As presented in Table 5, the incorporation of up to
5.0 phr of ALK into the silica-filled rubber compound
increased the torque difference (MHdML), i.e. the
maximum torque minus the minimum torque. Further increases in the ALK loading decreased the torque difference.
It is also evident that the minimum torque (ML)
decreased with increases in the ALK loading. It has been
reported that ML corresponds to the filler-filler inter
agglomeration [11] and is a measure of the stock viscosity
[12]. The incorporation of ALK into the silica-filled NR
compound reduced the viscosity of the compound and
facilitated a relatively strong interaction between the ALK
and the silica filler, while the silica particles had a weaker
tendency to interact with each other and form a filler-filler
agglomeration. Consequently, the processability of the silica
dispersion in the rubber phase became easier and
increased the degree of silica dispersion.