2.3 Compound preparation
Rubber compounds were prepared using the formulations as shown in Table 1. The ENR content was varied in a range of 2.5–15.0 phr. Amounts of TESPT and DPG were calculated relating to the silica CTAB specific surface area, as suggested by Guy et al. [26]. Mixing was carried out using an internal mixer (Brabender Plasticorder 350s) with an initial mixer temperature setting of 110 °C, rotor speed of 60 rpm, according to the mixing procedure as shown in Table 2. The silica-filled NR compounds with and without TESPT and without ENR were prepared and treated as reference.