Determinación de la cinética de pirólisis del polipropileno (PP) y polietileno de alta densidad (HDPE) mediante el uso de análisis termogravimétrico y algoritmos genéticos

Abstract

This thesis optimizes the calculation of the kinetic parameters of the pyrolysis of polypropylene (PP) and high-density polyethylene (HDPE) at three heating rates (5, 10, and 15 °C/min) with the use of genetic algorithms and thermogravimetric data. For the execution of the project, it first collected the thermogravimetric data of both plastics, each at the three heating rates, selecting the data that have a mass loss constant according to the thermogravimetric curve and observing that there are no peaks in the data in their values. Three isoconversional models were selected to evaluate the kinetics of thermal degradation: activation energy (Ea), preexponential factor (Ao), and reaction order (n). Their use is essential because this process is complex, so the International Confederation of Calorimetry of Thermal Analysis (ICTAC) recommends its use. The study selected the Friedman, KAS, and FWO models. Three essential steps for code execution implemented two optimizations: a nonlinear optimization with the fmincon function and a heuristic optimization with the ga function (genetic algorithms), respectively, the second and third steps. The application of the Genetic Algorithm (GA) in the second optimization fulfills the function of optimizing the calculation of the kinetic parameters by comparing their data in the differential thermogravimetric curve, experimental DTG vs. calculated DTG, using the mean square error (MSE) and determination factor as validators for the reliability of the results. Better results could be seen depending on the MSE and determination factor at each point, and visually, according to the DTG graphs, the calculated data better fits the experimental curve.