Simulation and Energetic Optimization of Continuous Vulcanization Processes

Continuous vulcanization of extruded elastomers represents one of the most energy consuming processes during the manufacture of elastomer profiles. Several conflicting objectives have to be resolved to establish cost- and energy-efficient vulcanization: Low thermal conductivities, material-specific absorption of infrared (IR) and microwave (UHF) radiation, temperature limits due to degradation or further reacting systems like decomposing blowing agents may lead to inhomogeneous vulcanization and require throughput- and material-specific vulcanization processes.

Thus, in collaboration with Gerlach Maschinenbau GmbH, Nettetal, Germany, the Institute of Plastics Processing (IKV) simulates the temperature development in the cross section of extruded rubber profiles during vulcanization in IR-preshock, hot air and UHF vulcanizing units. For validation, the predicted temperature development, the local degree of vulcanization of extruded profiles (core and surface) has been measured after vulcanization in different vulcanizing units. Vulcanizing efficiency increases with increasing throughput and at the same time increasing vulcanizing energy. Yet, this is limited by beginning degradation on the surface and decreasing homogeneity of the vulcanization in profiles’ cross sections.

The combination of different vulcanizing units can help increasing homogeneity of vulcanization in profiles’ cross sections. To find an optimum for this multi-parameter problem, the temperature development is measured in a special vulcanizing oven, which allows a variation and combination of IR, UHF and hot air vulcanization with simultaneous temperature measurements on the surface and within rubber profiles.

In future, investigations will be extended to different materials and compounds to validate the vulcanizing model.