Exploring sustainable alternatives to PTFE (TEFLON) tape as reference material in icing tests

Abstract

Ice accretion poses severe operational, safety and economic hazards across critical sectors such as aerospace, wind power and power grid infrastructure. To mitigate these challenges, the development of effective anti-icing and deicing technologies has become a crucial area of research. However, a major bottleneck in evaluating these surfaces is the lack of standardized testing protocols and the high degree of inter-laboratory variability in measured ice adhesion strength. To address this, researchers heavily rely on reference surfaces to validate and calibrate individual icing events. Polytetrafluoroethylene (PTFE) film tape, commercially known as TEFLON, has become the de facto standard reference material in TAU icing laboratory and also by many of the other researchers for PAT, CAT and similar shear tests. PTFE is used mainly due to its exceptionally low surface energy, consistent hydrophobic baseline and ease of applying it afresh for every test run without damaging the substrate. Moreover, this ease of tape re-placeability effectively eliminates surface history and contamination effects. Despite its technical excellence, the long-term regulatory future of PTFE is highly uncertain. PTFE is classified as a member of the per- and polyfluoroalkyl substances (PFAS) family, widely classified as "forever chemicals" due to their environmental persistence and bioaccumulation risks. Stringent restriction frameworks are being implemented by global environmental bodies most notably the European Chemicals Agency (ECHA) under REACH regulations and the US Environmental Protection Agency (EPA). Therefore, industries and research institutions face an urgent mandate to transition away from fluoropolymer containing materials. Consequently, there is an immediate need to discover sustainable fluorine-free alternative reference materials that can fall close to PTFE in the reliability and low ice adhesion performance without compromising experimental reproducibility. This thesis focuses on step by step screening and evaluating commercially available non-fluorinated polymer tapes as potential sustainable replacements for PTFE tape which is used as reference material in TAU’s Ice Laboratory in ice adhesion testing. A comprehensive material selection matrix was established, shortlisting candidate materials including ultra-high-molecular-weight polyethylene (UHMWPE), polypropylene (PP), polydimethylsiloxane (PDMS), polyester (PET) and polyvinyl chloride (PVC). To capture a complete profile of the candidates' surface properties and mechanical performance under varying environmental and loading conditions, a rigorous multiple tests method characterization approach was employed. Surface wettability parameters, including static water contact angles (WCA) and solid surface free energies (SFE) were measured at ambient conditions using Krüss DSA100 Drop Shape Analyzer and evaluated via the Owens-Wendt-Rabel-Kaelble (OWRK) method. Ice adhesion testing was performed across three distinct testing configurations available at Tampere University to account for different loading modes and ice morphologies. The Push ice Adhesion Test (PAT) for static mold ice, the Centrifuge ice Adhesion Test (CAT) for aerodynamic impact ice accreted in an icing wind tunnel and the newly developed Arctic Test (AT) to evaluate larger sized bulk ice on cylindrical specimens. Ultimately, this work maps the interfacial behavior, handling practicalities and low temperature durability of non-fluorinated candidates against the baseline metrics of PTFE. In a nutshell, this research is providing a clear pathway toward regulatory compliant and eco-friendly benchmarking standards in icing research.