Turbostratic Carbon Structure Research Articles

High temperature oxidation of additively manufactured silicon carbide/carbon fiber nanocomposites

An additive manufacturing process and subsequent pyrolysis cycle were used to fabricate SiC matrix/carbon fiber hybrid composites. The matrix was fabricated using a mixture of preceramic polymer and acrylate monomers, while polyacrylonitrile (PAN) precursor was used to fabricate fibers via electrospinning. The precursor matrix and reinforcing fibers at 0, 2, 5, or 10 wt% were printed using digital light processing, and both were simultaneously pyrolyzed to yield the final ceramic matrix composite structure. After pyrolysis, XRD and SEAD analysis proved the existence of SiC nanocrystals and turbostratic carbon structure in the matrix, while the reinforcement phase was shown to have a turbostratic carbon structure similar to commercial carbon fibers. Thermogravimetric analysis (TGA) in air up to 1400 °C was used to evaluate the oxidation resistance of this material. TGA results showed some weight loss due to oxidation of SiC and/or carbon up to about 900 °C, followed by weight gain to about 1200 °C due to the formation of a protective SiO2 layer. Although increasing carbon fiber content negatively impacted the total mass loss for the first heating cycle, exposure of the composite to second-run air revealed negligible weight loss. This is explained by SiO2 layer formation which acts as a protective film that prevents oxygen diffusion. Oxidation of SiC and the formation of a glassy layer has been proven to protect the sample from further oxidation, as well as provide healing of surface cracks and defects as revealed by SEM analysis.

Synthesis of nitrogen doped and nitrogen and sulfur co-doped carbon cryogels and their application for pharmaceuticals removal from water

In this study carbon cryogel, cryogel doped with nitrogen, and both nitrogen and sulfur co-doped carbon cryogels (nominal concentration of nitrogen was in the range 2–10 wt%) were synthesized and used as an adsorbent for the removal of carbamazepine, naproxen, diazepam and diclofenac from water. A batch adsorption kinetics study was performed by determination of contact time influence, the effect of pH, and adsorption isotherms. Structural and morphological analysis showed that there are no changes in turbostratic carbon structure induced by doping/co-doping, but noticeable morphology changes were observed. The presence of both nitrogen and nitrogen/sulfur were confirmed and results showed low content on the surface, especially for sulfur. Obtained high values of the specific surface area for co-doped samples (up to 1530 m2/g) can be caused by sulfur atoms burning or leaving the material during carbonization. The results of the adsorption kinetics study showed that the adsorption of all pharmaceuticals on all tested samples followed the pseudo-second-order kinetic model. The maximum adsorption capacity obtained from the Langmuir isotherm model is higher for doped (91.28–168.92 mg/g) and co-doped (152.97–488.06 mg/g) samples than for pristine sample (59.75–266.28 mg/g). Calculated adsorption energy values from the Dubinin-Radushkevich model indicate that the possible mechanism was physisorption. Desorption tests that were carried out showed satisfactory reusability for all samples. The favorable adsorption characteristics for the co-doped sample with a higher nominal concentration of nitrogen and sulfur qualifies as a potentially good adsorbent for the removal of pharmaceuticals from water.

Adsorptive removal of multiple organic dyes from wastewater using regenerative microporous carbon: Decisive role of surface-active sites, charge and size of dye molecules

Present work addresses the synthesis of microporous activated carbon (SDAC) by a facile thermochemical conversion of teak sawdust powder. The high surface area (1999 m2 g−1), excellent microporosity (average pore size: 2.62 nm), and turbostratic carbon structure with intertwined graphitic domains make SDAC a highly efficient adsorptive material for the removal of organic pollutants. The spectroscopic analyses (FTIR, Raman, and XPS) and adsorption locator calculations revealed multiple interactions between organic dyes and SDAC adsorbent, i.e., electrostatic, π-π, n-π interactions, and hydrogen linkages. The size, chemical functionalities, aromatic rings, electronegative and heteroatoms in dye molecules, along with the surface-active sites, microstructured and textural features of SDAC adsorbent collectively governed the interaction pathways and adsorption efficiency. The calculated adsorption energy using Monte Carlo-based simulation annealing method signified faster and higher adsorption of malachite green than methylene blue dye at surface-active sites (-COOH, CO, C–OH, and π-electron-rich domains) of SDAC adsorbent, corroborating the experimental results. The batch-mode adsorptive separation results showed remarkably high adsorption efficiency (>99%) for industrial wastewater to remove cationic and anionic dyes together. The SDAC displayed significantly high adsorption of methylene blue dye (625 mg.g-1) with excellent recyclability without measurable loss of adsorption efficiency even after ten cycles. The SDAC fixed-bed column showed a dye removal capacity of 594 mg.g-1 at 90% breakthrough in a continuous-mode process signifying its applicability for a real-time industrial run. The excellent conformity between batch mode and fixed bed continuous column adsorption data, along with higher removal capacity and remarkable recyclability, promise the use of SDAC adsorbent for industrial wastewater treatment to remove multiple organic pollutants.

