Insight into stabilization behaviors of Lignin/PAN-derived electrospun precursor fibers
Graphical abstract
Introduction
Carbon fibers (CFs) have attracted considerable attention throughout the world as a kind of high strength lightweight material in the composites industry for applications such as aerospace, automotive, and renewable energy resources [1,2]. CFs can be manufactured from pitch [3,4] , rayon [5,6] and polyacrylonitrile (PAN) precursors [7,8], and more than 90% of commercial CFs were produced from PAN-derived precursors [9]. To fabricate the high-performance PAN-based CFs, the precursor fibers (PFs) need undergo a sequence of heating treatment processes (e.g., stabilization in oxidative environment and carbonization in protective atmosphere) [10,11]. Among them, stabilization is of great importance to convert into infusible structure, which preventing the stabilized fibers (SFs) from fusing at the following carbonization process. Meanwhile, stabilization is the most complicated and time-consuming step in the manufacture of CFs [8,12]. Therefore, the optimization of stabilization process is not only beneficial to improve the performance of CFs, but also contribute to minimize their production cost. Thus, many researchers focused on improving the thermal behavior of PAN-derived PFs according to their stabilization conditions, including temperature, time and tension [[13], [14]–15] . Bajaj et al. [16] pointed out that the exothermic reaction of homopolymer PAN-derived PFs such as cyclization was initiated and transferred by free radicals, which would cause the sudden and rapid heat evolution during stabilization. The results showed that their corresponding stabilization processes were difficult to control and the resultant CFs with superior mechanical properties could not be produced because of the chain scission caused by the intense heat release. Generally, acrylonitrile (AN) was copolymerized with other polar comonomers, such as methyl acrylate, acrylic acid, or itaconic acid (IA) to achieve controllable adjustment of PFs during stabilization process, and this design could improve the property of PAN-derived PFs [[17], [18]–19]. Thermal behaviors of copolymer PAN-derived PFs was investigated by Preta et al. [20] . They found that the corporation of certain comonomers (acrylic acid (AA), methacrylic acid (MAA) and IA) could trigger the cyclization reaction and reduce the cyclization temperature. Jin et al. [9] prepared the PAN-derived nanofibers with functional groups through the alkaline hydrolysis modification, and found the cyclization temperature of the hydrolyzed PAN-derived nanofibers was also shifted to a lower temperature owing to the fact that the nitrile (C = N) groups of PAN were converted into the amide (CONH2) and carboxylic (-COOH) groups. Besides, our previous work also clarified the effect of oxygen that was introduced in pitch precursor on the properties and structure evolution of fibers during stabilization, carbonization and graphitization, and found that the introduced oxygen of pitch precursor was beneficial to fabricate the pitch-based CFs with high tensile strength [21]. Therefore, these previous findings implied that the oxygen-containing groups units in PFs would promote the stabilization and carbonization behaviors.
Actually, Lignin is an aromatic biopolymer and has been investigated as a precursor for the production of CFs because of its low-cost and bio-renewable feedstock [22,23]. The molecular structure of Lignin consists of the phenylpropane units with a large number of hydroxyl (–OH), carboxyl (–COOH) and carbonyl (–C = O) oxygen functional groups [24,25] resulting to low spinnability of Lignin and obvious pore structures of Lignin-based CFs with low mechanical properties. However, the blended Lignin/PAN has been used as a low-cost precursor for CFs production to combine the advantages of PAN and Lignin [26,27]. In our previous reports [28], the influence of Lignin units on the properties of Lignin/PAN-derived CFs was demonstrated and the Lignin units exhibited positive effects on the fabrication of Lignin/PAN-derived fibers, especially their stabilization process. Notably, the stabilization behaviors and precise mechanism Lignin/PAN-derived fibers were not clear, though Lignin could attenuate the exothermal reaction to avoid excessive heat eruptions during the stabilization.
Herein, the stabilization behaviors of Lignin/PAN-derived PFs were deeply investigated by various characterization techniques. Based on the evolutions of chemical composition, thermodynamics and kinetics process of fibers, this work insighted into the stabilization behaviors of Lignin/PAN-derived PFs according to the effects of oxygen structural units in Lignin, and deeply explored the influence of oxygen containing groups of Lignin on the stabilization of Lignin/PAN-derived PFs. More importantly, the results further demonstrated that introducing the oxygen-rich structural unit in Lignin was a facile and effective strategy to improve the stabilization behavior of the PAN-based fibers.
Section snippets
Materials
The Lignin/PAN-derived electrospun precursor fibers (PFs) were prepared by the electrospinning technology using the PAN (Mw=150,000 g/mol, Sigma-Aldrich, USA) and Lignin (Mw=528 g/mol, Shanghai Macklin Biochemical Co., Ltd., China) as raw materials. Specific experimental parameters were presented in our previous published paper [28]. The obtained Lignin/PAN-derived PFs were named as LPx-PF, where x (0, 10, 20) represented the added Lignin content.
