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In this contribution, we propose a new approach to enhance the ablation properties of carbon/carbon (C/C) composites. 2.5D CFMP/C composites were obtained by mesophase pitch-based carbon fiber (CFMP) as the reinforcing carbon fibers, which facilitates the high aerodynamic heat flow near the stagnation to be rapidly guided to the low heat flow region at the rear of the structure. The results show that the surface temperature of 2.5D CFMP/C composites is 100 °C lower than that of 2.5D CFPAN/C composites prepared by traditional PAN-based carbon fiber (CFPAN), and the mass ablation rate and linear ablation rate of 2.5D CFMP/C composites decreased from 3.307 mg/s to 1.412 mg/s and from 3.067 µm/s to 0.501 µm/s, respectively. In addition, the mechanical properties of the 2.5D CFMP/C composites are outstanding, which will lay the foundation for their stability in ablative environments. Our work will bring new blessings for the further development of C/C composites in the aerospace field. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The production of high-performance carbon fibers relies heavily on the structural transformations of polyacrylonitrile (PAN) fiber during processing. In this article differential scanning calorimetry (DSC), synchrotron small-angle X-ray scattering (SAXS), and synchrotron wide-angle X-ray diffraction (WAXD) were used to study the changes of the thermal properties, voids and crystal structure of the PAN precursor fibers on industrial lines during the continuous processing stages, i.e., after the treatment in the coagulation bath, after stretching in boiling water and after stretching in high-temperature steam. The findings of this study suggest that after boiling water stretching the molecular chain motion of the PAN precursor fiber weaken, resulting in the expansion of the voids. After high-temperature steam stretching the voids became elliptical and oriented in the stretching direction. Although the boiling water stretching process partially damaged the (100) crystal planes of the PAN precursor fibers, it does not hinder their overall crystalline structure. The high stretching ratio primarily affected the orientation of the molecular chains. This orientation, even in the context of partial crystal plane disruption, further promoted the crystallization of the (100) crystal planes in the fibers. These experiments explored the correlation between the processing technology and fiber structure transformation of PAN-based carbon fibers, resulting in producing a guide for the preparation of high-performance carbon fibers with fewer defects. [ABSTRACT FROM AUTHOR]

The tensile properties of polyacrylonitrile (PAN)-based and pitch-based single carbon fibers were assessed using Raman scattering. Parameters and ratios related to Raman scattering and stress measurement for the G- and D-bands were analyzed. These include the peak values of Raman shifts (RG, RD), full width at half maximum (FWHMG, FWHMD), peak value slopes (|AG|, |AD|), peak value intercepts (BG, BD), the intensity ratio (ID/IG), the peak value ratio (RD/RG), the full width at half maximum ratio (FWHMD/FWHMG), the slope ratio (AD/AG), and the intercept ratio (BD/BG). These parameters and ratios were determined by analyzing the PAN-based and pitch-based carbon fibers and were correlated to the tensile modulus (E), interlayer spacing (d002), lattice spacing (d10), and crystalline size (Lc and La). In addition, a linear relationship was identified between the Raman scattering, stress measurement parameters, ratios and E, d002, d10, as well as between the Raman scattering, stress measurement parameters, ratios and La and LC on the log–log scale. [ABSTRACT FROM AUTHOR]

Thermal protection systems (TPS) are vital for re-entry vehicles for their safe passage into the atmosphere from space. Hence, researchers took a keen interest in improving the thermal and ablative properties of composites to be used in making thermal protection systems. Therefore, an attempt was made to improve the thermal and ablative properties of composites made of carbon fibers (Cf) and resorcinol formaldehyde phenolic (Ph) resin with the incorporation of silicon carbide (SiC) particles. The filler was added in various percentages (0 wt% - blank, 1 wt%, 3 wt%, and 5 wt%), and the composites were tested for ablative, thermal and mechanical properties. The results demonstrate that the SiC-modified PAN-based carbon fiber reinforced phenolic (SiC-PANCf-Ph) composite with 3 wt% SiC enhancement exhibited ideal properties. The post-ablation phase composition and microstructure were examined through X-ray diffraction (XRD), Scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). The surface morphology evidences the formation of a silicon dioxide (SiO2) layer on the composites. The SiC-PANCf-Ph composites demonstrated the lowest ablation rate, enhancing their potentiality for effective TPS applications. [ABSTRACT FROM AUTHOR]

While carbon fibers (CFs) are still the most attractive reinforcement material for lightweight structures, they are mostly manufactured using crude oil-based process chains. To achieve a higher eco-efficiency, the partial substitution of polyacrylonitrile (PAN) by renewable materials, such as lignin, is investigated. So far, this investigation has only been carried out for batch manufacturing studies, neglecting the transfer and validation to continuous CF manufacturing. Therefore, this work is the first to investigate the possibility of partial substituting lignin for PAN in a continuous process. Lignin/PAN-blended CFs with up to 15 wt.-% lignin were able to attain mechanical properties comparable to unmodified PAN-based carbon fibers, achieving tensile strengths of up to 2466 MPa and a Young's Modulus of 200 Pa. In summary, this study provides the basis for continuous Lignin/PAN-blended CF manufacturing. [ABSTRACT FROM AUTHOR]

Carbon-based composite materials, denoted as C/C composites and possessing high thermal conductivity, were synthesized utilizing a three-dimensional (3D) preform methodology. This involved the orthogonal weaving of mesophase pitch-based fibers in an X (Y) direction derived from low-temperature carbonization, and commercial PAN-based carbon fibers in a Z direction. The 3D preforms were saturated with mesophase pitch in their raw state through a hot-pressing process, which was executed under relatively low pressure at a predetermined temperature. Further densification was achieved by successive stages of mesophase pitch impregnation (MPI), followed by impregnation with coal pitch under high pressure (IPI). The microstructure and thermal conductivity of the C/C composites were systematically examined using a suite of analytical techniques, including Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and PLM, amongst others. The findings suggest that the volumetric fraction of fibers and the directional alignment of the mesophase pitch molecules can be enhanced via hot pressing. The high graphitization degree of the mesophase pitch matrix results in an increased microcrystalline size and thus improved thermal conductivity of the C/C composite. Conversely, the orientation of the medium-temperature coal pitch matrix is relatively low, which compensates for the structural inadequacies of the composite material, albeit contributing minimally to the thermal conductivity of the resultant C/C composites. Following several stages of impregnation with mesophase pitch and subsequent impregnation with medium-temperature coal pitch, the 3D C/C composites yielded a density of 1.83 and 2.02 g/cm3. The thermal conductivity in the X (Y) direction was found to be 358 and 400 W/(m·K), respectively. [ABSTRACT FROM AUTHOR]

The article evaluates the HexTow 85 Polyacrylonitrile (PAN) carbon fiber from Hexcel Corporation which is utilized for manufacturing ablative carbon-carbon structures in various applications.

