A new softening agent for melt spinning of softwood kraft lignin

• Published in: Journal of applied polymer science Vol. 129; no. 3; pp. 1274 - 1279
• Main Authors: Nordström, Ylva, Norberg, Ida, Sjöholm, Elisabeth, Drougge, Rickard
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 05-08-2013; Wiley; Wiley Subscription Services, Inc
• Subjects: Applied sciences; biopolymers and renewable polymers; biopolymers and renewable polymersblends; blends; Carbon fibers; Exact sciences and technology; extrusion; Fibers; Fibers and threads; Forms of application and semi-finished materials; Hardwoods; lignin; Materials science; Melt spinning; Polymer industry, paints, wood; Polymers; Softening agents; Softwoods; Spinning; Technology of polymers; thermal properties; Wood; Lignin; Heat treatment; Artificial fiber; Polymer blends; fibers; Property composition relationship; Temperature effect; Melt spinning; Hardwood; Softwood; Experimental study; Mineral fiber; biopolymers and renewable polymers; Precursor; Carbonization; Thermal properties; carbon fibers; Softening agent; Extrusion; Technological properties; Spinnability; blends; Carbon fiber
• ISSN: 0021-8995; 1097-4628; 1097-4628
• DOI: 10.1002/app.38795

Kraft lignin obtained from the pulping of wood is an interesting new precursor material for carbon fiber production because of its high carbon content and ready availability. However, continuous spinning of softwood kraft lignin (SKL) has been impossible because of its insufficient softening characteristics and neat hardwood kraft lignin (HKL) has required extensive pretreatments to enable fiber formation. Softwood kraft lignin permeate (SKLP) and hardwood kraft lignin permeate (HKLP), fractionated by membrane filtration, were continuously melt spun into fibers. To improve the spinnability of SKL and HKL, HKLP was added as a softening agent. SKL‐ and HKL‐based fibers were obtained by adding 3–98 wt % HKLP. A suitable temperature range for spinning was 20–85°C above the Tg of the lignin samples, and this range gave a flawless appearance according to the SEM analysis. Smooth, homogeneous fibers of SKLP, HKLP, and SKL with HKLP were successfully processed into solid carbon fibers. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013