Abstract
Previous work has examined how the loss modulus measured using a small strain oscillation varies as a function of the prestrain for a range of unfilled or filled rubbers. It has been shown that the loss modulus, when calculated in terms of the prestrained dimensions, is independent of prestrain and is also isotropic over the engineering strain range for many filled and unfilled rubbers. This earlier work has been extended by examining the damping behavior of a silica filled rubber to see if the method can help understand the reinforcement of silica filled rubber in more detail. Silica fillers are ideal fillers to investigate as the interaction at the filler interface can be easily controlled by using an appropriate amount of a suitable silane coupling agent. The investigation shows that the loss modulus calculated in terms of the prestrained dimensions is again largely independent on prestrain up to extension ratios greater than 1.6 for all filler and coupling agent volume fractions considered. The technique identifies the amount of silane coupling agent required to saturate all the available sites for coupling on the filler surface. The results also confirm that the coupling agent improves the filler dispersion during mixing. (C) 2011 Elsevier Ltd. All rights reserved.
