Spinneret geometry modulates the mechanical properties of man-made cellulose fibers

Funding Information: This project has received funding from the Academy of Finland (under the project WTF-click-nano), Jenny and Antti Wihuri foundation, Puunjalostusinsinöörit Oy and FinnCERES. The authors also gratefully acknowledge Katrina Räty for proofreading the article. Additionally, the authors acknowledge the provision of facilities and technical support by Aalto University at OtaNano -Nanomicroscopy Center (Aalto-NMC) and D22 instrument at ILL, Dr. Lionel Porcar. Publisher Copyright: © 2021, The Author(s).The production of cellulose-based textile fibers with high toughness is vital for extending the longevity and thus developing a sustainable textile industry by reducing the global burden of microplastics. This study presented strategies to improve fiber toughness by tuning spinneret geometries. Experimental studies were conducted by spinning with different spinneret geometries and measuring the mechanical and structural properties of the spun fibers. In addition, numerical simulation tools were used to better understand the effects of spinneret geometry. The altering parameters of the spinneret geometries were the capillary diameters D, the angle of the entry cone into the spinning capillary, and the ratio of capillary length to diameter L/D. The highest fiber toughness could be achieved at a capillary aspect ratio of 1 to 2. The obtained maximum fiber toughness was 93 MPa with a tensile strength of 60 cN/tex and a concomitant elongation of 16.5%. For these fiber properties, a 13 wt% solution of a high-puritypulp with higher viscosity in [DBNH][OAc] was spun into a 1.3 dtex fiber using a D100 spinneret with a capillary of 1:1 length/diameter and an entrance angle of 8°. It was noticeable that the microvoid orientations decreased almost linearly with increasing toughness of the fibers. The morphologies of the fibers were similar regardless of the spinneret geometries and the raw materials used in the spinning process. In summary, by modulating the spinneret geometries, Ioncell fibers obtained high toughness that have the potential to replace synthetic fibers.Peer reviewe