Rice hull is a residue from agro-industry that can be used to produce nanocellulose. We produced nanocellulose from rice hulls through bleaching (with a 5% NaOH solution followed by a peracetic acid solution) and acid hydrolysis at a mild temperature (45ºC) followed by ultrasonication. We investigated the microstructure, crystallinity and thermal stability of these materials and studied their effects on the properties of starch films. After bleaching, the compact structure around the cellulosic fibers was removed, and the lignin content of the residue decreased from 7.22 to 4.22%. The obtained nanocellulose presented a higher crystallinity (up 70%), higher thermal stability than the raw material and lignin contents below 0.35%. The nanocellulose formed interconnected webs of tiny fibers (< 100 nm in diameter), which decreased the opacity, water vapor permeability and improved the mechanical properties when added as reinforcement in the starch films.
RESUMO
Os objetivos deste trabalho foram a incorporação de casca de soja in natura (CS) e celulose microcristalina (CMC) em cinco formulações de filmes biodegradáveis a base de amido de mandioca e glicerol, que foram produzidos via extrusão por sopro e, ainda, caracterizar estes filmes quanto à sua morfologia e propriedades mecânicas. Todas as formulações levaram à obtenção de filmes com boa homogeneidade, com ausência de bolhas e rachaduras, com destaque para os incorporados com CMC. A incorporação de CMC (2,5%) melhorou a flexibilidade dos filmes, e a adição de 5% de fibras (CS ou CMC) levou à produção de filmes mais quebradiços e menos flexíveis.Palavras-chave: Resíduos agroindustriais, morfologia e propriedades mecânicas.
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