Síntese e Caracterização de Filmes Biodegradáveis de Amido de Milho pela Adição de Glicerol e\ou Sorbitol

Abstract

The indiscriminate use of plastic products has led to environmental problems, economic and social crises caused by the accumulation of solid waste in nature. These socio-environmental problems have encouraged the search for biodegradable materials, capable of mitigating these effects caused by materials from fossil sources. A promising alternative has been the use of biodegradable films in the manufacture of plastic bags daily used. In this context, this work aims at synthesize starch-based biofilms and verify the influence of glycerol and/or sorbitol plasticizers in fixed and variable proportions in relation to the mass of corn starch. The tap casting methodology was used to synthesize these films based on corn starch, glycerol and/or sorbitol in the proportions of 30%, 20%, 15% and 10%. After that, these films were characterized for thickness, solubility, chemical structure, mechanical properties and biodegradability. The analysis of the results indicated that the films with higher sorbitol contents have maximum film rupture and high elasticity modulus, lower thicknesses and higher water solubility. The films with higher glycerol contents presented higher values of deformation and thickness, and lower water solubility. Regarding to films biodegradability, the degradation was evaluated through two systems, at first the films were placed between two layers of soil and at second, the films were placed on the soil surface. The results indicated that there is no difference in degradation as a function of the plasticizers used and their percentages. In the period of seven days the samples have shown signs of decomposition as well by changing color appearance. In fifteen days, mass loss was verified due to the action of microorganisms. It is observed that in buried films (between two layers of soil), the degradation process tends to be faster compared to films that were only on the ground. In thirty and in sixty days as well, the films are almost completely degraded. These results indicate that the synthesized films are promising to be used as raw material for plastic bags because they have appropriate chemical and mechanical characteristics, in addition to presenting high biodegradability.