Estudo da dependência do teor de glicerol sobre propriedades mecânicas de bioplásticos contendo bagaço de malte em diferentes granulometrias como carga

Abstract

The increase in production and improper disposal of petroleum-based plastics has intensified the search for alternative materials from renewable sources. In this context, bioplastics emerge as a viable and sustainable alternative, especially when associated with the recovery of agro-industrial waste. This study aimed to develop and characterize bioplastics based on starch, glycerol, and malt bagasse in different particle sizes, evaluating the influence of glycerol concentration and residue particle size on the physical and mechanical properties of the films obtained. The malt bagasse was donated by a local brewery, processed by drying, grinding, and sieving, resulting in four distinct fractions. The bioplastics were produced using the casting technique, with formulations varying the glycerol content between 10% and 40% m/m and incorporating the different fractions of the vegetable waste. The materials were subjected to optical microscopy, infrared spectroscopy (FTIR), thermogravimetric analysis (TG), as well as thickness, weight, density, and mechanical tensile tests. The results showed that the glycerol content had a significant influence on the malleability and rigidity of the films, while the particle size of the bagasse impacted structural aspects and density. Glycerol concentrations equal to or greater than 30% gave the materials greater flexibility, while lower contents resulted in more rigid films. The addition of malt bagasse, especially in larger particle fractions, also contributed to the reduction of Young's modulus. The data indicate that the combination of starch, glycerol, and malt bagasse allows the production of materials with adjustable properties, suitable for sustainable applications, such as biodegradable packaging. The findings reinforce the potential of agro-industrial waste utilization and the importance of variables such as plasticizer and particle size in modulating the properties of bioplastics, promoting advances in the development of products aligned with the circular economy.