Production and modification of Eucalyptus microfibres and nanofibres for reinforcement of polymeric nanocomposites

Abstract

The interest for cellulose nanofibres from renewable sources has growing mainly because of the exceptional mechanical characteristics of these materials. Several studies have been reported in the literature about using cellulosic fibres and nanofibres in polymeric matrices to obtain nanocomposites. However, in the majority of these studies the composites did not present adequate performance against humidity due mainly to the hidrophylic character of the polysaccharides used. The problems with nanofibres dispersion need to be better investigated. The objective of the present work is to obtain, characterize and modify superficially (with physical-chemical treatments) the eucalyptus cellulose microfibres and nanofibres for production of biodegradable polymeric composites / nanocomposites with higher resistance to water absorption. In the first stage of the work, the eucalyptus cellulosic fibres will be milled or refined in order to increase their fibrillation and improve their dispersion into the polymeric matrix. Nanofibres will be produced by acidic hydrolysis of the bleached cellulosic fibres. The final products (microfibres and nanofibres) of this first stage of the project will be characterized by thermogravimetry (TG), scanning (SEM) and transmission (TEM) electron microscopy, atomic force microscopy (AFM), X-ray diffraction and about the surface energy or wettability (contact angle) of the microfibres / nanofibres. In the second stage of the project, composites / nanocomposites will be produced by extrusion and thermopressing or by casting, with polymeric matrices of different constitution (starch and starch/latex/PVA blends). Special atention will be dispended to composite processing and optimization of nanofibre dispersion. Composites / nanocomposites will be evaluated about the thermal stability (TG), dynamic mechanical thermal analysis (DMTA), mechanical performance in different conditions of temperature and humidity, resistance to water absorption and wettability (contact angle), surface roughness (AFM), cristalinity (X-ray diffraction) and fibre to matrix interface (SEM). It is expected, with the present work, to contribute to the nanofibres production methods and to obtain biodegradable composites / nanocomposites with adequate mechanical performance and with higher water resistance.