Analysis of Morphology Changes in Thermoplastic Polyurethane During Storage and Processing Using FTIR Spectroscopy

This study investigates the influence of storage and processing (injection moulding, meltblown) on the morphological structure of commercially available thermoplastic poly(ether‐urethane)s using Fourier Transform Infrared (FTIR) spectroscopy. Many of the physical properties of thermoplastic polyurethane (TPU) materials and products are caused by the block‐copolymer chain, which consists of soft and hard segments. According to the literature, the degree of separation of these segments and their content can be evaluated by FTIR spectroscopy measurements. Granules of TPU grades with different compositions were stored for up to 900 days to assess morphological changes. In addition, peaks of ether and urethane groups, as well as free‐ and hydrogen‐bonded carbonyl (C = O) peaks were analysed for a total amount of six injection moulded materials with different ratios of hard to soft segment. The results of the C─O and C = O peaks were correlated with the segment content and the degree of phase separation, validating the measurement principle. In the second part, nonwovens made of Elastollan 1180 A were characterised using the validated FTIR method. The distinct influence of the processing route and processing parameters is a novel finding and is analysed to evaluate the potential analytical capabilities for TPU nonwovens.