Comportamento de tensão-deformação de filmes poliméricos produzidos de triacetato de celulose obtido através da palha de milho Zea mays

Abstract

Corn straw (CS) is considered as an agricultural residue, usually incinerated or used as a bed in poultry farms on Brazilian farms, being an abundant material, but little used in order to generate income, except when destined to the production of handicrafts. In this work, the CS residue was used to produce cellulose triacetate (CTA) and polymer films of the same, with addition of plasticizer - glycerol - in order to test its mechanical properties. To obtain the cellulose, the corn straw underwent a process of delignification by reflux in nitric acid / ethanol solution (20/80% v/v) and then it was kept in a solution of sodium hydroxide 1 mol L-1 an then washed to obtain neutral pH. Then, the CTA was obtained from acetylation of the cellulose using acetic acid and acetic anhydride. CTA films were produced using dichloromethane as the solvent and glycerol as plasticizer in percentages of 10, 20 and 30% w / w relative to the mass of CTA. The SEM images of the films showed that the plasticizer adhered to the matrix and modified its surface in relation to the pure sample, causing the appearance of pores. The mechanical tests showed that the films containing the plasticizer had better results of tensile strength, elongation at break, Young's modulus and toughness, in relation to the film without the additive. In addition, it was possible to compare the results with other studies in the group using mango as a source of cellulose. Results from the mechanical assay indicated that the films made from corn straw presented better mechanical properties, indicating that the characteristics of the residues such as percentage of cellulose, lignin and viscosimetric molar mass directly influence the properties of the polymer produced.