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The hyperbranched polyester based on poly dimethyl 5-(4 hydroxybutoxy) isophthalate ate has been successfully fractionated and a complete analysis of the solution properties has been carried out. Fractions with an average polydispersity of 1.8 over a range of molecular weight from 5x10(^3) g mol(^-1) were produced starting from an initial polymer with an approximate polydispersity of 7 and average molecular weight of l.3x10(^5) g mol(^-1). A linear analogue of the hyperbranched polyester has been also synthesised and different molecular weight samples were obtained by the use of a transesterification reaction. The hyperbranched fractions were investigated in the dilute regime by size exclusion chromatography, viscometry and light scattering techniques, while the semi-dilute regime has been studied by small-angle neutron scattering. Dilute solution properties in chloroform and in THF have been investigated, whilst D-THF was the solvent for the semi-dilute regime. In the dilute solution regime a whole range of physical parameters have been determined for the hyperbranched fractions and compared, where possible, with the linear analogues. From these results it is concluded that chloroform is a good solvent and THF a poor solvent for the hyperbranched polyester. The molar mass dependence of the radii of gyration has been interpreted by fractal dimension analysis and for the hyperbranched polyester the exponents obtained gave a fractal dimension d(_f)=2.5 ± 0.3 in both the solvents. The exponents obtained by the molar mass dependence of the radius of gyration in the semi-dilute regime have confirmed these values. These exponents also fit with those obtained from analysis of the intermediate g range of the small-angle neutron scattering cross sections, where an average slope 2.5 ± 0.1 was obtained. The values suggested the hyperbranched polymer is a mass fractal object with a rough surface.

The work in this thesis is concerned with the study of dynamics, scattering and stability of solitons in planar models, i.e. where spacetime is (2+l)-dimensionaI. We consider both integrable models, where exact solutions can be written in closed form, and nonintegrable models where approximations and numerical methods must be employed. For theories that possess a topological lower bound on the energy, there is a useful approximation in which the kinetic energy is assumed to remain small. All these approaches are used at various stages of the thesis. Chapters 1 and 2 review the planar models which are the subjects of this thesis. Chapters 3 and 4 are concerned with integrable chiral equations. First we exhibit an infinite sequence of well-defined conserved quantities and then we construct exact soliton and soliton-antisoliton solutions using analytical methods. We find that there exist solitons that scatter in a different way to those previously found in integrable models. Furthermore, this soliton scattering resembles very closely that found in nonintegrable models, thereby providing a link between the two classes. Chapter 5 develops a numerical simulation based on topological arguments, which is used in a study of soliton stability in the (unmodified) 0(3) model. This confirms that the sohtons are unstable, in the sense that their size is subject to large changes. The same results are obtained by using the slow-motion approximation.

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Copies of author's previously published articles inserted. / Includes bibliographical references. / viii, 162, [9] leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / A study of stimulated Brillouin scattering and its use for correcting phase aberrations in laser oscillators. / Thesis (Ph.D.)--University of Adelaide, Dept. of Physics and Mathematical Physics, 1998

Copies of author's previously published works inserted. / Bibliography: p. 119-127. / 12, 127, [8], 35 p., [3] leaves : ill. (chiefly col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This thesis demonstrates the combined use of stimulated Brillouin scattering (SBS) for aberration correction, auto alignment and pulse compression as an ideal technology for studies of nonlinear optical processes, in particular nonlinear optical scattering (NLS). / Thesis (Ph.D.)--University of Adelaide, Dept. of Physics and Mathematical Physics, 1998

152 leaves : diags, photos ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Physics, 1976