Dissertation > Aviation, aerospace > Aviation > Aerospace materials > Resin-based composite materials

Synthesis and Application of Self-healing Microcapsules

Author LuoYongPing
Tutor ZhangHuiPing
School South China University of Technology
Course Chemical Engineering
Keywords Microcapsule Dicyclopentadiene In-situ polymerization Self-healing
CLC V258
Type Master's thesis
Year 2011
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Thermosetting resin-based composites for replacing metal matrix composites have been used more and more in aerospace field. The properties of thermosetting resin composites were affected by the microcrack from the aging damage during use. It is a frontier research field to prepare thermosetting resin composites with self-healing function which could greatly extend the service life of materials and improve the safety of the materials. Embedded technology of self-healing microcapsules is one of the possible ways for self-healing of thermosetting resin-based composites, and the research on the synthesis and application of self-healing microcapsules is of a great significance in engineering applications.Self-healing microcapsules were synthesized by in-situ polymerization with urea-formaldehyde resin as shell material and dicyclopentadiene as core material, respectively. The optimum technology of micro-encapsulation was investigated by examining the effects of some reaction parameters such the kind and concentration of emulsifier, rotation speed, acidification time, core-wall ration, pH and the amount of additive NaCl etc on the properties of microcapsules. At the same time, the properties of microcapsules such as morphology, structure and storage performance are characrerized using optical microscope, laser particle size analyzer, scanning electron microscope(SEM), fourier transform infrared (FTIR) and thermogravimetric analysis (TGA) etc. The results showed that the microcapsules were of smooth surface, good dispersibility and good chemical stability in the conditions of DBS of 5.0% for the core, rotation speed of 6000 r/min, the acification time of 90 min, the pH of 3.0, and the core-wall ration of 1:1, and the encapsulation is greatly improved by adding of NaCl. By adding 4.0% NaCl solution, the encapsulation ratio of microcapsules increased from 73.0% to 89.2% compared with the microcapsules without adding NaCl.At the same time, self-healing properties of thermosetting resin-based composites with the self-healing microcapsules was evaluated from the experimental restoration. The influence of dosage of both microcapsule and catalyst on self-healing efficiency were studied.The results indicated that the self-healing efficiency of the thermosetting resin-based composites materials with self-healing microcapsules increases first and then decreases with increasing the amount of microcapsules and catalyst, the maximum self-healing efficiency of 62.23% for the material were obtained at the amount of the microcapsule matrix material weight of 2.0% and the GrubbsⅡdosage of 0.05g.

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