The thermal oxidative aging process of octavinyl-polyhedral oligomeric silsesquioxane (OVPOSS) heated at 180 ℃ in the N2 atmosphere with low oxygen concentration was investigated by series of instrumental analyses.1H-NMR

13C-NMR

29Si-NMR were used to analyze the molecular structure before and after this process

while FTIR

MALDI-TOF

ESR

TG-IR

DSC were used to monitor the changes of characteristic groups

molecular weight

active species

mass loss and enthalpy.The method of aging process in the N2 atmosphere with low oxygen concentration would decrease peroxidatic reaction of the double bonds

only to clarify other mechanisms in this process.The experimental results indicated that the double bonds transformed to single bond in this process and C free radical center was verified

as well as the exothermic efficiency

little weight loss and increasing of molecular weight.The conclusion was drawn that the free-radical polymerization exists in thermal oxidative aging process of OVPOSS at low temperature (180 ℃) in the N2 atmosphere with low oxygen concentration.This research may enrich the thermal oxidative aging theory of polyvinylsiloxane.