Examination of the Aging Effects of Silicone Molds During Vacuum Casting Processes via Scanning Electron Microscopy

We present an in-depth investigation of contaminated silicone molds by use of scanning electron microscopy, that provides additional insight into the aging process of the molds. The molds lifetime in vacuum casting processes of polyurethane is limited due to contamination with the diisocyanate compound of the PUR resin. SEM investigations, combined with FIB cross-sections and EDX measurements show that three different types of particles are distributed in the contaminated silicone matrix. The particles differ in shape and size, with a range from 50 nm to 50 µm. This explains the loss in transparency and the hardened haptics of contaminated molds.