CARBON-BLACK CHARACTERIZATION .1. EFFECTS OF DYNAMIC PARAMETERS ON THE BEHAVIOR OF CARBON-BLACK IN RUBBER

Rubber compounds, during their service life, are subjected to changes in amplitude, temperature and frequency. Rubber compounds are subjected to these changes in the dynamic mode. Carbon black, as a reinforcing filler, also experiences these fluctuations. This paper discusses the dynamic mechanical properties of carbon black/rubber composite that were obtained, in shear and compression, utilizing a non-resonant hydraulic instrument. Data were obtained on unfilled and filled rubber compounds using a wide spectrum of carbon blacks at constant and variable loadings. The data consist of forward and reverse amplitude, frequency, and temperature sweeps that ranged from 0,2 to 100 % DSA (Dynamic Strain Amplitude), 0,1 to 250 Hz, and -25 to 100-degrees-C, respectively. Furthermore, the relationship between dynamic parameters and a single carbon black entity, Available Surface Area (ASA), is also discussed. The ASA is derived from carbon black properties of structure (DBP, 24M4, Void Volume), surface area (N2SA, CTAB, Iodine No.) and volume fraction of the carbon black in a compound. Results demonstrate that both dynamic and carbon black parameters play an important role in reinforcing unfilled rubber. Of the dynamic parameters, the effects of strain amplitude supersede those of temperature and frequency. To further elucidate the behavior of carbon black, the sigmoidal curve was divided into four vertical zones so as to delineate the amplitude at which major changes in the carbon black/rubber composite occur. The relationship between carbon black's behavior and strain amplitude is of technological importance, especially in the selection of carbon blacks to obtain critical compound usage properties. Since the magnitude of reinforcement is strain dependent, data presented relate a single carbon black parameter, ASA, to dynamic properties over a range of strain amplitude.