Polyacrylonitrile (PAN) copolymers are important precursors for the preparation of high-performance PAN-based carbon fibers. In this study, different ratios of P(AN-co-AMPS) and P(AN-co-MA-co-AMPS) were prepared by solution polymerization. The compositional structure, thermal, and crystallization properties of P(AN-co-AMPS) and P(AN-co-MA-co-AMPS) were characterized. The results show that an increase in the AMPS feeding ratio is beneficial for improving the thermal stability and crystallization ability of the PAN copolymer; however, it also reduces the molecular weight of the copolymer and increases the cyclization exothermic peak temperature, which is not conducive to the preparation of high-performance carbon fibers. This problem is avoided in P(AN-co-MA-co-AMPS), which maintains its high thermal stability and crystallization properties when appropriate amounts of MA and AMPS are introduced, and P(AN-co-MA-co-AMPS) has smoother cyclization exothermic rates, lower onset exothermic temperatures and lower peak exothermic temperatures. The structural changes of PAN, P(AN-co-MA), and P(AN-co-MA-co-AMPS) during thermal stabilization were investigated in detail using Fourier-transform infrared spectroscopy and it was found that P(AN-co-MAco-AMPS) formed more stable structures at lower temperatures. Furthermore, when the AN:MA:AMPS mass ratio is 97.5:1.5:1, P(AN-co-MA-co-AMPS) has the best overall performance. Our results suggest that the P(AN-co-MA-co-AMPS) has potential as a precursor for carbon fibers. [ABSTRACT FROM AUTHOR]

An experimental study was performed to investigate damage sensing and fracture toughness of multifunctional conductive glass fiber composites under dynamic mode-I fracture loading. Carbon nanotubes (CNTs) were dispersed within the epoxy matrix using a shear mixing and sonicating process. An electrostatic wet flocking process was used to reinforce milled short PAN-based carbon fibers onto each of the layers of glass fiber fabric along the thickness direction in the composites. These layers of flocked fabric were stacked, and a vacuum infusion process was employed to fabricate the composites. The parametric study consisted of two carbon fiber lengths (80 μm and 150 μm) and two fiber densities (1000 fibers/mm2 and 2000 fibers/mm2) and was performed to investigate the damage sensing capabilities of a three-dimensional conductive network generated through CNTs and carbon fibers. A double cantilever beam (DCB) configuration was considered, and a modified Hopkinson pressure bar setup along with a high-speed camera was used to investigate dynamic fracture toughness of the composites. The piezo-resistance response of the composites during dynamic fracture was measured using a modified system of four probes. For comparison, composites were also characterized for fracture toughness and piezo-resistance under quasi-static fracture loading conditions. The addition of short, milled PAN-based carbon fibers significantly increased the fracture toughness of glass/epoxy composites. The piezo-resistance response of the composites was easily correlated with instances of sudden crack growth during static fracture loading. [ABSTRACT FROM AUTHOR]

The demand for revolutionizing the lightweight design of Li‐ion batteries has become inevitable due to the ever‐increasing development of electric transportation modes. Integration of structural and energy storage functionalities into a single structural battery device can be a smart way to improve the overall performance of electric vehicles. In this study, we propose a facile and cost‐effective approach to develop a prospective anode for structural Li‐ion batteries through electrophoretic deposition of silicon (Si) particles onto polyacrylonitrile (PAN)‐based carbon fiber. The synthesis method is able to selectively deposit small‐sized silicon particles on the surface of carbon fiber, producing a thin, continuous, and porous coating of silicon nanoparticles on commercial PAN‐based carbon fiber. The synthesized Si/PAN‐based carbon fiber electrode exhibits remarkable mechanical properties, delivering a tensile strength of 2.57 GPa and a tensile modulus of 118.2 GPa. Benefitting from the morphology of the deposited silicon, the discharge capacity of silicon/PAN‐based carbon fiber anode can reach 565 mAh g−1 with 81 % capacity retention after 50 cycles. This work highlights the potential of silicon‐modified carbon fiber electrodes obtained via a simple and cost‐effective deposition method for structural Li‐ion battery applications. [ABSTRACT FROM AUTHOR]

A series of Polyacrylonitrile (PAN) co- or terpolymers as PAN-based carbon fiber precursors was prepared using methyl acrylate (MA) as neutral comonomer and fumaric acid (fa) or maleic acid (ma) as acidic comonomer which is trans/cis isomer, respectively. In order to establish the optimized condition of polymerization, PAN polymers with different acrylonitrile weight ratios (92, 94, and 96 wt%) were synthesized with appropriate yield via stepwise solution polymerization system. The efficiency of cyclization reaction of PAN polymers containing fa or ma were dramatically improved as compared to PAN homopolymer, and initiation of cyclization showed a rapid progress at 210 °C despite short thermal treatment time during thermal oxidative stabilization (TOS). Additionally, the char yield of PAN co- or terpolymers was reasonable value which was similar to PAN homopolymer. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Functional Materials / Gongneng Cailiao is the property of Chongqing Functional Materials Periodical Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The main objective of the work was to create a layer of carbon nanofibre on the surface of the NiTi shape memory alloy. The coating process was carried out in three stages. First, polyacrylonitrile was deposited by electrospinning. Then it was stabilized at temperatures up to 250°C. The last stage was the carbonization performed below 1000°C. The microstructure of the obtained coatings was observed using a scanning electron microscope. The X-ray diffraction techniques were applied to analyze the coating structure. After the polyacrylonitrile deposition, the fibers had an average diameter of about 280 nm, and the final fibers were almost twice as tiny. The applied steps also changed the phase and crystalline state of the fibers, finally leading to the formation of amorphous-nanocrystalline graphite. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Materials Engineering / Cailiao Gongcheng is the property of Journal of Materials Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Polyacrylonitrile (PAN) carbon fibers are often used to prepare high-performance paper-based materials owing to their high strength, good electrical and thermal conductivity, and superior comprehensive properties. In this study, a novel method for preparing PAN-based carbon fibers by centrifugal spinning was developed, and a stable and homogeneous PAN carbon fiber paper was successfully obtained. Subsequently, the formation process, microscopic morphology, electrical conductivity, electrochemical performance and hydrophobicity of the PAN carbon fiber paper were studied and evaluated. The results showed that the electrical conductivity of the PAN carbon fiber paper prepared via this method reached 43.250 s·cm−1, resistivity was as low as 0.023–0.033 Ω·cm, and contact angle exceeded 140°. This study adopted a new method to prepare PAN carbon fiber paper, which provided another method for the preparation of high-performance fiber paper. [ABSTRACT FROM AUTHOR]

