Biobased TPU for Melt Spun Multifilament Yarns as a Sustainable Alternative for Conventional Fossil Based TPU

Abstract Thermoplastic polyurethane (TPU) is a unique polymer known for its excellent physical and chemical properties including exceptional elasticity and durability, excellent abrasion resistance and resistance to oil, water, acids and alkalis, making it indispensable in various industries. In recent years, growing environmental concerns have let to the development of bio-based thermoplastic polyurethane from renewable resources which provide a sustainable alternative to conventional fossil-based TPUs. This study investigates the melt spinning process of two types of TPU: Desmopan 385E, a conventional TPU, and Desmopan CQ33085AUEC, a partially bio-based TPU, focusing on their potential for high performance multifilament yarns. A comprehensive study evaluated their thermal, rheological and mechanical properties, as well as their processability at different drawdown ratios (DDR). Thermogravimetric analysis (TGA) revealed differences in decomposition temperatures and thermal stability while melt flow rate (MFR) testing optimized melt spinning parameters. Rheological measurements showed viscosity reductions of up to 90% after spinning, reflecting structural transformations such as chain alignment and scission, with implications for processing and yarn performance. Both TPU types were successfully processed into multifilament yarns under comparable spinning conditions, achieving process speeds of up to 2000 m/min. Mechanical tests revealed differences in tensile strength and elongation, with the bio-based TPU achieving mechanical properties comparable to or 7,4% better in tensile strength than those of its conventional counterpart, highlighting the potential of bio-based TPU as a sustainable alternative for technical textile applications.