Carbon black is used as a reinforcing filler in many rubber products to enhance the compound’s mechanical properties such as crack growth resistance, tear strength and tensile properties. Stretching of carbon black filled rubber evolves heat which can be attributed to the intrinsic entropic elasticity and viscoelasticity of the rubber, the breakdown of the filler network and in certain rubber types, strain induced crystallization. These processes contribute to the strengthening and reinforcement provided by carbon black in rubber and help explain why reinforcing fillers such as carbon black are widely used in tyre compounds.
Although there have been previous studies on the effect of carbon black on temperature change and crystallization during stretching and retraction in natural rubber compounds, there has been limited effort to correlate these effects with the basic structure and morphology properties for a wide range of different grades of carbon black filler. This study measures the change in temperature using an infrared camera, during rapid adiabatic stretching and retraction, for several different natural rubber filled compounds incorporating specific grades of carbon black. These temperature changes are analyzed to investigate how they might indicate the onset and extent of strain induced crystallization in these filled compounds. The results show an influence on the temperature measurements and calculated strain induced crystallization with some of the basic structural properties of the carbon black.