Systematic study of the presence of microplastic fibers during polyester yarn production

Synthetic fibers, especially polyester, have over past decades managed to overtake and dominate the textile industry. Microplastic fibers are shed from synthetic textiles during their user phase, primarily during washing. However, there is little known about their origin, except that they are likely embedded in textiles already since their production. Therefore, we systematically examined the presence of microplastic fibers during the process of yarn production. We started with one bale and took samples from the bale opening step throughout carding, sliver handling and finally to spinning. We extracted microplastic fibers from all samples in order to quantify and characterize them. We also investigated the impact of process parameters, especially 4 different spinning methods (ring, compact, rotor, and air-jet spinning). We found microplastic fibers in all studied samples, ranging between 44 fibers/g to 8057 fibers/g. Rotor-spun yarns were identified as a material with a high content of microplastic fibers (2000–8000/g) while the other samples, including yarns spun with alternative methods, showed fiber numbers in tens and hundreds of fibers/g. Varying the operational settings of carding and spinning had none to minimal impacts on fiber number with the exception of rotor spinning, where we observed a 4 fold increase when the speed was increased by 25%. The released fibers have each a unique fiber length distribution with varying medians: 210 μm for rotor yarns, 330 μm for air-jet yarns and 530–580 μm for ring and compact yarns. The results from this study will allow textile companies to select processes or operating conditions that minimize the presence of microplastic fibers.