Background Healthcare workers around the world are experiencing skin injury due to the extended use of personal protective equipment (PPE) during the COVID-19 pandemic. These injuries are the result of high shear stresses acting on the skin, caused by friction with the PPE. This study aims to provide a practical lubricating solution for frontline medical staff working a 4+ hours shift wearing PPE. Methods A literature review into skin friction and skin lubrication was conducted to identify products and substances that can reduce friction. We evaluated the lubricating performance of commercially available products in vivo using a custom-built tribometer. Findings Most lubricants provide a strong initial friction reduction, but only few products provide lubrication that lasts for four hours. The response of skin to friction is a complex interplay between the lubricating properties and durability of the film deposited on the surface and the response of skin to the lubricating substance, which include epidermal absorption, occlusion, and water retention. Interpretation Talcum powder, a petrolatum-lanolin mixture, and a coconut oil-cocoa butter-beeswax mixture showed excellent long-lasting low friction. Moisturising the skin results in excessive friction, and the use of products that are aimed at 'moisturising without leaving a non-greasy

Polyurethane (PU) has been studied as alternative bearing material for marine water-lubricated stern tube due to its excellent wear resistance, remarkable mechanical properties and so on. In this study, nine types of PU samples which are composed of different additives were prepared and tested in order to investigate their tribological properties under various working conditions. A pin-on-disc tribo-tester was used to conduct tests. Then comparison analyses were conducted from three aspects, including the friction coefficient, wear mass loss, and the wear surface topography. The analysis results showed that: (1) the different additives as well as the mass fraction of these additives lead to significant difference in terms of tribological properties of PU; (2) the lubricating grease, as one of additives, improved the wear resistance and friction performance effectively; (3) modified PU is eligible to work as matrix because of satisfied mechanical properties and specific internal morphology. It is believed that understandings in this study are beneficial to the improvement of the tribological properties of PU and also provide the real practical basis for the studies of polymer materials which applied on waterlubricated marine stern tube bearing.

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