Carbon Fiber Production Research Articles

A comparison of the effect of oxygen partial pressure on microstructural evolution of PAN fibers during industrial carbon fiber production line at different altitudes

Understanding and regulating the oxidative stabilization behavior of polyacrylonitrile (PAN) precursor fibers are critical subjects of high-performance carbon fiber production technologies. Here, we performed continuous stabilization and carbonization of PAN fibers at industrial carbon fiber production lines in different locales (different oxygen partial pressure in atmosphere), and investigated the microstructural evolution of the fibers with a systematically analysis at different stages. Influence of oxygen partial pressure in oxidative stabilization atmosphere on tensile modulus of the obtained carbon fibers was obvious. Oxygen diffused into PAN fibers during oxidative stabilization, more homogeneous and crosslinked structures generated under higher oxygen partial pressure atmosphere, and gave the stabilized fibers lower skin-core ratio. The graphite layers gradually generated in the subsequent carbonization stages, and the gathered graphite layers transformed into graphite microcrystalline, the wide-angle x-ray diffraction (WAXD) demonstrated that higher oxygen partial pressure conditions contributed to the generation of higher crystallite preferred orientation and bigger crystallite size, Raman spectroscopy also confirmed the obtained carbon fibers with higher oxygen partial pressure conditions possessed more ordered graphite structures. Thus, relatively higher oxygen partial pressure in air gave the stabilized fibers more crosslinked structures, and contributed to the formation of high-performance carbon fibers.

Aqueous Photoiniferter Polymerization of Acrylonitrile.

Polyacrylonitrile (PAN) is a key industrial polymer for the production of carbon fiber for high-strength, lightweight composite material applications, with an estimated 90% of the carbon fiber market relying on PAN-based polymers. Traditionally, PAN synthesis is achieved by conventional radical polymerization, resulting in broad molecular weight distributions and the use of toxic organic solvents or surfactants during the synthesis. Additionally, attempts to improve polymer and processing properties by controlled radical polymerization methods suffer from low monomer conversions and struggle to achieve molecular weights suitable for producing high-performance carbon fiber. In this study, we present an aqueous photoiniferter (aqPI) polymerization of acrylonitrile, achieving high monomer conversion and high PAN molecular weights with significantly faster kinetics and dispersity control when compared to traditional methods. This approach allows for the unprecedented control of polymer properties that are integral for downstream processing for enhanced carbon fiber production.

Effects of Moisture Content and Heat Treatment on the Viscoelasticity and Gelation of Polyacrylonitrile/Dimethylsulfoxide Solutions.

Polyacrylonitrile (PAN) gels create significant obstacles in industrial fiber spinning by forming insoluble networks that compromise solution stability and uniformity. This study investigates the rheological properties of PAN/dimethyl sulfoxide (DMSO) solutions, examining how aging time, moisture content, and polymer concentration affect gelation behavior. Dynamic rheological analysis revealed that both physical and chemical crosslinks play crucial roles in gel formation, with gelation accelerating markedly when moisture content exceeds 3% and aging progresses. Under heat treatment at 80 °C, samples with increased moisture content demonstrated rapid transitions to solid-like states, indicating a critical moisture threshold for enhanced gelation kinetics. Additionally, reductions in polymer concentration disrupted physical crosslink density, thereby mitigating gel formation. These results underscore the importance of precisely controlling moisture and concentration parameters in PAN solutions to stabilize solution properties and minimize gel formation, thus enhancing process efficiency and quality in PAN-based carbon fiber production.

Evaluating priority strategies for decarbonising offshore wind turbine blades through lifecycle assessment

