Characterisation of novel polymeric antioxidant and its thermo-oxidative aging resistance for natural rubber vulcanizates

Abstract

Hydroxyl terminated polybutadiene bound 2,2-methylenebis (4-methyl-6-tert-butylphenol) (HTPB–IPDI–MPH) was prepared by binding 2,2-methylenebis (4-methyl-6-tert-butylphenol) (MPH) onto hydroxyl terminated polybutadiene (HTPB) using isophorone diisocyanate (IPDI) as bridging agent. The structure of HTPB–IPDI–MPH was characterised by Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance (NMR) spectroscopy, 13C NMR spectroscopy and gel permeation chromatography. The thermal stability of HTPB–IPDI–MPH was studied by thermal gravity analysis (TGA). The thermo-oxidative aging resistance of HTPB–IPDI–MPH for natural rubber (NR) vulcanizates was investigated by mechanical properties, cross-link density assessment and TGA, and then, possible mechanism of thermo-oxidative aging resistance of HTPB–IPDI–MPH for NR was proposed. The results showed that HTPB–IPDI–MPH had better thermal stability than the corresponding low molecular antioxidant MPH. The thermo-oxidative aging resistance and thermo-oxidative degradation of NR vulcanizates containing HTPB–IPDI–MPH were better than that of NR vulcanizates containing MPH obviously, indicating that the synergetic effect of phenolic –OH and –NHCOO– groups existed in HTPB–IPDI–MPH, which could enhance ability to scavenge free radical.