Abstract
A new process, called thermoset in-mold forming, for combining thermoset master forming and thermoset forming in one mold is in development. A pre-impregnated continuous-fiber reinforced sheet based on epoxy (prepreg) is formed in the injection molding machine, followed by instantaneous overmolding of a short-fiber reinforced epoxy compound in one step. Compared with conventional processes in which thermoset injection molding, prepreg compression molding, and hence curing of the materials are separated, the new process allows for the combination in one step and simultaneous curing of both components. The result is a hybrid component, which features a continuous-fiber reinforced part for higher mechanical performance and a short-fiber reinforced part with high design freedom for integration of additional functions. For a successful combination of both materials in one process, it is essential to investigate the bond strength between them in relation to the processing parameters and their influence on the degree of cure. This paper analyzes the influence of the mold temperature in this process on curing degree, bond strength, and the processing viscosity.
Funding: This work was carried out as part of the research project “Duro-IMF” (funding no. 20W1503D) funded by the German Federal Ministry for Economic Affairs and Energy according to a decision of the German Federal Parliament. The “Duro-IMF” process was developed together with Schmidt WFT GmbH, C.K. Siebenwurst GmbH & Co. KG, Gubesch Group, and the German Aerospace Center (DLR). Furthermore, the authors gratefully acknowledge the companies Raschig (Germany, Ludwigshafen) and Mitsubishi Chemical Corporation (Japan, Tokio) for offering the materials for this research.
Conflict of interest statement: The authors declare no conflict of interests.
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