Optimised EPDM Compounding: Mathematical Models for Filler Incorporation
The manufacture of high-quality elastomer products requires precise mixing processes. A new research project is modelling the complex phase of filler incorporation in the internal mixer in order to optimise mixing quality. Based on experimental data, prediction models for key process variables are developed with an accuracy of up to 85%. The aim is an AI-supported search engine that delivers optimised mixing strategies for specific material requirements.
Initial situation / problem:
Compound production in the discontinuous internal mixer is an elementary component in the manufacture of high-quality elastomer products. The compound components such as rubber, fillers, plasticisers and chemicals are processed into a homogeneous compound. An individual mixing specification is developed for each mixture recipe. The choice of process parameters such as the rotor speed and the rotor and mixing chamber temperature control have a significant influence on the quality of the mixture. The development of mixing instructions is currently based on expert knowledge. The aim is therefore to describe the mixing process using mathematical models. So far, modeling has only been possible under simplified conditions. The neglect of the complex rheological properties and the partial filling of the mixing chamber should be mentioned. Furthermore, material properties such as density and specific heat capacity change during the mixing process.
Objective:
The aim of the research project is to develop a search engine that uses process and material models to determine strategies for compound production based on predefined properties. To this end, models are to be created based on the raw material properties and the process parameters to generate an optimised mixing specification. In order to be able to carry out a higher-level optimisation of the entire mixing process, models are first developed for individual mixing phases. The focus here is on the description of the basic mixing process, as this is more complex than the final mixing process due to the incorporation of the fillers. The filler incorporation phase is considered below, as this represents the first step in filler incorporation.
Solution and results:
The models to be developed for the filler incorporation phase are based on experimentally determined data from an intermeshing laboratory internal mixer. Compounds based on ethylene propylene diene rubber (EPDM) with the addition of carbon black as an active filler are being investigated. With the aim of being able to predict the temporal progression of the punch path, the power input and the compound temperature, mixtures are produced with varying process parameters (rotor speed and mixer temperature control) and material parameters (polymer molecular weight and carbon black content). This is followed by the correlation of the variables to be described as a function of the selected process and material parameters. The resulting models enable the parameters to be predicted with a maximum deviation of 15 % from the values determined by measurement.
Project data and funding
The project on which this report is based was funded by the Federal Ministry of Education and Research under grant number 13XP5169A. Our thanks go to the BMBF.
Project duration:
Project partners
