Novel biobased micro- and nanomaterials in porous foam formed structures

This work applies the knowledge on multi-scale lignocellulosic fibres and proteins to create novel porous fibre structures using a foam forming technology. In particular, the aim is to enable new material properties by combining multi-scale wood and agro fibres, fines, cellulose nanofibrils and surface active proteins when using foam-assisted forming process. The design driven approach contributes to the selection of raw materials and tailoring of desired micro and macro structures through the processes. The future applications include e.g. cushioning elements in packaging and acoustic materials in indoor construction. The compression strength is one of the most critical mechanical properties in both applications areas. In our study, lignin-rich fines made of spruce wood and cellulose nanofibrils improved the compression strength of foam formed structures made with SDS and PVA as foaming agents. The used cellulose nanofibrils were TEMPO-oxidised (TCNF) and native grades (CNF). In this work, the retention of CNF fibrils in foamed porous structures was studied using x-ray tomography images and elementary analysis from iron-cobalt labelled mass and water samples. The surface active proteins were investigated as a mean to strengthen the lamella of air bubbles for stabilizing the aqueous fibre foams made with SDS. The produced stronger wet foamed structures can reduce drying time significantly allowing vacuum-based dewatering. Overall, wide-range selection of novel bio-based micro -and nanomaterials significantly improved the important process and product properties of highly porous foamed structures.