Preparation of carrageenan fibers promoted by hydrogen bonding in a NaCl coagulation bath

Carrageenan fibers developed by wet spinning have been extensively studied due to their remarkable flame-retardant characteristics. However, its mechanical properties have not been significantly improved, which limits the further development of carrageenan fibers. Traditionally, the first coagulation bath has been selected as a KCl solution, which can promote the formation of gels from carrageenan without reacting with NaOH to produce precipitates. In this study, a new type of carrageenan fiber was prepared for the first time employing an underappreciated NaCl solution as the first coagulation bath in combination with an AlCl₃ coagulation bath. A comparison was made using fibers produced with KCl as the first coagulation bath under the same conditions. The potential mechanism of wet forming of carrageenan fibers was revealed using performance testing, compositional analysis, and structural characterization, which systematically investigated the differences between the two fibers. In contrast to prior studies, the NaCl coagulation bath primarily promoted hydrogen bonding between carrageenan molecular chains, and the produced fibers outperformed the KCl coagulation bath.