Carbon Fiber Precursor Research Articles

Close Packing of Cellulose and Chitosan in Regenerated Cellulose Fibers Improves Carbon Yield and Structural Properties of Respective Carbon Fibers.

A low carbon yield is a major limitation for the use of cellulose-based filaments as carbon fiber precursors. The present study aims to investigate the use of an abundant biopolymer chitosan as a natural charring agent particularly on enhancing the carbon yield of the cellulose-derived carbon fiber. The ionic liquid 1,5-diazabicyclo[4.3.0]non-5-enium acetate ([DBNH]OAc) was used for direct dissolution of cellulose and chitosan and to spin cellulose–chitosan composite fibers through a dry-jet wet spinning process (Ioncell). The homogenous distribution and tight packing of cellulose and chitosan revealed by X-ray scattering experiments enable a synergistic interaction between the two polymers during the pyrolysis reaction, resulting in a substantial increase of the carbon yield and preservation of mechanical properties of cellulose fiber compared to other cobiopolymers such as lignin and xylan.

Cellulose-lignin composite fibers as precursors for carbon fibers: Part 2 – The impact of precursor properties on carbon fibers

Carbon fibers, despite being responsible lightweight structures that improve sustainability through fuel efficiency and occupational safety, remain largely derived from fossil fuels. Alternative precursors such as cellulose and lignin (bio-derived and low cost) are rapidly gaining attention as replacements for polyacrylonitrile (PAN, an oil-based and costly precursor). This study uses a cellulose-lignin composite fiber, to elucidate the influence of precursor fabrication parameters (draw ratio and lignin content) on the efficiency of stabilization and carbonization, from the perspective of the chemical, morphological and mechanical changes. The degradation of cellulose chains was the primary contributor to the decrease in mechanical properties during stabilization, but is slowed by the incorporation of lignin. The skin-core phenomenon, a typical effect in PAN-based carbon fibers production, was also observed. Finally, the carbonization of incompletely stabilized fibers is shown to produce hollow carbon fibers, which have potential application in batteries or membranes.

Structure-tunable Mn3O4-Fe3O4@C hybrids for high-performance supercapacitor

Controlling the morphology and structure of nanomaterials is of great importance for enhancing the electrochemical properties. In the paper, Mn3O4-Fe3O4@C hybrids with different architectures were synthesized by incubation of electrospun FeOx-containing carbon fiber (Fe-CNF) in KMnO4 solution followed by annealing. The presence of FeOx on the CNF plays a vital role in determining the morphology and structure of the final hybrids, and the Mn3O4-Fe3O4@C hybrids with half-tube, tube and oolite-filled fibers are formed conveniently by tuning Fe content in the carbon fiber precursor. The good conductivity of fiber and various redox states of Mn and Fe afford the facile charge transfer and excellent reversible redox properties, thus enhancing the capacitor performance. The oolite-filled Mn3O4-Fe3O4@C with tubular structure exhibited a high specific capacitance of 178 F g−1 at a discharge rate of 1 A g−1. This capacitor electrode has an excellent cyclic stability with 95% capacitance retention after 1000 cycles at 3 A g−1. This work provides a very simple strategy to tune the unique nanostructures of metal oxide on Fe-CNF for high-performance supercapacitor application in the future.

Life cycle impact assessment of different manufacturing technologies for automotive CFRP components

A comparative life cycle assessment analysis among pressure bag molding and bag molding with autoclave for the manufacturing of car components in carbon fiber reinforced plastic (CFRP) was carried out. Four scenarios were analyzed: i) autoclave bag molding with aluminum mold, ii) autoclave bag molding with CFRP mold and plastic master, iii) autoclave bag molding with CFRP mold and medium density fiberboard master, and iv) pressure bag molding with aluminum mold. The collected data for life cycle inventory derives from an Italian manufacturer of CFRP car components, scientific references and Ecoinvent database. Cumulative energy demand, global warming potential, ReCiPe midpoint and endpoint methods were used as impact and damage categories for quantifying the environmental impacts of the different manufacturing processes investigated. The results showed that the pre-impregnated composite fibers with thermoset polymer matrix, used as input material for the four investigated scenarios, represents the main source of total environmental impact, due to the use of polyacrylonitrile as a precursor for carbon fibers. The comparison among the environmental assessments of the different scenarios demonstrated that the most impacting process is the autoclave bag molding with composite mold and polyurethane master, whilst the most sustainable process is the autoclave bag molding with aluminum mold.