Abstract While offshore wind is at the early stage of expansion, global capacity is expected to increase rapidly, reaching 330 GW by 2031. This work uses lifecycle assessment (LCA) to evaluate the opportunity for offshore wind energy decarbonisation through wind blade sustainable developments. The findings from the LCA are used to give informed recommendations towards priority areas of development across the blade lifecycle, that are critical to accelerate the sector’s transition towards net-zero targets. The production of raw materials was found to be the largest contributor to cradle-to-gave global warming potential (GWP). The sector should prioritise the utilisation of more sustainable materials, with an emphasis on the decarbonisation of carbon fibre production. Waste produced during blade manufacturing alone accounts for 10% of the blade’s GWP; therefore, increasing the material efficiency in this phase of the lifecycle is a significant opportunity for blade decarbonisation and should be a focus for the sector going forward. O&M was found to be the second largest contributor to GWP, with full decarbonisation of O&M practices potentially realising an 8% reduction in GWP. A range of alterative blade material scenarios were analysed, finding that recyclable resin systems have the greatest potential to decarbonise offshore blades. There are currently no commercial recycling operations for these resins therefore scale up of the recycling technologies is needed before they can be recycled in practice. Additionally, the development of low impact, economically viable circular solutions for legacy blade waste must be an immediate priority for the wind energy sector, given the anticipated exponential growth in global wind turbine blade waste generation. Graphical abstract

Evaluating storage conditions on the effect of peroxide content in acrylonitrile

AbstractThe content of peroxide in acrylonitrile is critical for the production of polyacrylonitrile‐based carbon fibers. Peroxide‐free acrylonitrile is used as a blank solution for testing the peroxide content of acrylonitrile, which storage conditions are important to the test. Of course, for the change of peroxide content in acrylonitrile stored for a period of time has an effect on the production of carbon fiber. In order to study the effect of storage conditions on peroxide in peroxide‐free acrylonitrile and acrylonitrile, the changes at refrigerator and room temperature were studied, respectively. Studies have shown that storage at temperatures below 20 °C for 3 months hardly affect the use of either peroxide‐free acrylonitrile or acrylonitrile. The experimental results obtained are useful for practical production and testing, which can improve the accuracy of testing and stability of production.

Synthesis of Carbon Nanofibers from Lignin Using Nickel for Supercapacitor Applications

Carbon fiber is known for being lightweight and adaptable, making it useful for various current and future applications. However, to broaden the use of carbon fibers beyond niche applications, production costs must be lowered. A potential approach to achieving this is by using more affordable raw materials, such as lignin, which is renewable, cost-effective, and widely available compared with the materials commonly used in industry today. This study explores the impact of metal ions on the quality of carbon fiber derived from lignin, focusing on its mechanical and electrochemical properties and morphology. The effect of a specific metal ion (Ni(NO3)2·6H2O) was examined by incorporating it into the spinning solution. The carbonization stage of the fiber was conducted at temperatures of 800, 900, and 1000 °C in an inert atmosphere. Scanning electron microscopy (SEM) analysis showed no defects or damage in any of the fibers. Therefore, it was concluded that moderate concentrations of Ni2+ ions in the fibers do not influence the stabilization or carbonization processes, thus leaving the mechanical properties of the final carbon fiber unchanged. These carbon nanofibers were also tested as a sustainable alternative to the non-renewable materials used in electrodes for energy storage and conversion devices, such as supercapacitors. Electrochemical performance was assessed in a 6 M KOH solution using a two-electrode cell configuration. Galvanostatic charge–discharge tests were performed at different current densities (0.1, 0.25, 0.5, 1.0, and 2.0 A g−1). The specific capacitance of the carbon nanofibers was determined from CVA data at various scan rates: 5, 10, 20, 40, 80, and 160 mV s−1. The results indicated that at 0.1 A g−1, the capacitance reached 108 F g−1, and at a scan rate of 5 mV s−1, it was 91 F g−1. The innovation of this work lies in its use of lignin, a renewable and widely available material, to produce carbon fibers, reducing costs compared with traditional methods. Additionally, the incorporation of nickel ions enhances the electrochemical properties of the fibers for supercapacitor applications without compromising their mechanical performance.

Epoxy Modified Polymethylpenylsiloxane Emulsions for Oil Agent in Carbon Fibers Production with Different Epoxy Content to Improve the Thermal Stability and Decrease the Surface Tension

Epoxy Modified Polymethylpenylsiloxane Emulsions for Oil Agent in Carbon Fibers Production with Different Epoxy Content to Improve the Thermal Stability and Decrease the Surface Tension

Molecular origin of viscoelasticity and influence of methylation in mesophase pitch

