Influence of water on dynamic mechanical properties of silica loaded tire tread vulcanizates

The damping behavior of silica-loaded vulcanizates is significantly affected by the amount of absorbed water. It results in the formation of a new tan δ peak around -5 ∼ 0 °C and an increase of the loss modulus G'', which can be taken as an indicator for the improvement of wet skid resistance. By the removal of water from the sample, the process is reversible. At temperatures ≤ 80 °C water adsorption occurs by physisorption to hydrophilic areas on the silica surface. From dynamic measurement it is concluded that adsorbed solid water at < 0 °C acts as filler, because at low temperatures the stiffness (G') and the loss energy (G'') of the vulcanizates are increased, whereas at temperatures > 5 °C adsorbed water acts as a plasticizer. The loss modulus at high temperatures (60 °C) is reduced, which is an indicator for reduced rolling resistance.