Crystal transition from cellulose I to cellulose II in NaOH treated Agave americana L. fibre

This study investigates the cellulose polymorphic transformation of Agave americana L fibre during alkali processing at different NaOH concentrations. X-ray diffraction was used. The polymorphic transition from cellulose I to cellulose II begun at NaOH concentrations at the order of 5-10% and the complete transformation was achieved for the alkali concentration of 15%. The crystallinity index of agave fibre increased for alkali treatments not exceeding 2% (w/v), whereas higher NaOH concentrations (>2%) induce a considerable decrease of the crystallinity index. The unit cell parameters of A. americana L fibre vary with the NaOH concentration which results from the formation of different alkali celluloses during the mercerisation process. As far as mechanical properties are concerned, treatments with low alkali concentrations produce fibres that are stronger than the untreated fibres, whereas treatments with high concentrations (>2% w/v) result in weaker fibres. (C) 2011 Elsevier Ltd. All rights reserved.