Full Record for Micrograph 559

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Micrograph no: 559
Brief description: Shear bands in stressed polycarbonate
Keywords: craze , polycarbonate (PC), polymer , 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-Non-Commercial-Share Alike 2.0 UK: England & Wales