Full Record for Micrograph 578

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Micrograph no: 578
Brief description: Sprue in a sample of polypropylene (PP)
Keywords: alignment, birefringence , injection moulding , polymer , polypropylene (PP), sprue
Categories: Polymer
System: Polypropylene (PP)
Composition: Not specified
Standard codes
Reaction
Processing: Polypropylene is injected into a mould via this inlet or 'sprue'
Applications: Polypropylene has good resistance to chemicals and to fatigue. It is widely used in food packaging in the form of rigid tubs, lids and screw-tops as well as in flexible films.
Sample preparation
Technique: Cross-polarised light microscopy
Length bar: 10 mm
Further information: The colours in the image are the result of birefringence and relate to the residual strain in the polypropylene. The pattern of strain is indicative of the flow of material during the injection process and highlighting the injection point or 'sprue' from which all the material flows radially into the mould. The molecules are aligned parallel to the direction of flow.
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