Controllable synthesis of isotropic pitch precursor for general purpose carbon fiber using waste ethylene tar via bromination–dehydrobromination

Nowadays, the substantial amount of waste ethylene tar (ET) lacks a clean and efficient route for utilization. In this work, a feasible approach was developed to fabricate general purpose carbon fiber (GPCF) using ET as a raw material. The method of bromination–dehydrobromination was used to synthesize controllably isotropic pitch precursor for GPCF. The results show that bromination–dehydrobromination reaction promotes the cyclization and aromatization of small molecules and relatively low molecular weight components and also prevents excess condensation during thermal treatment. The molecular structure of pitch precursor generated from bromination–dehydrobromination reaction has more linear and cross-linked structures as more naphthenic groups and the side chain of aromatic rings. The spinnability of pitch precursors and the mechanical performance of GPCFs are optimized when 10 wt% of bromine is introduced in synthetic reaction. The tensile strength, Young’s modulus, and elongation property of the final GPCF are 1072 ± 66 MPa, 47 ± 7 GPa, and 2.3%, respectively, with the diameter of 10.3 ± 0.5 μm.

Current overview of carbon fiber: Toward green sustainable raw materials

Lignin, as a potential precursor of carbon fiber, has the characteristics of abundant reserves, renewable and high carbon content, and its application in the preparation of carbon fibers has substantial cost advantages if some important processing and quality hurdles can be overcome. This paper reviews the preparation process of lignin-based carbon fibers, and moreover, describes the characteristics of carbon fiber prepared by different precursors compared with the presently used precursors. Three preparation methods for lignin-based carbon fibers are introduced: melt spinning, solution spinning, and electrospinning. The applicability, advantages, and disadvantages of the three preparation methods are analyzed from the aspects of process conditions and performance characteristics. Possible directions for future research are considered, with the goal of providing a reference for further study of lignin-based carbon fibers.

Analysis of Terpolymerization Systems for the Development of Carbon Fiber Precursors of PAN

The thermal stabilization of polyacrylonitrile fibers (FPAN) is one of the most important steps in the production of carbon fibers (CFs). In this paper, new precursor polymers from PAN have been synthesized with different chemical characteristics using a solution polymerization, and FPAN was obtained using an unconventional wet spinning system in the drying and collapsing steps. The effect of different operation conditions, comonomers, and termonomers on the properties of precursor polymers, polymerization reactions, mechanical properties, structural characteristics, and stabilization of the FPAN was studied and analyzed. FTIR and optical microscopy were used to analyze structural changes of FPAN in the thermal stabilization. The impact of the chemical composition of the precursor polymers on the physicochemical characteristics of FPAN and their behavior in the thermal stabilization process were evaluated. In particular, itaconic acid termonomer improved the tensile strength of the fibers from 8.07 to 16.87 cN/dtex, and the extent stabilization increased from 1.81 to 4.6. FTIR indicated that the reaction of stabilization of the terpolymer developed was initiated at a lower temperature compared to that of a commercial precursor polymer.

Manufacturing carbon fibres from pitch and polyethylene blend precursors: a review

Carbon fibres are one of the newer, emerging materials with multiple engineering applications, from automobiles to space vehicles. Carbon fibres have high mechanical strength, are lighter than metals with better chemical resistance.There have been reports on the use of polyethylene and pitch precursors for the production of carbon fibres, but there are few reports of how these blends could be used for carbon fibre preparation. Bearing in mind the myriad of benefits that using carbon fibres could bring, this paper reviews recent advances published in the literature on how mesophase pitch and polyethylene could be suitable precursors for carbon fibres. It also provides an introduction to the development of precursor blends that allow the properties of carbon fibres to be tailored to specific applications, including processing techniques, fibre parameters, fibre properties and fibre structure.

