With high redox activity, superior conductivity, abundant pores, and large specific surface area, nitrogen-doped graphitic carbon featuring a hierarchically porous structure is regarded as ideal electrode material for supercapacitors. In this work, hierarchically porous nitrogen-doped graphitic carbon (PG-PZC50) was fabricated via non-solvent induced phase separation and high-temperature calcination processes. SEM images showed its three-dimensional network structure, with abundant macro- and mesopores distributed throughout. XRD and Raman spectra confirmed the phase purity and graphitic nature of the as-prepared material, while XPS revealed its surface elemental composition, especially the content and doping states of nitrogen atoms. The graphene oxide-induced three-dimensional network, combined with the mesoporous structure of metalorganic framework-derived N-doped carbon particles, creates abundant migration channels and a large adsorption surface area for the electrolyte ions. Benefiting from its hierarchically porous structure and high nitrogen-doping content, the formed PG-PZC50 reached high specific capacitances of 499.7 F g− 1 at 0.1 A g− 1 and 179.6 F g− 1 at 20 A g− 1. Notably, the material also demonstrated robust cyclic stability with no capacitance loss after 10,000 charge–discharge cycles. The proposed synthetic strategy provides new ideas for the facile and reproducible construction of nitrogen-doped graphitic carbon with 3D hierarchically porous structure and high capacitive performances.

To optimize the electrochemical properties of Ni-rich cathode materials, CPAN@SC-NCM811 is prepared via surface modification of single-crystalline LiNi0.8Co0.1Mn0.1O2 cathode material by adding 1, 2 and 3 wt.% of polyacrylonitrile, respectively. Significantly, the results obtained from X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) verify the successful synthesis of CPAN@SC-NCM811 cathode, which exhibits better electrochemical properties compared to SC-NMC811. After thorough milling and calcination of 2 wt.% polyacrylonitrile with SC-NCM811, the initial discharge specific capacity of prepared S2 sample is 197.7 mAh g− 1 and the capacity retention reached 89.2% after 100 cycles at a rate of 1.0 C. Furthermore, the S2 sample exhibits superior rate performance compared to the other three samples, in which these superior electrochemical properties are largely attributed to the optimal ratio of conductive cyclized polyacrylonitrile coatings. Overall, this work offers guidelines for modifying the surface of SC-NCM811 cathode materials for lithium-ion batteries with exceptional cycling and rate performance.

Lightweight materials with favorable mechanical, electromagnetic interference (EMI) shielding and thermal insulation performance are highly desirable for applications in harsh environments. Polyacrylonitrile (PAN)-derived carbon nanofibers/ carbon foams containing hollow closed microspheres have been developed, and their balanced multifunction is noteworthy. The addition of CNFs resulted in a gradual enhancement of the specific compressive strength of carbon foams, reaching a maximum value of 26.6 MPa·cm3·g−1 with content of 3 wt.% CNFs, improved by as much as 62%, compared to that of pristine carbon foam. Additionally, the fracture toughness exhibited the maximum fracture energy absorption of 118.6 MJ‧m−3 at 3 wt.% CNFs. The appropriate amount of CNFs and hollow carbon microspheres resulted in effective toughening and strengthening of carbon foams. Incorporation of CNFs into carbon foams also resulted in an improvement in their electromagnetic shielding performance, with a maximum EMI-shielding effectiveness of 65.8 dB. Reflection loss was the main contributor to electromagnetic shielding efficiency. Furthermore, carbon foams presented remarkable high-temperature thermal insulation, with a minimum thermal conductivity of merely 0.509 W·m−1·K−1 at 800 °C. They exhibited the ability to withstand the butane flame ablation at 1000 °C, which substantiated the potential of carbon foams for aerospace applications.

The surface treatment processes of carbon fibers is very important, because of their significant impact on fiber handling, filament protection, and interfacial properties. In this study, the effects of two different sizing agents with different molecular weights, with or without a nonionic surfactant, on the performance of a melt-spun polyacrylonitrile-based carbon fiber and carbon fiber/epoxy interfacial adhesion are investigated. The focusing property and spread-ability of a low-molecularweight sizing agent with a surfactant show outstanding performances because of the high penetration between the fibers and high interfacial bonding with the fibers. In addition, wettability of the matrix (epoxy resin) of the low-molecular-weight sizing agent are superior to those of the high-molecular-weight sizing agent. Furthermore, the nonionic surfactant used as an assistant improves the sizing amount and wettability by forming micelles with the epoxy. The interfacial shear strength (IFSS) of the low-molecular-weight sizing agent with a surfactant is also superior to that of other sizing agents. The IFSS is closely related to the sizing amount of the coating on the carbon fiber surface and matrix wettability.

