PAN Fibers Research Articles

Well‐dispersed copper nanorods grown on the surface‐functionalized PAN fibers and its antibacterial activity

ABSTRACTβ‐Cyclodextrins/polyacrylonitrile/copper nanorods (β‐CDs/PAN/CuNRs) composite fibers were fabricated by two steps including the preparation for the β‐CDs/PAN composite fibers by electrospining, and the preparation of the β‐CDs/PAN/CuNRs composite fibers by adsorption and reduction. The β‐CDs/PAN/CuNRs composite fibers were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, and X‐ray photoelectron spectroscopy respectively. The results indicated that the CuNRs were not only successfully synthesized on the surface of composite fibers but also the CuNRs were distributed without aggregation on the composite fibers. Furthermore, microorganism Escherichia coli had been used to check the antibacterial efficacy of the β‐CDs/PAN/CuNRs composite fibers. Subsequently, antibacterial tests have indicated that the composite fibers have good bactericidal effects. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41011.

Green synthesis of reduced graphene oxide/polyaniline composite and its application for salt rejection by polysulfone-based composite membranes.

In this study, a novel, simple, and eco-friendly enzymatic-reaction-based approach to produce reduced graphene oxide/polyaniline (rGO/PANI) composite material was proposed. Glucose oxidase (GOx) was used as an effective catalyst producing hydrogen peroxide, in the presence of glucose, for the oxidative polymerization of aniline under ambient conditions. The prepared rGO/PANI composite was dispersed in polysulfone (PSf), and the mixed membranes were prepared by the phase inversion polymerization method. The morphology of membranes was investigated using scanning electron microscopy (SEM), atomic force microscopy (AFM), and contact angle (CA) techniques. The performance of membranes was studied in terms of salt rejection and pure water flux. The incorporation of rGO into the membrane matrix led to hydrophobic membrane surface with the enhanced macro-voids. On the contrary, the contact angle data revealed that the rGO/PANI-incorporated membrane surface is partly hydrophilic due to the PANI fibers in membrane, whereas SEM images showed the enhanced macro-voids. Membranes exhibited an improved salt rejection after rGO/PANI doping. The rGO/PANI-modified membrane loading exhibited a maximum of 82% NaCl rejection at an applied pressure of 10 bar. In addition, the results showed that the PSf-rGO/PANI composite membrane had the highest mean porosity and water flux.

Ion-beam erosion of carbon fibers of the composites

The results of experimental studies of the structural and morphological changes of the surface of carbon PAN fibers of a carbon-carbon KUP-VM (1D) composite as a result of high-dose irradiation (1018–1019 ion/cm2) with Ne+ and Ar+ ions with an energy of 10–30 keV are presented. The threshold values of radiation damage, resulting in an amorphization of the PAN carbon fibers at room temperature and ion-induced crimping at temperatures greater than the annealing temperature of the radiation damage, are determined.

Analysis and characterization of orientation structure of pre-oxidized PAN fibers in high magnetic fields

PAN fibers pre-oxidized at 240 °C, 260 °C, 280 °C, 300 °C were treated in 8 T, 12 T, 16 T high magnetic fields, respectively. The experimental result implied that there were two kinds of magnetic units cyan and carbon-nitrogen heterocycle in pre-oxidized PAN fibers, and the movement of magnetic units resulted in changes of orientation structure of pre-oxidized PAN fibers in high magnetic fields. Overall orientation increased with increase of magnetic field intensity and extension of processing time, whereas change of crystalline orientation depended on magnetic field intensity and content of carbon-nitrogen heterocycle due to the competition of two magnetic units. Furthermore, magnetic fields induced the conversion from amorphous region to crystal region and improved crystalline properties of pre-oxidized PAN fibers.

Improving Preferred Orientation and Mechanical Properties of the PAN-Based Carbon Fiber Precursors by Using Saturated Steam Stretching Process

The saturated steam stretching process of the PAN-based carbon fiber precursors was studied. The orientation,crystallinity, and mechanical properties of the PAN fiber were analyzed by means of X-ray diffraction and XQ-2 tensile testing machine. The results demonstrated that the property of PAN fiber was very sensitive to the temperature, and the tensile strength and orientation degree increased with increasing temperature, which might be attributed to the changes of the super molecular structure. The stretching ratio also had great influence on the crystalline orientation of PAN fiber. Therefore, the temperature and stretching ratio for a certain fiber of the stretching process were matched and limited.