Polyacrylonitrile (PAN) with C≡N bonds can be converted to nitrogen-doped carbon during carbonization, which enhances electronic conductivity by compensating for the deficiency of the Li2ZnTi3O8 (LZTO) anode. In this study, LZTO was modified by carbonizing a homogeneous PAN/LZTO powder mixture at approximately 800◦C for 5 h in nitrogen stream to uniformly coat nitrogen-doped carbon around the LZTO particles and to yield nitrogen-doped LZTO. PAN-60 exhibited a capacity retention of 74.8% as the current density increased from 0.1 to 1.6 A g−1, and had charge/discharge capacities of 250.1/250.8 mAh g−1 even after 1100 cycles at 0.5 A g−1. Structural and compositional analysis along with electrochemical tests showed that the uniform nitrogen-doped carbon coating and the nitrogen-doped LZTO favor electron transfer, while the defects induced by nitrogen-doping in LZTO promote Li-ion migration. The enhanced electronic and ionic conductivities are favorable to alleviate the polarization during cycling, and thus are responsible for the optimized performance. [ABSTRACT FROM AUTHOR]

Composite materials based on magnesium–lithium (MgLi) and magnesium–yttrium (MgY) matrices reinforced with unidirectional carbon fibers were prepared using the gas pressure infiltration method. Two types of carbon fibers were used, high-strength PAN-based T300 fibers and high-modulus pitch-based Granoc fibers. The PAN-based carbon fibers have an internal turbostratic structure composed of crystallites. The pitch-based carbon fibers have a longitudinally aligned graphite crystal structure. The internal carbon fiber structure is crucial in the context of the interfacial reaction with the alloying element. There are various mechanisms of bonding to carbon fibers in the case of magnesium–lithium and magnesium–yttrium alloys. This paper presents the use of the DMA method for the characterization of the role of alloying elements in the quality of interfacial bonding and the influence on the complex modulus at increasingly elevated temperatures (50–250 °C). The complex modulus values of the composites with T300 fibers were in the range of 118–136 GPa. The complex modulus values of the composites with Granoc fibers were in the range of 198–236 GPa. The damping capacity of magnesium-based unidirectionally aligned carbon fiber composites is related to the quality of the interfacial bonding. [ABSTRACT FROM AUTHOR]

The physicomechanical characteristics of PAN-based carbon fibers were investigated by SEM-EDS, XRD, TEM and AFM analysis while the mechanical properties of the composites were studied by tensile, flexural and Charpy impact tests with ASTM standards. Regarding the tensile test of carbon fiber fabric, the average tensile strength of CF-I, CF-II and CF-III fibers were around 147 MPa, 137 MPa and 225 MPa and the tensile modulus of those were 12.8 GPa, 13.2 GPa and 12.8 GPa, respectively. Later, the nanostructure of carbon fiber was recognized not as a pure graphite carbon structure because they mixed with graphite and amorphous structures. The higher tensile strength and modulus of CF-III fiber fabric was lower interlayer spacing (d002) because it consisted of more graphene layers in the graphite structure when compared with CF-I and CF-II fiber fabrics. Concerning AFM analysis's results, CF-I fiber fabric has higher surface roughness (Ra) of 34.8 nm and more in-depth with wider pit lines along the fiber axis, which caused higher mechanical properties among the three composites. According to this article, the nanostructure of carbon fibers had a lower impact on CFRP composite because the interfacial bonding between fiber and epoxy matrix, which obtained the higher mechanical properties in the composite, was directly enhanced by the higher surface roughness of the fibers. [ABSTRACT FROM AUTHOR]

Carbon fibers (CFs) are made mostly from a non-environmentally friendly polyacrylonitrile (PAN) and little from rayon. PAN-based CFs, require huge amount of energy for its production aside its contributions to the global CO2 emission. Therefore, there is recourse to a more environmentally friendly sources of CFs biomass. Recently lignin has been recognized as a potential renewable raw material for carbon fibers to replace PAN-based. The magnitude and quality of CO2 emission of lignin-based CFs are dependent on the processing route. On this premise; this review examines the various lignin-based CFs processing route adopted by researcher in the recent past to establish the most viable route with minimum carbon footprint emission. Outcome of the review shows that the major advantages of aromatic polymer (AP) generated precursor over PAN is the presence of higher quantity of guaiacyl units and oxygen content which makes the stabilization phase efficient and faster requiring less energy. Though there are several methods and options for the various stages of conversion of lignocellulosic biomass into CFs as highlighted in the study, establishing an optimum processing route will be a trade-off amongst various issues of concern; carcinogenic risk, carbon footprint emission, CFs Yield and mechanical strength of the CFs. Inferences from the study shows that the L-CF significantly produced reduced climatic impact in terms of CO2 emission. [ABSTRACT FROM AUTHOR]