Polyimide-derived carbon molecular sieve membranes for high-efficient hydrogen purification: The development of a novel phthalide-containing polyimide precursor

Hydrogen-based economy has been considered as a potential solution for energy security and sustainability in the future. And the ever-increasing demand for high-purity hydrogen (H2) provides an urgent force for the H2 purification technologies. Herein, a novel polyimide (BATPPP-6FDA) with rigid and contorted structure was synthesized and used as a precursor to fabricate the carbon molecular sieve membranes (CMSMs) for H2 purification. The structural changes from precursor to CMS were detected and the H2 separation performance of the membranes was optimized by the pyrolysis temperature. The CMSM pyrolyzed at 550 °C exhibited the highest H2 permeability of 10054.1 Barrer and moderate H2 permselectivity due to its highly disordered and turbostratic carbon structure originated from the generally decomposition of thermally labile -CF3 groups and the lactone rings of phthalide structure in the early stages (<550 °C) of pyrolysis. As the pyrolysis temperature raised, the H2 permeability of the derived CMSM decreased, and the H2 permselectivity enhanced greatly. The CMSM pyrolyzed at 800 °C demonstrated a high H2 permeability of 2622.4 Barrer and superior selectivity with H2/N2 of 524.48, H2/CH4 of 1248.76 and H2/CO2 of 7.51, respectively, which was attributed to the low densification of carbon structure resulting from the rigid and contorted structure of the BATPPP-6FDA precursor. The excellent H2 separation performance showed a great potential in hydrogen purification application.

Impact of chemical structure of coal on coke quality produced by coals in the similar category

In order to study the association of coke quality with the little fluctuation of chemical structure of the coal, three coals (C1, C2 and C3) from the similar category were employed to prepare coke in a 10 kg-scale coke oven. The status-oriented (G value, inorganic and organic component, etc.) and process-oriented (fluidity, volatile release, etc.) properties of the three coals are assessed. The association of coal chemical structure with these properties and final coke quality is clarified based on the experimental results by 13C NMR, Raman, etc. Clearly, the three coals from the similar category produce cokes with different properties. Chemical structure information obtained from 13C NMR and Raman shows that large aromatic clusters (higher far, Ca, etc.) with short chain hydrocarbon (lower CH2/CH3), and low graphitization degree (lower AG/AD, PG-D) of coal are not favorable for the coke strength. On the one hand, these structural properties determine the low vitrinite reflectance of coal and restrict the crosslinking reaction that may assist in the formation of the turbostratic carbon structures and affect coke strength. On the other hand, large aromatic clusters but short chain hydrocarbon are difficult to be depolymerized to form mobile components or transferable hydrogen-rich radical donor or acceptor. The development of the fluidity is insufficient to enhance coke strength, which is manifested by narrow plastic range, high temperature zone of thermoplastic stage, and low fluidity. In addition, defected structures (high GR+VL+VR and IGR+VL+VR/ID) in coal contribute to the high reactivity of corresponding coke. The unprotonated aromatic carbons (farN) may correspond to these defected structures in aromatic macromolecular. The results assist in establishing the association of apparent coal property and coke strength with coal chemical structure. The findings also support the assessment and prediction of coke strength for different coals, in particular, for coals that may fall into the similar category according to their similar apparent property.

