The aim of this study was to develop a new single-part healing system for self-healing composites. The self-healing approach to composite repair has been developed in the last two decades and means that a damaged area can be repaired by material already housed within the structure. The background and development of self-healing has been reviewed. The two main self-healing mechanisms are discussed. To date only two part self healing systems have been examined. These require diffusion of the separate constituents to a single location in order to effect cure and restore strength. Single part adhesives do not have this disadvantage and are therefore very attractive. Several candidate single-part adhesive or resin systems were considered and discussed according to the critical requirements of a self-healing system. A series of experiments was undertaken to evaluate the possibility of candidate adhesive systems being effective for self-healing by focusing on the determination of storage stability and bonding efficiency. The results of storage stability testing showed that the stability of cyanoacrylate and polyurethane adhesives was poor. However silane and polystyrene cements showed good storage stability. Very low bonding efficiency was achieved with polystyrene cement but a 22% strength recovery was obtained with the silane 3-[tris(trimethylsiloxy)silyl]-propylamine. Suggestions for further research into single-part healing systems are also given.

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Vita. Includes bibliographical references. Available also from UMI Company.

Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Dr. Steve Johnson; Committee Member: Dr. Andrew Makeev; Committee Member: Kyriaki Kalaitzidou. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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This research work focuses on single wall carbon nanotube (SWNT)/polymer composites and novel structured electrospun polymer materials. Poly (methyl methacrylate) (PMMA) is used as polymer matrix. Obtaining SWNT/PMMA composite with enhanced mechanical and electrical properties is one of the research goals. The first important step is to figure out a method for achieving uniform SWNT dispersion in PMMA. Eight different solvents were used to disperse SWNT in PMMA. It is found that the polar component of the solubility parameter (£_p) of the solvent affects SWNT dispersion in PMMA. SWNT dispersion in PMMA improves with increasing solvent Ôp value, and the most uniform dispersion is obtained in nitromethane, which is the most polar solvent employed in this study. SWNT/PMMA composite films at various SWNT concentrations were processed employing nitromethane as the solvent. Mechanical and electrical property enhancements are observed. Processing, structure, morphology, and properties of these composites are discussed. A comparison between reinforcement efficiency of SWNT, multiwall carbon nanotubes (MWNT), and vapor grown carbon nano fibers (VGCNF) in PMMA is also discussed. In order to electrospin SWNT/PMMA/nitromethane solution into composite nanofibers successfully, first PMMA was electrospun. With increasing solution concentration, morphology of the electrospun polymer changed from particles to fibers. At relatively low solution concentrations, micro- and nano-structured polymer particles, and at higher solution concentrations, porous and solid nanofibers are observed. SWNT/PMMA/nitromethane solution was electrospun into polymer shell-SWNT core nanofibers. Solvent characteristics play an important role on particle or fiber mat morphology. The qualitative relationship between solvent properties (evaporation rate, dielectric constant, surface tension, and viscosity) and particle morphologies is discussed. By tailoring solution properties and electrospinning conditions, one can produce particles or fibers with controlled morphology for specific applications.

The aim of this study was to develop a new single-part healing system for self-healing composites. The self-healing approach to composite repair has been developed in the last two decades and means that a damaged area can be repaired by material already housed within the structure. The background and development of self-healing has been reviewed. The two main self-healing mechanisms are discussed. To date only two part self healing systems have been examined. These require diffusion of the separate constituents to a single location in order to effect cure and restore strength. Single part adhesives do not have this disadvantage and are therefore very attractive. Several candidate single-part adhesive or resin systems were considered and discussed according to the critical requirements of a self-healing system. A series of experiments was undertaken to evaluate the possibility of candidate adhesive systems being effective for self-healing by focusing on the determination of storage stability and bonding efficiency. The results of storage stability testing showed that the stability of cyanoacrylate and polyurethane adhesives was poor. However silane and polystyrene cements showed good storage stability. Very low bonding efficiency was achieved with polystyrene cement but a 22% strength recovery was obtained with the silane 3-[tris(trimethylsiloxy)silyl]-propylamine. Suggestions for further research into single-part healing systems are also given.