Surface Modification of Cellulose Nanofibrils for Reinforcement of Composites

Cellulose nanofibrils (CNF) are a class of high axial ratio, nanoscale materials that can be sustainably derived from wood and plant products. Of particular interest is using CNFs as a reinforcement additive in polymer composites as a replacement for petroleum derived carbon fibers. The major obstacle to the use of CNF in resin applications is the incompatibility of their surface chemistry to that of most conventional polymer matrices leading to poor dispersion or agglomeration. Researchers at Luna Innovations, in collaboration with engineers at Virginia Tech, have identified a cost effective and highly scalable process for the surface treatment of CNF to enhance their compatibility with hydrophobic materials. Luna’s team has developed technology specifically for creating hydrophobic surfaces on nanoparticles for a number of applications including self-cleaning textiles, corrosion coatings and rain repellent canopies that are relevant to this effort. In this Phase I effort Luna will acquire a number of CNF products for treatment and down select the best candidates based on overall cost and final composite properties. A hydrophobic treatment will be applied to CNF dispersions through a high throughput aerosol/spray drying system at Luna’s Blacksburg facility and the resulting solids collected through a combination of vortex and bag filtration. The engineering team can fabricate both thermoplastic and thermoset based polymer composites using the treated CNF material and evaluate the dispersion through microscopic methods. It is anticipated that the dispersion treatment developed in this feasibility study will be of benefit to the automotive industry which makes up a large component of the reinforced thermoplastic composite market. These CNF nanomaterials may also have use in other nanocomposite applications in the defense, energy and aerospace markets.