Thermo-oxidative stabilization of polyacrylonitrile-based copolymers with guanidinium itaconate

Thermo-oxidative stabilization of polyacrylonitrile (PAN) is a highly exothermic reaction that can be regulated through judicious addition of comonomers. Herein, guanidinium itaconate (GIA) was synthesized and copolymerized with acrylonitrile (AN) as a candidate for PAN-based carbon fiber precursors. P(AN-co-GIA) copolymers were compared to analogous itaconic acid (ITA)-containing PAN copolymers through Fourier-transform infrared spectroscopy and differential scanning calorimetry (DSC). The kinetic parameters of activation energy and pre-exponential factor were determined along with the cyclization index at given conditions. DSC analysis significantly indicates that P(AN-co-GIA) copolymers initiate stabilization at lower temperature and reduce exothermic heat flow by as much as 37% in air as compared to P(AN-co-ITA) copolymers. Further, the cyclization rate proceeds at faster kinetic rates for the GIA-containing copolymers, thereby providing opportunity for increased process speeds through oxidation of PAN-based precursors.

One-step firing of carbon fiber and ceramic precursors for high performance electro-thermal composite: Influence of graphene coating

Carbon fiber/ceramic composite demonstrates excellent electro-thermal performance that can be applied in various heating applications. However high temperature ceramization inevitably causes oxidation of carbon fiber and negatively influences its electro-thermal property. Herein, a graphene coated carbon fiber/ceramic composite via one-step firing with rapid and stable temperature responsiveness is proposed. Crystal structure, morphological feature, electrical property and electrothermal behavior of the modified carbon fibers and carbon fiber/ceramic composite were investigated. The results showed effectively protective effect of coating and sintering of carbon fiber under N2 environment, resulting in greatly improved electro-thermal and mechanical properties. The composite based on 24 k carbon fibers and 1 cm thickness ceramic sintering reached about 65 °C at 6 V in only 10 min and the cooling process lasted 30 min from 82 °C to room temperature, presenting highly responsive heating and good temperature storage performance. The tensile strength and elongation at break of the single graphene coated carbon fiber increased 12% and 200%. The great electro-thermal features and strong mechanical properties of the modified carbon fibers make the carbon fiber/ceramic composite a good candidate for in-door temperature control and out-door deicing applications.

Hydroxypropyl-modified and organosolv lignin/bio-based polyamide blend filaments as carbon fibre precursors’

Hydroxypropyl-modified lignin (TcC) and organosolv lignin (TcA) were melt blended with two types of bio-based polyamides (PA) (PA1010 and PA1012) before being melt spun into filaments. With a lignin/bio-PA ratio 50/50 wt%, the filaments could be continuously produced and spooled having tensile strengths ≥ 20 MPa and moduli ≥ 500 MPa. The influence of each polyamide blended with each lignin on structural (FTIR), thermal (DSC, TGA, DMA), mechanical, rheological and morphological properties of the resultant extrudates and/or filaments was studied. The melting point of each polyamide was reduced in the presence of TcA and TcC lignin, and shifts in the glass transition temperature (Tg) and FTIR characteristic peaks occurred, which suggests that the selected polyamides and lignins are compatible with each other. The improved lignin/polyamide compatibilities were further supported by Pukanszky interfacial adhesion modelling. Despite the evidence for strong interactions, heterogeneous morphologies were observed in the resulting blends and scanning electron microscopy was used to determine dispersed lignin domain sizes which decreased when stronger lignin/polyamide interactions resulted. As a possible indicator of carbonization efficiencies, blends were subjected to a simulated stabilization/cross-linking process and subsequent TGA char residues were higher than those theoretically calculated at 880 °C, indicating that the bio-polyamide acted as a char-promoting agent for the lignin besides being a good blending partner. Overall, this study has indicated that the developed lignin/bio-polyamide filaments have potential as melt-extrudable precursors for carbon fibre production.

