Polyurethane reinforced with nano/micro sized cellulose fibers

AUAD, MARÍA L.; CONTOS, V.S.; NUTT, STEVE; ARANGUREN. MIRTA I.; MARCOVICH, NORMA E.

Buenos Aires, Argentina

Conferencia; Internacional Conference on Composite Materials, COMAT 2005; 2005

Internacional Conference on Composite materials, COMAT 2005, Buenos Aires, Argentina, 11 al 14 de diciembre de 2005. 2 páginas The association of the existing materials, rather than their synthesis, has been preferentially used to obtain new materials. As far as short-fiber composites are concerned, the improvement of the mechanicals properties with respect to those of the neat polymer depends mainly on the quality of the dispersion of the fibers in the matrix [1-2], the fiber aspect ratio and the interfacial adhesion between the fibers and the matrix [3]. Shape memory polymers (SMPs) are typically polyurethane-based materials (PU) that have the capability to recover from unusually large strains imposed by mechanical loading. Compared with their metallic analogs (shape memory alloys, SMA), SMPs present much lower density, easier processing, larger recoverable strains, and lower cost [4-5]. The unconstrained recoverable strain limits are on the order of 100%, in contrast to shape memory metals or ceramics, which typically recover only ~10% and 1% strain, respectively [4,6]. Native cellulose is an abundant and inexpensive macromolecular compound that reinforces most plant cell walls [7]. Cellulose whiskers have polar groups that can interact with polar polymers, such as polyurethanes, leading to a composite material with good interfacial adhesion. This is essential to obtain a material with enhanced properties. Furthermore, the cellulose ?OH groups can co-react during the PU synthesis, leading to strong interfacial adhesion, thereby improving the load transfer from the polymer matrix to the high modulus crystals.