A Cost-Effective and Environmentally-Friendly Method to Improve Surface Compatibility of Cellulose Nanofibrils (CNF) in Hydrophobic Matrix Materials

Cellulose nanofibrils (CNFs) are promising light-weight additives for thermoplastic composite ap- plications. However, the large number of hydroxyl groups on CNFs have strong hydrogen bonding interactions between CNFs that leads to a gel-like structure when produced. The key challenge is to remove >95% of hydrogen-bounded water from the production slurry to yield a dispersible powder while maintaining the structural integrity of the CNFs. CNFs high hydrophilicity limits its uses in composites as they can form agglomerates in hydrophobic polymer resins. Environmentally benign and scalable surface modifications are needed to produce composites materials for various applications. Nano Terra will work with the University of Maine to develop an energy-efficient, environmentally-friendly and cost-effective surface modification process to improve manufactur- ing and surface compatibility of CNFs in hydrophobic matrix materials. We will functionalize CNFs directly in the water slurry using environmentally-friendly chemistry and reagents. This new approach will have the following advantages: 1) The surface of CNFs will be tailored to match various hydrophobic resin materials to improve dispersion quality in composite formulations; 2) Surface modification in the production water slurry will reduce hydrogen bonding interactions between CNFs and water, facilitating separation of CNFs from water. Excess water will be filtered off, significantly reducing drying cost and improving energy efficiency; and 3) The green process will not use organic solvents and hazardous chemicals, thus significantly reducing the cost of waste management.