Micrograph 592 and full record
- Micrograph no
- 592
- Brief description
- The tip of a craze in polycarbonate
- Keywords
- craze , fibril , polycarbonate (PC), 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
- To induce crazing in polycarbonate, acetone is used. This results in the otherwise tough material becoming very brittle
- Technique
- Scanning electron microscopy (SEM)
- Length bar
- 4 μm
- Further information
- Fibrils of oriented polymer are visible in the tip of the remnant of a craze near a fracture surface in a fractured specimen of polycarbonate. 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
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