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Ian Boustead introduces the programme. He has with him a differential scanning calorimeter (DSC). Ian Lowe performs a simple experiment to obtain a heating curve for a linear alkane. He explains t...he experiment and apparatus as he goes along. The phase transition, as the alkane melts, is clearly shown on the resulting curve. Lowe explains how the total energy required to complete the phase transition can be calculated. Lowe, with the aid of animated diagrams, explains how the total energy calculation above can be improved by the use of a reference sample in the experiment. Boustead uses the DSC to perform the above experiment. He explains the set up and experiment as he goes along. A photograph and animated diagrams of the apparatus and experiment are used as aids. A double peaked curve results. To find an explanation for the double peaked curve in the above experiment, Ian Lowe looks at several traces from the DSC for different materials. Ian Boustead poses the question: Does the crystal structure of a polymer re-form on cooling when it has been disrupted by heating He shows the trace of a cooling polymer on the DSC. Boustead examines some of the physical properties of a polymer specimen. He stretches, then heats the specimen. Boustead looks at some x-ray diffraction photographs of a polymer before and after heating. The change from preferred to random orientation of molecules is clearly seen. Boustead conducts an experiment to observe a polymer being heated under the light microscope. The sample is seen to shrink. Boustead demonstrates this phenomenon on a macroscopic scale by putting a flame to a sample he is holding. This also shrinks along the direction of preferred orientation. Film shots of a melted polymer cooling under the microscope. Growth of circular spherulites can be seen with no sign of preferred orientation. Commentary by Boustead.
Metadata describing this Open University video programme
Module code and title: TS251, An introduction to materials
Item code: TS251; 03; 1973
First transmission date: 24-03-1974
Published: 1974
Rights Statement: Rights owned or controlled by The Open University
Restrictions on use: This material can be used in accordance with The Open University conditions of use. A link to the conditions can be found at the bottom of all OUDA web pages.
Duration: 00:23:21
Note: Record previously confused with video for T251/05, VF1557, 'Tensile testing'.
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Producer: Colin Robinson
Contributors: Charles Newey; Nick Reid
Publisher: BBC Open University
Keyword(s): Differential scanning calorimeter ; Electron diffraction ; Energy, temperature and time ; Polymer sample ; Spherulitic structure ; Thermal analysis ; X-ray diffraction
Master spool number: 6HT/70810
Production number: 00525_5145
Videofinder number: 1555
Available to public: no