Franciele Maria Pelissari

Achira as a source of biodegradable materials: Isolation and characterization of nanofibers.

In this study, variations in the delignification and bleaching stages, acid hydrolysis and high-pressure homogenization, led to the development of 12 different treatments applied for obtaining nanofibers using fibrous residues arising from the starch extraction process from the achira rhizomes. The treatments were evaluated based on some properties and characteristics of nanofibers such as: morphology and size (by means of transmission electron microscopy), surface charge (by means of zeta potential measurements), crystallinity index (by means of X-ray diffraction analysis) and functional groups (by means of infrared spectroscopy). In general, the nanofibers showed particle diameters between 13.8 and 37.2nm, length between 832.8 and 2223.8nm and high crystallinity index (57.5% and 69.8%) compared with achira fibrous residue (17.3%). The results evidenced that fibrous residue from achira rhizomes can be used as a source of biodegradable materials of commercial interest.

Nanocomposites based on banana starch reinforced with cellulose nanofibers isolated from banana peels

Cellulose nanofibers were isolated from banana peel using a combination of chemical and mechanical treatments with different number of passages through the high-pressure homogenizer (0, 3, 5, and 7 passages). New nanocomposites were then prepared from a mixed suspension of banana starch and cellulose nanofibers using the casting method and the effect of the addition of these nanofibers on the properties of the resulting nanocomposites was investigated. The cellulose nanofibers homogeneously dispersed in the starch matrix increased the glass transition temperature, due to the strong intermolecular interactions occurring between the starch and cellulose. The nanocomposites exhibited significantly increased the tensile strength, Youngs modulus, water-resistance, opacity, and crystallinity as the number of passages through the homogenizer augmented. However, a more drastic mechanical treatment (seven passages) caused defects in nanofibers, deteriorating the nanocomposite properties. The most suitable mechanical treatment condition for the preparation of cellulose nanofibers and the corresponding nanocomposite was five passages through the high-pressure homogenizer. In general, the cellulose nanofibers improved the features of the starch-based material and are potentially applicable as reinforcing elements in a variety of polymer composites.