Prevention of Rubber Degradation by Use of Microencapsulated Antioxidants

Abstract A new approach of preventing evaporation and migration of antioxidants in rubber is presented. The antioxidant N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine (6PPD) was microencapsulated in silica (MC6PPD) prior to compounding with the rubber. The microencapsulated antioxidants were characterized by differential scanning calorimetry and thermogravimetric analysis, indicating reduced rates of evaporation compared to free antioxidant. The stress-strain properties, flex cracking resistance and discoloration of the rubber were examined as samples containing equal amounts of antioxidant but in the different forms of 6PPD and MC6PPD. The results clearly indicated superior rubber performance in the case of MC6PPD, suggesting that antioxidant encapsulation is an effective technique to prevent rubber degradation due to aging.