James Gregory Gillick

Microencapsulated antidegradants for extending rubber lifetime

Abstract Microcapsules containing rubber antidegradants were formed in a spray-drying process. Studies were carried out to select the proper wall material based on the processing properties, migration rate of the antidegradant through the capsule wall, thickness of the capsule wall, and overall capsule diameter. The resulting capsules were incorporated into a rubber article, providing a reservoir of antidegradant during the exposure lifetime. Testing of the rubber compounds with microcapsules having diameters less than 50 µm containing AN-(l,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine in a matrix of cellulose acetate showed a significant increase in the crack-free lifetime of the rubber when flexed in exposure to ozone.