Avaliação da biodegradabilidade de resíduos de poli(ácido lático) - (PLA) provenientes de impressão 3D

Abstract

Poly(lactic acid) (PLA) is a biodegradable polymer obtained mainly from renewable sources, from the fermentation of carbohydrates of plant origin, such as corn and sugar cane. PLA is a material that can be biodegraded naturally, leading to its disintegration, resulting in carbon dioxide, water and humus. One of the most widespread applications of PLA is its use as a raw material in the form of filament for 3D printing. With the aim of improving alternatives for the final destination of PLA, confirming and minimizing its effects on the environment, this work aimed to find out the biodegradability behavior of 3D printed PLA waste items during the composting process, in two types of soil: landfill soil with leachate, and garden soil, over a period of 90 days and 180 days. The characteristics of the soils were evaluated by means of microbiological analysis and the properties of the material by means of a three-point bending test, thermogravimetric analysis, differential scanning calorimetry, Fourier transform infrared spectroscopy, optical microscopy and color analysis. Soil analysis showed that during the experiment there were changes in soil composition and a considerable loss of microorganisms. The results of the material analysis showed that the mechanical properties of the PLA did not change significantly; optical microscopy showed the formation of fungal colonies and incrustations on the surfaces, as well as alterations to the original color. Knowing that PLA is a biodegradable material, higher levels of biodegradability were expected. It is possible that controlled temperature and humidity conditions would be necessary for higher biodegradability rates. In other words, according to the natural composting conditions used in this work, PLA showed few initial signs of degradation, which would require more time for total degradation and could accumulate in the environment, causing future pollution problems.