All-Cellulose Composites by Partial Dissolution of Cotton Fibres

In this work isotropic 'self-reinforced cellulose' or 'all-cellulose' composites have been successfully prepared from cotton pads by means of a fibre surface dissolution method in lithium chloride dissolved in N, N-dimethylacetamide (LiCl/DMAc). Solvent exchange was used as activation pretreatment, involving subsequent immersion of the fibres in water, acetone and DMAc. Three different parameters have been studied: (i) dissolution time, (ii) activation time and (iii) cotton source. The morphological, thermal and mechanical properties of the obtained all-cellulose composites were characterized. It was found that a dissolution time of 18 h lead to biobased materials with the best overall mechanical performance, as this time allowed for the dissolution of a sufficient amount of fibre surface to obtain good interfacial bonding between fibres, while keeping a considerable amount of remaining fibre cores that provide a strong reinforcement to the composite.