DIELECTRIC PROPERTIES OF RAW COTTON

Abstract

SOME evaluation of the dielectric properties of cotton at various moisture contents was needed because of a project to use thermionic heating on the eighty ovens of the Alexandria Testing House. The directly usable facts having been obtained, it seemed worth while to extend the inquiry by measuring the dielectric 'constant' in fields which traversed the hair lengthways, instead of the usual transverse direction. Facilities for preparation of such material were freely available from our spinning test mill. Results show that the values are twice as large lengthways, the 'K' of cotton dried at 100° C. being about six longitudinally and three transversely. It is not surprising that such a structure as the cellulose wall of the cotton hair¹ should be electrically aniso-tropic, and the results obtained have some interest for interpretation of the properties of all fibrous materials, including wood.