Impact of cellulose nanofiber preparations on rheology of polyols: A comparison of bead milling, high-pressure homogenisation, and deep eutectic solvent pretreatment

Nanocellulose is a recognised additive that enhances the functional properties of polymer systems, such as polyurethanes, and also acts as a rheological modifier. However, its performance varies due to different production methods, which affect dispersion and distribution in polyols, thus influencing rheology, reactivity, and structure-property relationships of polyurethane composites. This study examines the rheological behaviour of cellulose nanofibers (CNF) with three different morphologies, produced using agitator bead milling (ABM), high-pressure homogenisation (HPH), and deep eutectic solvent (DES) treatment followed by HPH. These CNFs were dispersed in polyol and assessed for their effects on flow behaviour and reactivity. The results demonstrate that each CNF type interacts differently with the polyol matrix, highlighting the importance of selecting specific CNF morphologies to control properties. ABM-treated CNF promotes rapid foaming, HPH-treated CNF allows for uniform foam formation, and DES-HPH-treated CNF produces high-density, reinforced foams. These findings highlight the significance of considering nanocellulose morphology during processing and showcase its potential for tailoring polyurethane systems to meet particular industrial performance criteria.