Papers by Keyword: pan

Abstract: In this study two types of PAN-based continuous carbon fibers were compared: high-modulus UMT-430 and high-strength UMT-49. The dynamics of carbon fibers oxidation at a temperature of 600°C with an exposure from 1 to 6 hours was evaluated. It was found that high-strength fibers burn out faster than high-modulus. The surface of the fibers in the initial state and after annealing was investigated. Composite samples with an Al-6Mg alloy matrix, reinforced with these types of carbon fibers, were tested for three-point bending. It was found that the strength of the composite with high-modulus fiber was more than 2 times higher than strength of the composite with high-strength fiber. The samples fracture surfaces of Cf/Al composites after mechanical tests are investigated.

Abstract: Nowadays, construction often is used a composite material. Including fibro concrete of reinforcing synthetic fibers. In this title was survey the effect of fiber reinforcement. PAN and HC on the properties of concrete in depend of length fibers, its design, types dressing, composition of concrete, aggregate fineness and etc. As a result of influence was revealed that is not depend of length fibers in the same mobility of concrete mix and differente flow consumption of cement concrete strength in compressive decreases and increases a concrete of fiber. The same conditions strength concrete in flexural with increases content fibro rising. In attendance fibro model is deformation decreases but maximum permission increase.

Abstract: The calculations of the dimer, trimer and tetramer molecules of polyacrylonitrile (PAN) using the quantum-chemical method are carried out. The computer simulation of formation of a polymer PAN chain by the Monte-Carlo method taken with the Metropolis and Wang-Landau algorithm is done. Technology of fabrication of gas-sensing material based on metal-containing PAN is developed. Electroconductive metal-containing PAN films are fabricated by method of pyrolysis under the influence of incoherent IR-radiation. Their sensing properties are studied.

Abstract: The interaction between polyacrylonitrile (PAN) and various plasticizer at different temperature was discussed by infrared analysis. At the room temperature, the interaction between nitrile groups of polymer is so strong that the conventional plasticizer propylene carbonate (PC) or new-type plasticizer ionic liquid can’t have interaction with nitrile groups. However, the interaction between nitrile groups weakens at higher temperature, i.e. 160°C, and the interaction between the nitrile groups and IL is formed, which is maintained when natural cooling to 90°C. The interaction between the nitrile groups and IL weakens again when natural cooling to room temperature, it may be attributed to the interaction between IL and water is stronger than that of IL and PAN.

Abstract: Polyacrylonitrile (PAN) is widely used for its superior properties, and comonomers are usually introduced to improve its properties. In this paper, 2-acrylamide-2-methylpropanesulfonic acid (AMPS) and acrylamide (AM) were used as comonomers to prepare polyacrylonitrile by aqueous slurry polymerization. Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) was used to characterize the chemical structures, the thermal properties, degree of crystallinity of polyacrylonitrile copolymer. The results show that the best thermal property of AN/AMPS/AM ternary copolymer in cyclization reaction was achieved in the proportion (w/w/w) 98/1/1. The exothermic quantity of AN/AMPS/AM ternary copolymer is 612.1 J/g while that of PAN homopolymer is 519.5 J/g during the cyclization reaction, carried out in DSC under nitrogen atmosphere. The introduction of AMPS and AM has small impact on the degree of crystallinity of PAN, the degree of crystallinity approximates 53.8%

Abstract: Conductive polyacrylonitrile film reinforced by multiwall carbon nanotubes was prepared via ultrasonic dispersion and vacuum casting. The structure of MWNT/PAN composite film was characterized by WAXD and FT-IR. The LOI of the blend was enhanced from 18.1 % to 24.5 % and TGA show better thermal stability. MWNT composite at 10 wt% MWNT loading showed an electrical conductivity of 10^-2S/cm.

Abstract: In this paper, the hollow or porous carbon nanofibers based on the PAN with high molecular weight were manufactured through concentric electrospinning. The PAN terpolymers with the viscosity-average molecular weight of 30 kDa were synthesized via aqueous precipitation polymerization. Then the prepared PAN was dissolved in DMF to afford the shell. Two kinds of solutions, silicone oil and the 10% PVP DMF solution, were used as the core. After the concentric electrospinning, the obtained core-shell PAN nanofibers exhibit the different morphology. Compared with the 10% PVP DMF solution as the core, the silicone oil as the core led to the greater and more uneven in diameter. After the oxidative stabilization and carbonization, the PAN based carbon nanofibers (CNFs) showed the obvious hollow cores no matter the silicone oil or 10% PVP DMF solution is in core. When the silicone oil is in core, the profiles of the PAN based CNFs reveal the better fibrous shape and thinner diameter. Furthermore, a mixture of PAN and PMMA with the molecular ratio of 1:1 in shell and the 10% PVP DMF solution in core were also concentrically electrospun. FESEM reveals that the addition of PMMA made the nanofibers more even and thinner diameters. After carbonization, the resulted PAN based CNFs show the porous cross-section.

Abstract: Low-temperature fuel cells have been attracting more and more attentions for the direct conversion of chemical energy into electricity. Efficiencies of fuel cells to a great extent depend on the activity of the catalytic platinum and its alloys. Increasing the reaction surface area and decreasing the diameter of platinum particles can enhance the activity of the platinum. In this paper, we report a platinum catalyst supported on porous carbon nanofibers. Two kinds of PAN terpolymers with various molecular weights of 15 kDa (PAN-1) and 30 kDa (PAN-2) were first prepared by aqueous precipitation polymerization. The mixtures of PAN with various molecular weights and PMMA were then electrospun, stabilized and carbonized to provide the porous carbon nanofibers. It was found that the PAN with lower molecular weight results in the even fibrous surface and thick diameter, indicating a stable spinning process. Moreover, the PAN-based carbon nanofibers were immersed into a platinum complex solution to support the platinum positive ions. After calcination, the platinum ions deposited on the carbon nanofibers were converted into nanoplatinum particles to provide the platinum catalyst supported on the porous carbon nanofibers.

Abstract: PAN/POSS nanofibers membrane with different content POSS have been prepared by electrospinning. The morphology and thermal properties of PAN/POSS nanofibers are characterized by SEM and DSC, respectively. The addition of different content of POSS into PAN matrix have a slight effect on the diameter of nanofibers. Compared to pure PAN fibers, the exothermic peak shift to higher temperatures by 6.8°C when POSS loading is 3wt%, and the corresponding Tg have increased 17.3°C.

Abstract: This study mostly investigated the influences of electrolytic conditions and the structure of electrospinning nanofibers electrodes on the degradation of methylene blue in details. For PAN and Fe/PAN electrodes, was prepared by electrospinning.It was found that the ESF electrodes with higher specific surface area, and higher mesopore percentage could be push the electrochemical degradation. As the same time, adjusted the initial pH, increased the current, and added to electrolyte also could improve the treatment effect of electrochemical degradation. After 90min of electrolysis, the color removal efficiency of methylene blue reached 97.6% at current with 100mA, supporting electrolyte of NaCl with 0.1mol/L and initial pH with 3~5. Under the same current conditions with the Pt-Fe/PAN anodes the color removal rate of degradation were higher efficiency than the other two anodes.