The diffusion of small molecules into glassy polymers is often observed to be of the anomalous Case II type. This thesis describes the first comprehensive study of acetone vapour penetrating into PVC. It has been shown that this diffusion process is of the Case II type. The initial stages of the diffusion process have been studied using ion beam nuclear reaction analysis (NRA) whilst long range diffusion has been studied using broadline nuclear magnetic resonance (NMR) imaging techniques. This is the first time that short and long term behaviour has been studied in the same system and has permitted a test of the Thomas and Windle theory covering both regimes. It is also the first time that broadline NMR imaging has been used to study Case II diffusion and this has permitted a study of the polymer as well as the penetrant. A new NMR technique has been developed for this. Characteristic parameters of the diffusion process have been determined. The velocity of the diffusion front advance is typically 0.042 mmhr-1 and the diffusion coefficient is 7 x10-11 cm2s-1 at room temperature. The effects of variation of exposure temperature and the activity of the vapour on the diffusion dynamics have been investigated. The NMR profiles have shown an unexpectedly long Fickian precursor extending into the inner glassy core of the samples. To complement the NMR imaging results, the NMR spin spin relaxation times of samples have been measured, and high resolution 13C NMR spectroscopy has been performed on the samples. Evidence has been found for continued disentanglement of the polymer chains long after mass equilibration of the region of the PVC swollen by acetone vapour. This disentanglement has been shown to be strongly dependent on the exposure temperature.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:308402 |
| Date | January 1994 |
| Creators | Perry, Katherine Louise |
| Publisher | University of Surrey |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://epubs.surrey.ac.uk/844641/ |
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