Multiscale modeling of lignocellulosic foams under compression

Biodegradable lignocellulosic foams have the potential to replace foams produced from petroleum sources that have environmental issues. These lignocellulosic foams contain randomly oriented fibers or particles bonded by cellulose nanofibrils (CNFs). In this work, effort was focused on the production of lignocellulosic foams using wood flour or thermomechanical pulp (TMP) fibers bound with CNFs. Multiscale modeling is proposed to predict the mechanical properties. Microwave drying was employed to produce the low-density porous foam structures. Compression tests conducted on the foams exhibited elastic–plastic responses. Finite element analysis (FEA), a numerical method to determine the elastic–plastic mechanical properties was utilized. The Young’s modulus of lignocellulosic foams calculated from fiber-scale modeling methods exhibits strong agreement with experimental results for strains up to 10%. Meso-scale modeling indicates an FEA approach to determine Young’s modulus considering cellulose as matrix and porosity inclusions to create different porous structures. Macro-scale FEA was performed using crushable foam material model to determine the elastic–plastic behavior of the foams for strains up to 20% reveals a solid agreement with the experimental results. Modeling results at different scales promise a robust numerical framework to predict mechanical behavior of these novel lignocellulosic foams.