Analysis of the flow behavior of thermally conductive thermosets during injection molding

• Applicant: Professor Dr.-Ing. Dietmar Drummer
• Subject Area: Plastics Engineering
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 491900621

With the increasing power of today's electrical devices and simultaneously reduced size, the heat balance of electronic components has become a challenge, as more and more heat is generated and must be dissipated from the system. A concrete example of this is the high demand for heat dissipation for electric motor enclosures, which have a high power rating and must remain functional during continuous operation at a wide range of ambient temperatures. Corresponding enclosures are made of thermoset molding compounds based on epoxy resin. In addition to the necessary classic proper-ties, such as electrical insulation capability, the thermal conductivity of the thermoset insulation material is thus increasingly becoming the focus of users.A major obstacle for the application of these materials is that a prediction of the local thermal conductivity in the part is hard to make because the basic understanding of the flow behavior and the resulting filler orientation during injection molding is missing. The aim of the research project is to use an innovative measuring mold to investigate the direction-dependent thermal conductivity in relation to the material composition, production process and design of a structural part. The focus here is on a better under-standing of the filler orientation as a result of the flow behavior during mold filling. For this purpose, the measuring mold will be designed according to the Mooney concept, with which the flow behavior of the melt can be characterized under realistic boundary conditions for the first time. By using ultrasonic and dielectric sensors integrated in the mold, the curing process is observed directly in the process and, for the first time, it is possible to analyze the relationship between the curing speed and the flow behavior in the process. It is also planned to use magnetic fillers and a tes-lameter to determine the filler orientation directly in the mold.. In addition, it is planned to determine the filler orientation directly in the mold with the use of magnetic fillers and a teslameter. Using this innovative measuring technique, the material- and process-dependent influences on the flow behavior will be fundamentally investigated within the scope of the project. The focus of material-related factors lies on the filler geometry, filler content and ther-mal conductivity of the fillers. The process investigation focuses on the process heat balance and the shear effect in the molding compound. To that end, the main factors influencing the flow behavior, such as unit temperature, mold temperature and injec-tion speed, are to be fundamentally investigated.

• DFG Programme: Research Grants