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Full Record for Micrograph 590

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Micrograph no
590
Brief description
Remnants of crazes on a polycarbonate fracture surface
Keywords
craze Link to MATTER Glossary entry for craze, craze remnants, fibril Link to MATTER Glossary entry for fibril, fracture Link to MATTER Glossary entry for fracture, polycarbonate (PC), polymer Link to MATTER Glossary entry for polymer
Categories
Fracture, 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
The surface has been sputter-coated with gold, to give a conducting surface
Technique
Scanning electron microscopy (SEM)
Length bar
10 μm
Further information
The fracture surface shows fibrils of oriented polymer which are the remnants of crazes. Crazes are both a precursor to cracking and a toughening mechanism in stressed polymers. They only form when a certain critical tensile stress has been attained and form perpendicular to the largest tensile principal stress. They are very fine crack-like projections from the fracture surface but are bridged by even finer material, giving approximately 50% voids. It is these fibrils which interfere with light in an otherwise transparent polymer to make the crazing visible as a whitening of the strained material. It is the remnants of these fibrils which are visible on this fracture surface.
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
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