Synthesis of CNS, ZnO/CNS and ZnCr2O4/CNS composites from patchouli biomass by using microwave for remediation of pesticide contaminated surface water in paddy field

Patchouli biomass is a potential precursor for CNS synthesis. In this research, the patchouli was pyrolyzed using the microwave. The purpose of this research is to study the effect of microwave energy and activator toward physicochemistry of CNS and composite (ZnO/CNS) and application of ZnCr2O4/CNS for the pesticide polluted surface water remediation in paddy field. In the process, the biomass was pyrolyzed at four and 8W with and without the ZnCl2 activator. The products were blended and evaporated to obtain CNS and ZnO/CNS. The products were characterized using FTIR spectrometry, XRD, and dispersion test. The composites were used to synthesize ZnCr2O4/CNS at 600W in the microwave. The composites were used for buthylphenylmethyl carbamate pesticide degradation test (BPMC) for 48 h with H2O2 oxidation. The FTIR spectra indicated better carbonization for products taken using an activator at both microwave energies. The X-ray diffractograms showed the turbostratic structure of carbon obtained at 4W pyrolysis (with activator), meanwhile 8W pyrolysis (without activator). ZnO and turbostratic carbon structures were shown by the product of 8W pyrolisis with activator. The calcined composite indicated ZnCr2O4/CNS. The degradation test showed that ZnCr2O4/CNS(8W) catalyst decreased the BMPC concentration almost three times that of the composite (4W).

Ultraselective carbon molecular sieve membrane for hydrogen purification

Abstract Hydrogen is a green clean fuel and chemical feedstock. Its separation and purification from hydrogen-containing mixtures is the key step in the production of hydrogen with high purity (>99.99%). In this work, carbon molecular sieve (CMS) membranes with ultrahigh permselectivity for hydrogen purification were fabricated by high-temperature (700–900 °C) pyrolysis of polymeric precursor of phenolphthalein-based cardo poly(arylene ether ketone) (PEK-C). The evolution of the microstructural texture and ultramicroporous structure and gas separation performance of the CMS membrane were characterized via TG-MS, FT-IR, XRD, TEM, CO2 sorption analysis and gas permeation measurements. CMS membranes prepared at 700 °C exhibited amorphous turbostratic carbon structures and high H2 permeability of 5260 Barrer with H2/CH4, H2/N2 and H2/CO selectivities of 311, 142, 75, respectively. When carbonized at 900 °C, the CMS membrane with ultrahigh H2/CH4 selectivity of 1859 was derived owing to the formation of the dense and ordered carbon structure. CMS membranes with ultrahigh permselectivity exhibit an attractive application prospect in hydrogen purification.

Self-Organization of Hexane-Insoluble Asphaltenes of Coal Pitch

Recently, there has been growing interest in asphaltenes, which are byproducts of petroleum processing and coal liquefaction. However, most data on the macromolecular structure and morphological characteristics of asphaltene aggregates relate to the petrochemical industry. We know that the concentration of asphaltene in solution affects the structure of their associates, which is also modified by the presence of various additives. The formation of planar associates of asphaltenes and condensed graphite-like structures are of particular interest. In order to optimize the graphitization of the anode mass, coal pitch (the β fraction) is investigated. In the heat treatment of the anode mass, the best binder is pitch with a high content of β fraction. The structuring of the asphaltene macromolecules in solution has not been studied for coal pitch. In the present work, in order to investigate the self-assembly of molecular aggregates of coal-pitch asphaltenes, the morphology and structure of powder particles for coal-pitch asphaltenes are investigated by various methods. The β fraction of pitch containing asphaltenes is separated by means of selectively soluble groups. Toluene and hexane are used as the selective solvents. On the basis of X-ray phase analysis, the coke residue of coal-pitch asphaltenes contains crystallites of naphthene–aromatic layers. The crystalline properties of the deposited asphaltene particles hardly depend on the deposition conditions. The powder mainly consists of turbostratic carbon structures.

Non-Solvent Fractionation of Lignin Enhances Carbon Fiber Performance.

