STRUCTURE–PROPERTY OF WET-SPUN ALGINATE-BASED PRECURSOR FIBERS MODIFIED WITH NANOCARBONS Grzegorz Szparaga*, Magdalena Brzezińska, Ewelina Pabjańczyk-Wlazło, Michał Puchalski, Sławomir Sztajnowski, Izabella Krucińska Department of Material and Commodity Sciences and Textiles Metrology, Faculty of Material Technologies and Textile Design, Lodz University of Technology, Zeromskiego Str. 116 , 90-924 Lodz, Poland *Corresponding author email: grzegorz.szparaga@p.lodz.pl 1. Introduction Man-made fbers composed of natural polymers have attracted increasing attention in materials engineering and novel technologies. They are used in a wide range of solutions in many industries, both as strengthening elements for classical polyolefn materials and as systems with special functional properties [1]. Among the technologically interesting polymers with wide application potential, alginates are noteworthy. Alginates are linear polysaccharides made of ß-d-mannuronic (M) and α-l-guluronic (G) acids and can have widely varying compositions and unit sequence confgurations [2,3]. An important aspect afecting the polymeric properties is the interaction between neighboring carboxylic groups in a-l- guluronic acid in the presence of a bivalent metal ion, such as calcium, copper, or magnesium. The zigzag structure of a-l- guluronic acid makes it possible to join two neighboring parallel repeat units with a chemical bond generated by a bivalent metal ion, resulting in a so-called “egg-box” structure [4]. The possibility to create various structural forms of alginate and thus to obtain materials with diferent physicochemical properties is also very interesting from a scientifc standpoint [5]. In the current study, a wet-spun method of obtaining fbers was elected due to the type of the selected polymer, which requires dissolving in a solvent to be spun. In this process, fbers are extruded directly into a liquid bath, called coagulation bath, which is a non-solvent to the polymer solution and then have to be in order to orient the polymers to give the fber its strength. Using the special composition of coagulation bath in the wet- spinning technique, one can obtain a range of diferent alginate fbers incorporating copper, sodium, or calcium or fbers made of alginic acid. Currently, alginate fbers are widely applied in medicine, primarily as dressing materials [6-12]. Due to their swelling and gelling properties, such dressings do not adhere to the wound and can easily be removed. Moreover, alginate- based medical products can also be used for controlled drug release [13,14] as well and in many other areas of regenerative medicine [15-22]. Unfortunately, their low strength and high hydrophilicity are major challenges for the use of alginate- based materials in technical applications. However, one characteristic feature makes them interesting in other areas of investigation. Given that their structure is similar to cellulose, alginate fbers can act as precursors for carbon fbers (PCFs). Currently, carbon fber technology is based on two types of precursors (polyacrylonitrile fbers and mesophase pitches), both of which are quite harmful to the natural environment. Therefore, it seems preferable to use a natural precursor, which is abundantly available and cheap to obtain carbon fbers with specifc functional properties. In analyzing the carbonization process, one should remember that strength properties largely depend on the supramolecular and molecular structure, porosity, and strength of the precursor fbers. Given that the tensile strength of alginate fbers is much lower than that of polyacrylonitrile fbers, the resulting carbon fbers are suitable only for specifc technical application such as absorptive materials or applications that do not require Abstract: The results of studies assessing the infuence of the addition of carbon nanofllers, such as multiwalled carbon nanotubes (MWCNTs) and graphene oxide (GO) that difer in size and structure, on the molecular and supramolecular structure and properties of alginate fbers that might be prospective precursors for carbon fber (PCF) industry are presented in this article. The investigation was carried out by Fourier transform infrared (FTIR) spectroscopy, wide-angle X-ray difraction (WAXD), and tension testing. In the frame of the current study, two types of alginate fbers were examined and compared: alginic acid and calcium alginate fbers. Alginic acid fbers were formed by chemical treatment of calcium alginate fbers with hydrochloric acid due to the fact that Ca 2+ ions presented in the fbers were expected to adversely afect the prospective carbonization process. This investigation brought important conclusions about the infuence of nanofllers on the physical properties of the fnal material. Understanding the link between the incorporation of carbon nanostructures and a possible infuence on the formation of ordered carbon structures in the precursor fbers brings an important opportunity to get insights into the application of alginate fbers as a prospective base material for obtaining cost-efcient carbon fbers. Keywords: precursor fbers, alginic acid, calcium alginate, wet-spinning, carbon nanotubes, graphene, nanomaterials http://www.autexrj.com AUTEX Research Journal, Vol. 20, No 1, March 2020 DOI: 10.2478/aut-2019-0003 © AUTEX 32