Cellulosic nanoparticles from alfa fibers (Stipa tenacissima): extraction procedures and reinforcement potential in polymer nanocomposites Ayman Ben Mabrouk • Hamid Kaddami • Sami Boufi • Fouad Erchiqui • Alain Dufresne Received: 23 November 2011 / Accepted: 2 February 2012 / Published online: 14 February 2012 Ó Springer Science+Business Media B.V. 2012 Abstract The microstructure and chemical compo- sition of alfa (Stipa tenacissima) were investigated. The polysaccharide and lignin contents were around 70 and 20 wt%, respectively. From the bleached and delignified fibers, two types of nanosized cellulosic particles were extracted, namely cellulose nanocrys- tals and microfibrillated cellulose (MFC). The former correspond typically to the elementary crystallite units of the cellulose fibers, with a rod-like morphology and an aspect ratio of about 20. The latter, mechanically disintegrated from oxidized bleached fibres, presents an entangled fibrillar structure with widths in the range 5-20 nm. The reinforcing potential of the ensuing nanoparticles was investigated by casting a mixture of acrylic latex and aqueous dispersion of cellulose nanoparticles. Thermo-mechanical analysis revealed a huge enhancement of the stiffness above the glass transition of the matrix. Significant differences in the mechanical reinforcing capability of the nanoparticles were reported. Keywords Alfa  Structure  Nanocrystals  Microfibrillated cellulose (MFC)  Nanocomposites Introduction Alfa, also named Esparto grass, is an endemic gray grass plant constituting the main biomass source in semi-arid ecosystems of the south western Mediterra- nean basin, namely in North Africa and south of Spain. It covers a large area estimated to about 7 million ha (Algeria: 4,000,000 ha, Morocco: 3,186,000 ha, Tuni- sia 400,000 ha, Libya 350,000 ha, Spain: 300,000 ha.) (Terre et Vie 2002). Thanks to roots being deeply buried in the soil, it presents a high capacity of acclimatization to limited water resource, good resis- tance to extreme droughts and thermal stress, as well as relatively indifference to the substratum on which it grows. Alfa plants play a key role in protecting and maintaining the ecological integrity of the whole ecosystem by preventing the soil from being exposed A. B. Mabrouk  S. Boufi Laboratoire Sciences des Mate ´riaux et Environnement, LMSE, University of Sfax, BP 802-3018 Sfax, Tunisia H. Kaddami Laboratoire de Chimie Organome ´tallique et Macromole ´culaire - Mate ´riaux Composites, Cadi Ayyad University, Faculty of Sciences and Technologies of Marrakesh, Avenue Abdekrim Elkhattabi, BP549, Marrakesh, Morocco F. Erchiqui Laboratoire de Plasturgie et Nanocomposites, Universite ´ de Que ´bec en Abitibi-Te ´miscaminque, Boulevard de l’Universite ´, Rouyn-Noranda, QC J9X5E4, Canada A. Dufresne (&) The International School of Paper, Print Media and Biomaterials (Pagora), Grenoble Institut of Technology, BP65, 38402 Saint Martin d’He `res Cedex, France e-mail: Alain.Dufresne@pagora.grenoble-inp.fr 123 Cellulose (2012) 19:843–853 DOI 10.1007/s10570-012-9662-z