Improved structure and highly conductive lignin-carbon fibers through graphene oxide liquid crystal

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.

High molecular weight of poly(acrylonitrile-co-3-aminocarbonyl-3-butenoic acid methyl ester) used as carbon fiber precursor: preparation and stabilization

A bifunctional 3-aminocarbonyl-3-butenoic acid methyl ester (ABM) was used to prepare high molecular weight poly(acrylonitrile-co-3-aminocarbonyl-3-butenoic acid methyl ester) [P(AN-co-ABM)] by suspension polymerization in aqueous medium. The influence of ABM monomer feed ratios on the structure and stabilization of P(AN-co-ABM) was characterized by element analysis, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Based on reactivity ratio calculation, the comonomer ABM possesses greater reactivity than acrylonitrile. The molecular weight of P(AN-co-ABM) in this work is 10 times larger, as compared to the one prepared by solution polymerization; it is the key to producing high-performance carbon fiber. The FTIR, XRD and DSC results illustrate that the stabilization of P(AN-co-ABM) is significantly improved as compared with PAN homopolymer and P(AN-AA-MA), for instance, lower initiation temperature, smaller cyclization activation energy (Ea), broadened exothermic peak and larger stabilization extent, due to the ionic cyclization initiated by ABM, which makes the resultant P(AN-co-ABM) a potential precursor for carbon fiber.

Synthesis and Characterization of Aromatic Poly(azomethine ether)s with Different meta- and para-Phenylene Linkage Contents

New aromatic poly(azomethine ether)s (PAMEs) bearing different meta- and para-phenylene linkage ratios in the main chains were synthesized via solution polycondensation reactions of terephthalaldehyde and/or isophthaldehyde with 3,4′-diaminodiphenyl ether. The molecular structures, thermal stability, thermo-mechanical and optical properties of the synthesized PAME homopolymers and copolymers were investigated by using FT-IR, TGA, DMA, and UV-visible/ fluorescence spectroscopy, respectively. The synthesized PAMEs were characterized to be thermally stable up to ~400 °C under nitrogen or air atmosphere and to have high char residues of above 55 % at 800 °C under nitrogen condition. The DMA data revealed that the glass transition temperatures of PMAEs are in the range of 150–200 °C, depending on the relative contents of meta- and para-phenylene linkages. The maximum absorption wavelength of transparent yellowish PAME films was detected at 410±10 nm. In addition, all PAME films exhibited a broad visible emission band at 500–800 nm and two infrared emission bands at 800–1400 nm. The synthesized PAMEs with high thermal stability and thermo-mechanical performance can be thus used as functional polymeric materials for technical fibers, optoelectronic films, and carbon fiber precursors.

Ultrastructures and Mechanics of Annealed Nephila clavipes Major Ampullate Silk.

The semicrystalline protein structure and impressive mechanical properties of major ampullate (MA) spider silk make it a promising natural alternative to polyacrylonitrile (PAN) fibers for carbon fiber manufacture. However, when annealed using a similar procedure to carbon fiber production, the tensile strength and Young's modulus of MA silk decrease. Despite this, MA silk fibers annealed at 600 °C remain stronger and tougher than similarly annealed PAN but have a lower Young's modulus. Although MA silk and PAN graphitize to similar extents, annealing disrupts the hydrogen bonding that controls crystal alignment within MA silk. Consequently, unaligned graphite crystals form in annealed MA silk, causing it to weaken, while graphite crystals in PAN maintain alignment along the fiber axis, strengthening the fibers. These shortcomings of spider silk when annealed provide insights into the selection and design of future alternative carbon fiber precursors.

