Valorização do resíduo do processamento do cacau para usos múltiplos: compósitos

Abstract

The cocoa industry in Brazil has consolidated itself as one of the main in the world. However, this large-scale production entails large volumes of by-products with no specific purpose. One of the main residues generated is the cocoa bean tegument - TAC, which is generally sold as agricultural cover or discarded in the soil. Allied to this, there is an interest in the development of innovative and sustainable materials in various industrial spheres. Thus, composites appear as a link between these topics, when it comes to the union of materials to produce a product with improved characteristics. Agro-industrial wastes are already being studied to act as reinforcements or fillers in composites of varied matrices. This, in addition to producing innovative material, adds economic value to them, expands the supply of raw materials and contributes to sustainable consumption. Thus, the objective of this work was, from the TAC, to produce and verify the feasibility of using three different composites which are: 1) Medium density particles panel - MDP; 2) Polymeric composite - WPC and 3) Plaster-based composite. Chemical analysis of the waste was carried out, evaluating lignin, total extractives, holocellulose and ash contents. The inclusion of the waste in the matrices occurred in different percentages for each composite (mass / mass ratio). The influence of the addition of waste was analyzed, mainly, through physical and mechanical tests in the composites in addition to scanning electron microscopy. For the MDP panel, there was an increase in the compression ratio, influencing physical properties, increasing hygroscopicity, and mechanical ones, reducing its values. However, the inclusion of up to 23% of the waste to replace pine wood still meets the standardization of all properties of MDP panels for internal use. For polymeric composite, the addition of waste in the recycled LDPE matrix resulted in a lighter final product. There was an increase in humidity and water absorption and a decrease in tensile strength and elongation, indicating greater rigidity of the material. These factors are not limiting the use of the composite since its formulation can be adapted to the required application. For the plaster-based composite, the added reinforcements resulted in a lighter final product with less moisture and water absorption. There was also an improvement in thermal resistance and acoustic insulation. For the mechanical properties, there was a decrease in values so that, for regulatory compliance, the inclusion of up to 8.15% of the waste as reinforcement is feasible to be used in the composite. In general, the most limiting factor for the use of cocoa waste was its high content of total extractives, which influenced the interaction of the particles with the matrices. However, in the case of raw material in natura, there is still viability of use for the production and commercialization of composites, respecting the established limits. Finally, with the valorization of waste and its use as a substitute for primary resources, it is understood that this work can support changes in production and consumption patterns, making processes increasingly sustainable and innovative.