Infrared and Raman studies of thin polymer films

Abstract

[Keywords:- Waveguide; Raman; Attenuated Total Reflection; Infrared; Polymer Films; Barrier Films; Epoxy; Diffusion; Isocyanate; Crosslinking Agents; Cure Time; Kinetics; Urethane; Film Quality]This thesis describes the experimental work carried out between October l(^st), 1990 and 30th September, 1993, in the Chemistry Department of the University of Durham, in association with Courtaulds Coatings plc, m partial fulfilment of the requirements for the degree of Doctor of Philosophy. The thesis is divided into three sections, namely Theoretical Considerations (three Chapters), Experimental Results (three Chapters) and Discussion of Results (one Chapter). There are also three appendices. The theoretical section presents a working description of Paint Chemistry, Vibrational spectroscopy, Waveguide Raman Spectroscopy, Attenuated Total Reflection Fourier Transform Infrared Spectroscopy and Diffusion Processes. The experimental section is divided into three chapters. The first describes methods of film preparation and characterisation and includes methods of film thickness determination and the development of an off-line waveguiding rig at the University of Durham. Raman spectroscopic results are detailed in the second chapter, and include waveguide experiments on both single polymer films and laminate systems, some of which are reported for the first time, along with some FT-Raman results, also reported for the first time. The FT-IR ATR spectroscopic results are presented in the third chapter and include some barrier film studies on polymeric laminate systems, plus the study of certain diffusion processes, along with an estimation of the associated diffusion coefficients and some kinetic parameters, occurring in epoxy resins, which are reported for the first time. The discussion section concentrates on a full elucidation of the results, and conclusions that may be drawn from them, and ends with suggestions for future work. Refractive indices quoted, unless otherwise stated, refer to indices measured usmg 632.8 nm radiation, and have been estimated either using previous literature, or with the off-line rig. It is accepted that electric field calculations performed with these values will be slightly different to the actual fields observed in the Raman experiments, due to slightly different refractive indices at 514.5 nm. T in tables, unless otherwise stated, refers to band intensities in absorbance units. Finally, the attention of the reader is drawn to the fact that some of the materials used in the course of this project have no precise structure given. This is due to the fact that some of the substances used are of either a highly complicated and/or confidential nature.