Even though lignin carbon fiber has been sought after for several decades, the poor mechanical performance remains to be a major barrier for commercial applications. The low mechanical performance is attributed to the heterogeneity of lignin polymer. Recent advances in fractionation technologies showed the great potential to reduce lignin heterogeneity, but current fractionation methods often depend on costly chemicals and materials such as enzymes, organic solvents, membranes, and dialysis tubes. Here, a new non-solvent strategy was developed to fractionate lignin by autohydrolysis. By using only water, lignin was efficiently fractionated into water-soluble and -insoluble fractions. The latter fraction had increased molecular weight and uniformity and resulted in more β-O-4 interunitary linkages as analyzed by size-exclusion chromatography and 2D heteronuclear single quantum coherence NMR spectroscopy, respectively. In particular, the water-insoluble fraction significantly enhanced the mechanical performances of the resultant carbon fibers. Mechanistic study by differential scanning calorimetry (DSC) revealed that the miscibility of lignin with guest polyacrylonitrile molecules was improved with the reduced lignin heterogeneity. Crystallite analyses by XRD and Raman spectroscopy revealed that the crystallite size and content of the pre-graphitic turbostratic carbon structure were increased. The fundamental understanding revealed how lignin fractionation could modify lignin chemical features to enhance the mechanical performance of resultant carbon fibers. The autohydrolysis fractionation thus represents a green, economic, and efficient methodology to process lignin waste and boost lignin carbon fiber quality, which could open new horizons for lignin valorization.

Amorphous Carbon Chips Li-Ion Battery Anodes Produced through Polyethylene Waste Upcycling.

Remediation process produces high-value functional material from low-cost or valueless waste feedstock. Current research demonstrates an innovative solvothermal approach to effectively react sulfuric acid on polyethylene (PE) chains, modifying the PE at a moderate temperature. In this process, the polymer undergoes a cross-linking step above 120 °C, whereas above 500 °C, it transforms into turbostratic carbon structures. Scanning electron micrographs confirmed the free-standing carbon sheet architecture. Raman spectroscopy and X-ray diffraction verified the amorphous/disordered sp2/sp3 hybrid carbon structure in the produced carbons. A high Brunauer–Emmett–Teller surface area of 752.3 and 673.5 m2/g for low-density PE-derived carbon (LDPE-C) and high-density PE-derived carbon (HDPE-C), respectively, was recorded. Thermogravimetric analysis analysis established a total mass retention of 50 and 46% for LDPE and HDPE, respectively, from sulfonated materials. Li-ion battery composite anode comprising LDPE-C and HDPE-C, with a binder and a carbon additive (vs lithium), produced 230 and 350 mA h/g specific capacities for LDPE-C and HDPE-C, respectively, when cycled at room temperature at C/5 rate. Elevated temperature (50 °C) battery cycling produced 290 and 440 mA h/g specific capacities for LDPE-C and HDPE-C, respectively, at C/5 rate. On the basis of the literature survey, this is the first report, which demonstrates that a solvothermal sulfonation process followed by thermal treatment successfully converts waste LDPE and HDPE plastic bags to functional energy-storing carbons.

Biowaste-Derived Hierarchical Porous Carbon Nanosheets for Ultrahigh Power Density Supercapacitors.

Low-cost activated carbons with high capacitive properties remain desirable for supercapacitor applications. Herein, a three-dimensional scaffolding framework of porous carbon nanosheets (PCNSs) has been produced from a typical biowaste, namely, ground cherry calyces, the specific composition and natural structures of which have contributed to the PCNSs having a very large specific surface area of 1612 m2 g-1 , a hierarchical pore size distribution, a turbostratic carbon structure with a high degree graphitization, and about 10 % oxygen and nitrogen heteroatoms. A high specific capacitance of 350 F g-1 at 0.1 A g-1 has been achieved in a two-electrode system with 6 m KOH; this value is among the highest specific capacitance of biomass-derived carbon materials. More inspiringly, a high energy density of 22.8 Wh kg-1 at a power density of 198.8 W kg-1 can be obtained with 1 m aqueous solution of Li2 SO4 , and an ultrahigh energy density of 81.4 Wh kg-1 at a power density of 446.3 W kg-1 is realized with 1-ethyl-3-methylimidazolium tetrafluoroborate electrolyte.

Biomass-Derived Carbon Nanospheres with Turbostratic Structure as Metal-Free Catalysts for Selective Hydrogenation of o-Chloronitrobenzene

Nowadays, metal-free catalysts are sought after for synthesis of fine chemicals. Herein, we utilized the natural biomass xylose as the precursor to fabricate carbon nanospheres with turbostratic carbon structure via hydrothermal treating and high-temperature calcinating. These green and sustainable carbon materials were used as metal-free catalysts in selective hydrogenation of o-chloronitrobenzene (o-CNB), exhibiting a significantly enhanced catalytic activity with the increasing calcination temperature, as well as 100% selectivity to o-chloroanilines (o-CAN). In terms of the systematic characterization and simulated calculation, it is found turbostratic carbon formed in the calcination process might act as the catalytic active center in this reaction, and its selective reaction with −NO2 in o-CNB results in the enhanced catalytic activity and fully selectivity to o-CAN.

