Processing, e.g. extrusion, injection molding, typically involves rheologically complex materials in complex flow configurations. The deformation history therein experienced by materials is generally characterized by a series of shear, extensional, or a combination of the two deformations, at high isotopic pressures and temperatures. Therefore, a fundamental understanding of the material response in simple shear and extensional conditions is essential for determining optimal compositions and flow conditions for biocomposites with favorable properties. In addition, due to the large / fast deformations usually employed, polymers are subjected to nonlinear deformations, and subsequently, the quality/performance of the final product is determined by therein induced structural changes through the flow field – matter (matrix, fillers) interactions. The main scientific goals is to investigate nanocellulose based systems using advanced rheological characterization techniques, with a particular focus on nonlinear material response functions and the tailoring of flow – field filler interaction.