Effects of drawing process on the structure and tensile properties of textile-grade PAN fiber and its carbon fiber

AbstractCarbon fibers (CFs) were prepared using low-cost, textile-grade polyacrylonitrile fibers, which were 200% to 400% drawn in a hot water bath at 90°C or/and in a tubular furnace at 180°C. X-ray diffractograms confirmed that the drawing process led to higher crystallinity and molecular orientation. These fibers were stabilized in a convection oven at 25–255°C for 390 min. After stabilization, carbonization was performed to obtain carbon fibers. The tensile strength of CFs without drawing was ∼0.8 GPa; however, CFs with 200% and 200% drawing in a hot water bath at 90°C and in a tubular furnace at 180°C, respectively, showed a tensile strength of ∼1.7 GPa. These results suggest that the drawing process of precursor fibers affected the tensile properties of the resulting CFs significantly.

Waterproof and breathable membranes of waterborne fluorinated polyurethane modified electrospun polyacrylonitrile fibers

Novel waterproof and breathable fibrous membranes with superhydrophobic surface, adjustable pore size and adhesion structure were fabricated by modifying electrospun PAN fibers with WFPU emulsion.

A highly efficient gold/electrospun PAN fiber material for improved laccase biocathodes for biofuel cell applications

We explore for the first time the ability of a three-dimensional polyacrylonitrile/gold material prepared by a low-cost and scalable synthesis method, based on the combination of electrospinning and sputtering, as a new material with large surface area to provide high loadings of enzymes to enhance the electrochemical performances of enzyme electrodes in biofuel cells (BFCs). An ethanol/O2 BFC has been developed based on enzymatic reactions performed at both the cathode and anode with immobilization of the respective enzymes and mediators on the three-dimensional nanostructured electrodes. The power density delivered is 1.6 mW cm−2 at 0.75 V, which is five times the power density delivered by the BFC built on flat bioelectrodes. The greatly improved performance of these synthesized nanostructured electrodes makes them exciting materials for their implantation in biofuel cell applications.

Performance of Collagen Modified PAN Fiber

PAN fiber is one that contains at least 85% by mass of acrylonitrile co-monomer in the polymer chain. It has low moisture-absorbency and electrostatic tendency. Using collagen modified PAN fiber can overcome the shortcomings. Collagen modified PAN fiber is a kind of surface modification fiber which was hydrolyzed by NaOH aqueous solution first, and then grafted with collagen. The performance of collagen modified PAN fiber was studied. The results show that: compared with PAN fiber, the surface of collagen modified PAN fiber is smooth and covered by collagen composition, the moisture regain increased from 2% to 6.1%,the breaking strength and elongation of collagen modified PAN fiber are decreased, the breaking strength is 2.31 cN/dtex, the breaking elongation is 22.8%, dyeing properties of collagen modified PAN fiber with cationic dyes and acid dyes are excellent and the goods have bright color and good color fastness.

Effect of carbon microfiber materials on sensitivity of adenosine and hydroxyadenine at carbon microfiber sensors

The relationship between the sensitivity measurements and microfiber electrodes made from different carbon microfiber materials, such as polyacrylonitrile (PAN T650 and PAN HCB) and Pitch P25 was established in this work. The different microfiber electrodes were nanostructured by an electrochemical pretreatment method. Sensitivity of adenosine (ADO) and 2,8-dihydroxyadenine (2,8-DHA) was measured at different carbon microfiber sensors made from different carbon microfiber materials. Sensitivity of PAN microfiber electrodes for ADO and 2,8-DHA determinations measured at 500Vs−1 vs. SCE is higher than that measured at Pitch P25 microfiber electrodes due to more defects in PAN microfiber electrodes. Adsorption of ADO and 2,8-DHA is greater at PAN HCB electrodes. High conductivity of PAN fibers correlates with sensitivity determinations of the investigated analytes.

Influence of POSS Content on the Thermal Properties of PAN/POSS Nanofibers

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.

