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Title: Time dependent characteristics in tablet compaction
Author: Ho, A. Y. K.
ISNI:       0000 0001 3579 2640
Awarding Body: CNAA
Current Institution: Open University
Date of Award: 1986
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A single punch tablet machine has been instrumented to measure top and bottom punch force and punch displacement. A system has been developed for instrumenting rotary tablet machines using radio telemetery techniques and compared with conventional instrumentation systems. It is shown that the positioning of the measuring devices is critical for accurate measurements of forces and punch displacement. Samples of Micro crystalline cellulose (Avicel PH-102) and various grades of Lactose have been characterised and their compaction properties measured by a variety of techniques including breaking strength, changes in bed density under compaction and stress relaxation. The properties were determined using a specially constructed laboratory compaction simulator capable of reproducing compaction events typical of full scale production. It is shown that none of the conventional indices of compaction behaviour adequately predict the compaction properties of materials as described by their breaking strength: force profile. A phenomenon is described whereby the measurement of maximum force is not coincidental with the measurement of maximum punch penetration. Using model materials it is suggested that these differences are due to the visco elastic and plastic components of materials during compression. A new index - rise time - (the time between the initiation of compression and the point of maximum force application) is proposed as a useful means of predicting the behaviour of pharmaceutical solids during compression.
Supervisor: Not available Sponsor: Wellcome Foundation Ltd
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Pharmacology & pharmacy & pharmaceutical chemistry