Silicone rubber profiles are used in an increasing amount of applications, for example in seals for automotive applications or in medical equipment. A cellular structure of the silicone rubber profile enhances the damping properties and leads to a reduction of component weight, material consumption and cost at the same time. For production of cellular rubber profiles, the use of chemical blowing agents is state of the art. However, physical blowing agents such as nitrogen offer ecological, economical and procedural advantages. So far, an application of a physical foaming process on silicone rubber has been difficult due to the sorption properties of the material. At the IKV, a continuous foaming process for high-temperature vulcanising (HTV) silicone rubber is developed using a lab-scale extrusion plant with gear pumps and a mixing section. A constant foaming process was realised in first experiments. The silicone rubber profiles are analysed in terms of cellular structure, surface quality and density. Experimental investigations show that the amount of blowing agent injected has a significant influence on density, foam structure and surface roughness. The use of a nucleating agent improves the cellular structures in terms of cell size and homogeneity. Besides, the foam structure can be influenced by the pressure at the extrusion die. Primary objective of further investigations is the analysis of the influence of silicone rubber material properties on the profile quality.
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