Fabrication of large‐scale superhydrophobic composite films with enhanced tensile properties by multinozzle conveyor belt electrospinning

ABSTRACTLarge‐scale superhydrophobic composite films with enhanced tensile properties were prepared by multinozzle conveyor belt electrospinning. First, a strategy of conveyor belt electrospinning was introduced for large‐scale fabrication since the conveyor belt can expand the electrospinning area unlimitedly. During the electrospinning (or electrospraying) process, certain kinds of fibers are combined on the conveyor belt in one electrospinning (or electrospraying) step. The superhydrophobicity of electrospun film can be achieved by the presence of PS beads and bead‐on‐string PVDF fibers, while submicron PAN fibers are responsible for the improvement of mechanical properties. The result shows that CA value of the surface comprising of PS beads and bead‐on‐string PVDF fibers could reach up to 155.0°. As the submicron PAN fibers increased, the value of CA decreased, changing from 155.0° to 140.0°, meanwhile the tensile strength of composite film was enhanced from 1.14 to 4.12 MPa correspondingly which is beneficial to putting the films into practice. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39735.

Effect of stationary high heat flux and transient ELMs-like heat loads on the divertor PFCs

The experimental evaluation of the divertor plasma facing components (PFCs) lifetime under transient events, such as edge localized modes (ELMs) and high heat flux (HHF) thermal fatigue expected during ITER normal operations and slow transient events is here presented. The experiments have been performed in the frame of an EU/RF collaboration. For carbon fiber composite material the erosion is caused by PAN fiber damage whilst the erosion of tungsten is determined by the melt layer movement and crack formation. The conclusion of this study is that, in addition to the structural change produced in the armor materials by ELMs-like loads, some mock ups showed also a degradation of the thermal fatigue performances

TiO<sub>2</sub> Immobilized in RPF-AA Fiber for Photocatalytic Degradation of Low Concentration Methylene Blue in Aqueous Solution

The reactive polymer fiber with high adsorption capacity and good mechanical properties, RPF-AA, was prepared by the processes of pre-treatment, modification of the commercial PAN fiber. In order to improve the repeating circles of the semiconductor titania photocatalyst and broaden its applications, fine titania particles immobilized in RPF-AA fibers (TiO2/RPF-AA) were prepared successfully at room temperature by a dip-coating method. Tetrabutyl orthotitanate (TBOT) was hydrolyzed in presence of hydrolysis control agent tetrabutylammonium hydroxide (TBA)OH and the TiO2 fine particles were crystallized under microwave (MW) irradiation. The X-ray diffraction (XRD) analyses indicated that the fine particles obtained with MW irradiation have much higher crystallinity with a single phase anatase compared with the non-MW-treated solution. The continuous layers of titania were found on RPF-AA fibers by the scanning electron microscopy (SEM) analysis. The fibers with anatase coatings showed high photocatalytic property and better repetition on the photodegradation of MB. The coated fibers were scattered on the water surface and the catalytic reaction proceeded. After completion the decomposition process, the coated fibers were easily recovered using a filter.

2D SAXS/WAXD analysis of pan carbon fiber microstructure in organic/inorganic transformation

Structure of PAN fibers during pre-oxidation and carbonization was studied using two dimensional small angle X-ray scattering/wide angle X-ray diffraction (2D SAXS/WAXD). The SAXS results show that during pre-oxidation between 180 °C and 275 °C, the volume content of microvoids increases with the temperature increasing, which may be one of reasons for the decrease of tensile strength of pre-oxidized fibers. 253 °C was the critical transition temperature, the length, diameter, aspect ratio and orientation distribution of microvoids increased with temperature before this temperature and decreased after this temperature. After the high temperature carbonization, lots of spindly microvoids formed. WAXD patterns demonstrate that the crystallite size of PAN fibers first increased before 230 °C and then decreased with the increase of temperature during the pre-oxidation. The diffraction peak of PAN fibers at 2θ ≈ 17° almost disappeared at the end of preoxidation while the diffraction peak of aromatic structure at 2θ ≈ 25° appeared at 253 °C. During carbonization, the peak intensity at 2θ ≈ 25° increased apparently due to the formation of graphite structure. The results obtained give a deep understanding of the microstructure development in the PAN fibers during pre-oxidation and carbonization, which is important for the preparation of high performance carbon fibers.