The viscoelastic and thermomechanical properties of pitches are responsible for their melt-spinning behavior, a critical step for manufacturing high-performance pitch-based carbon fibers. Here, we systematically explore the impact of methyl group modifications on the viscoelastic and thermal properties of mesophase pitches. We employ a range of atomistic modeling approaches, including Density Functional Theory (DFT), Density Functional Tight Binding (DFTB), and Classical Molecular Mechanics (MM), to provide detailed insights into the molecular interactions and structural changes. Our results revealed the molecular mechanisms that promote layered structures leading to the anisotropic nature of the viscoelastic behavior of mesophase pitch. Furthermore, we propose a modified molecular representation of naphthalene-based mesophase pitch based on the analysis of x-ray diffraction measurements. This study provides fundamental insights into the molecular structures of mesophase pitch and the role of methyl groups controlling its viscosity, which offer valuable insights into mesophase-based carbon fiber production.

Prospects and Challenges of Carbon Fiber Production from Heavy Petroleum Fractions

Prospects and Challenges of Carbon Fiber Production from Heavy Petroleum Fractions

Improvement of interfacial properties and hygrothermal resistance of CF reinforced epoxy composites by fluorine-containing sizing agent

To enhance the interfacial bonding performance between carbon fibers (CFs) and epoxy resin, the fluorine-containing sizing agent was prepared by the unique characteristics of fluorine. The incorporation of C-F bonds endows the interfacial layer with a higher degree of homogeneity, effectively mitigating stress concentrations that arise from surface imperfections. This mitigation is attributed to the repulsive interactions among fluorine atoms. The test results showed that the interlaminar shear strength (ILSS) of carbon fiber reinforced epoxy composites (CFREs) can be increased to a maximum of 66.01 MPa, representing a notable enhancement of 15.79 % in comparison to unsized CFREs. The enhancement of interfacial bonding ability is primarily ascribed to the synergistic effects of mechanical interlocking and chemical bonding interactions at the interface between CFs and resin. Concurrently, the hygrothermal resistance of CFREs was subjected to rigorous testing. The electron cloud of fluorine atoms exerts a pronounced shielding effect on the carbon chains, thereby significantly bolstering the hygrothermal resistance of CFREs. This enhancement is critical for the CFREs ' application in environments with high humidity and temperature. Moreover, the sizing agent developed in this study boasts a streamlined production process, which is expected to be applied in the commercial large-scale production of CFs.

A Proposal for a Carbon Fibre-Manufacturing Life-Cycle Inventory: A Case Study from the Competitive Sailing Boat Industry

The competitive sailing boat industry uses carbon fibre for high-performance purposes. Nevertheless, this material is known to cause environmental issues during its manufacturing. We can currently observe, based on the literature, difficulty integrating a reliable, justified, and transparent inventory of carbon-fibre production for LCA applications of high-performance composite materials. The current study aims to gain a better understanding of carbon fibre’s environmental impacts by suggesting a justified, reliable, and transparent inventory, based on the life-cycle assessment methodology. It also aims at providing a LCA of high-performance composites. An EcoInvent flows inventory is suggested, based on the literature presenting primary inventories. It is then discussed in terms of data quality, flows under study, and indicators calculated. Eventually, the inventory is used to assess the environmental impact of carbon fibre-reinforced composites applied to an industrial example representative of the competitive sailing boat industry: a hydrofoil mould. Regarding results on carbon fibres’ scale and impacts, indicators commonly highlighted by the literature, were calculated in this study (GWP = 72 kgCO2eq and CED = 1176 MJ), as well as other indicators. These indicators are two to five times higher than the inventories suggested in the literature, due to high heat-production value, production scales, or the quality of the fibre under study. The composite scale results show a major contribution from carbon fibre compared to other flows under study, highlighting the need to suggest a reliable inventory of carbon-fibre production.

