Effect of calendering on the performance of 100% recycled polyester weft-knitted fabrics

Government policies focus on the textile sector to follow a tendency towards sustainability and circular economy, thus, raising the use of recycled textiles which require further performance improvement to be completely competitive with other textile products while using secondary treatments that are also environmentally friendly. In this study, a 100% recycled polyester weft-knitted fabric, currently used by commercial brands in the apparel and sport textile industry, is calendered and its properties are examined before and after such treatment. This research investigates variations in the physical (appearance and thickness), mechanical (tensile strength and elastic recovery), and physiological (water vapour resistance, spray test, and wettability) characteristics of the samples. The calendering treatment reduces water vapour resistance up to 23%, which is particularly interesting for garments used in sports. Additionally, the contact angle is increased by the calendering process which translates in poorer wettability. Novel findings of this work include that, whereas in the original fabric sweat marks are visible, sweat stains do not appear on the calendered fabric and moisture management improves, while mechanical properties do not undergo significant changes. These results have not been previosly found in the literature, giving a particular interest to a conventional process in this type of recycled fiber that can contribute to the advancement of knowledge in the textile industry and enhance the performance of treated fabrics. All these aspects make the treatment particularly interesting to improve the technical performance of the textile material while using an economic treatment with low effect on the environment.