Rheological Behavior of Nano-Cellulose Reinforced Polyurethane

MIRNA A. MOSIEWICKI; TARA RICHARSON; NORMA E. MARCOVICH; MIRTA I. ARANGUREN; MARIA L. AUAD

Río de Janeiro, Brasil

Conferencia; International Conference on Science and Technology of Composite Materials, COMAT 2007; 2007

COMAT

Shape memory polymers are intelligent materials able to recover their original shape after being subjected to large strains [1]. In general, these materials present low stiffness and small recovery force that limit some of their applications. This disadvantage could be overcome with the incorporation of rigid nanoparticles [2]. Specifically, cellulose is an interesting alternative due to its high modulus, high strength, low cost, low density and wide disponibility from biodegradable and renewable resources. An important concept in the field of nano-composites related with the improvement in properties (mechanical, electrical etc) is the percolation, defined as a characteristic threshold concentration (mcG’) of filler at which a step variation in properties occurs. The reinforcement of polymers using nano-particles, even in very low concentrations, can generate important changes in the viscoelastic properties of the melts [3]. The presence of direct mechanical contacts between embedded particles or fibers can give rise to many non-linear rheological features. The study of the viscoelastic properties at low filler concentration can be used to investigate the occurrence and location of the percolation threshold. Thus, in this work, the rheological behavior of molten polyurethanes (PU) reinforced with microcrystalline cellulose whiskers was studied. The results were analyzed using a simple percolation model.