Stabilization of precursor fibers
The PFs were stabilized from room temperature to
General properties of Lignin/PAN-derived precursor fibers
The elemental composition of Lignin/PAN-derived PFs by elemental analysis and XPS analysis are summarized in Table 1. The carbon, hydrogen and nitrogen contents of LP0-PF, LP10-PF and LP20-PF were from 70.05 to 64.63%, 5.75 to 4.01% and 23.17 to 12.21%, respectively. Notably, the oxygen contents of Lignin/PAN-derived PFs increased from 2.79 to 16.52% with the introduction content of Lignin from 0 to 20%, it mean oxygen containing functional groups of PFs could adjust by promoting the content of
Conclusions
In this work, the introduction of Lignin provided abundant oxygen-containing functional groups for the Lignin/PAN-derived PFs, especially carboxyl functional groups. The Lignin was involved into the stabilization process, which improved the fibers shrinkage and significantly improved the rapid heat release. The decreasing of cyclization activation energy was ascribed to the transformation from the free-radical reaction to the ionic reaction. During the stabilization process, the Lignin acted as
CRediT authorship contribution statement
Xiaxiang Zhang: Conceptualization, Methodology, Data curation, Writing – review & editing. Yong Qi: Investigation, Data curation, Formal analysis. Jianxiao Yang: Conceptualization, Supervision, Writing – review & editing, Funding acquisition. Silin Dong: Writing – review & editing. Jiahao Liu: Writing – review & editing. Jun Li: Funding acquisition, Writing – review & editing. Kui Shi: Data curation, Formal analysis, Writing – review & editing.
Declaration of Competing Interest
The authors declare that they have no conflict of interest.
Acknowledgments
This research was funded by the National Natural Science Foundation for Young Scientists of China (Grant No.51702094) and the Natural Science Foundation of Hunan Province, China (Grant No. 2020JJ4203 and 2019JJ50651).
References (44)
- et al.
High strength and high modulus carbon fibers
Carbon
(2015) - et al.
Preparation of pitch based carbon fibers using hyper-coal as a raw material
Carbon
(2016) - et al.
Adsorption and desorption behaviors of cesium on rayon fibers coated with chitosan immobilized with Prussian blue
Int. J. Biol. Macromol.
(2017) Porous structure evolution of cellulose carbon fibres during heating in the initial activation stage
Fuel Process. Technol.
(2004)- et al.
Effect of alkaline hydrolysis on cyclization reaction of PAN nanofibers
Mater. Des.
(2017) - et al.
Correlative study of critical reactions in polyacrylonitrile based carbon fiber precursors during thermal-oxidative stabilization
Polym. Degrad. Stabil.
(2013) - et al.
Optimization of stabilization conditions for electrospun polyacrylonitrile nanofibers
Polym. Degrad. Stabil.
(2012) - et al.
Simultaneous DSC/TG analysis on the thermal behavior of PAN polymers prepared by aqueous free-radical polymerization
Polym. Degrad. Stabil.
(2016) - et al.
Thermal behaviour of acrylonitrile copolymers having methacrylic and itaconic acid comonomers
Polymer
(2001) - et al.
Mechanism and kinetics of the stabilization reactions of itaconic acid-modified polyacrylonitrile
Polym. Degrad. Stabil.
(2008)
Effect of oxygen-introduced pitch precursor on the properties and structure evolution of isotropic pitch-based fibers during carbonization and graphitization
Fuel Process Technol
Lignin - an alternative precursor for sustainable and cost-effective automotive carbon fiber
J. Mater. Res. Technol.
NMR a critical tool to study the production of carbon fiber from lignin
Carbon
Rheological behavior of polyacrylonitrile and polyacrylonitrile/lignin blends
Polymer
Nitrogen, oxygen and sulfur co-doped hierarchical porous carbons toward high-performance supercapacitors by direct pyrolysis of Kraft lignin
Carbon
A high surface area N-doped holey graphene aerogel with low charge transfer resistance as high performance electrode of non-flammable thermostable supercapacitors
Carbon
A doped activated carbon prepared from polyaniline for high performance supercapacitors
J. Power Sources
Stabilization kinetics of gel spun polyacrylonitrile/lignin blend fiber
Carbon
Gel-spun carbon nanotubes/polyacrylonitrile composite fibers. Part II: stabilization reaction kinetics and effect of gas environment
Carbon
Effect of controlled tacticity of polyacrylonitrile (co) polymers on their thermal oxidative stabilization behaviors and the properties of resulting carbon films
Carbon
The free radical species in polyacrylonitrile fibers induced by gamma-radiation and their decay behaviors
Radiat. Phys. Chem.
Significantly reduced pre-oxidation period of PAN fibers by continuous electron beam irradiation: optimization by monitoring radical variation
Polym. Degrad. Stabil.
Cited by (13)
Understanding the behaviors of ZIF-67 reinforced electrospun carbon nanofibers in the preparation and stabilization
2024, Composites Science and TechnologyProgress in advanced electrospun membranes for CO<inf>2</inf> capture: Feedstock, design, and trend
2024, Journal of Environmental ManagementConstruction of self-supporting ultra-micropores lignin-based carbon nanofibers with high areal desalination capacity
2023, International Journal of Biological MacromoleculesCitation Excerpt :In L2P1-CNFs, graphitic N is dominant, with increasing lignin amount, L4P1-CNFs show an increase in pyridinic N and pyrrolic N, while graphitic N decreased, in addition, O=C-O functional group shows excellent improvement. The results prove that the introduction of lignin could improve the surface chemistry of carbon nanofibers, providing more active sites [37]. L0P1-CNFs, L2P1-CNFs and L4P1-CNFs electrodes are firstly characterized in 6 M KOH electrolyte in a three-electrode configuration to examine the electrochemical performance.
Corncob waste as a potential filler in biocomposites: A decision towards sustainability
2022, Composites Part C: Open AccessCitation Excerpt :It can be observed from Fig. 6 (b) that the burning rate increased with the addition of the CCF. This can be attributed to the poor filler-matrix interface because a poor interfacial bonding between fiber-matrix can affect the thermal decomposition and therefore the combustion behavior of the composites [36–39]. However, a positive response in terms of reduced dripping effect was also observed.
Electrospinning of PAN/lignin blends aiming the production of carbon nanofibers
2024, MRS Communications