Tribological investigation into achieving skin-friendly artificial turf surfaces

Abstract

A main concern with artificial turfs is the increased incidences of skin abrasions compared to playing on natural grass. The proliferation of these surfaces draws attention to the skin-friendliness and related test methods of the products. This study focuses on the yarn component and explores the significance of tribopairs in identifying the skin-friendly property of hydrophilically-modified polypropylene. The frictional behaviour of poly(sulfobetaine methacrylate)-grafted substrates were studied under dry and hydrated conditions with standard steel tribotips, commonly used in frictional assessments. The measurements were repeated with tribotips made from silicone skin, used in large-scale artificial turf testing. Results showed that when hydrated, hydrophilic polymer brushes were successful in reducing silicone skin-sample friction by 75.8%. Interestingly, when extended trials were conducted, a step-jump in the frictional values of highly-modified samples was observed, attributed to the diminishing hydrated layer with prolonged testing. In contrast, the standard steel tribotips were unable to discern the effects of surface grafting or hydration, measuring consistently low frictional values across all samples. This study highlights the importance of tribotip selection and introduces a bench-top test method that can potentially be used for the quantification of skin-friendliness of artificial turf yarns during product development stages.