The pyrolysis mechanism of polyisobutylene (PIB) which is commonly used as a filler in high-voltage cable terminals remains unclear. In this paper

the pyrolysis products of PIB under 2 400 K and 3 000 K conditions

and their generation paths are obtained by using ReaxFF molecular dynamics software. The study results show that the content of pyrolysis products of PIB at 3 000 K is higher than at 2 400 K

indicating that the aging temperature increase can accelerate the pyrolysis of PIB and the generation of characteristic gases

and H

2

and CH

4

can be used as the main characteristic products of PIB pyrolysis. The thermal aging of PIB is performed at at 473 K to verify the effectiveness of the numerical simulation results. Meanwhile

for exploring the key factors affecting the gas production characteristics of PIB

the thermal-electric combined aging experiment of PIB and thermal-electric aging asw ell as thermal-electric aging experiment of PIB affected by moisture are performed further. Gas chromatographic analysis results show that

in case of spark discharge

the content of each gas component in PIB is the highest

followed by partial discharge

and the lowest in case of thermal aging. The change of C

2

H

2

content can be used as the assessment basis of PIB discharge. In particular

the results of accelerated aging experiments of PIB with different degrees of moisture show that moisture would promote the pyrolysis of PIB and the formation of various characteristic products. This paper can provide theoretical guida

nce for further study of PIB fault criterion.