Abstract FR:

This work describes the use of some Brazilian natural fibers (Sisal, Luffa Cylindrica and Capim Dourado) as sources of cellulose nanowhiskers and microfibrillated cellulose (MFC) for the preparation of polymeric nanocomposites. It proposes a new way of obtaining cellulose nanoparticles and exploits their intrinsic properties. For this purpose two main routes were investigated, namely (i) use of chemically grafted cellulosic nanoparticles reacted with isocyanates and incorporated in a -polycaprolactone (PCL) matrix, and (ii) direct use of cellulose nanoparticles as reinforcement in a natural rubber (NR) matrix. The thermo-mechanical properties were investigated by DSC and DMA. In both cases it was demonstrated that low amounts of fillers provides high mechanical properties when compared to the neat matrix, PCL or NR. The study of crystallization kinetics of PCL and PCL-nanocomposites provided additional information for cellulosic nanofillers acting as nucleating agents accelerating the crystallization process of nanocomposites. Enzymes were also used to prepare such nanoparticles thus yielding nanofillers with different morphologies. As a result, the final NR-nanocomposites showed different mechanical performances and gain in both Young’s and storage modulus with respect to the neat polymeric matrix.