Closing the Loop on Silicone Elastomers: Life Cycle Evaluation of Virgin Materials and Recycling Processes

Abstract

Silicone elastomers are widely used materials whose production is energy-intensive and reliant on fossil-based precursors.This study evaluates their environmental impacts through a combined life cycle assessment (LCA) and prospective LCA, covering both virgin production and five chemical recycling routes. The cradle-to-gate greenhouse gas (GHG) emissions of a representative room-temperature-vulcanizing (RTV-1) silicone sealant were quantified as 5.79 kg CO2-equivalent (CO2 eq.) per kilogram, dominated by poly(dimethylsiloxane) (PDMS) synthesis (82 %). Prospective LCA of recycling technologies, including base-, acid-, fluoride-, and metal-catalyzed depolymerization, as well as thermal depolymerization, revealed strong dependencies on reaction temperature, solvent use, and stoichiometric reagents. Among the assessed routes, potassium hydroxide-catalyzed depolymerization showed the lowest GHG emissions (1.83 kg CO2 eq. per kilogram of regenerated PDMS). Incorporating recycled PDMS into RTV-1 formulations can reduce product-level emissions by up to 55 %. Sensitivity analyses demonstrated that thermal energy sources and solvent recycling, particularly in fluoride-and boron-based processes, substantially influence environmental outcomes. Overall, the results highlight that chemical recycling can significantly reduce the environmental footprint of silicone elastomers and represents a viable strategy for enabling a more circular and sustainable silicone materials value chain.