Pyrolytic Behavior of Polyvinyl Chloride: Kinetics, Mechanisms, Thermodynamics, and Artificial Neural Network Application

Abstract

Pyrolysis of waste polyvinyl chloride (PVC) is considered a promising and highly efficient treatment method. This work aims to investigate the kinetics, and thermodynamics of the process of PVC pyrolysis. Thermogravimetry of PVC pyrolysis at three heating rates (5, 10, and 20 K/min) showed two reaction stages covering the temperature ranges of 490–675 K, and 675–825 K, respectively. Three integral isoconversional models, namely Flynn-Wall-Qzawa (FWO), Kissinger-Akahira-Sunose (KAS), and Starink, were used to obtain the activation energy (Ea), and pre-exponential factor (A) of the PVC pyrolysis. On the other hand, the Coats-Redfern non-isoconversional model was used to determine the most appropriate solid-state reaction mechanism/s for both stages. Values of Ea, and A, obtained by the isoconversional models, were very close and the average values were, for stage I: Ea = 75 kJ/mol, A = 1.81 × 106 min−1; for stage II: Ea = 140 kJ/mol, A = 4.84 × 109 min−1. In addition, while the recommended mechanism of the first stage reaction was P2, F3 was the most suitable mechanism for the reaction of stage II. The appropriateness of the mechanisms was confirmed by the compensation effect. Thermodynamic study of the process of PVC pyrolysis confirmed that both reactions are endothermic and nonspontaneous with promising production of bioenergy. Furthermore, a highly efficient artificial neural network (ANN) model has been developed to predict the weight left % during the PVC pyrolysis as a function of the temperature and heating rate. The 2-10-10-1 topology with TANSIG-LOGSIG transfer function and feed-forward back-propagation characteristics was used.

Kinetics of poly(vinyl chloride) thermal and thermo‐mechanical degradation in the presence of epoxidized plasticizer. Induction effect

“…This value is unusually low, indicating alternative HCl elimination mechanism. Activation energy values obtained for HCl elimination (stage I of solid PVC degradation) reported for solid PVC vary with the reaction model and experimental condition 47–51 . Thus, applying 1st order PVC degradation model to TGA monitored degradation, Kim obtained apparent activation energy ≈129.95 kJ mol −1 , remarkably close to the value of 128.6 kJ mol −1 obtained by us using TGA‐MS method 49 .…”

Effect of gamma-rays on the thermal and mechanical properties of epoxy/tungsten boride composites

“…There are several methods (Friedman, Coats and Redfern, Chang, Ozawa, Vyazovkin, Horowitz and Metzger, and Broido) to study the thermal degradation of materials. 36–38 All these methods are based on the general pyrolysis process, which expresses the decomposition of material as shown in equation (1). where (α) is a function describing the reaction process; k ( T ) is defined as a rate constant depending on temperature T .…”

Pyrolysis Study of Mixed Polymers for Non-Isothermal TGA: Artificial Neural Networks Application

“…The literatures surveyed listed below will be limited only for the papers handling ANN for TGA data [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18].…”

“…Zaker et al [14] investigated the effects of two catalysis (HZSM5 and sludge-derived activated char) on the pyrolysis of sewage sludge. Dubdub and Al-Yaari [15,16] and Al-Yaari and Dubdub [17,18] tried to use the ANN to predict the performance for different samples. They used a feed-forward LM optimization technique for backpropagation process in the ANN model, in two hidden layers.…”