STUDYING THE STORAGE MATURATION OF FRESHLY MIXED RUBBER COMPOUNDS ANDITS EFFECTS ON PROCESSING PROPERTIES

Experiments were performed to study the variation upon storage at room temperature of both the bound rubber and the rheological properties o f filled rubber compounds, prepared either with high cis-1,4 polybutad iene or with natural rubber and various levels of a reinforcing carbon black. It was found that the bound rubber and the rheological propert ies very upon storage according to a two-stage model. Depending on the chemical nature of the rubber, several hundred hours storage are nece ssary before constant properties are measured. These variations are re lated to changes occuring in the rubber-black morphology of the compou nds. Large strain rheological tests are most sensitive to storage matu ration which suggests an explanation for well-known hardening effects observed on the factory floor. (C) 1994 John Wiley & Sons, Inc.