Produção de filmes de celulose regenerada a partir de bucha vegetal (Luffa Cylindrica) e caroço de manga (Mangifera Indica L.) para a peliculização de sementes de girassol

Abstract

The development of new biodegradable polymer materials using inexpensive renewable lignocellulosic sources, used in biochemical processes such as controlled release of active principles, immobilization of enzymes and seed coatings, are important topics of several researches worldwide. In this work, regenerated cellulose films produced from cellulose extracted from mango seed coat (MI) and vegetal bush (LC), were used in the coating of sunflower seeds through the film coating technique, to act as an alternative agricultural defensive in fungal control. The regenerated cellulose films were produced by regenerating the cellulose dissolved in bis (ethylenediamine) copper (II) hydroxide with 0,4 mol/L sulfuric acid. The films were produced without and with the addition of 1% diethyleneglycol and 1% n, n-dimethylacetamide. Cellulose is the major bulk species in the two lignocellulosic sources studied, with about 67,76% for LC and about 58,60% for MI. The average viscosimetric molar mass of the cellulose extracted from LC and MI was 190.550,21 g/mol and 85.263,79 g/mol, respectively. The results showed that the films have a crystal structure of cellulose II, are dense and with no apparent pores. The data of thermogravimetric analysis indicate that there is a small difference in thermal stability between the sources and the films. The permeability is higher in the regenerated cellulose films without the additives as the degree of swelling is high for these films. Considering the high permeability, the percentage of degree of moderate swelling of the films and the higher molar mass of the LC cellulose, the films produced with LC cellulose were used in the coating of the sunflower seeds. The adhesion of the film in the seeds after the coating was investigated by the microscopy technique, where the presence of a thin layer on the surface of the seeds is observed with about 1 to 3 μm. In the sanity test, there was little or no proliferation of fungi, this effect may be related to the presence of Cu (II) ions that act as a fungicide. Seeds coated with regenerated cellulose film (FLC) and FLC with fungicide presented the highest percentage of germination, 97% and 85%, respectively, compared to the control that presented 39% and seeds treated only with fungicide that had 54%. However, of all the seeds coated with the regenerated cellulose film, the one that presented the best germination and emergence performance, were the seeds coated with FLC.