Full Record for Micrograph 612

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Micrograph no: 612
Brief description: Nematic liquid crystalline polymer
Keywords: alignment, birefringence , disclination, liquid crystalline polymer (LCP), polymer
Categories: Polymer
System: Liquid crystalline polymer
Composition: K24 (4-cyano-4'-8-alkylbiphenyl)
Standard codes
Reaction: N/A
Processing
Applications: Liquid crystalline polymers remain fluid whilst possessing long range order. This self-alignment enables the drawing of strong, stiff fibres such as Kevlar, as well as mouldable systems live Vectra. The response of LCPs to external fields is also useful in display technology
Sample preparation: A hot stage has been used to heat the LCP to over 35 degrees C
Technique: Cross-polarised light microscopy
Length bar: 100 μm
Further information: Liquid crystalline polymers (LCPs) exhibit a mesophase above their melting temperature. In this phase, they are fluid yet they retain long-range orientational order. The self-alignment of crystallites manifests itself as patterns of optical birefringence when the liquids are viewed between crossed polars. Defects in the patterns are analogous to dislocations in crystal systems. This specimen is K24 (4-cyano-4'-8-alkylbiphenyl), which is nematic above 35 degrees C. The general gradation of colour is simply due to a wedge plate placed over the specimen.
Contributor: Prof T W Clyne
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