The effect of ultrasonic extrusion on the structure and properties of BR gum and prepared compounds and vulcanizates

Abstract

Abstract Ultrasonic extrusion of BR was conducted and processing characteristics were evaluated. Ultrasonic power consumption increased with the increase of ultrasonic amplitude. Die pressure decreased with the increase of ultrasonic amplitude indicating that the imposition of ultrasound can be used to increase extrusion output rate. The effect of ultrasonic amplitude on molecular structure of BR, including molecular weight and gel formation behavior were studied. Depending on the ultrasonic amplitude, structure changes occurred in BR, including a degradation, formation of long-chain branching and gel. Untreated and treated BR were mixed with CB, silica and silica/silane. Bound rubber content and flocculation behavior were studied. Formation of the long-chain branching was shown to increase the bound rubber content and rubber-filler interaction and to reduce the filler-filler interaction and flocculation of BR/silica compound. Both the untreated and treated BR, BR/CB, BR/silica and BR/silica/silane were vulcanized and their crosslink density, gel fraction and mechanical properties were measured. Based on DMA temperature sweep of BR/silica vulcanizate, it was shown that formation of the long-chain branching during ultrasonic treatment reduced the loss tangent at 60 °C, predicting a lower rolling resistance if the rubber used in tires.