The objective of this work was the investigation of the polymeric interactions in tablet coating films in relation with effective film formulations. The polymeric interactions were studied by means of torsional braid analysis. For this purpose an existing torsional braid analyser was improved and successfully interfaced to a microprocessor for data acquisition and reduction. Discussion on the contribution of the substrate to the thermomechanical spectra of the TBA as well as factors associated with the optimisation of the technique are presented. The dynamic mechanical behaviour of EC, HPMC, HPMCP-HP50, HPMCP-HP55, HPC and CAP film formers was studied with particular attention to structure- Tg relationship. The plasticisation of two of the most common film formers, namely EC and HPMC, with a series of polyethylene glycols was investigated. It was shown that PEGs efficiently plasticise HPMC, whereas they exhibited limited interactions with EC. The relation of the plasticising efficiency to the size and concentration of the PEGs with respect to the optimisation of the tablet coating formulation is also discussed. The thermomechanical behaviour of blends of EC with water-/pH-dependent film formers was also studied with TBA, in conjunction with the requirements for controlled release coatings. All polyblends exhibited phase separation and the required domain morphology, which was shown capable of retaining small amounts of water-/pH-dependent components even after prolonged leaching. Moreover, the modification of the thermomechanical performance of 80/20 w/w EC/HPMC blends plasticised with PEG200 and PEG400 was investigated. These studies indicated diffusion of the plasticisers into both phases. Finally, the effects of blend composition and interactions in terms of efficient sustained release coatings are identified and discussed.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:356082 |
| Date | January 1984 |
| Creators | Sakellariou, P. |
| Publisher | University of Manchester |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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