Full Record for Micrograph 640

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Micrograph no

640

Brief description

Fracture surface in a liquid crystalline polymer, oriented by a magnetic field

Keywords

alignment, fibre

, fibrillation

, fracture $Link to MATTER Glossary entry for fracture$ , liquid crystalline polymer (LCP), lyotropic, magnetic, nematic, polymer

Categories

Fracture, Polymer

System

Liquid crystalline polymer

Composition

Random copolyester of average molecular weight 14401

Standard codes

Reaction

Processing

A 1.1T magnetic field has been applied for one hour (magnetic axis vertical)

Applications

The molecules in a LCP mesophase can be steered by external fields; a property used in display technology. Alignment is also exploited in high strength fibres like Kevlar and mouldable Vectra

Sample preparation

Technique

Scanning electron microscopy (SEM)

Length bar

4 μm

Further information

Above their melting point, liquid crystalline polymers exhibit a mesophase within which, although able to flow and are not arranged in a crystal, they exhibit long range orientational order. This molecular alignment can be exploited to make high strength and stiffness fibres such as Kevlar, or even mouldable thermotropics such as Vectra. Molecular alignment can also be controlled by an external applied field; a property exploited in liquid crystal displays. This polymer has been subjected to a magnetic field of 1.1T (normal to the fracture plane) for one hour and the resulting alignment is evident in the fractured surface.

Contributor

Prof A H Windle

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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