Three-dimensional beehive-like hierarchical porous polyacrylonitrile-based carbons as a high performance supercapacitor electrodes

Three-dimensional beehive-like hierarchical porous carbons (HPCs) have been prepared by a facile carbonization of polymethylmethacrylate (PMMA)/polyacrylonitrile (PAN) core-shell polymer particle followed by KOH activation. The all-organic porogenic core-shell precursor was synthesized by a simple and green surfactant-free emulsion polymerization. The as-obtained HPCs show favorable features for electrochemical energy storage such as high specific surface area of up to 2085 m2 g−1, high volume of pores up to 1.89 cm3 g−1, hierarchical porosity consisting of micro, meso, and macropores, turbostratic carbon structure, uniform pore size and rich oxygen-doping (21.20%). The supercapacitor performance of HPCs exhibit a high specific capacitance 314 F g−1 at a current density of 0.5 A g−1 and 237 F g−1 at a current density of 20 A g−1, ultra-high rate capability with 83% retention rate from 1 to 20 A g−1 and outstanding cycling stability with 96% capacitance retention after 2000 cycles. The facile, efficient and green synthesis strategy for novel HPCs from polymer sources could find use in supercapacitors, lithium ion batteries, fuel cells and sorbents.

Correlations Between Structures of Expanded Graphite – Polymer Composites and Acoustic Emission Phenomena / Korelacje Pomiędzy Strukturą Kompozytów Grafit Ekspandowany-Polimer A Zjawiskami Emisji Akustycznej

Compressed expanded graphite was applied as a base matrix to the preparation of microporous composites as products of impregnation, polymerization and carbonization of poly-furfuryl alcohol. During carbonization, the original polymeric structure is transformed into an amorphous turbostratic carbon structure with ultramicropores. The structure, porosity and many chemical and physical properties change after each stage of their technological treatment. The acoustic emission method was used for accurate determination of these changes. It is possible to determine a large number of acoustic emission parameters and therefore to increase the amount of information provided by the studied materials. Acoustic emission pulses, counts rate, events rate, signal peak value and their sums were measured. Also frequency spectrum was received as a result of acoustic emission signal analysis with use of Fourier transformation procedure. The conclusions resulting from the Fourier analysis of the registered spectrum are very interesting and provide information about composite structures as well as bonds between the graphite matrix and the polymer that fills it. Analysis of acoustic emission parameters provides data on physical and chemical processes that would be very difficult to study by means of other techniques. Wide applications of these porous composites make them very interesting subject of the study.

Catalytic Graphitization for Preparation of Porous Carbon Material Derived from Bamboo Precursor and Performance as Electrode of Electrical Double-Layer Capacitor

The combination of addition of Fe (as a catalyst for graphitization) and CO2 activation (a kind of gaseous activation) was applied to prepare a porous carbon material from bamboo powder (a waste product of superheated steam treatment). Regardless of the heat treatment temperature, many macropores were successfully formed after the heating process by removal of Fe compounds. A turbostratic carbon structure was generated in the Fe-added sample heated at 850°C. It was confirmed that the added Fe acted as a template for pore formation. Moreover, it was confirmed that the added Fe acted as a catalyst for graphitization. The resulting electrochemical performance as the electrode of an electrical double-layer capacitor, as demonstrated by cyclic voltammetry, electrochemical impedance spectroscopy, and charge–discharge testing, could be explained based on the graphitization and activation effects. Addition of Fe could affect the electrical properties of carbon material derived from bamboo.