To ascertain the best multi-peak fitting model for first- and second-order Raman spectral of both high-strength carbon fibers (T series) and high-strength and high-modulus carbon fibers (MJ series), three statistical evaluation methods including R2, Akaike information criterion (AIC) and Bayesian information criterion (BIC) values were calculated. And by establishing the relationship between spectral parameters and mechanical properties, the inconsistencies of fitting results under different peak fitting models were discussed. Results indicated that all fitting models of MJ series showed higher statistical consistency compared with that of T series. A five-peak model consisting of D, G, A, I and D′ peak and a four-peak model including 2I, G′, D+G and 2D′ peak with Voigtian function was recommended for first- and second-order Raman spectral of MJ series. But for T series, the above five-peak model with Lorentzian function might be recommended for first-order spectral. Importantly, for MJ series, it was found that the relationship between ID/IG value and tensile strength or modulus was almost the same as that between full width at half maximum (FWHM) of G′ peak and tensile strength or modulus. It was considered that the second-order spectral parameter of FWHM of G′ peak was helpful to supplement the first-order spectral parameter of ID/IG value, both of which were related to disorder features of carbon fibers. [ABSTRACT FROM AUTHOR]

Carbon fibers were successfully fabricated via the electrospinning technique, followed by stabilizing and carbonizing electrospun PAN fibers. A wide range of analytical techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), vibrating sample magnetometer (VSM) techniques, and Hall effect were performed to study of the effect of carbonization temperature on the physical and chemical characterization of carbon fibers. The SEM images of the PAN precursor exhibit a smooth outer surface, after the stabilization and carbonization process, along with a broken fiber at higher carbonization temperature about 1400 °C. Morphological characterization based on the recorded TEM images of carbonized fibers at 1000 °C and 1400 °C, showed that the obtained morphology can be classified as fiber structures, where their diameters ranged from 196 to 331 nm. The XRD patterns of PAN-based carbon fibers confirm the structural changes from linear structure into a graphite-like structure. The DRS study indicates the possible π–π*/σ–π* and n–π* transitions. The presence of the surface functional groups and different trapped radiative recombination on the emission bands is confirmed by the PL. VSM results shows the weak ferromagnetic nature of the carbon fibers. [ABSTRACT FROM AUTHOR]

Gas-phase chlorination of carbon fiber based on polyacrylonitrile was performed and active chlorine-containing precursors were obtained, in which chlorine can be replaced by sulfur-containing functional groups. It is shown that chlorination of carbon fiber samples with carbon tetrachloride at temperatures of 300, 450 and 6000C in an argon stream leads to the introduction of 0.2-1.7 mmol g-1 of chlorine into the surface layer of the fiber. The thermodesorption properties of the modified carbon fiber samples were investigated by thermogravimetry and thermoprogrammed desorption with mass spectrometric registration of products. It was established that the obtained samples exhibit a relatively high thermal stability. The study conducted by means of thermoprogrammed desorption method showed that chlorine is desorbed from the surface in a wide temperature range (up to 8000C). It was found that the treatment of chlorinated samples with sulfur-containing reagents with subsequent oxidation produce the samples of carbon fiber with a concentration of sulfo-groups up to 0.3 mmol g-1, which are catalytically active in the dehydration reaction of isopropyl alcohol in the gas phase. The temperature of 50% conversion of isopropyl alcohol to propylene was used as a measure of catalytic activity. It was found that pre-chlorination leads to an increase in the catalytic activity of the fiber modified with sulfur-containing reagents: the temperature of 50% conversion of isopropyl alcohol to propylene is 215-2900C, depending on the concentration of sulfo-groups. [ABSTRACT FROM AUTHOR]

For the improvement of the processing of melt‐spun lignin‐based fibers, the use of a spinning oil is necessary. The use of spinning oils is standard for the processing of PAN based carbon fiber precursors. Since no commercial spinning preparations for lignin fibers are available on the market, a study on different oils, such as technical oils, food‐grade oils or spinning avivages, is performed. A stepwise approach with applied tests (viscosity measurement, fiber etching, melt‐spinning, stabilization, carbonization) was developed to eliminate oils which are not suitable. The physical properties of the tested oils are determined and spectroscopic studies of these avivages are performed. Mechanical properties are characterized for as‐spun lignin fibers, stabilized lignin‐based fibers and lignin‐based carbon fibers with and without a spinning preparation. Four of seven tested spinning oils improve the handling during the processing of lignin‐based fibers but only two spinning oils lead to good quality carbon fibers and improve even the tensile strength of the resulting carbon fibers. [ABSTRACT FROM AUTHOR]

The results of the effect of high-fluence irradiation (fluence ~3 × 1018 cm–2) with 30-keV C+ ions at a temperature of 250°C on the structure and surface morphology of polyacrylonitrile-based carbon fibers reinforcing the composite KUP-VM are presented and discussed. Scanning electron microscopy shows that the irradiation of carbon fibers with their own ions does not lead, as in the cases of irradiation with ions of inert gases and nitrogen, to corrugation of the fiber surface. The roughness of the composite surface remains comparable to the nonirradiated sample. According to Raman-spectroscopy data, irradiation with carbon ions at temperatures above that of dynamic annealing of radiation-induced damage leads to the formation of a disordered graphite-like layer, as in the cases of irradiation with inert-gas ions. The lack of corrugation of the carbon-fiber surface under irradiation with carbon ions is associated with the lack of a gradient of radiation-induced damage in the modified layer and a texture characteristic of a carbon-fiber shell based on polyacrylonitrile. [ABSTRACT FROM AUTHOR]

Thermal‐oxidative stabilization of the polyacrylonitrile (PAN) precursor was performed employing a multi‐step heat treatment strategy in an air circulating furnace. In this approach, the applied temperature was gradually increased from 200°C to 250°C employing several stages for different stabilization durations. Fifteen percent guanidine carbonate (GC) was found as optimum to incorporate with the PAN precursor fibers to accelerate the thermal‐oxidative stabilization process. Characterization techniques, including X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FT‐IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), tensile strength, volume density, linear density, fiber thickness, and burning test have been performed to monitor the changes in PAN structure. Test results of the stabilized samples were compared with the reference sample results to demonstrate the accelerating effect of GC integration. Findings showed that GC pretreatment enhanced and accelerated the cyclization of nitrile groups in the PAN polymer structure and allowed the quicker formation of a thermally stable structure. The analysis of the experimental results revealed that GC integration and employing the multi‐step heat treatment strategy helps greatly to cut the overall PAN‐based carbon fiber production cost. [ABSTRACT FROM AUTHOR]

