Modification des fibres cellulosiques. Amélioration des propriétés hydrophiles des pâtes bisulfites

Abstract

This works focus on the sorption properties improvement of bisulfite fibres. The cellulose is modified by middle oxidation to increase the intra-fibres cross-linking. Two approaches are studied to manage the oxidation. The first concerns a physical approach with plasma treatment and the second a chemical approach with chemical oxidants in aqueous medium. Two different systems of plasma generation have been used, corona discharges under atmospheric pressure and the cold oxygen plasma under reduced pressure. The both processes lead to an improvement of the wettability of fibres with decrease of contact angle fibre. The chemical oxidation of the cellulose is realized by transformation of primary or secondary alcohol groups in carboxylic acid groups. The oxidation of secondary alcohol groups is obtained by a sequence in two steps of sodium periodate following by sodium chlorite and hydrogen peroxide. Concerning primary alcohol, the one step oxidation is obtained by an electrochemical process using TEMPO derivatives. In the both processes, the modification induce by the treatment is significant and the compromise between fibrous properties and acidic group ratio is a key factor. The tests of intra-fibres cross-linking show an improvement of sorption properties. Modified fibres characteristics are evaluated by chemical and spectrometric analysis, and the performance by the specific tests related to the absorption and the retention of liquids in fibrous network.