Bio-pohjaisesta 2,5-furaanidikarboksyylihaposta ja kemiallisesti kierrätetystä elastaanikuidusta valmistetut elastomeeriset polyesterit

Today, the majority of textile waste lands is mismanaged in landfills. Textile waste consists mainly of synthetic fibres, contributing to the accelerating plastic pollution crisis. Elastane is an expandable textile fibre, often blended with other synthetic and natural fibres. It belongs to the large family of polyurethanes, particularly to thermoplastic polyurethanes. To address the growing issue of waste mismanagement, research is exploring chemical recycling methods for polyurethanes. Among the most promising techniques are hydrolysis, glycolysis, acidolysis, and aminolysis, which offer pathways to transform waste into valuable resources. Elastane, like other polyurethanes, consists of soft and hard segments. The aim of this thesis is to provide a method for open-loop recycling of elastane waste, by utilising soft segment diols in a new copolymer. In this work, an unknown elastane yarn was recycled via glycolysis. A split-phase glycolysis resulted in three phases, where poly(tetramethylene ether)glycol-based (PTMG) soft segment was extracted, characterised, and utilised for further polymerisation. According to Fourier-transform infrared (FT-IR) and proton nuclear magnetic resonance (1H-NMR) spectroscopy experiments, pure PTMG oligomers were extracted, with a molecular weight of 960-980 g/mol. Inspired by elastane, the diols were used as the soft segment for the copolymer, while bio-based 2,5-furandicarboxylic acid (FDCA) was chosen as the hard segment. FDCA is a monomer acquired from agricultural waste or lignocellulosic biomass. It can be polymerised into polyethylene furanoate (PEF), which is predicted to replace a widely used commercial petroleum-based polymer, polyethylene terephthalate (PET). By varying soft segment concentration, reaction temperature and time, and the choice of two FDCA derived hard segments, thermally stable copolyesters were synthesised. Size-exclusion chromatography (SEC) demonstrated that the combination of elevated reaction temperature and reduced pressure yielded samples with the highest molecular weight, achieving values up to 178.2 kg/mol. Thermal analysis confirmed that the samples were thermally stable up to 370 °C, with a melting temperature of around 200 °C. Results aligned with those reported in the literature for pure PEF and PEF-PTMG copolymers.