Screening of spinning oils for melt‐spun lignin‐based carbon fiber precursors

Abstract

For the improvement of the processing of melt-spun lignin-based fibers, the use of a spinning oil is necessary. The use of spinning oils is standard for the processing of PAN based carbon fiber precursors. Since no commercial spinning preparations for lignin fibers are available on the market, a study on different oils, such as technical oils, food-grade oils or spinning avivages, is performed. A stepwise approach with applied tests (viscosity measurement, fiber etching, melt-spinning, stabilization, carbonization) was developed to eliminate oils which are not suitable. The physical properties of the tested oils are determined and spectroscopic studies of these avivages are performed. Mechanical properties are characterized for as-spun lignin fibers, stabilized lignin-based fibers and lignin-based carbon fibers with and without a spinning preparation. Four of seven tested spinning oils improve the handling during the processing of ligninbased fibers but only two spinning oils lead to good quality carbon fibers and improve even the tensile strength of the resulting carbon fibers.

Recent advances in lignin-based carbon fibers (LCFs): precursors, fabrications, properties, and applications

“…Enengl et al investigated the ability of different spinning oils to improve LCFs performance. 125 The results indicated that readily available silicone oils are suitable for the processing of LCFs and can serve as a starting point for further research. In practice, several parameters need to be considered and optimized for lignin melt-spinning.…”

Carbon Fibers from Wet-Spun Cellulose-Lignin Precursors Using the Cold Alkali Process

“…The tenacity of 26 cN/tex for the neat cellulose precursor is on a par with that of a conditioned textile-grade viscose fiber, but the tenacity of 12 cN/tex observed for the fibers with 30% lignin is very low. A tenacity of 12 cN/tex (~180 MPa) is, however, significantly higher than the typical tensile strength of melt-spun lignin fibers used for CF preparation (20-40 MPa) [16,40], and it is thus sufficient for processing to CF.…”

Continuously processing waste lignin into high-value carbon nanotube fibers

“…The methods for preparing carbon fibers from lignin include melt spinning 5 , dry spinning 6 , wet spinning 7 , dry jet wet spinning 8 , and electrospinning 9 . Lignin can be processed into carbon fibers through multiple steps, including extraction, purification, spinning, stabilization, and carbonization 10 .…”