Experimental investigation and numerical modeling of oxidative pyrolysis mechanism of mining PVC cable sheath

Abstract

Cables modified with flame retardants are widely used in the coal mining process to enhance their fire safety performance. This paper investigates experimentally and numerically the thermo-oxidative degradation process of PVC-based mining cable sheath, which consists of PVC resin and plasticizers (Phthalate esters), fillers (Calcium carbonate), and flame retardant (Antimony trioxide) as additives. Thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR) experiments were performed at different heating rates in an air atmosphere. TG results showed that the decomposition processes of mining PVC cable sheath are more complicated than those of pure PVC with additional degradation steps, which was further confirmed by FTIR gas analysis. A deconvolution method was used to distinguish the independent reactions from the overlapped derivative thermogravimetric (DTG) peaks. It was found that the whole degradation process can be divided into seven steps, based on which an oxidative pyrolysis model was developed: pyrolysis of plasticizers (steps 1 and 2), dehydrogenation (step 3), emission and combustion of volatile fraction (step 4), carbon combustion (step 5), oxidative pyrolysis of complicated additives (step 6), and decomposition of residues (step 7). The kinetic triplets (activation energy, pre-exponential factor, and reaction model function) for each reaction were firstly calculated using three commonly used model-free methods and then further optimized using the genetic algorithm (GA). Based on the optimized parameters, the reaction mechanisms and their associated kinetic parameters were determined. The findings of this study are important in understanding the oxidative pyrolysis process of PVC cable sheath, and the obtained kinetic parameters can also be used for its pyrolysis and fire modeling, waste recycling, and risk assessment.

Thermal Oxidation Behavior and Mechanisms for Silicon-Containing Arylacetylene Resins: Experimental and Reactive Force Field Molecular Dynamics Simulations

“…15−17 In addition, TGA coupled with infrared spectroscopy (TG-FTIR) enables online analyses of the generated volatile components to evaluate the oxidation products and determine the thermal oxidation mechanism. 18 In-depth studies of the microstructural evolution of PSAs throughout the oxidation process are important for determining the thermal oxidation mechanism. FTIR 19−22 and XPS 23,24 analyses have been used to explore microstructural changes.…”

“…Thermogravimetric analysis (TGA) is often performed to characterize thermal oxidation stability, , especially the kinetics of thermal oxidation. The thermal oxidation processes of PSAs are recognized to involve multistep reactions, and rigorous kinetic analyses of these steps relating the kinetic behavior to the structural properties of the PSAs would facilitate improvement of the PSAs structure and synthesis process. − In addition, TGA coupled with infrared spectroscopy (TG-FTIR) enables online analyses of the generated volatile components to evaluate the oxidation products and determine the thermal oxidation mechanism . In-depth studies of the microstructural evolution of PSAs throughout the oxidation process are important for determining the thermal oxidation mechanism.…”