Lignin is a promising bio‐based precursor for sustainable carbon fibers. Limiting factors for their development include the brittleness of lignin and the lack of large‐scale production routes. Here, a simple and economic wet‐spinning method, suitable for the fabrication of fibers based on softwood Kraft lignin (KL) and polyvinyl alcohol (PVA), is proposed. These two polymers reveal a partial miscibility in solution, and form metastable dispersions in solid state. KL‐PVA fibers are prepared at a weight ratio of 70:30 and are carbonized without thermo‐stabilization. A tailor‐made temperature program leads to a decreased microporosity on the fiber surfaces. The obtained carbon structures at 1000 °C are found to be poorly ordered, leading to only intermediate mechanical and electrical properties. However, graphitic domains appear at temperatures above 1500 °C and indicate a high potential for the system.

Lignin is considered as a promising bio-sourced precursor for more sustainable and low-cost carbon fibers (CFs). However, lignin-based CFs generally have a poor graphitic structure, compared to polyacrylonitrile CFs. In this paper, we present an original approach that uses graphene oxide liquid crystal (GOLC) as a templating agent to promote the formation of graphitic structure in the fibers at low carbonization temperature. Both lignin and hybrid lignin/GOLC CFs were carbonized/graphitized up to 2700 °C. Structural analyses by X-ray diffraction, Raman spectroscopy and electrical measurements manifest a significant improvement in graphitic structure and a preferred orientation of graphene planes for lignin/GOLC fibers. These effects are the result of axial propagation of the templated graphitic order nucleated by the large GO flakes. The current approach reveals the possibility of preparing low-cost lignin-based CFs with improved graphitic structure and high electrical conductivity at low temperature for electrochemical or smart textile applications.

No abstract

The global demand for packaging materials and energy is constantly increasing, requiring the exploration of new concepts. In this work, we presented a bioeconomic concept that uses steam explosion and phase separation to simultaneously generate fibers for the packaging industry and biogas substrate for the energy sector. The concept focused on fiber-rich residues and fiber-rich ecological energy crops from agriculture. Feasibility of the concept in the laboratory using feedstocks, including Sylvatic silphia silage, Nettle silage, Miscanthus, Apple pomace, Alfalfa stalks, and Flax shives was confirmed. Our results showed that we were able to separate up to 26.2% of the methane potential while always extracting a smaller percentage of up to 17.3% of organic dry matter (ODM). Specific methane yields of 297–486 LCH4 kgODM−1 in the liquid and 100–286 LCH4 kgODM−1 in the solid phase were obtained. The solid phases had high water absorption capacities of 216–504% due to the steam explosion, while the particle size was not significantly affected. The concept showed high potential, especially for undried feedstock.