Porous carbon nanofiber (CNF) electrodes for supercapacitors were prepared by using polyacrylonitrile (PAN) and cucurbituril (CB), which is a macrocyclic compound comprising glycoluril units containing hollow cores. Mixture of PAN and CB in dimethyl sulfoxide was electrospun, and thermally treated to produce CNF electrodes. Their thermal stability, surface morphology, carbon microstructures, and surface porosity were investigated. Electrochemical properties were measured using three-electrode with synthesized CNFs without further treatment as a working electrode and 1 M Na2SO4 as an electrolyte. CNFs derived from PAN and CB exhibited a high specific capacitance of 183.5 F g− 1 and an energy density of 25.4 Wh kg− 1 at 0.5 A g− 1 with stable cyclic stability during 1000 cycles, which is significantly higher than those for CNFs derived from PAN only. This demonstrated that the introduction of CB successfully improved the energy storage performance of CNF electrodes.

The evolvement in the microstructure and electrical properties of PAN-based carbon fibers during high-temperature carbonization were investigated. The study showed that as the heat treatment temperature increases, the change of carbon fiber resistivity around 1100 °C can be divided into two stages. In the first stage, the carbon content of the fiber increased rapidly, and small molecules such as nitrogen were gradually released to form a turbostratic of carbon crystal structure. The resistivity dropped rapidly from 3.19 × 10− 5 Ω·m to 2.12 × 10− 5 Ω·m. In the second stage, the carbon microcrystalline structure gradually became regular, and the electron movement area gradually became larger. At this time, the resistivity further decreases, from 2.12 × 10− 5 Ω·m to 1.59 × 10− 5 Ω·m. During carbonization, the tensile strength of carbon fiber first increased and then decreased. This is because the irregular and disordered graphite structure is formed first. As the temperature rose, the graphite layer spacing decreased and the grain thickness gradually increases. The modulus also gradually increased.

By polymerizing acrylonitrile in the presence of ammonium persulfate as an initiator and Pterocladia capillacea-activated carbon (P-AC) as a filler, a composite material polyacrylonitrile/Pterocladia capillacea-activated carbon (PAN/P- AC) was developed. By reacting hydroxylamine with the composite's nitrile groups, the prepared composite was functionalized by amidoximation. FTIR spectrometry, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Brunauer–Emmett–Teller (BET) analysis were all applied to thoroughly characterize the fabricated adsorbent. For the treatment of Cr(VI) ions from synthetic solutions, the adsorption properties of amidoximated polyacrylonitrile/Pterocladia capillacea-activated carbon (PAO/P-AC) were investigated. The pH effect, uptake kinetics, adsorption isotherms, and thermodynamics studies were used to characterize adsorption properties. As a kinetic model analysis, the data confirmed that the pseudo-second-order rate equation matched well the adsorption process. With coefficients of determination (R2) of 0.9998, the Tempkin isotherm model had the lowest error, suggesting that it is the best fitted model to describe this adsorption mechanism. Thermodynamic parameters demonstrated that Cr(VI) adsorption was endothermic.

Polyacrylonitrile (PAN)-based carbon fibers (CFs) and their composites, CF-reinforced plastics, have garnered significant interest as promising structural materials owing to their excellent properties and lightweight. Therefore, various processing technologies for fabricating these advanced materials using thermal energy have been intensively investigated and developed. In most cases, these thermal energy-based processes (heat treatment) are energy and time consuming due to the inefficient energy transfer from the source to materials. Meanwhile, advanced processing technologies that directly transfer energy to materials, such as radiation processing, have been developed and applied in several industrial sectors since the 1960s. Herein, general aspects of radiation processing and several key parameters for electron-beam (e-beam) processing are introduced, followed by a review of our previous studies pertaining to the preparation of low-cost CFs using specific and textile-grade PAN fibers and improvements in the mechanical and thermal properties of CF-reinforced thermoplastics afforded by e-beam irradiation. Radiation processing using e-beam irradiation is anticipated to be a promising method for fabricating advanced carbon materials and their composites.

