Otimização de aditivo termoplástico à base de amido: avalição de propriedades físicas e mecânicas

Abstract

The vast majority of conventional plastics are derived from non-renewable resources, such as petroleum, and their environmental decomposition is extremely slow, taking up to 500 years. This prolonged process generates significant environmental impacts, as the structure of these plastics is not easily metabolized by microorganisms. In response to this issue, the concept of bioplastics or biodegradable plastics has emerged, aiming to offer more sustainable solutions with the ability to degrade more quickly and reduce environmental damage. Despite the growing demand for eco-friendly alternatives, the Organisation for Economic Co-operation and Development (OECD) predicts that the use of conventional plastics will continue to increase in the coming decades, resulting in an even greater generation of non-biodegradable plastic waste, making the development of viable and effective alternatives to traditional plastics increasingly urgent. In this context, the objective of this study was to develop and optimize the formulation of a biodegradable thermoplastic additive through an experimental design that varied the proportions of plant-based starch, glycerin, and water. The aim was not only to improve the material’s mechanical properties but also to enhance its biodegradability. The first phase of the study involved analyses to evaluate the mechanical properties of thermoplastic samples derived from different starch sources (potato, cassava, rice, and corn). The mechanical parameters investigated included tensile strength, Young's modulus, and elongation, which are essential for determining the functionality of plastic bags under typical usage conditions. The degradation of starch under composted soil conditions was also investigated to assess its environmental efficiency after disposal, and an objective color analysis was conducted to determine the opacity of the films. In the second phase, an experimental design was implemented to optimize the thermoplastic formulation, varying the plasticizer, water, and potato starch content. The results of the mechanical properties of samples T1 to T5 indicated that sample T3, containing 5% potato starch, 3% glycerin, and 92% water, achieved the best results in terms of tensile strength (243,39 MPa), moderate Young's modulus (365,28 MPa), and elongation (7,73%). This combination of mechanical properties made it the best option for producing biodegradable bags, balancing strength and flexibility. Based on the results obtained, sample T3 was identified as the best option for manufacturing biodegradable plastic bags. This sample offered a good balance between mechanical strength, flexibility, and biodegradability while maintaining a stable crystalline structure, making it an excellent choice for sustainable applications without compromising material performance.