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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Synthesis and characterisation of hydrogels with controlled microstructure and enhanced mechanical properties

An, Jingyi (Caroline) January 2016 (has links)
For the application of advanced hydrogel-based artificial muscle systems, conventional polymeric hydrogels usually suffer from various limitations such as structural inhomogeneity and poor mechanical strengths. Thus, improving the mechanical strength of a specific hydrogel system while maintaining its other useful properties become increasingly important. In this project, three different approaches were employed to improve the mechanical properties of hydrogels though microstructural control, including physical cross-links, copolymerisation, and interpenetrating systems. Analytical tools such as FTIR and XRD were used to confirm the success of sample preparation. Morphological SEM characterisations were applied to reveal direct graphic information on hydrogels microstructures. Equilibrium water swelling tests as well as uniaxial compression measurements were conducted to evaluate the influences of various experimental parameters on the hydrogels water-holding and mechanical properties. The physical cross-linker approach was proved to be successful since comparable swelling capacities and dramatically enhanced mechanical strength were achieved in nanocomposite systems in comparison with conventional chemically cross-linked gel systems, due to the presence of flexible cross-linking points and the multifunctional cross-linker role played by clay. The copolymerisation approach, both between two neutral monomers and between one neutral and the other ionic monomer, was unsuccessful in terms of mechanical property enhancement due to the low cross-linking density as a result of the dominate competition of copolymerisation rather than cross-lining kinetics. The interpenetrating approach was concluded as successful since hugely improved mechanical toughness and slightly reduced swelling capacities were observed in most IPN gel systems.
2

Rapid Infrared Thermal Processing of AA 2618 and AA 6061 Forgings

Gowreesan, Vamadevan 29 December 2008 (has links)
No description available.

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