Turbostratic pyrocarbon structure study by means of exit wave reconstruction from high‐resolution transmission electron microscopy

AbstractThis paper reports results of turbostratic pyrolytic carbon structure study using high‐resolution electron microscopy techniques. We obtained a through‐focus series of images and noted that domain‐like contrast features were varied depending on defocus of the objective lens. Since these features are commonly explained in terms of the domain model of pyrocarbon structure we carried out exit wave reconstruction to obtain the phase map. The visual appearance of the map indicates that the ribbon‐like model more appropriately describes the pyrocarbon structure in comparison to the domain model. In the context of the ribbon‐like model we constructed a test carbon structure using the recovered phase map and molecular dynamics modeling. After determination of atomic positions we simulated high‐resolution images of the structure. Our calculations demonstrated that high‐resolution micrographs showing domain‐like image features can be obtained without carbon domains presented in the actual structure. (© 2015 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

The effect of oxidation pressure on the equilibrium nanostructure of soot particles

The notion of equilibrium soot nanostructure was introduced by Hurt et al., who argued that the peculiar turbostratic carbon structure is an equilibrium arrangement of lamellar, graphene-like molecules. It was proposed that the typical, onion-like internal structure of primary soot particles can be satisfactorily described by thermodynamic principles. There are two main objectives of this paper. First, the effects of oxidation pressures above atmospheric pressure on soot nanostructure are investigated experimentally. The analyzed soot was generated in premixed flames of liquid fuels: n-dodecane, m-xylene and n-butanol and further oxidized in a thermogravimetric analyzer under atmospheric, 10atm and 40atm pressures. Nanostructure is described by utilizing high-resolution transmission electron microscopy and recently developed image analysis techniques. Second, empirical observations are compared against behavior that is semi-quantitatively predicted by the thermodynamic model. The utilization of the novel analysis technique made direct comparison between observed and computed properties possible. Reasonable consistency was found between experimental and computational results. The results suggest that the known thermodynamic model can be used to predict equilibrium structure even when soot is oxidized under pressurized conditions. Since diesel and jet engines operate at elevated pressures, the conclusions drawn in this paper may find their use in predicting soot nanostructure in the limiting case of equilibrium conditions.

Turbostratic carbon supported Ni-Pd alloys in aqueous-phase hydrodechlorination of 1,1,2-trichloroethene

AbstractTwo step modification of Norit CNR115 active carbon led to formation of mesoporous turbostratic carbon structure. Ni-Pd catalysts were prepared by incipient wetness impregnation of turbostratic active carbon with an aqueous solution of nickel and palladium chloride salts and were investigated by the Temperature-Programmed Reduction (TPR), Scanning Electron Microscopy (SEM), High Resolution Transmission Electron Microscopy (HRTEM), X-Ray Diffraction (XRD) and Temperature- Programmed Hydrogenation (TPH). The aqueous-phase hydrodechlorination of 1,1,2-trichloroethene (TCE) were carried out in a batch reactor at room temperature. Addition of palladium to nickel catalysts resulted in increasing of TCE conversion from 85% for Ni100 to more than 90% for Ni95Pd05 after 150 minutes of reaction. Aqueous-phase hydrodechlorination of TCE led to the formation of hydrocarbons (ethane and ethene) as the main products. Temperature-programmed hydrogenation of the catalysts after kinetic run have shown that during reactions with TCE only a small amount of carbon species were deposited on the catalysts surface and that chloride species were not observed.

Синтез и применение углеродных наноструктурированных материалов в электродах суперконденсаторов

Results of the study of micro-mesoporous carbonaceous materials with characteristic turbostratic carbon structure and specific surface area of 1000 - 2000 m 2 /g were shown. These materials were derived by use the method of chemical activation of plant fiber represented by apricot and walnut shells, and also by the rice husk. Derived carbon-containing samples were used to manufacture composite electrode materials, which were subsequently subjected to electrochemical testing in the composition of capacitors with a double electric layer. The possibility of using these electrode materials assembled as a part of composite electrodes of supercapacitors was studied; the maximum specific electric capacity of which amounted to 160 F/g.

Peculiarities of thermochemical transformations of polyacrylonitrile synthesized by anionic polymerization

Abstract The behavior of polyacrylonitrile synthesized by anionic polymerization (A-PAN) was studied during heating up to 550 °C in dynamic conditions in inert atmosphere and in air. Endo- and exothermic effects without mass losses were revealed within the 400–550 °C. The data of differential scanning calorimetry (DSC), differential thermal analysis (DTA) and X-ray analysis confirm the formation of mesogenic structures determined by the conformation of initial A-PAN samples. Changes in quantitative characteristics of phase states were explained by reorganization of the formed structures resulting from thermotropic mesophase transition from cyclic macromolecules to nuclei of turbostratic carbon structure.