MAGNETIC CELLULOSE FIBERS AND PAPER - PREPARATION, PROCESSING AND PROPERTIES

Magnetic cellulose fibres can be prepared either by 'lumen loading' or by in situ synthesis of ferrites. By using the lumen-loading technology, commercially available magnetic pigments can be introduced into the lumens of softwood fibres from which magnetic paper may be prepared. Lumen-loaded fibres act as magnetic dipoles allowing manipulation of fibre orientation in papermaking. In situ synthesis of iron oxide particles is performed through oxidation of ferrous hydroxide precipitated with caustic from the ferrous ion-exchanged form of sodium carboxymethyl cellulose fibres. The latter are characterized by conductometric titration to determine the number of functional groups available for the in situ chemistry. Superparamagnetically responsive fibres have smaller and less-coloured pigments which are only magnetic in the presence of a field.