Biocompósitos de acetato de celulose e fibras curtas de Curauá tratadas com CO₂ supercrítico

In this work, the effect of preprocessing of short Curaua fibers with supercritical carbon dioxide on the properties of biocomposites with cellulose acetate was studied. The treatment with supercritical CO2 may result in the partial lignin extraction from the fibers. Two series of biocomposites, one plasticized with dioctyl phtalate (DOP) and another with triethyl citrate (TEC), were prepared by extrusion. Fibrilation and uniform distribution of fibers in the cellulose acetate matrix were observed for both biocomposites. As a consequence, the composites showed a higher specific heat, lower thermal conductivity and higher coefficient of thermal expansion than plasticized cellulose acetate. The treatment of the fibers increased such differences. Among the plasticizers, DOP was more efficient, decreasing Tg and Young's modulus of plasticized cellulose acetate. The fiber addition had a relatively low impact on the modulus (10%), however caused a decrease in the impact resistance. Taken together, the results show that these biocomposites are promising as thermal insulators, with the additional advantage of biodegradability of all components in the case of biocomposites plasticized with TEC.