## 1 Introduction  
According to the European Association of Plastic Materials Producers [1], the production of plastics in the world reached 359 million tons in 2018. One of the reasons for this high use is due to their great versatility, which makes them the preferred option to be used in a bewildering range of consumer goods. With the growth of the human population and development activities, the consumption of these materials is also increasing at an accelerated rate, which has led to them be considered a latent environmental problem, being one of the largest contributors to urban solid waste worldwide [2].  
The production of polymers from renewable resources as a substitute of polymers of petrochemical origin has increased significantly in recent years [3]. One of the most popular biodegradable polymers is the Polylactic Acid (PLA), represented by the chemical formula (C\({}_{3}\)H\({}_{4}\)O\({}_{2}\))\({}_{n}\). PLA can be produced from renewable non-toxic raw materials. In addition, PLA has aroused a large amount of interest not only due to being a renewable material but because of its biocompatibility, biodegradability, mechanical properties, thermoplastic processability and low environmental impact, which make it a versatile option for use in biomedicine and tissue engineering as an alternative to conventional polymers [4]. In recent years, additive construction or 3D printing has increased for the manufacture of many technological components. This construction procedure has and will have a great industrial impact. There are many 3D printing procedures and, among them, the best known is called Fused Deposition Modeling (FDM), in which a thermoplastic such as PLA is used in both amorphous and crystalline states, due to its optimal behavior in the process of impression. In addition, PLA is generally used for the manufacture of automated analytical devices such as lab-on-a-chip platforms due to the proven potential of this renewable and biodegradable aliphatic polyester (PLA) to replace petrochemical-based polymers in industrial applications.  
Currently, the study of PLA is focusing on its processing, since its main problem is thermal stability, which has been reported as a complex issue when subjected to different recycling techniques such as pyrolysis [5]. In this sense, a promising solution to describe its behavior, as well as to determine the thermal properties of this material, is through thermogravimetry (TG). TG is a widely used technique to study different polymeric materials and to determine the reaction order, activation energy, frequency factor and the rate of thermal decomposition that a given material undergoes [6; 7]. PLA presents a different activation energy with respect to conventional thermoplastics due to its particular structure that determines its properties, as seen in several studies using isoconversional kinetic models for non-isothermal TG data [8; 9; 10; 11]. This difference depends on several factors: (1) polymer preparation method; (2) molecular weight of the polymer; (3) operational conditions such as sample weight, particle size, heating rate, mass flow rate, type of gas used and sample-holder thermal contact; (4) mathematical treatment of TG data according to different methods (integral, differential and special) [12]. The data of TG analyses are also used to estimate thermodynamic parameters such as enthalpy, Gibbs free energy and entropy from kinetic models, which are of importance for the analysis of mixtures and the energy required for the thermal degradation process and the waste treatment of this plastics type by chemical recycling, which help to decrease its environmental impact [13]. Thus, according to the information summarized so far, the objective of the present work is to obtain and examine the changes in the thermodynamic parameters of PLA under conditions of thermal degradation by applying a non-isothermal TG method at three different heating rates. In addition, this study covers a kinetic analysis of the thermal degradation process of PLA.