The effect of carbon nanotubes (CNTs) on the tensile properties of polyacrylonitrile (PAN)-based carbon fiber epoxy impregnated bundle composites was investigated. To grow CNTs on the carbon fibers, the following catalysts were selected: Ferrocene ([Fe(C5H5)2]) catalyst applied to the bundles using chemical vapor deposition (CVD), and iron (III) nitrate nonahydrate ([Fe(NO3)3•9H2O]) catalyst applied by dipping the bundles in ethanol solutions of different concentrations ranging from 0.01 to 0.5 M. For bundle composites with Fe(C5H5)2-catalyzed CNTs, the Weibull modulus was 29% higher than the as-received state, although the tensile strength is almost unchanged. The Weibull modulus is 9–39% higher than the as-received state for Fe(NO3)3•9H2O catalyst solutions in the range 0.01–0.3 M, while it decreases by 22–32% for 0.4–0.5 M solutions. The tensile strength is lower in both cases; 4–7% lower for 0.01–0.3 M solutions and 14–17% lower for 0.4–0.5 M solutions. Fe(NO3)3•9H2O catalysts 0.1 M solutions gives the best combination of tensile strength and Weibull modulus improvement. The results also show that for each type of CNT-grafted and as-received PAN-based carbon fibers, an almost linear relation between the Weibull modulus and average tensile strength on the log-log scale is observed. This relation indicates that Fe(C5H5)2 catalyst-grafting of CNTs gives better tensile strength and Weibull modulus results. [ABSTRACT FROM AUTHOR]

In this study, the effects of different spinning methods including traditional wet and dry‐jet wet spinning, and newly developed dry‐jet gel spinning, on the structures and performances of polyacrylonitrile fibers, as well as the structural evolution during stabilization and carbonization, are compared in detail. The structural differences along radial direction, surface roughness, and chain orientation of carbon fibers are inherited from their precursor fibers, and these factors are determined by spinning technologies and processing conditions. Among all spinning methods, dry‐jet gel spinning could prepare fibers with the best chain orientation, the highest tensile properties, and the lowest surface roughness, which would be favorable for achieving higher mechanical performance. Additionally, for the resultant carbon fibers, the surface modification of dry‐jet gel spun carbon fibers is easier than dry‐jet wet spun carbon fibers, and comparable to wet spun carbon fibers. Overall, dry‐jet gel spinning is promising to make carbon fibers with both excellent tensile properties and good interfacial adhesion with epoxy matrix. [ABSTRACT FROM AUTHOR]

The main objective of this study was to evaluate the efficiency of Na2CO3 activation and to examine polyacrylonitrile-based activated carbon fibers (PAN-ACFs) for phosphate ion adsorption in aqueous solution. PAN-ACFs were prepared by Na2CO3 activation (Na2CO3/PAN-CF weight ratio of 1–3) at 800°C and then heat treatment at 950°C under N2 gas flow using a horizontal furnace. The batch adsorption results on the effects of Na2CO3 impregnation ratio showed that equilibrium adsorption capacities were more than 0.2 mmol/g at the initial phosphate ion concentration of 3 mmol/L, especially the PAN-ACF prepared with N2CO3/PAN-CF weight ratio of 1 had the highest capability (0.27 mmol/g). This result was also supported by the characterization data, such as specific surface area (2600 m2/g) and quaternized-nitrogen (N-Q) content (1.6 wt %) for adsorption site calculated from the experimental N2 adsorption-desorption isotherm at –196°C and N1s spectra using XPS, respectively. The experimental data of optimized PAN-ACF for phosphate ion adsorption were well fitted to both Langmuir adsorption isotherms and pseudo-second-order kinetic model with high correlation coefficients of 0.96 and 0.98, respectively. The calculated maximum adsorption capacity was 0.7 mmol/g and the adsorption process reached equilibrium within 1 h, indicating that PAN-ACF has great adsorption ability as a carbonaceous material compared to other adsorbents. The solution pH influenced phosphate ion adsorption as well, and the most suitable pH for adsorption amount was around 6. As for regeneration performance, PAN-ACF still remained more than 90% adsorption amount of the fresh one at the first and second cycles after rejuvenation treatment using 1 mol/L HCl as desorption solution, indicating great reuse performance. [ABSTRACT FROM AUTHOR]

Nanomaterials are solid systems composed of 1–100 nm particles. These systems usually include nanomaterial sensors, nanomolecules, imaging technology, drug transportation, and DNA delivery. Therefore, nanomaterials are widely used in biomedicine, biochemical analysis, mechanics, and magnetism. Based on the above background, this paper mainly studies the application of nanomaterials in the repair of basketball sports ligament injury. In this paper, the nanomaterials used in medical treatment were analyzed, and the polyacrylonitrile based carbon fiber was selected to replace the anterior cruciate ligament (ACL). In this paper, based on polyacrylonitrile based carbon fiber for ACL replacement surgery in rabbits, the drawer test, IKDC score, and Lysholm score were compared between the rabbits after operation and those in the control group. The experiment proved that the function of the left knee joint was gradually restored after the ACL was excised and replaced by polyacrylonitrile based carbon fiber. After 8 weeks, the function of the left knee joint recovered 90%, which proved the feasibility of polyacrylonitrile based carbon fiber in the repair of anterior cruciate ligament injury. [ABSTRACT FROM AUTHOR]

