Thermal decomposition characteristics of polyvinyl chloride sheathing in MYJV-type mining cables

This study investigated the thermal decomposition characteristics of polyvinyl chloride (PVC) sheathing in MYJV-type mining cables. Firstly, thermogravimetric-Fourier transform infrared spectroscopy (TG-FTIR) analysis was employed. The experimental results revealed that the thermal decomposition of PVC sheathing occurs in four stages, primarily yielding products, such as hydrogen chloride, carbon monoxide, carbon dioxide, and chlorinated hydrocarbons. Notably, carbon dioxide and carbon monoxide, emitted during PVC sheathing decomposition, exhibited prominent absorbance. Secondly, a comparative analysis of the thermal decomposition characteristics of chlorinated PVC (CPVC) sheathing in MYP-type mining cables was conducted. It was found that the residue rate of PVC sheathing was lower than that of CPVC sheathing, mainly because all chlorine in PVC was converted to hydrogen chloride during the first stage of decomposition, and CPVC sheathing demonstrated lower thermal stability and reaction rate compared to PVC sheathing. Finally, the study explored the kinetic parameters using the Kissinger and Ozawa methods. The results indicated that the primary chain scission reaction, occurring in the second stage of PVC decomposition, released a substantial amount of combustible and toxic gases, posing threats to fire spread and personal safety. This research provides a theoretical basis for assessing the fire hazard of mine cables by analyzing and comparing the thermal decomposition characteristics and thermokinetic parameters of PVC sheathing with CPVC sheathing.