Feasibility of Natural Fibre Usage for Wind Turbine Blade Components: A Structural and Environmental Assessment

There are two key areas of development across wind turbine blade lifecycles with the potential to reduce the impact of wind energy generation: (1) deploying lower-impact materials in blade structures and (2) developing low-impact blade recycling solution(s). This work evaluates the feasibility of using natural fibres to replace traditional glass and carbon fibres within state-of-the-art offshore blades. The structural design of blades was performed using Aeroelastic Turbine Optimisation Methods and lifecycle assessment was conducted to evaluate the environmental impact of designs. This enabled the matching of blade designs with preferred waste treatment strategies for the lowest impact across the blade lifecycle. Flax and hemp fibres were the most promising solutions; however, they should be restricted to use in stiffness-driven, bi-axial plies. It was found that flax, hemp, and basalt deployment could reduce Cradle-to-Gate Global Warming Potential (GWP) by around 6%, 7%, and 8%, respectively. Cement kiln co-processing and mechanical recycling strategies were found to significantly reduce Cradle-to-Grave GWP and should be the prioritised strategies for scrap blades. Irrespective of design, carbon fibre production was found to be the largest contributor to the blade GWP. Lower-impact alternatives to current carbon fibre production could therefore provide a significant reduction in wind energy impact and should be a priority for wind decarbonisation.

Evaluation of Chemical and Physical Triggers for Enhanced Photosynthetic Glycerol Production in Different Dunaliella Isolates.

The salt-tolerant marine microalgae Dunaliella tertiolecta is reported to generate significant amounts of intracellular glycerol as an osmoprotectant under high salt conditions. This study highlights the phylogenetic distribution and comparative glycerol biosynthesis of seven new Dunaliella isolates compared to a D. tertiolecta reference strain. Phylogenetic analysis indicates that all Dunaliella isolates are newly discovered and do not relate to the D. tertiolecta reference. Several studies have identified light color and intensity and salt concentration alone as the most inducing factors impacting glycerol productivity. This study aims to optimize glycerol production by investigating these described factors singularly and in combination to improve the glycerol product titer. Glycerol production data indicate that cultivation with white light of an intensity between 500 and 2000 μmol m-2 s-1 as opposed to 100 μmol m-2 s-1 achieves higher biomass and thereby higher glycerol titers for all our tested Dunaliella strains. Moreover, applying higher light intensity in a cultivation of 1.5 M NaCl and an increase to 3 M NaCl resulted in hyperosmotic stress conditions, providing the highest glycerol titer. Under these optimal light intensity and salt conditions, the glycerol titer of D. tertiolecta could be doubled to 0.79 mg mL-1 in comparison to 100 μmol m-2 s-1 and salt stress to 2 M NaCl, and was higher compared to singularly optimized conditions. Furthermore, under the same conditions, glycerol extracts from new Dunaliella isolates did provide up to 0.94 mg mL-1. This highly pure algae-glycerol obtained under optimal production conditions can find widespread applications, e.g., in the pharmaceutical industry or the production of sustainable carbon fibers.

Effects of Different Fiber Sizes in PLA/Carbon Fiber Composites on Mechanical Properties

This study assessed the morphology and chemical composition of coir coconut husk carbon fiber, as well as the impact of fiber diameters on the physical and mechanical properties of polylactic acid composites. Researchers are studying polylactide acid, a biodegradable material. This eco-friendly material’s excellent features, generated from sustainable and renewable sources, have drawn many people. Malaysia’s high coconut fiber output made coir husk a popular commodity. Coconut fibers are lignin, cellulose, and hemicellulose. Alkaline treatment eliminates hemicellulose, oil, wax, and other contaminants from coir fibers and removes lignin. Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy were used to examine the treated coconut fibers’ chemical modification analysis and morphology. Coconut coir husk was carbonized to produce carbon fiber using a furnace operated at 300°C for 2 hours. Fiber and polylactic acid were mixed in different fiber sizes (0, 53 μm, 75 μm, and 212 μm) via extrusion and injection processing techniques. The results showed that the alkali treatment reduced the hydroxyl (-OH) group and separated the area from the carbonyl (C=O) group of coconut coir husk, which changed the filler’s hydrophilicity. The fiber size of 212 μm was discovered to have the highest tensile and flexural strength values. According to testing, the modified material structure had a better surface fill-matrix bond. Thus, generalized fiber sizing and characterization methods were developed. Regardless of the matrix, this method can characterize natural fiber strength and interfacial shear strength of varied diameters and solid contents.

