The Processing of Filler-Reinforced Rubber

Abstract

Further insight into the mixing process has allowed a definition of the intermediate objectives of processing, which relate to the different transformations that occur as mixing energy is added to a rubber formulation. These convert the ingredients into a coherent mass with specific flow characteristics and determine the efficiency of the next unit, therefore contributing to overall productivity. The total energy added to the batch is derived from a combination of Banbury, mill, and extruder. These processing units vary in the efficiency with which they achieve the required material transformations. Proper allocation of mixing energy to the most effective equipment, with a knowledge of the total energy required to achieve the desired quality, allows a rational optimization of productivity and product quality. Operating profiles for each unit have been constructed in order to aid in optimizing the process. Using a fixed total energy input, these profiles were used to estimate the productivity of each processing unit. The study shows that in a semicontinuous operation with laboratory-size Banbury, mill, and extruder, the extruder is the primary determinant of overall productivity. The study also shows that maximizing productivity in a single unit will not necessarily lead to the highest productivity along the equipment train. Material properties affect overall productivity in several ways. In this work, carbon black surface area determined the total energy required to attain the desired quality level, the flow rate in the extruder, and the energy required to attain the maximum flow rate. Future studies should focus on the derivation of operating equations for specific equipment and materials. These equations should quantify the interrelationships between the different engineering parameters (such as screw or rotor speeds and Banbury ram pressure), the processing parameters (such as mixing time, fill factor, and temperature), and material variables (such as Mooney viscosity, carbon black morphology, and black and oil loading).

Correlations in rheological behavior between large amplitude oscillatory shear and steady shear flow of silica‐filled star‐shaped styrene‐butadiene rubber compounds: Experiment and simulation

“…The presence of a reinforcing filler significantly impacts the rheological behavior of elastomers. In contrast to unfilled elastomers, filled compounds show a reduced or even undetectable linear viscoelastic region, a significant wall slip effect, a decreased melt fracture, a decreased die swell, and an anisotropy in flow 1–6 . Since fillers significantly influence the viscoelastic properties of a rubber compound, understanding the structure of a filled elastomer is crucial to describing its rheological behavior.…”

“…Extensive investigations have been carried out on the steady shear flow behavior of CB‐filled rubber 1–4,31,33–45 . These studies noted strong shear thinning behavior and an increase in viscosity with CB loading and surface area.…”

The nonlinear stress relaxation behavior after a step shear of star‐shaped styrene‐butadiene rubber filled with precipitated silica: Experiment and simulation

“…The presence of a reinforcing filler significantly impacts the rheological behavior of elastomers. In contrast to gum elastomers, particle‐filled compounds show a reduced or even undetectable region of linear viscoelastic behavior, a noticeable slip at a solid boundary, a decreased melt distortion, a decreased die swell, and anisotropic properties due to flow 1–6 . Since incorporation of fillers significantly influences linear and nonlinear behaviors of a rubber compound, the ability to understand the structure of filled elastomers is crucial to describing their viscoelastic behavior.…”

A Study of the Stages of Mixing of a Model Mixture of Rubber and Carbon Black on a Brabender Plastograph

“…Determination of the mixing stages directly during the process is possible by recording the following parameters: the rotor shaft torque, the temperature, and the torque spread or electrical conductivity of the rubber mix; according to literature data, it is possible to determine the black incorporation time (BIT), i.e. the time at which the process of carbon black dispersion ends [3][4][5][6][7]12]. It is also worth noting that attempts have been made on more than one occasion in the literature to describe the kinetics of mixing of rubber with carbon black by means of a first-order reaction equation [6,8,9,10], but the equations proposed have not been widely used and have characterised only the interaction of rubber with carbon black.…”