Obtenção e caracterização de nanofibras de celulose a partir de biomassas lignocelulósicas e estudo da aplicação em matriz polimérica biodegradável

Abstract

In the search to enable the use of materials that meet environmental requirements, such as the origin of the raw material and biodegradability, while maintaining satisfactory performance when compared to conventionally used materials, research aimed at using cellulose on different scales has intensified. Cellulose nanofibers are present in this context, being widely investigated for use as filler in different matrices and demonstrating the ability to meet the technical and environmental needs presented by new materials. In this sense, the present study used cellulosic sources to obtain cellulose nanofibers through ultrafine friction grinding of fibers from the mesocarp of palm oil, eucalyptus and microcrystalline cellulose to evaluate the differences promoted in cellulose from different sources based on the grinding times (30 minutes, 2.5 hours and 5 hours) and the characteristics inherent to the loads produced. The morphological, thermal and structural characterizations carried out revealed that grinding during the times studied led to changes in the materials, such as a decrease in size and an increase and/or decrease in the crystallinity index. After obtaining and characterizing the cellulose nanostructures, a study was carried out on the application of nanofibers in a thermoexpanded polymer matrix made from starch using the thermal expansion process. To this end, some of the nanofibers obtained were used for insertion into cassava starch foams. Physical evaluations provided data on the behavior and potential use of these cellulose nanofibers as a reinforcement material for the polymer matrix in question. It was found that the longer grinding time, although it leads to greater defibrillation of the cellulose, did not necessarily contribute to a significant improvement in terms of flexural resistance when comparing the control formulation and the nanocomposites with a content of 0.5% of fiber nanofibers cellulose. Furthermore, the small interference of cellulose nanofibers in the density of the foams was detected. The foam made through the insertion of palm cellulose nanofibers after 2.5 hours of grinding (ESP-DND230) was also evaluated for impact resistance and crystallinity index, allowing the study of the influence of the nanofibers that make up this formulation on these parameters. In this way, the potential for using cellulose nanofibers in the evaluated matrix can be inferred, targeting the packaging sector.