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Polyaniline Modified Nanocellulose as Reinforcement of a Shape Memory Polyurethane
M. I. ARANGUEN; M. L. AUAD; T. RICHARDSON; S. ADANUR; W. J. ORTS; E. S. MEDEIROS; L. H. C. MATTOSO; M. A. MOSIEWICKI; N. E. MARCOVICH
Conferencia; 13th European Conference on Composite Materials; 2008
Shape memory polymers (SMPs) are smart materials capable of remembering and autonomously recovering their original shape after being deformed, as a response to a stimulus. Segmented polyurethanes (PU) that present a two-phase microstructure consisting on hard and soft segments, can show this type of behavior. In this work, electrically conductive cellulose nanocrystals were used to reinforce shape memory polyurethanes, adding an extra variable to tune up the properties of these nanocomposites. The modified nanocrystals were prepared by an in situ polymerization method, growing polyaniline (PANI) on the surface of the cellulose nanofibrils. These crystals combine the good mechanical properties of the cellulose nanocrystals and the conductive properties of the PANI. The crystals were added to a thermoplastic-segmented polyurethane showing shape memory properties. Electrical measurements were performed to characterize the conductive properties of the resulting composite films. Reinforcement was clearly observed in the polyurethane nanocomposites at cellulose concentrations above 4-10 wt%. This range was higher than that observed previously in non-conductive nanocellulose composites, probably due to agglomeration of the crystals after PANI modification. The shape memory behavior was studied and compared with that of the unfilled commercial system. Addition of the conductive nanocellulose improved fixity, but reduced shape recovery.