Coir yarn - yarn interaction in dry contact condition

Technical textiles made of synthetic materials find extensive use in automotive and environmental protection measures in large quantities and end up as landfill after service. Coir fibre, extracted from coconut husks, is an environmentally friendly natural fibre for geotextile applications due to its technical benefits and cost-effectiveness. Yarn-yarn interfaces in the textiles experience relative motion during service and lead to early failure. This study aims to understand the effect of relative motion between yarns using a novel in-house developed test device, which simulates the contact conditions between yarns in textiles. Two-ply coir yarns used in commercial geotextiles were used. Tribo tests were conducted at different displacement amplitudes ranging from 100 to 2000 µm. The coefficient of friction increased with displacement amplitude and remained constant beyond 1200 µm. The fibre rolling and packing within the yarn influence the friction and wear characteristics in yarn-yarn interaction. The presence of the waxy outer layers in the fibres lubricates the interface and contributes to reduced friction. The inter-yarn coefficient of friction of coir yarns under displacement-controlled reciprocating sliding is reported for the first time, and it is observed that visible fibre damage occurred only beyond 800 µm displacement amplitude. These findings suggest that restricting the relative motion between interacting coir yarns in textiles during service will improve the durability.