Edinburgh Napier University

  In this study, surface chemistry, the morphological properties, water retention values, linear viscoelastic properties, crystallinity index, tensile strength and thermal properties of water hyacinth (WH) cellulose were correlated with the degree of mechanical processing under high-pressure homogenisation. An initial low-pressure mechanical shear of WH stems resulted in the ease of chemical extraction of good quality cellulose using mild concentrations of chemical reagents and ambient temperature. Further passes through the homogeniser resulted in an overall improvement in cellulose fibrillation into nanofibrils, and an increase in water retention property and linear viscoelastic properties as the number of passes increased. These improvements are most significant after the first and second pass, resulting in up to 7.5% increase in crystallinity index and 50% increase in the tensile strength of films, when compared with the unprocessed WH cellulose. The thermal stability of the WH cellulose was not adversely affected but remained stable with increasing number of passes. Results suggest a high suitability for this process to generate superior quality cellulose nanofibrils at relatively low energy requirements, ideal for sustainable packaging applications and as a structural component to bioplastic composite formulations.