was measured using optical microscope and the size distribution was investigated based on data sets of at least 200 measurements. The chemical structure and thermal properties of microcapsules were characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis, respectively. The storage stability and isothermal aging experiment of microcapsules were also investigated. Results indicted that the chitosan/urea-formaldehyde microcapsules containing dicyclopentadiene were synthesized successfully; the copolymerization occurred between chitosan and urea-formaldehyde prepolymer. The microcapsule size is in the range of 10-160 mu m with an average of 45 mu m. The shell thickness of microcapsules is in the range of 1-7 mu m and the core content of microcapsules is 67%. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121: 2202-2212, 2011