Biocomposites are seen as a key solution to find an effective circular Economy for plastics. Biocomposites provide an industrially attractive balance between low cost, environmental footprint and high performance. The mechanical properties of biocomposites are determined by their architecture, the mechanical properties of the constituents, and their interfacial properties. There are to date no modelling systems that can predict the impact of the interface stiffness and cohesive properties in cellulose composite materials. The use of a numerical modelling technique at the microstructural level offers a way to explore these interfaces, and to analyse their impact on the macroscale level. The objective of this project is to experiment and model the interfacial properties of cellulose fiber biocomposites, with the ultimate goal of improving their properties and adoption. To understand the extent of current limitations to interface strength, and potential improvements.