Novel carbon foam composites derived from various pitch precursors have been fabricated and characterized. This paper specifically focuses on developing an effective process for fabricating the carbon foam composites from Polyacrylonitrile (PAN)-based carbon felt as a reinforcement and various readily available pitch matrix such as petroleum pitch, coal tar pitch, and mesophase pitch. The paper endeavors to develop the carbon foam composites and to carry out detailed morphological, thermal, and mechanical characterization. Traditional carbon foams have been known to offer poor mechanical performance, and hence, in this paper, the pitch-based carbon foams were innovatively reinforced with the PAN-based carbon fiber felt. Carbon foam composites were subjected to partial oxidation, and their morphological and mechanical response after the heat treatment was studied thoroughly. Thermal gravimetric analysis and thermal mechanical analysis techniques reveal an appreciable thermo-physical and thermo-mechanical response at elevated temperatures. Also, it was found out that the factors such as volatile content and quinoline insoluble fraction affect the morphology as well as the physical robustness on the composite foams. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A metal-dissolved oxygen seawater battery (SWB) uses metal and dissolved oxygen as the reactants, and it is ideal for use as a long-time low-power distributed power supply in deep sea, due to its advantages of open structure in service without electrolyte. However, several simulating deep-sea environmental factors, such as flow rate, dissolved oxygen concentration, and temperature of seawater may affect the oxygen reduction reaction (ORR) rate and the stability of electrochemically modified polyacrylonitrile-based carbon fiber brush (MPAN-CFB) cathode, which was studied by steady-state polarization and galvanostatic discharge methods. In addition, the scales formed on MPAN-CFB surface were characterized by SEM and XRD. Results show that the ORR rate increased quickly with the increase of the seawater flow rate up to 3 cm/s, and then gradually stabilized. Moreover, the ORR rate was largely affected by dissolved oxygen concentration, and the concentration of >3 mg/L was favorable. Compared with surface layer temperature of 15°C, the low temperature of deep sea (4°C) has a negligible effect on ORR rate. When the working current is too high, it will lead to the formation of CaCO3 scales (aragonite) of at the cathodic surface, resulting in the decrease of ORR rate, and consequently the damage to the long-time stability of MPAN-CFB. [ABSTRACT FROM AUTHOR]

Effects of different electrolytes on the surface structure and interfacial property with epoxy resin of PAN-based carbon fiber are evaluated, which is used to find out the key factor that affects the improvement in the interfacial adhesion. It is found that the carbon fiber treated in H2SO4 electrolyte owns the most abundant oxidative groups but bonds relatively weak with epoxy resin by the maximum interlaminar shear strength of 60 MPa. The carbon fiber oxidized in NaOH electrolyte and then restored in HCl solution owns less oxidative groups but shows a strongest bonding with epoxy resin by the maximum interlaminar shear strength of 69 MPa. We conclude this phenomenon is mainly ascribed to the graphene layers covering on the fiber surface that are formed during carbonization and connect weakly with the substrate of carbon fiber, thus called weak layers. The weak layers can be peeled off effectively in NaOH electrolyte but not in H2SO4 electrolyte. An attempt for modification is tried by removing the weak layers in NaOH electrolyte and adding more oxygen groups in H2SO4 electrolyte. The interlaminar shear strength of the fiber with epoxy resin is not increased as expected; however, it shows oxidation in H2SO4 electrolyte does not generate weak layers on carbon fiber surface. [ABSTRACT FROM AUTHOR]

An experimental setup for 3ω method with a constant current source and two differential amplifiers was built to measure the thermal conductivity and the volumetric heat capacity of single polyacrylonitrile (PAN)-based carbon fiber. In complement to a well-known analytical thermal model, a numerical one was developed that can check the validity of the analytical one and can also take into account the effect of convective heat loss on the measurements. A detailed sensitivity analysis of the unknown parameters was presented that would finally help in the better design of the setup for 3ω method. The tests were performed under vacuum and atmospheric pressure for chromel wire as a reference sample and under vacuum for two types of PAN-based carbon fiber. Detailed measurements were performed displaying the influence of convective loss and the thermal contact resistance between fiber and copper electrodes on the estimation of thermal properties of carbon fiber. [ABSTRACT FROM AUTHOR]

In this study, the influence of type of carbon fiber, sizing amount on the fiber surface and the degree of compaction on the through-thickness electrical resistivity of dry unidirectional carbon fiber tows is investigated to validate the conduction pathways and mechanisms proposed by our previously reported micromechanics electrical resistivity model. An automated experimental setup has been developed and implemented, which measures the electrical resistivity and fiber volume fraction of carbon fiber tows under compression in real time. An extensive experimental study is conducted with five types of commercial PAN-based carbon fibers which vary in fiber diameter, number of fibers in a tow including two unsized fibers and three sized fibers with sizing amount of 0.25% and 1.0% by weight. The fiber volume fraction was increased by compacting the fiber tows using a mechanical testing system (Instron, Norwood, MA). The results show that the fiber sizing and fiber volume fraction impact the through-thickness electrical resistivity of carbon fiber tows. Sized fibers demonstrate 1–2 orders of magnitude higher electrical resistivity than the unsized fibers at lower fiber volume fractions (below 45%), while at higher fiber volume fraction (60%–70%), the electrical resistivity of the two fiber systems tends to be of similar magnitude. Fibers with more sizing (1 wt.%) demonstrated 10 times larger through-thickness resistivity than those with less sizing (0.25 wt.%), indicating the significant impact of fiber sizing on electrical resistivity. The results show good agreement with our micromechanics electrical resistivity model. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to prepare a spherical modifier-modified activated carbon fiber of high specific capacitance intended for electrode materials of supercapacitor. Design/methodology/approach: In this study, phenolic-based microspheres are taken as modifiers to prepare PAN-based fiber composites by electrospinning, pre-oxidation and carbonization. Pearl-chain structures appear in RFC/ACF composites, and pure polyacrylonitrile fibers show a dense network. The shape and cross-linking degree are large. After the addition of the phenolic-based microspheres, the composite material exhibits a layered pearlite chain structure with a large porosity, and the RFC/ACF composite material is derived because of the existence of a large number of bead chain structures in the composite material. The density increases, the volume declines and the mass after being assembled into a supercapacitor as a positive electrode material decreases. The specific surface area of RFC/ACF composites is increased as compared to pure fibers. The increase in specific surface area could facilitate the diffusion of electrolyte ions in the material. Owing to the large number of bead chains, plenty of pore channels are provided for the diffusion of electrolyte ions, which is conducive to enhancing the electrochemical performance of the composite and improving the RFC/ACF composite and the specific capacitance of the material. The methods of electrochemical testing on symmetric supercapacitors (as positive electrodes) are three-electrode cyclic voltammetry, alternating current impedance and cycle stability. Findings: The specific capacitance value of the composite material was found to be 389.2 F/g, and the specific capacitance of the electrode operating at a higher current density of 20 mA/cm2 was 11.87 F/g (the amount of the microsphere modifier added was 0.3 g). Using this material as a positive electrode to assemble into asymmetrical supercapacitor, after 2,000 cycles, the specific capacitance retention rate was 87.46 per cent, indicating excellent cycle stability performance. This result can be attributed to the fact that the modifier embedded in the fiber changes the porosity between the fibers, while improving the utilization of the carbon fibers and making it easier for electrolyte ions to enter the interior of the composites, thereby increasing the capacitance of the composites. Originality/value: The modified PAN-based activated carbon fibers in the study had high specific surface area and significantly high specific capacitance, which makes it applicable as an efficient and environment-friendly absorbent, as well as an advanced electrode material for supercapacitor. [ABSTRACT FROM AUTHOR]