In this study, we developed a facile and template-free strategy for the preparation of activated porous carbon beads (APCBs) from polyacrylonitrile. The chemical activation with KOH was found to enhance the pore properties, such as specific surface area (SSA), pore volume, and pore area. The APCBs exhibited a large SSA of 1147.99 m2/g and a pore area of 131.73 m2/g. The APCB-based electrodes showed a good specific capacitance of 112 F/g at 1 A/g in a 6 M KOH electrolyte, and excellent capacitance retention of 100% at a current density of 5 A/g after 1000 cycles. Therefore, the APCBs prepared in this study can be applied as electrode materials for electric double-layer capacitors.

This study demonstrates that low processing rate for producing polyacrylonitrile (PAN)-based carbon fiber is a critical to obtain a homogeneous radial microstructure with high resistance to oxidation, thereby resulting in their improved mechanical strength. The dry-jet wet spun PAN organic fibers were processed (e.g., stabilized and then carbonized) utilizing two different rates; one is 1.6 times longer than the other. The effect of processing rate on the microstructural evolutions of carbon fibers was analyzed by scanning electron microscopy after slow etching in air, as well as Raman mapping after graphitization. The rapidly processed fiber exhibited the multilayered radial structure, which is caused by the radial direction stretching of the extrusion in the spinning. In case of the slowly processed fiber, the layered radial structure formed in the spinning process was changed into a more homogeneous radial microstructure. The slowly processed fibers showed higher oxidation resistance, higher mechanical properties, and higher crystallinity than the rapidly processed one. Raman mapping confirmed that the microstructure developed during spinning was sustained even though fiber was thermally treated up to 2800 °C.

가속화되는 산업화로 인해 중금속 이온의 침출이 환경문제로 떠오르고 있다. 수질 정화를 위한 몇 가지 방법 중 기능성 고분자 섬유를 이용한 흡착은 효율적이며 경제적이라는 장점이 있다. 특히, 폴리아크릴로나이트릴(polyacrylonitrile, PAN)은 금속 이온을 흡착할 수 있는 작용기가 많아 관심을 끌고 있다. PAN은 쉽게 전기방사를 통해 고분자 나노 섬유화될 수 있으며 높은 표면적을 가질 수 있다. 본 총설에서 다룰 복합 PAN 섬유는 폐수 처리를 위한 또 다른 유형의 고분자이다.

Milled carbon fiber (mCF) was prepared by a ball milling process, and X-ray diffraction (XRD) diffractograms were obtained by a 2θ continuous scanning analysis to study mCF crystallinity as a function of milling time. The raw material for the mCF was polyacrylonitrile- based carbon fiber (T700). As the milling time increased, the mean particle size of the mCF consistently decreased, reaching 1.826 μm at a milling time of 18 h. The XRD analysis showed that, as the milling time increased, the fraction of the crystalline carbon decreased, while the fraction of the amorphous carbon increased. The (002) peak became asymmetric before and after milling as the left side of the peak showed an increasingly gentle slope. For analysis, the asymmetric (002) peak was deconvoluted into two peaks, less-developed crystalline carbon (LDCC) and more-developed crystalline carbon. In both peaks, Lc decreased and d002 increased, but no significant change was observed after 6 h of milling time. In addition, the fraction of LDCC increased. As the milling continued, the mCF became more amorphous, possibly due to damage to the crystal lattices by the milling.

Polyacrylonitrile/pitch nanofibers were prepared by electrospinning as a precursor for a gas sensor material. Pitch nanofibers were properly fabricated by incorporating polyacrylonitrile as an electrospinning supplement component. Polyacrylonitrile/pitch nanofibers were activated with steam at various temperatures followed by subsequent carbonization to make carbon nanofibers with a highly conductive graphitic structure. Steam activation was effective in facilitating gas adsorption onto the carbon nanofibers due to the increased surface area. The carbon nanofibers activated at 800°C had a larger surface area and a lower micro pore fraction resulting in a higher variation in electrical resistance for improved CO gas sensing properties.

