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September 22, 2016
Marcos Mariano, Ph.D. student of LGP2 and of Laboratoire Rhéologie et Procédés, defended his Ph.D. thesis: "Applications of cellulose nanocrystals: thermal, rheological and mechanical properties of new materials".
The preparation of composites based on cellulose nanocrystals (CNC) is normally performed using techniques such as melt processing or casting/evaporation. In the last one, impressive mechanical properties can be reached due to the creation of a particle 3D network that is based on new hydrogen bonds between the cellulose nanorods. This process of new H-bond formation normally takes time and is dependent of the nanoparticle size and its volume fraction. Besides, the quality of filler dispersion into the polymeric matrix is also an important parameter to provide the highest surface area and provides an ideal structure for the rigid structure.
This thesis proposes different preparation methods and characterizations to obtain nanocomposites with a simple preparation either by casting-evaporation or melt processing. Nanocomposites materials based on cellulose nanocrystals and amorphous or semi-crystalline polymer as matrix were prepared and characterized. Most of the work has focused on the optimization of their properties and the impact of the processing method, in particular by extrusion or injection molding. The impact of the nanofiller-induced crystallization of the matrix, and the possibility of reorganization of the nanocrystals after processing, were notably addressed.