Cellulose nanofibrils (CNF) possess properties that are highly desirable in many material applications. They are produced from renewable resources, have high aspect ratio, nm size and high stiffness and strength, just to name a few. Nanocellulose materials are commonly formed from dilute aqueous dispersions, in which the nanofibrils can be electrostatically stabilized by charged groups introduced to the particle surface. However, as the particle concentration is increased the nanofibrils have a strong tendency to aggregate and form transparent arrested states at very low solids concentration. The final mechanical properties of the materials made from CNF are strongly dependent on the distribution of the nanofibrils within the materials and therefore, aggregation must be controlled in order to maximize the benefits of the excellent properties of nanofibrils. In this project we study the colloidal stability of CNF dispersions, and how the stability is influenced by changes in particle concentration and chemical environment, and by formation and redispersion of arrested states. We use different types of counterions to the surface charges of CNF, and we investigate how the choice of counterion affects the colloidal interactions in the system, and thereby can alter the properties of the dispersions. The systems are studied using a combination of different scattering techniques and the goal is to use the results collected from the experiments to formulate new models that can describe the colloidal behavior of cellulose nanofibrils. We will also use the results to optimize the preparation of cellulose filaments using our recently developed fibre spinning methodology (Håkansson et al, Nature Comm. (2014)5, 4018).

Colloidal interactions in nanocellulose systems

251st National Meeting (2016)

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