Dissemination of IT for the Promotion of Materials Science (DoITPoMS)

DoITPoMS Micrograph Library Full Record for Micrograph 560

Full Record for Micrograph 560

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Micrograph no
560
Brief description
Crazing near a fracture surface in polystyrene
Keywords
craze Link to MATTER Glossary entry for craze, crazing, fracture Link to MATTER Glossary entry for fracture, polymer Link to MATTER Glossary entry for polymer, polystyrene (PS)
Categories
Fracture, Polymer
System
Polystyrene (PS)
Composition
Not specified
Standard codes
Reaction
Processing
Applications
Polystyrene is hard and inexpensive and its use is very widespread. CD cases and clear plastic cups are common examples. Domestic appliance casings are also typically made from PS
Sample preparation
Technique
Photography (no microscope)
Length bar
10 mm
Further information
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.
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