본 연구에서는 다공성 PAN(Polyacrylonitrile) 중공사 분리막을 지지체로 이용하여 계면중합반응을 통해 나노여과막을 제조하였다. 지지체로는 PAN을 사용하였으며 수용상으로는 피페라진으로 중공사 분리막 내부에 코팅한 후 유기상인 TMC와 반응하여 계면중합이 일어나도록 진행하였다. 지지체로 사용된 UF 중공사 분리막은 분획분자량 10,000, 30,000, 100,000Da를 각각 사용하였으며 피페라진(Piperazine) 농도를 0.1%, 02%, 0.3%, TMC(Trimesoyl Chloride)의 농도를 0.05%, 0.1%, 0.2%로 변화시켜 제조 하여 5bar에서의 수투과도(LMH)와 MgSO4 2000ppm, Na2SO4 2000ppm, NaCl 500ppm 수용액으로부터 염배제율(Rejection, %)을 확인하였다.

Polyacrylonitrile (PAN)-based carbon fibers have high specific strength, elastic modulus, thermal resistance, and thermal conductivity. Due to these properties, they have been increasingly widely used in various spheres including leisure, aviation, aerospace, military, and energy applications. However, if exposed to air at high temperatures, they are oxidized, thus weakening the properties of carbon fibers and carbon composite materials. As such, it is important to understand the oxidation reactions of carbon fibers, which are often used as a reinforcement for composite materials. PAN-based carbon fibers T300 and T700 were isothermally oxidized in air, and microstructural changes caused by oxidation reactions were examined. The results showed a decrease in the rate of oxidation with increasing burn-off for both T300 and T700 fibers. The rate of oxidation of T300 fibers was two times faster than that of T700 fibers. The diameter of T700 fibers decreased linearly with increasing burn-off. The diameter of T300 also decreased with increasing burn-off but at slower rates over time. Cross-sectional observations after oxidation reactions revealed hollow cores in the longitudinal direction for both T300 and T700 fibers. The formation of hollow cores after oxidation can be traced to differences in the fabrication process such as the starting material and final heat treatment temperature.

The process of oxidizing polyacrylonitrile (PAN)-based carbon fibers converts them into an infusible and non-flammable state prior to carbonization. This represents one of the most important stages in determining the mechanical properties of the final carbon fibers, but the most commonly used methods, such as thermal treatment (200°C to 300°C), tend to waste a great deal of process time, money, and energy. There is therefore a need to develop more advanced oxidation methods for PAN precursor fibers. In this review, we assess the viability of electron beam, gamma-ray, ultra-violet, and plasma treatments with a view to advancing these areas of research and their industrial application.

New precursors, poly(acrylonitrile-co-crotonic acid) (poly(AN-CA)) and poly(acrylonitrile-co-itaconic acid-co-crotonic acid) (poly(AN-IA-CA)) copolymers, for the preparation of carbon fibers, were explored in this study. The effects of comonomers with acidic groups, such as crotonic acid (CA) and/or itaconic acid (IA), on the stabilization of nanofibrous polyacrylonitrile (PAN) copolymers were studied. The extent of stabilization, evaluated by Fourier transform infrared spectroscopy, revealed that the CA comonomer could retard/control the stabilization rate of PAN, in contrast to the IA comonomer, which accelerated the stabilization process. Moreover, the synthesized PAN copolymers containing CA possessed higher Mv than those of the IA copolymers and also showed outstanding dimension stability of nanofibers during the stabilization, which may be a useful property for improving the dimensional stability of polymer composites during manufacturing.

In this work, activated carbon nanofiber(ACNF) electrodes with high double-layer capaci-tance and good rate capability were prepared from polyacrylonitrile nanofibersby optimiz-ing the carbonization temperature prior to H2O activation. The morphology of the ACNFs was observed by scanning electron microscopy. The elemental composition was determined by analysis of X-ray photoelectron spectroscopy. N2-adsorption-isotherm characteristics at 77 K were confirmedby Brunauer-Emmett-Teller and Dubinin-Radushkevich equations. ACNFs processed at different carbonization temperatures were applied as electrodes for electrical double-layer capacitors. The experimental results showed that the surface mor-phology of the CNFs was not significantlychanged after the carbonization process, although their diameters gradually decreased with increasing carbonization temperature. It was found that the carbon content in the CNFs could easily be tailored by controlling the carbonization temperature. The specificcapacitance of the prepared ACNFs was enhanced by increasing the carbonization temperature.