Diffusion Coefficients of Dimethyl Sulphoxide (DMSO) and H2O in PAN Wet Spinning and Its Influence on Morphology of Nascent Polyacrylonitrile (PAN) Fiber

Wetspun nascent PAN fibers were immersed into a DMSO/H2O coagulation bath. Diffusion of DMSO from nascent fiber and that of H2O into nascent fiber were studied at different temperatures and concentrations of coagulation bath. The diffusion coefficient of H2O is larger than that of DMSO. As the coagulation bath temperature increased, the diffusion coefficients of DMSO and H2O increased. Diffusion activation energy of DMSO is smaller than that of H2O during the diffusion. Cross sectional and surface structure of nascent PAN fiber were observed in relation to coagulation ability (the product of diffusion coefficients of two solvents). Coagulation ability was found to have a significant influence on both the cross sectional and surface morphology of nascent fiber. To obtain nascent fiber with circular cross sectional and smooth surface morphology, coagulation ability should be controlled at low value.

Preliminary study of in situ transformed carbon fibers/Al 2 O 3 ceramic matrix composites

The fabrication process, formation of carbon fibers and mechanical properties of in situ transformed carbon fibers/Al2O3 ceramic matrix composites prepared by hot-press sintering were investigated. In the sintering process, pre-oxidized polyacrylonitrile fibers (below named as pre-oxidized PAN fibers) were used as the precursors of the in situ transformed carbon fibers at the sintering temperature of 1700 1C. Twice grade heating was employed respectively at 444 1C and 1070 1C for 10 min before reaching the sintering temperature in order to encourage the transformation of pre-oxidized PAN fibers into carbon fibers. XRD analysis shows that the composites present an apparent diffraction peak at 26.31, which corresponds to (002) crystal face of carbon fibers. By EDX analysis the carbon content of the in situ transformed carbon fibers is 92.68%. These evidences certificate the PAN fibers have been in-situ transformed to carbon fibers during the sintering process. The fracture toughness of the composites with 20 vol. % pre-oxidized PAN fibers reaches 6.29 MPa m 1/2 . Compared with 4.75 Mpa m 1/2 of alumina, it is clear that the in-situ transformed carbon fibers remarkably improve the fracture

Preparation and Characterization of Electroless Silver Plating on PAN Fiber with Chelating Agent of APTES/MPTES

Modified by silane coupling agents APTES and MPTES, PAN fiber was provided with multi-chelating-group on it. Through the chelating effect, it can be directly used to eletroless silver plating without roughening, sensitization and activation. The molecule structure, morphology and thermal stability were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and therm-gravimetric (TG) analysis. In addition, electrical conductivity, and washing performance were also tested respectively. The results indicated that silver-coated PAN fiber based on APTES/MPTES modification had high conductivity with a compact and homogeneous silver layer, as well as good washing fastness performance.

Oxidation process of polyacrylonitrile fibers

The effect of the content of active co-monomer, itaconic acid (IA), in PAN fiber on the thermal chemical transformations of the fiber during oxidation was studied. It was shown that the temperature for the start of the exotherm decreased as the IA content increased to 1.8-1.9% and remained constant at 182°C as the content was increased further. A study of the effect of the degree of oxidation on the change of thermochemical characteristics of PAN fiber found that two successive exothermic processes occurred. The difference in their mechanisms was explained by the effect of autocatalysis that was due to catalytically active centers of the macromolecules that arose during the oxidation and contained polyconjugated bonds.

Synchrotron Radiation SAXS Study of Microvoids Structure of PAN Fiber during Spinning Process

The microvoids structure changes of the PAN fibers were characterized by synchrotron radiation SAXS. The synchrotron radiation SAXS patterns and the changes of scattering intensity show that after various fiber spinning process, microviods were gradually oriented in parallel with the fiber axis, and the number of the microvoids was decreased. Fankuchen tangent method was used to deal with the experimental data. After the first coagulation bath, a large number of microvoids were formed in fibers, the aspect ratio was close to 1.0, the shape was nearly spherical, and the radius of gyration (Rg) was 14nm. During plasticizing drawing and washing process, the dimension of microvoids was decreased. Rg was 10nm, the aspect ratio reached 1.6, the shape of the microvoids was nearly ellipsoidal, and the microvoids exhibited preferred orientation along the fiber axis direction. After the processes drying collapsing and drawing in vapor, the scattering intensity of fiber drastically decreased, the number of microvoids significantly reduced, Rg turned to 12.9nm, and the aspect ratio reached 1.9. During heat setting process, the aspect ratio of microvoids reduced, but Rg slightly increased.