Nanocellulose from hemp for fully biobased photocured composites

Multipurpose cultivation of hemp, requires to grow the plants to a higher degree of maturity leading to higher lignification of the fibers. Stems processed so-called “disordered” methods produce non-aligned fibers unsuitable e.g. for textile applications, but are very abundant. Therefore, high added value applications are sought after. First, hemp fibers were transformed into nanocellulose through chemical, mechanical and enzymatic pre-treatment steps, followed by processing in an ultrafine friction grinder. The dimensions and chemical composition of the fibers during all steps were monitored by optical and field emission scanning electron microscopy, infrared spectroscopy (FTIR), and thermogravimetric analysis. The thermal and mechanical properties, and the permeability to water vapour of nanopaper prepared from nanocellulose were also assessed. Secondly, the nanocellulose was combined with a photocured polymer matrix, derived from agri-food industry waste, to prepare composites, potentially usable in packaging. A photopolymer matrix was selected, being photopolymerization a green technology, owing to low energy requirements, high reaction rates, and low VOC emissions. The extent of curing was evaluated by FTIR, and the thermal and mechanical properties were assessed. The preparation of sustainable composites derived from biomass (both filler and matrix), through the use of an environmentally friendly curing process, is therefore hereby demonstrated.