Effects of Multiple Mechanical Recycling Loops on the Material Properties of Liquid Silicone Rubber

Liquid silicone rubbers (LSR) are thermoset elastomers, with a wide range of use across many industries and applications. Their crosslinked structure made them rather unattractive for material recycling up to now. In previous studies, mechanical recycling via the introduction of ground LSR particles was shown to be generally possible, but it has not yet been investigated what happens when the recycled LSR is recycled over again. In our study we investigated four consecutive mechanical recycling cycles of liquid silicone rubbers by adding 10, 20, and 30 wt% recycled content repeatedly. Mechanical tests showed that such a reprocessing of LSR is possible without significant loss in material performance. Thermal degradation tests revealed that the addition of ground particles has no negative effects on thermal stability. The properties of the recycled silicones were almost independent of the recycled content and the recycling round.