Optimization of Serial Modular Continuous Mixing Process Parameters for Natural Rubber Composites Reinforced by Silica/Carbon Black

Influence of process parameters of a continuous final mixer on the properties of carbon black/rubber composites

As the final stage of the mixing process, the final mixing has a profound impact on the properties of rubber compounds. The influence of the process parameters of a continuous final mixer on the properties of carbon black/rubber composites is studied. It is found that there are two factors affecting the performance of the composite: the rotating speed of the dual rotors and the temperature of the continuous final mixer. When the temperature is unchanged, the extruding temperature of the final-mixing rubber compound increases with increasing rotating speed, and the Mooney viscosity, T10, T90 and rolling resistance gradually decrease. The Payne effect decreases first and then increases, and the overall trend gradually decreases. When the rotating speed is constant, as the temperature of the continuous final mixer rises, the extruding temperature also rises, and the temperature difference between feeding and extruding increases. Mooney viscosity and tensile strength increase. The Payne effect is more significant. T10, T90 and rolling resistance gradually decrease. The M300 of a vulcanized sample shows the following laws: When the control temperature is low, the influence of rotational speed is small, the fluctuation range is small, and has a steady rising trend; however, when the temperature is higher, M300 fluctuates greatly under the influence of rotational speed. The optimal process parameters of the rubber continuous final mixer are determined: the double rotor speed is 30RPM, and the temperature control temperature is 60–70 °C.

Enhancement of Green Tires Performance through Ultrasound-Assisted Mixing

Combined with the traditional internal mixing process, a custom-built ultrasonic generator was introduced in this study. The effect of ultrasonic parameters on the comprehensive performance of tread rubber formulations was investigated. Compared to the traditional mixing process without ultrasonic wave loading, the introduction of ultrasonic enhanced the dispersion and distribution of composite particles in the rubber matrix and improved the overall performance of rubber products. The devil’s triangle relationship among the rolling resistance, wet skid resistance, and abrasion resistance of tires was improved. When the wet skid resistance was slightly lost, the rolling resistance and wear rate were effectively reduced. This study provides new insights into a strategy for optimizing the mixing process of the traditional internal mixer, reducing vehicle emissions, extending the service life of tires, and promoting the development of green tires.

Influence of Oligopeptide Length and Distribution on Polyisoprene Properties

The tuning of binding modes of polar groups is the key step to mimicking the structure and properties of natural rubber through the molecular design of synthetic polyisoprenes. Herein, the ordering and binding distances of oligopeptides could be altered systematically by changing their lengths and distribution along the polyisoprene chain, which impose huge impacts on the mechanical properties and chain dynamics of green rubber. In detail, a series of peptide-functionalized polyisoprenes with terminal blocks (B-2A-PIP, B-3A-PIP) or random sequences (R-2A-PIP, R-3A-PIP) are fabricated by using dipeptides (2A) or tripeptides (3A) as crosslinkers to explore the mechanism of terminal interaction on mechanism properties and chain dynamics. B-4A-PIP and R-4A-PIP served as control samples. It is found that the increased oligopeptide length and the block distribution improves the mechanical properties and confine the chain movement by elevate the contents of ordered and compact microstructures, which is indicated by XRD, broadband dielectric spectroscopy (BDS) and consistent with the result of molecular dynamics simulation. New relaxation signals belonging to oligopeptide aggregates are found which showed elevated dielectric strengths upon temperatures increase. Additionally, it also reveals that the binding modes of oligopeptide do not significantly influence the entanglements of polyisoprene.