Shape Memory Polyurethanes Reinforced With Electrically Conductive Cellulose Crystals

M. L. AUAD; M. A. MOSIEWICKI; T. RICHARDSON; S. ADANUR; E. S. MEDEIROS; L. H.C. MATTOSO; M. I. ARANGUREN; N. E. MARCOVICH

Río de Janeiro, Brasil

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

COMAT

Introduction Shape memory polymers (SMPs) are smart materials capable of ?remembering? their original shape after being deformed. [1]. Polymers with shape memory behavior have both a temporary form and a stored permanent form. A completely new approach that would allow making a better use of these novel polymeric systems is the incorporation of nanofillers. Adding small amounts of nano reinforcements can: i) change the mobility of the molecules and consequently the transitions, ii) affect the segmental phase separation of the SMPs, changing crystals structures, iii) modify the relaxation processes in the amorphous regions iv) change the mechanical/shape memory behavior of the systems. So, new mechanical, optical, electrical, etc. properties can be developed depending on the nature of the added nanofiller. In this work, the use of electrically conductive cellulose crystals as reinforcement for shape memory polyurethanes (PU) was investigated. They were prepared by growing polyaniline on the surface of cellulose nanofibrils by an in situ polymerization method. These cellulose fibers represent a new generation of coated cellulose fibers that can mimic the conductive properties of carbon nanotubes and carbon nanofibres, producing biodegradable reinforcement with electrical properties. The dispersion of fibers in the PU was corroborated by SEM. Rheological and electrical measurements were carried out in order to detect a step change in properties with the incorporation of filler. The modification of the shape memory behavior with the addition of CNF-Pani was also analyzed.