ENERGY EFFICIENT NANOCELLULOSE SHEETS FOR PRODUCT APPLICATION

Abstract

synthetic polymers and plastics which are currently used as barrier materials in the packaging industry are neither renewable nor biodegradable, creating a serious threat to the ecosystem. Nano cellulose which is obtained by breaking down cellulose fibers into nano-scale dimensions has unique properties with the potential to dramatically impact many commercial markets including packaging. This research investigates the refining of cellulose fiber to produce sustainable nano cellulose using a laboratory PFI mill and industrial Disc refiner. Refined pulp was made into nano cellulose sheets using standard laboratory paper making technique through vacuum filtration. The tensile index and sheet density for PFI mill refined BEK and Disc refined NBSK showed approximately five times and two times improvement over unrefined BEK and NBSK pulp respectively highlighting the role of refining in improving the mechanical structure of nano cellulose sheets. This strength enhancement comes at a cost of 17417 kWh/t specific refining energy in lab-scale PFI mill refining and 3346.3 kWh/t specific refining energy in industrial-scale Disc refining. Fines generation as a result of refining decreased the porosity by 37.972% and 48.939% in Disc refined NBSK and PFI mill refined BEK respectively which improved the water vapor and oxygen permeability. Refining decreased the water vapor permeability by approximately ten times for both BEK and NBSK making them very comparable with synthetic polymers such as polyethylene (PE). The lowest value of oxygen permeability achieved with PFI mill refined BEK and Disc refined NBSK was 0.533±0.098 and 0.762±0.03 (cc.µm)/(m2.day.kPa) which is very competitive with that of polymers used in plastics. Additionally, the surface roughness decreased by 77.05% and 52.8% for PFI mill refined BEK and Disc refined NBSK respectively which promises refining as an excellent tool to produce smooth nano cellulose sheets for printed electronics applications.