Recycling ETFE Foils in Architectural Membranes: Mechanical Characterisation of Post‐Use Materials

Abstract ETFE foils are widely used in architectural applications, yet at the end of their service life they are typically downcycled into smaller components, whether as post‐industrial or post‐consumer residues. This research investigates the potential reuse of reclaimed ETFE foils from the Chelsea and Westminster Hospital roof, constructed in 1990 by Vector Foiltec and dismantled in 2023. The foils, exposed to environmental conditions for approximately 33 years, underwent an experimental cleaning process and were subsequently pelletised by Fietz® Polychromos. The resulting ETFE pellets were extruded on a laboratory‐scale extruder into various formulations in collaboration with Nowofol® Kunststoffprodukte GmbH & Co. KG. Four formulations were produced to facilitate a comparative analysis of material properties: 1) 100% post‐consumer recycled (PCR) ETFE, 2) 50% PCR / 50% virgin ETFE, 3) 25% PCR / 75% virgin ETFE, and 4) 10% PCR / 90% virgin ETFE. The mechanical behaviour of these foils was assessed through a series of biaxial hysteresis tensile tests and analyse simulating wind loads, following the guidelines of CEN/TS 19102:2024 Design of Tensile Membrane Structures, at the Textiles Hub (Dept. ABC, Politecnico di Milano). This study represents a first step towards understanding the effects of recycling on the mechanical performance of ETFE foils and base to evaluate the feasibility of reintegrating recycled materials into architectural membrane systems.