Highlights from the article: A visible light-induced metal-free atom transfer radical polymerization strategy for the efficient synthesis of polyacrylonitrile (PAN) with predictable molecular weights and low dispersities has been developed. While no absorbance of the phenothiazines at visible region can be observed, high energy ultraviolet (UV) light is necessary in this process, leaving a space for improvement of using the abundant and "green" visible light to achieve the controlled polymerization of AN. (a) Plot of monomer conversion versus time demonstrating the dependency of light on the polymerization: light on (blue regions) and light off (white regions). The results of polymerization kinetics, light on/off switching experiments and chain extension polymerizations together proved the living nature of the visible light catalytic system.

This paper reports the molecular organization and mechanical properties of electrospun, post-drawn polyacrylonitrile (PAN) nanofibers. Without post-drawing, the polymer chain was kinked and oriented in hexagonal crystalline structures. Immediate post-drawing in the semi-solid state disrupted the crystal structures and chain kink at maximum draw ratio. Structural re-orientation at maximum draw resulted in a 500% increase in Young's modulus and a 100% increase in ultimate tensile strength. By applying post-drawing to electrospinning it may be possible to obtain PAN fibers and PAN-derived carbon fibers with enhanced mechanical properties compared to available fabrication technologies. [ABSTRACT FROM AUTHOR]

Microstructural characterization of polyacrylonitrile‐based carbon fiber (PAN‐CF) reinforced polybutylene terephthalate (PBT) and polyethersulfone (PES) polymer composites have been performed. The positron lifetime parameters viz., o‐Ps lifetime (τ3), o‐Ps intensity (I3) and fractional free volume (Fv) of PAN‐CF reinforced PBT (PBT/PAN‐CF) and PAN‐CF reinforced PES (PES/PAN‐CF) composites are correlated with the mechanical properties. The fractional free volume obtained experimentally show negative deviation from the linear additivity relation in PBT/PAN‐CF composites for lower wt% of PAN‐CF loading. This indicates the improved adhesion between PAN‐CF and polymeric chains of PBT matrix in PBT/PAN‐CF composites. The positive deviation of fractional free volume (Fv) in PES/PAN‐CF composites suggests the formation of interface between PAN‐CF and polymeric chains of PES matrix. The increased glass transition temperature (Tg) of PBT/PAN‐CF composites suggests the reduced main chain and segmental mobility of PBT polymeric matrix by the presence of PAN‐CFs. The decreased glass transition temperature (Tg) in PES/PAN‐CF composites indicates the reduced molecular packing due to interface formation. The increased crystallinity and improved mechanical properties of PBT/PAN‐CF and PES/PAN‐CF polymer composites are attributed to the increased nucleation density of carbon fibers in the composites. The FTIR results suggest the improved chemical interaction between the functional groups of PAN‐CF and PBT matrix. The hydrodynamic interaction is also high in PBT/PAN‐CF than PES/PAN‐CF composites. POLYM. COMPOS., 40:E939–E952, 2019. © 2018 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The influence of stabilized fibre structure and skin-core formation induced by rapid thermal stabilization of polyacrylonitrile (PAN) on the tensile properties of carbon fibres was investigated. Three sets of samples were prepared by stabilizing PAN fibres under three temperature profiles using a continuous carbon fibre processing line. Initially, the chemical structure and density variations in stabilized fibres were examined with respect to process conditions using Fourier Transform Infrared Spectroscopy (FTIR) and density column methods. Interestingly, while the cyclization and dehydrogenation indices are similar for all the stabilized fibres irrespective of temperature profiles used, the densities of these fibres varied from 1.34 to 1.366 g/cc. Micro-Raman studies showed the existence of structural heterogeneity in the fibres from low temperature (LT) carbonization (I(D)/I(G) ratio of core was ~5.6% higher than the skin) that eventually reduced with high temperature (HT) carbonization because of uniform sp3 to sp2 hybridization of carbons. However, modulus mapping revealed heterogeneous storage modulus distribution in the HT carbon fibre cross-section from Trial-2 (storage modulus of core was ~23 GPa less than the skin). Interestingly, this heterogeneity did not show a significant effect on the bulk properties of carbon fibres suggesting skin-core formation is an effect rather than a defect. [ABSTRACT FROM AUTHOR]

Novel electrospun polyacrylonitrile (PAN) nanofibrous membranes were prepared by using heat‐press lamination under various conditions. The air permeability and the burst‐pressure tests were run to select the membranes for point‐of‐use air and water cleaning. Membrane characterization was performed by using scanning electron microscopy, contact angle, and average pore size measurements. Selected membranes were used for both air dust filtration and cross‐flow water filtration tests. Air dust filter results indicated that electrospun PAN nanofibrous membranes showed very high air‐dust filtration efficiency of more than 99.99 % in between PM0.3 and PM2.5, whereas cross‐flow filtration test showed very high water permeability over 600 L/(m2hbar) after 6 h of operation. Combining their excellent efficiency and water permeability, these membranes offer an ideal solution to filter both air and water pollutants. Keep in clean: Electrospun polyacrylonitrile nanofibrous membranes are prepared under various conditions. Selected membranes are tested for air and water filtration purposed. [ABSTRACT FROM AUTHOR]

A very simple and efficient method was developed to improve the interfacial properties of aramid fibers reinforced composites. The aramid fibers and the acrylonitrile (AN) monomers were mutually irradiated by γ‐ray in cyclohexane solution, initiating AN to polymerize on the fibers surface. Surface morphologies, chemical structure, mechanical behavior, thermal stability of the polyacrylonitrile (PAN) grafted aramid fibers and interfacial properties of their composites were systematically characterized. The results indicated that the linear PAN fantastically united to be nanoscale particles with 200 nm size, and grafted on the aramid fibers surface uniformly and compactly. Despite a slight decrease with 4°C in fiber heat resistance, the mass loss of the PAN‐grafted fibers significantly reduced. Surprisingly, the interfacial shear strength of PAN grafted aramid fibers improved by 71.50% from 36.33 ± 1.08 to 62.31 ± 1.32 MPa. Moreover, the tensile strength of aramid fibers enhanced slightly. This surface modification strategy is facile to prepare, highly efficient to enhance interface, adaptable to other organic fibers, and meaningful in multifunctional applications. POLYM. COMPOS., 39:E2436–E2444, 2018. © 2018 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

