EFFECTS OF MIXING PARAMETERS AND THEIR INTERACTIONS ON PROPERTIES OF CARBON BLACK FILLED STYRENE-BUTADIENE RUBBER

The effects of various mixing parameters on state-of-mix and vulcanizate properties of carbon black filled styrene-butadiene rubber prepared by an intenneshing-rotor internal mixer were observed. The parameters studied include mixing time, rotor speed, fill factor, and filler loading. The interactions between these parameters are also focused. To do this, the mixing parameters are changed simultaneously, and the data are analyzed using response surface methodology. Results reveal that the dispersion index, Payne effect, and tensile properties are not linearly related to mixing time and filler loading but are linearly related to rotor speed and fill factor. The effect of mixing time on dispersion index and Payne effect depends strongly on the levels of rotor speed and filler loading. Increasing the rotor speed or filler loading reduces the effect of mixing time on dispersion index and, thus, on the Payne effect. Among the four parameters, filler loading shows the strongest effect on tensile strength (TS) and modulus at 100% elongation (M100). In addition, the effect of filler loading on the tensile properties depends mainly on the levels of mixing time and fill factor, for example, increasing of fill factor reduces the effect of filler loading on both TS and M100.