Material Processing and Mechanical Behavior of High-Performance Cellulose Nanopaper Made From Cellulose Nanofibrils

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This grant will enable research on developing cellulose ‘nanopaper’ made by self-assembly of cellulose nanofibrils for structural applications. Strong, stiff and tough materials with lightweight characteristics are critical for many engineering applications ranging from automotive to aviation industries to reduce energy consumption and increase structural agility, among others. This research aims to create green alternatives to traditional fossil fuel derived polymers and polymer composites by employing cellulose nanofibrils derived from lignocellulosic biomass as an alternative to petroleum-based resources. Educating and training students from diverse and underrepresented groups in areas of processing of green materials and mechanical characterization and modeling of novel nanostructured materials via non-contact, vision-based approaches is part of the overall research goal. Incorporating the research outcomes into the graduate curriculum, disseminating the findings to peers and the community at-large through demonstrations, presentations, publications and other outreach activities is integral to the research project as well. The high aspect ratio and semi-crystalline nanostructure that cellulose nanofibrils possess make them ideal to form three-dimensionally entangled microscopic networks suitable for processing high-performance structural materials via self-assembly. The resulting material is often referred to as cellulose nanopaper and has promising mechanical characteristics. This basic research, at the interface of material processing and mechanical behavior of cellulose nanopaper in ‘as-is’ and functionalized states, is to decipher process-microstructure-property relations for this non-traditional and potentially transformative material for high performance mechanical applications. On the material processing front, the focus will be on (a) studying the reaction conditions associated with the environmentally-friendly formic acid hydrolysis and mechanical fibrillation parameters on the cellulose nanofibril characteristics, (b) investigating different processing approaches to control the resulting nanopaper quality, microstructure and functionality. On the mechanical characterization front, the focus will be on (a) developing mechanics-based understanding of the tensile and fracture responses of fibrous cellulose nanopaper of different microstructures and functionalities at different length scales and loading rates, (b) developing and demonstrating monolithic and laminated high-performance cellulose nanopaper structures.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.