Methods for study of thermal aging and stabilization of grafted acrylonitrile-butadiene-styrene (ABS) terpolymers

Acrylonitrile-butadiene-styrene (ABS) grafted terpolymers are apt to oxidize at an elevated temperature and its stabilization by an antioxidant is critical to processing and performance. The differential thermal analysis was used to study the effect of the AgeRite® Geltrol, a modified high molecular weight hindered phenol antioxidant, on the ABS thermal oxidation. The Kissinger equation was found to be accurate enough to determine the activation energy of oxidation. The induction time was also measured and these results were compared with the activation energies. The polybutadiene component of ABS was oxidized rapidly around 200°C under an oxygen atmosphere while the styrene-acrylonitrile (SAN) component was oxidized at a higher temperature. Air oven aging at 130°C affected the Izod impact (notched), ultimate elongation, but not the ultimate tensile, melt index and morphology. It further confirmed that the polybutadiene component was oxidized and the SAN component was fairly stable at 130°C in air.