Lignin from oil palm empty fruit bunches (EFB) under subcritical phenol conditions as a precursor for carbon fiber production

Sustainable approach is needed to find an alternative precursor for carbon fiber. The resources should be low in cost with properties comparable to the present precursor. Malaysia as the second largest producer of palm oil produced hundred million tons of waste especially oil palm empty fruit bunches (EFB) from its plantation. The extraction of its lignin from biomass is a challenge as it binds together with cellulose and hemicellulose to form a complex network. Hence, phenol under subcritical conditions has the potential to shorten the reaction time to dissolve relatively high molecular weight compounds without catalyst. This study aimed to determine the effect of temperature (260–300 °C), reaction time (1–10 min), and solid loading (6 and 10 g) towards ash, volatile and carbon content of the lignin obtained from EFB under subcritical phenol conditions. Highest carbon content in the lignin (43.7%) was achieved at 260 °C, 1 min, and 10 g while its ash and volatile content were 23.5% and 0.3% respectively. The correlation of these properties is discussed in this paper to understand its suitability as a precursor for carbon fiber production.

Study on the Crystallization Behavior of PAN Fibers during Hot-Drawing Process in Supercritical Carbon Dioxide Fluid with Different Strain

Hot-drawing of polyacrylonitrile (PAN) fibers is an important step in the production of carbon fibers. In this article, we investigated the effect of strain on the crystallization behavior and mechanical properties of PAN fibers treated in supercritical carbon dioxide (Sc-CO2) fluid. We mainly used the methods of X-ray diffraction (XRD), monofilament strength analysis and differential scanning calorimeter (DSC) to study the crystallization behavior, mechanical properties and thermal behavior of PAN fibers during hot-drawing process. The experimental results showed that the crystallinity and mechanical properties of PAN fibers both increased a lot under the action of strain during hot-drawing in Sc-CO2 fluid. This provides an important method for preparation of higher performance PAN precursor for PAN-based carbon fibers.

Fiber-Forming Acrylonitrile Copolymers: From Synthesis to Properties of Carbon Fiber Precursors and Prospects for Industrial Production

The latest achievements in the field of synthesis of acrylonitrile copolymers are summarized. New ecofriendly methods of synthesizing acrylonitrile copolymers in ionic liquids and supercritical media are analyzed. The potential of various techniques of controlled radical and anionic polymerizations in tailoring the structure and properties of acrylonitrile copolymers is discussed. Methods for the synthesis of acrylonitrile copolymers, which may be used for the melt spinning of fibers, are considered. A patent search is conducted, and information relevant to new methods and recipes for the synthesis of acrylonitrile copolymers is generalized.

Thermal treatment of pyrolytic lignin and polyethylene terephthalate toward carbon fiber production

ABSTRACTIn this work, pyrolytic lignin (PL) was thermally co‐treated with polyethylene terephthalate (PET) to produce carbon fiber precursor. The produced PL‐PET precursors were thoroughly characterized and analyzed, and then being processed into carbon fiber. It was found that a novel precursor, rather than their physical blending, was formed by the thermal co‐treatment, indicating there were strong interactions between PL and PET. The novel PL‐PET precursors had enhanced thermal properties and rheological characteristics, therefore are more suitable for processing into better carbon fibers based on melt‐spinning method. In this study, the precursor fibers derived from the co‐treatment of PL and 5% PET were also stretched under tension during stabilization step to reduce the fiber diameter and improve molecular orientation. The resulting carbon fibers with an average diameter of 12.6 μm had the tensile strength of up to 1220 MPa. This work demonstrated that PET could be used to improve the processability and quality of lignin‐based carbon fiber when it is chemically bonded with lignin‐based precursor. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48843.

Pyrolysis of brominated polyethylene as an alternative carbon fibre precursor

Polyethylene as a polymeric precursor for carbon fibre production has attracted much attention over recent years. Not only is it a low-cost commodity polymer, it has a higher theoretical carbon yield (at 100%) than polyacrylonitrile (at 67%) and is very readily melt processed into fibres. The challenge is to efficiently dehydrogenate and graphitize polyethylene fibres. This paper explores the use of bromine as a novel oxidant to functionalise polyethylene prior to carbonisation, leading to efficient cyclisation and carbonisation on heating. Through a process of low-temperature photo-induced liquid-phase bromination followed by dehydrobromination at moderate temperature and subsequent carbonisation to 800 °C, a carbonaceous product was obtained in high carbon yield (>90%). The effects of a range of process conditions, as well as the use of different types of polyethylene and polyethylene blends, were explored.