Tribological investigation of potential green alternatives to PFAS-Teflon (PTFE)

PFAS (per- and polyfluoroalkyl substances) are a group of man-made chemicals that have been widely used in various industrial and consumer products since the 1940s. These compounds serve various purposes, however, PFAS face criticism due to health and environmental concerns. The problem with PFAS lies in their persistence, bioaccumulation, potential health effects, and widespread environmental contamination, highlighting the need for comprehensive strategies to mitigate their impact on human health and the environment. Polytetrafluoroethylene (PTFE) is a PFAS thermoplastic fluoropolymer, widely used in tribological applications (e.g. bearings, coatings) in the industry and common household products as well, due to its favourable tribological properties (low coefficient of friction, chemically inert, self-lubricating nature and high thermal stability). When seeking substitutes, it is essential to explore the relative wear resistance compared to PTFE and meet specific conditions encountered in its application (varying temperatures, chemical resistance, impact resistance, machinability/manufacturability, and acceptable friction behaviour). Currently, no direct substitute exists within the range of technical materials. The main objective is to gather tribological information (friction and wear performance) about potential PTFE replacement eco-polymers to be used in sliding bearings. The work aims to investigate the abrasive wear behaviour, including wear micro-mechanisms, surface damage, wear debris generation and micro-geometry changes along with the friction in contact. The pin-on-disc laboratory tests representative of the sliding bearing application will be conducted under various pressure-velocity conditions, providing a basis for comparison. By incorporating a better understanding of the wear/lifetime and surface degradation processes of green alternatives, the application of PTFE and its composites can be drastically reduced. The information to be obtained is crucial for sustainable development and could aid material developers and product manufacturers in further developing their products to comply with the more strict rules about environmental and human health protection.