Mise en forme et caractérisation thermo-mécanique de bionanocomposites polymères renforcés avec des celluloses microfibrillées et des whiskers de cellulose

Processing and thermo-mechanical characterization of polymer bionanocomposites reinforced with microfibrillated cellulose and cellulose whiskers

• Auteur / Autrice : Gilberto Antônio De Freitas Siqueira
• Direction : Alain Dufresne, Julien Bras
• Type : Thèse de doctorat
• Discipline(s) : Matériaux, mécanique, génie civil, électrochimie
• Date : Soutenance en 2010
• Etablissement(s) : Grenoble INPG

Mots clés

Mots clés libres

Nanowhiskers de cellulose

Cellulose microfibrillée

Greffage chimique

Nanocomposites

Résumé

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.

This work describes the use of sorne Brazilian natural fibers (Sisal, Luffa Cylindnca and Capim Dourado) as sources of cellulose nanowhiskers and mierofibrillated cellulose (MFC) for the preparation of polymerie nanocomposites. It proposes a new way of obtaining cellulose nanoparticles and exploits their intrinsic properties. For this purpose tvvo main routes were investigated, namely (i) use of cllernically grafted cellulosic nanoparticles reacted with isocyanates and incorporated in a []-polyeaprolactone (PCl) matrix, and (ii) direct use of cellulose nanoparticles as reinforcement in a natural rubber (NR) matrix, The thermo-mechanical properties were investîgated by DSe and DMA. Ln both cases it was dernonstrated that low amounts of fillers provides high mechanical properties when cornpared ta the neat matrix, PCL or NR.