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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 24: Poster Session I
CPP 24.38: Poster
Montag, 16. März 2020, 17:30–19:30, P3
The Aging Mechanism of Silicone Molds for Vacuum Casting — •Natalie Frese1, Martin Wortmann2, Alexander Heide2, Johannes Brikmann2, Elmar Moritzer3, Bruno Hüsgen2, and Armin Gölzhäuser1 — 1Bielefeld University, Bielefeld, Germany — 2Bielefeld University of Applied Sciences, Bielefeld, Germany — 3Paderborn University, Paderborn, Germany
The use of silicone casting molds in the vacuum casting process for the production of prototypes made of polyurethane is state of the art. Although the process is widely used for prototype replication, it is rarely considered for an extensive use in small batch production. With this, the gap in plastic processing between very small (rapid prototyping) and very large quantities (injection molding) might one day be closed. We present an in-depth investigation of the aging effects in silicone casting molds for vacuum casting processes. Their lifetime is limited to a few production cycles due to contamination with the diisocyanate component of the polyurethane casting resin. By using a wide variety of characterization methods, the chemical and physical mechanisms of the aging process have been identified. It has been shown that an anomalous diffusion process of diisocyanate into the silicone surface leads to the formation of interpenetrating polymer networks of polyurea derivatives in the poly(dimethylsiloxane) matrix. This has been proven by extracting and analyzing polyurea of low molecular weights from the silicone.