Optimisation of the degree of cross-linking of elastomer moulded parts through dielectric analysis
The research project is investigating the suitability of dielectric analysis for precisely recording the cross-linking process during elastomer injection moulding. The aim is to precisely control the degree of cross-linking and ensure consistent material properties of the elastomer moulded parts during production.
© IKVIn rubber extrusion, flow instabilities resulting in surface defects often occur when a critical production speed is surpassed. Rubbers tend to show to wall slip during flow, which favours flow instabilities. Various approaches exist to describe wall slip processes. Existing rheological measurement methods provide inadequate results when wall slip occurs. Without the necessary material data, an exact design of screws or extrusion tools is hardly possible. The measurement of non-linear pressure curves is required for the development of a closed modelling approach.
The aim of the research project is therefore to develop a new type of extrusion rheometer that can be used to determine local pressure along the entire length of the nozzle. In addition, a model is being developed that describes the pressure dependence of the critical wall shear stress, above which wall slip occurs. With the help of the new rheometer, the material parameters of the model are determined using various rubber compounds with a tendency to wall slip as an example. The new measuring method is validated by comparing it with established capillary rheometers.
With this disruptive approach, the flow behaviour of plastics can be reliably determined taking wall-slip into account. This improves the material data situation and thus the prediction accuracy in the simulative design. For SME, this results in shorter development times and less iterative effort for development. Product quality can be increased in a targeted manner with an improved mould and process design.
Project data and funding
We would like to thank the BMWK for funding the IGF project (funding code 23114 N) and the project partners for their cooperation.
Project duration: 01.11.2023 – 31.10.2025
Project partners / Funding
