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This study was designed to provide information concerning polyester resin as a material for jewelry making. The secondary purpose was to develop processes which create an artistic form for jewelry sustained by a poetic tone based on the fluid and translucent qualities of the material.

The study described in this thesis examines how modification with different thermoplastics affects the structure and properties of a tetrafunctional epoxy re5ín_ Polyetherimide (PEI) is found to give the best improvement in fracture properties without loss in Youngs Modulus and the PEI/epoxy system is used as the basis for further study. The influences of PEI concentration, initial cure temperature, test temperature and the presence of a second thermoplastic additive, are investigated. The information provided gives insight into the likely mechanisms of toughening in tetrafunctional epoxy/thermoplastic blends. Flory-Huggins Lattice Theory is used to describe miscibility behaviour for a number of curing thermoplastic/epoxy blends and the predictions compared with the actual morphologies observed. Further, the sensitivity of the expected miscibility behaviour to fluctuations in Flory Huggins interaction parameter X12 and number-average molecular weight Mn of the thermoplastic, is considered. Dynamic mechanical analysis is used to monitor the changing viscoelastic properties of curing thermoplastic/epoxy blends, allowing investigation of the way different thermoplastics influence the state transformation profile of a curing epoxy resin.

Resin-composites have been used in dentistry as direct restorative materials for over fifty years ago, and meanwhile their properties have been substantially improved. Recently a new class of light-cured resin-composites known as 'bulk-fill' materials has been introduced, and has increased the practical application of resin-composites in comparison to conventional incrementally applied materials. The aim of the present research was to assess bulk-fill resin-composites in comparison to conventional materials with respect to their composition, polymeric structure properties and hygroscopic behaviour in oral and food simulating substances. A variety of bulk-fill and conventional resin-composites were tested in this study. Monomer composition of materials has been qualitatively and quantitatively determined using high performance liquid chromatography and mass spectroscopy, and their degree of conversion assessed using Fourier transform infrared spectroscopy. It was found that the degree of conversion of the bulk-fill resin-composites was generally comparable to that of conventional materials and appeared to be governed by the type and quantity of monomers comprising the resin matrix. To evaluate the cross-link density of the polymer matrix, the extent of post-irradiation hardness development, chemical softening, and thermal stability were assessed using microhardness and thermogravimetric analysis. Materials showed variable results and it was suggested that two networks were present in the polymerized resin matrix, a primary network forming immediately after curing followed by a secondary network. The secondary network seemed to have poor cross-link density with low resistance to the degradative effects of solvents. Monomer elution from cured materials was assessed using High performance liquid chromatography over three months' storage in three different media. Elution from bulk-fill resin-composites was found to be comparable to that of conventional materials, despite their increased incremental thickness, with remarkably minimal elution taking place from two bulk-fill materials examined. Monomer elution was shown to be highly dependent on the hydrophobicity of the base monomers and the network characteristics of the resin-matrix. UDMA-BisEMA based systems appeared to be more vulnerable in organic solutions than BisGMA and BisGMA-BisEMA based systems in terms of monomer elution. Sorption and solubility were assessed after one years' storage in water and artificial saliva. Water sorption and solubility of resin-composites were material-dependent and highly affected by the filler loading and initial degree of conversion of the polymeric matrix. BisEMA and UDMA-BisEMA based polymer networks appeared to be more hydrophobic and resistant to sorption and solubility than BisGMA based systems in water based media. The bulk-fill and conventional resin-composites tested were considered stable in the long-term water storage, with the exception of one conventional flowable material.

Thèse : Sciences : Université impériale, Faculté des sciences de Paris : 1812. / Titre provenant de l'écran-titre.