Nano/Micro Composites from Polyurethanes and Cellulose

AUAD, MARÍA L.; BELLESI, NATALIA E.; ARANGUREN, MIRTA I.; MARCOVICH, NORMA E.

San Diego, CA, EEUU

Congreso; American Chemical Society, ACS; 2005

American Chemical Society, ACS

M.L. Auad, N.E. Bellesi, M.I. Aranguren, N.E. Marcovich, "Nano/Micro Composites from Polyurethanes and Cellulose", American Chemical Society, ACS, San Diego, CA, USA, March 14-17, 2005. (oral). Cellulose is a polydisperse linear polymer of poly-b(1,4)-D-glucose, which is biosynthesized by different living species in the form of threadlike rods called microfibrils. The microfibrils consist of cellulose chains aggregates that contain crystalline regions linked along by amorphous domains that act as structural defects and are responsible for the transverse break down of the microfibrils into short crystalline whiskers (diameter 2-20 nm, lengths several microns) upon the action of strong acids. Cellulose crystals have the potential for excellent mechanical performances because of low density in combination with high modulus and tensile strength. Moreover they are more biodegradable and not as expensive as other nanofillers. These facts make them very attractive for the use as polymer reinforcement in the production of composites. In this work cellulose crystals almost free of defects were obtained through acid hydrolysis and a technique for dispersing these crystals in non-aqueous solvents, such as DMF was developed. Afterward, polyurethane (PU) elastomeric films reinforced with cellulose crystals free of particle aggregates were obtained, and their dynamic mechanical behavior, morphology and capability to retain their original transparency were evaluated.