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Micrograph 559 and full record

Link to image file for micrograph 559
Micrograph no
559
Brief description
Shear bands in stressed polycarbonate
Keywords
craze Link to MATTER Glossary entry for craze, polycarbonate (PC), polymer Link to MATTER Glossary entry for polymer, shear bands Link to MATTER Glossary entry for shear bands
Categories
Polymer
System
Polycarbonate (PC)
Composition
Not specified
Standard codes
Reaction
Processing
Applications
Polycarbonate is a clear and relatively tough plastic used to make shatterproof windows, lenses and even helmets. It is also used to make compact discs.
Sample preparation
To promote the formation of shear bands in polycarbonate, acetone is used. This results in the otherwise tough material becoming very brittle
Technique
Scanning electron microscopy (SEM)
Length bar
800 μm
Further information
Yielding in glassy polymers often proceeds by a small sheared region propagating through the material. These patterns can be used in the stress analysis of fracture processes. In addition, the colours in the image are the result of birefringence and relate to the strain-induced alignment of the polycarbonate molecules. Because the specimen is below the glass transition temperature of PC (145 deg C), the material will relax when the stress is removed and there will be no residual alignment.
Contributor
J A Curran
Organisation
Department of Materials Science and Metallurgy, University of Cambridge
Date
03/10/02
Licence for re-use
Attribution-NonCommercial-ShareAlike 4.0 International

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