In this study, novel polyacrylonitrile (PAN) nanofiber adsorbent modified with 6-amino-1-hexanethiol hydrochloride (Ahh) was synthesized by electrospinning method and evaluated as an adsorbent for removing thorium (IV) (Th4+) ion from aqueous solution. The PAN/Ahh was characterized by X-ray diffraction (XRD), Fourier-transform infrared (FT-IR), scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET). Response surface methodology (RSM) was utilized in the optimization of Th4+ adsorption in terms of (i.e., initial Ahh concentration, pH, the initial metal ion concentration, and contact time). To ensure the validity of the model, the statistical measures were investigated, thus to specify that the developed model is proper. In addition, the adsorption kinetics was well defined by the pseudo-second-order equation, while the Langmuir model better fit the adsorption isotherms. The adsorption capacity of PAN/Ahh was 499 mg Th4+ g–1 composite, leads to 98.5% removal at 25°C. Moreover, thermodynamic parameters were determined which point out the natural and endothermic nature of the reactions. The loaded Th4+ can be easily regenerated with HNO³/HCl and the PAN/Ahh could be used repeatedly without any significant reduction in its adsorption capacity. The desorption level of Th4+ from the PAN/Ahh was more than 94%. [ABSTRACT FROM AUTHOR]

Fatigue is considered a major pavement structural distress and an important part of a performance-based mix design. Currently, the fatigue model of asphalt mixture, especially the mixture incorporated with fibers, is not perfect. In this paper, the central-point bending fatigue test was conducted by constant strain mode with MTS apparatus. The fatigue performance and model of polyacrylonitrile (PAN) fiber-reinforced asphalt mixture produced with different fiber contents and asphalt contents were reported. The results indicated that the fatigue life of fiber reinforced mixture was higher than the reference one. The effects of fiber contents and asphalt contents on fatigue life were discussed. The mechanism of an optimum fiber content for the fatigue life in the fiber reinforced asphalt mixture was explained. The statistical analysis of variance (ANOVA) method and regression method were used to evaluate the effects of fiber content, strain level, and volumetric parameters, etc. on the fatigue life of an asphalt mixture. This paper presents a new fatigue performance model of a PAN fiber-reinforced asphalt mixture, including the fiber content, tensile strain, mixture initial flexural stiffness, and voids filled with asphalt (VFA). Compared to the earlier fatigue equations, the accuracy of the new fatigue model with the fiber content is improved significantly according to the statistical analysis results. Meanwhile, the model can preferably reveal the effect of fiber content, strain level, initial stiffness, and VFA on fatigue life. [ABSTRACT FROM AUTHOR]

A novel functional resin, polyacrylonitrile-melamine (CPAN-M), was made through the nucleophilic addition reaction of cross-linked polyacrylonitrile (CPAN) with melamine. It was developed for the removal of Cu (II), Pb (II) and Zn (II) from aqueous solution. The sorption experiments were investigated by synthesized functional resin under different experimental conditions, such as temperature, initial concentration, pH and contact time. The results showed that the adsorption behavior of the resin for selected metal ions was found to be greater at higher pH values. The high adsorption rate (<20 min) was seen. The maximum adsorption capacity on CPAN-M was determined as123 mgg-1 for Cu (II). The adsorption kinetics followed the pseudo-second-order equation, while the adsorption isotherms were well fitted for the Langmuir model. The desorption experiments by elution of the obtained resin with a hydrochloric acid (HCl) show that the CPANM could be reused. The prepared resin and its metal chelates were characterized by Fourier transform infrared Spectroscopy (FT-IR), elemental analysis, thermogravimetric analysis (TGA), gravimetry, UV-vis spectroscopy, and atomic absorption techniques (AAS). [ABSTRACT FROM AUTHOR]

Airborne dust particles has become an ever-increasing environmental concern and is also a threat to public health, leading the way in the development of fibrous materials with fascinating features like high filtration efficiency and low pressure drop. To enhance the filtration efficiency of fibrous material, particularly for submicron-sized particles, here we report a promising and versatile electret polyacrylonitrile-silicon dioxide (PAN-SiO2) fibrous membrane, considering the higher particle capture efficiency for an electret filter compared to a conventional fibrous filter. The chemical bond nonwoven and spun bond nonwoven substrates were used as support material to enhance the mechanical property and also the handling property of the as developed electrospun nanofibrous membrane. In this research work, SiO2 is identified as the potential material for developing electret filter due to its dipolar nature. The concentrations of SiO2 nanoparticles (NPs) were varied to achieve better filtration efficiency. The morphology of fibrous membrane, its air permeability, areal density and thickness properties were analyzed as per standard test methods. The filter fabrics were developed and its filtration performance and pressure drop were also characterized. [ABSTRACT FROM AUTHOR]

Chemical polymerization of monomers of electroactive polymers and their processability have some challenges. Chemical polymerization of 1‐p‐(tolylsulfonyl) pyrrole has been realized first time by using Ce (IV)‐pyrrole redox initiating system to obtain poly (1‐p‐[tolylsulfonyl)pyrrole]. Moreover, the achieved polymer was used as a precursor for electrospinning, and their solutions with DMF were used to fabricate nano and submicron fibers via electrospinning method. Polymerization conditions were followed with UV–visible spectroscopy. Surface morphologies were examined with scanning electron microscopy, and elemental analysis measurements were obtained via scanning electron microscopy/energy‐dispersive X‐ray. Attenuated total reflection spectroscopy was used to record the characteristic peaks of the nanofiber webs before and after polymerization. Surface morphology of the polymer domains was examined with atomic force microscopy. Inherently conductive polymer, poly (1‐p‐[tolylsulfonyl)pyrrole] was successfully combined with the PAN and were fabricated to obtain nanofiber webs. [ABSTRACT FROM AUTHOR]