Development of a rheologically-based dispersion quality index for cellulose nanocrystals in non-polar and thermoplastic media

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Cellulose nanocrystals (CNCs) represent an abundant, renewable, sustainable, recyclable and biodegradable source of nanomaterials that can be used in the fabrication of polymer nanocomposites. However the industry is currently faced with a key issue: as synthesized, CNC is highly hydrophilic, hence it does not disperse well in non-polar solvents and thermoplastic polymer matrices. Without methods to characterize and quantify their level of dispersion, it is difficult to evaluate the success of different approaches for introducing and distributing CNC into non-polar matrices. A recent strategic NSERC project focusing on the development of rheological methods to characterize the properties of CNC-based polymer nanocomposites was completed in early 2015. It involved Carreau and Heuzey of École Polytechnique de Montréal (EPM) and Riedl of Université Laval (UL), in collaboration with Dr Wadood Hamad from FPInnovations (FPI). This ongoing collaboration leads to very interesting results on the potential of CNC in the fabrication of polymer nanocomposites, but has also served to identify key fundamental questions that remain unanswered. This proposal aims to take this research a step further, specifically by developing a rheologically-based "dispersion quality index" through an investigation of the effect of CNC surface modification approaches, building on the expertise of Tavares (EPM), van de Ven (McGill) and Riedl (UL) for surface treatment, and on Heuzey and Carreau's (EPM) extensive rheological background. Because rheological properties are very sensitive to small changes in microstructure, it is believed that rheometry could be efficient, low-cost techniques to characterize the state of dispersion of CNCs. The main goal of this project is therefore to develop correlations quantifying the extent of dispersion of CNCs into non-polar matrices by comparing rheological properties with actual microstructures observed by scanning and transmission electronic microscopy. This will position Canadian Universities as international leaders in new scientific and strategic fields, namely nanotechnology and biopolymers.******