Identification of a polyfuran network as the initial carbonization intermediate in cellulose pyrolysis: A comparative analysis with cellulosic hydrochars

Pyrolysis of cellulose is accompanied with different complex and superimposing transformations resulting in a broad mixture of isolable products with strong variations depending on the applied reaction conditions. The operative chemistry represents a challenge for analytical chemists and process engineers alike. Especially, the reactions leading to char formation cannot be described as sufficiently understood. In ongoing efforts to shed light on the major transformations during charring of cellulose, the occurrence of a thermostable condensed phase (TSCP) previously postulated as an important carbonization intermediate formed below 300 °C was revisited. It was attempted to isolate pure TSCP intermediates without cellulose contamination by applying dehydration catalysts known from cellulose based carbon fiber production and extensive isothermal treatments. It was shown that the weight loss levels off during isothermal treatment for 6 h in the temperature range of 200–250 °C, resulting in the formation of a common intermediate with an almost identical composition – irrespective of the employed temperature or catalyst. Moreover, isothermal treatment of pure cellulose at 270–280 °C for up to 12 hours also resulted in the formation of an intermediate which had a similar composition as the material prepared with added dehydration catalysts. To test the hypothesis of a proposed polyfuranic nature of the TSCP intermediate the prepared samples were compared with hydrochars obtained from hydrothermal treatment of cellulose as reference material for a polyfuranic humin. Similarities and differences are discussed and implications for the overall carbonization mechanism are summarized.

Production and mechanical characterization of Carbon fiber laminated composites modified by Graphene nano platelets (GnP) for high performance application

Polymeric materials play a pivotal role in diverse high-performance engineering domains, including aerospace, marine, automotive, and defense sectors. Their applications span from essential protective gear to intricate components vital for aircraft missiles, showcasing their versatility and significance in modern technology. The Graphene nano platelets (GnP) have the exceptional properties of a high contact area with the reinforcement material and enhanced synergistic effect, which is highly desired to improve the material performance. The present work describes the production of Carbon fiber laminated composites enhanced by Graphene nano Platelets (GnP) using a cost-effective Hand layup method (HLM). Herein, three different concentrations of GnP at 0.25, 1.0, and 1.75 wt% were used to modify the CFRP laminates. This is primarily performed to examine the viscoelastic and mechanical properties of the proposed GnP/CFRP sample. The findings of mechanical testing reveal that GnP nanofiller addition of 1.00 wt% significantly enhances the tensile and flexural properties by 20.7% and 10.05% respectively in comparison to neat sample. Also, the composites show satisfactory improvement in impact strength by 31.60% and enhanced viscoelastic properties at a 0.25 wt% of GnP loading. The XRD and DMA findings support GnP loading for high performance applications.

PAN-precursor to carbon fibre: An investigation of manufacture and material properties for varying comonomer composition

This study presents the conversion of polyacrylonitrile (PAN) co-polymers containing methyl acrylate (MA) and varying concentrations of itaconic acid (IA) comonomers, from precursor fibre into carbon fibre using pilot scale continuous processes. The impact of itaconic acid on fibre processability, thermal behaviour, energy consumption, and final mechanical properties during thermal oxidative stabilization (TOS) and carbonization are investigated. Itaconic acid concentration varies from 0.3 to 3 wt % and with increasing concentration of itaconic acid, the precursor fibre exhibited lower exothermicity and enhanced reactivity, resulting in 7 % less energy consumption during stabilization. Higher itaconic acid content led to improved carbon fibre properties. A 20 % increase in tensile strength was recorded for carbon fibres containing the highest amount of itaconic acid along with a higher amount of graphitic structure and carbon yield. Overall, this study explores the impact of precursor design on fibre properties as a route to the manufacture of carbon fibre with reduced embodied energy. The results of this study illustrate pathways to improve the efficiency and effectiveness of carbon fibre production, and to ultimately create high-performance, lightweight, and more sustainable carbon fibre-reinforced composites.

