Flexible epoxy‐silicone rubber laminates for high voltage insulations with enhanced delamination resistance

In this work, functionalized damping layers consisting of crosslinked silicone rubber are incorporated into brittle epoxy‐based composites to improve the delamination resistance of high voltage insulations. Selected functional organosilanes are attached onto the elastomer surface by a two‐step modification to ensure a covalent bonding between the thermosetting resin and the damping layer. Functional model insulations and stator bar prototypes are then prepared with a vacuum pressure impregnation process. The influence of the damping layer on the thermo‐mechanical and electrical properties as well as the delamination resistance is characterized. The results give evidence that the flexibility of the new composite materials can be increased significantly whereas the electrical properties are not affected by the elastomer layer. By evaluating the performance of the stator bar prototypes it can be clearly shown that both delamination resistance as well as high voltage endurance can be enhanced considerably by the application of flexible damping layers. POLYM. COMPOS., 36:2238–2247, 2015. © 2014 Society of Plastics Engineers