The safe and stable operation of submarine oil-filled cables is critical

but the internal dodecylbenzene(DDB) insulating oil is subject to rapid pyrolysis and gas production at localized high temperatures due to thermal faults. Against this issue

the pyrolysis and gas production processes of dodecylbenzene insulating oil are investigated based on reactive molecular dynamics simulations(ReaxFF-MD) and thermogravimetric-infrared spectroscopy(TG-IR) experiments. The pyrolysis simulation results show that

the initial cracking reaction of the dodecylbenzene molecule is mainly the breaking of C—C bond to produce long-chain macromolecules

and then the gradual pyrolysis produces small alkyl radicals and olefinic molecules

and the DDB will eventually be pyrolyzed to the short-chain alkylbenzene molecules with the side chains of ·C2H5

·CH3 and ·C3H7 groups. The main characteristic gases during pyrolysis are C2H4

H2

and CH4

which are the same as the results of IR experiments

and the main reaction mechanisms for the generation of the characteristic gases are:(i) the breaking of the C—C bond at the β-position

the hydrogenation reaction

and the dehydrogenation reaction;(ii) the attack of-H radicals to the H atoms on other radicals; and(iii) the reaction of the methyl radicals(·CH3) with the free hydrogen(·H) radicals

respectively. The kinetic results show that the activation energies of the TG experiment and ReaxFF-MD are 86.606 kJ/mol as well as 99.867 k J/mol

respectively

and the similar activation energies further validate the reasonableness of the simulation results. The study conclusion provides theoretical support for deep understanding of the cracking and gas production mechanism of dodecylbenzene insulating oil.