High-strain hysteresis of rubber vulcanizates over a range of compositions, rates, and temperatures

Hysteresis loss of natural rubber (NR) and styrene–butadiene rubber (SBR) vulcanizates having variations of loading of carbon black, silica, clay, resin, and curatives has been measured over a wide range of strain rates and temperatures as well as under swollen conditions. Hysteresis loss increases with an increase in strain rate, filler loading, resin loading (at high rates), crosslink density, and strain level. Hysteresis decreases with an increase in temperature, particle diameter of filler, and resin loading at high testing temperature. All the data of hysteresis loss of filled NR and SBR compounds have been found to be superimposable on single master curves with the help of the WLF shift factor. The master curves can be divided into three regions. The slope of the intermediate region, Δlog(hysteresis)/Δlog(RaT) has been found to be 0.1 for almost all the vulcanizates. Similar master plots have been obtained when the hysteresis loss has been measured at higher cycles and higher extensions and also by using the data of the hysteresis loss ratio. The hysteresis loss ratio of all the vulcanizates follows a similar trend, except for the highly crosslinked system, which shows a lower value. Carbon black contributes significantly to the hysteresis loss even when the energy dissipation is minimized by swelling. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 1429–1439, 1997