Enhancing spinnability and properties of carbon fibers through modification of isotropic coal tar pitch precursor

Producing general-purpose carbon fibers (GPCFs) with excellent properties using an economical raw material such as coal tar pitch (CTP) holds significant importance. To synthesize carbon fibers, the spinnability of precursor material plays an important role. However, the CTP impedes flowability during the spinning process due to possessing high molecular weight complex aromatic structures. To address this limitation, CTP was blended with varying proportions of petroleum pitch (5, 10 and 20 %) and spinnability and flow behavior were analyzed using Rheology measurements. The distinct constitutional properties of petroleum pitch also contributed to alterations in both the stabilization and carbonization processes. Carbon fibers produced from 10PP showed the highest tensile strength and modulus of ∼784 MPa and ∼47 GPa, respectively. The impact of oxidative and carbonization treatments on the resultant microstructural and mechanical properties of carbon fibers was thoroughly examined using various techniques such as FTIR, XPS, XRD, SEM, Raman and UTM. The results showed that the composition of petroleum pitch influenced the stabilization of fibers which eventually affected the carbonization process and resultant properties of carbon fibers. This study offers an understanding of the connection between the precursor's composition, stabilization conditions, and mechanical properties of the resultant carbon fibers.

Raman Spectroscopy for the characterization of the macromolecular structure of Highveld coals (South Africa)

Industrial applications of coal rely on understanding its macromolecular structure, which is primarily controlled by coal type and rank. The present study assessed five (5) samples from different collieries extracting coal from the No. 4 Seam of the Highveld Coalfield and their float products, produced at relative densities (RD) of 1.7 and 1.9 g/cm3. The aim was to assess changes in maceral composition and coal quality following the density fractionation, and to use Raman Spectroscopy to compare differences in macromolecular structures between the parent samples and the float products. Raman parameters were also determined for specific macerals, i.e., semifusinite and collotelinite. Mean random vitrinite reflectance (%RoV) values for the studied coals range between 0.57 and 0.60% (medium rank D/C bituminous) and the parent coals are inertinite-rich (70.3 to 88.7 vol% mmf), enriched in semifusinite and inertodetrinite. Following density fractionation, reactive macerals (a combination of liptinite, vitrinite, and reactive semifusinite) are enriched in the float products (designated by “F”), specifically in the products obtained at the 1.7 RD. In comparison, the proportion of inert macerals is higher in the F1.9 samples. These differences in maceral composition are reflected in the Raman spectra and parameters. Although the G and D1 bands for the parent coals and F1.9 samples are similar, these bands are narrower than for the F1.7 samples, indicative of greater aromaticity. The G FWHM values for the F1.9 samples are comparable to those for the parent coal samples, and lower than for the F1.7 samples. This reflects larger differences in maceral composition between the parent coals and the F1.7 samples. In contrast, the D1 FWHM values for the float products, particularly the F1.7 samples, are slightly higher than the parent coals, reflecting a disordered aromatic character mainly related to the presence of aliphatic chains. The Raman spectra for the F1.7 samples are more like that for collotelinite. In contrast, the Raman spectra and parameters (G and D1 FWHM) for the F1.9 samples are more comparable to semifusinite. Thus, the increased aliphaticity for the F1.7 samples is attributed to the relative enrichment of reactive macerals, whereas higher aromaticity for the F1.9 samples reflects a larger proportion of inert macerals. Raman spectroscopy expanded on the petrographic data by interrogating the macromolecular structure of the isorank Highveld coals and their float products. This may assist in predicting the behaviour of the coals during industrial applications (i.e., liquefaction, gasification, combustion, and carbon fibre production).

Carbon Fiber and Its Composites: Synthesis, Properties, Applications

Carbon fiber is often preferred in composite production as it is a light and strong material. Traditionally, it can produce based on Polyacrylonitrile (PAN) and Pitch. Today, biomass-based carbon fiber production has studied as an alternative to these petroleum-based initiators. For this purpose, cotton, wood, and cellulose are the most used biomass types. However, environment-friendly carbon fiber does not yet possess as good tensile strength as petroleum-based ones. So, researchers added PAN during the production of bio-based carbon fiber. Carbon fiber can be made as a composite with many materials like polymers, metals, ceramics, and cement. It has a wide range of uses. Nowadays, researchers have studied to heal the interface between epoxy and carbon fiber to increase the functional properties of the composite. By preparing carbon fiber-reinforced metal, it can be possible to use composite as a catalyst. Carbon fiber is used as filler in concrete production to avoid crack formation. It is a crucial property for a material to prevent earthquake disasters. In brief, one can enable comprehensive and contemporary information about the synthesis and applications of all types of carbon fibers (PAN, Pitch, bio-based) and their composites (polymer, metal, ceramic, concrete, carbon nanotube, and graphene).