Cellulose nanocrystals from curaua fibers and poly[ethylene-co-(vinyl acetate)] nanocomposites: Effect of drying process of CNCs on thermal and mechanical properties

Poly{[}ethylene-co-(vinyl acetate)] (EVA) and cellulose nanocrystals (CNCs) from curaua fibers were used to obtain nanocomposites. Due to polarity that acetate groups promote in EVA, they tend to present better affinity with cellulose nanostructures without compatibilizers. In addition, the influence of the drying conditions of CNCs suspension on their dispersion through the matrix was also evaluated. CNCs were obtained via acid hydrolysis in a mixture of sulfuric and hydrochloric acids. Part of CNCs in neutral suspension was freeze-dried and part was dried in an oven with air circulation. The dried CNCs were incorporated into EVA at concentrations of 1, 3, and 5 wt% of each CNCs. The compositions were processed in a corotating twin-screw extruder and injection molded. Morphological results showed better dispersion and adhesion of freeze-dried nanocrystals into EVA, and these nanocomposites also presented increase in elastic modulus and elongation at break, resulting in more resilient and elastic materials. (AU)