Optimising the continuous final mixing of rubber compounds

The primary aim of this research project was to uniquely redesign, develop and validate the continuous final mixing of rubber compounds using single screw extruder gear pump combinations.§The thesis describes the introduction of novel methods and reconfiguration of final mixing as a continuous process in a single screw extruder. This led to the elimination of one of the mixing steps in an internal mixer for most compounds and the continuous mixing of curing agents or additional filler material into the base compound. The radical changes introduced have several advantages for the process allowing cost and energy savings during the production of rubber compounds.§The project started with evaluation of the current available technology and scientific background of rubber processing and mixing in single screw extruders. The combination of technologies, such as different mixing geometries in screws and barrels and the combination of these systems with a gear pump allowed a new method of final mixing to be proposed, introduced and evaluated.§Following initial basic feasibility trials, the initial concept was elevated to the design and build of an industrial scale system. Finally, the system was rigorously evaluated and the outcomes from testing proved that scaling up and the transition to the new method into a working industrial system was successful. The resulting production machine is capable of final mixing conventional rubber compounds on an industrial scale and will replace the batch to batch process currently used.