Natural fiber composites are ecologically interesting materials because fibers are renewable, and they require less energy for their production compared to glass or carbon fibers. The fiber/thermoplastic polymer compound can be processed by injection molding, which allows large production rates. Economic and social issues are therefore important, and the use of this type of composites must be widened. The properties of molded parts depend on fiber orientation, length and concentration, which are influenced by injection. Cemef has a large expertise in glass fiber reinforced thermoplastic injection molding, and in the properteis of natural fibers. The objective of the PhD project is to combine this expertise to optimize the fiber microstructure in the process, in order to get the highest mechanical properties and compete with fiber reinforced thermoplastics. To reach the objective, it will be necessary to understand and predict the structural organization of molded natural fibers composites taking into account the specificities of these fibers due to their various intrinsic properties such as flexibility, initial organization (size, bundles, composition), mechanisms of breakage under mechanical stresses, etc. The work will consist of experimental part (observations of model and real fibre behaviour) and modelling (numerical modelling of flow allowing correlation of mechanical and thermal history to the observed microstructures).
Good knowledge in polymers and their processing. Good level of English (reading and writing)