Effect Of Stabilization Temperature Research Articles

Effect of Thermal Stabilization on PAN-Derived Electrospun Carbon Nanofibers for CO2 Capture.

Carbon capture is amongst the key emerging technologies for the mitigation of greenhouse gases (GHG) pollution. Several materials as adsorbents for CO2 and other gases are being developed, which often involve using complex and expensive fabrication techniques. In this work, we suggest a sound, easy and cheap route for the production of nitrogen-doped carbon materials for CO2 capture by pyrolysis of electrospun poly(acrylonitrile) (PAN) fibers. PAN fibers are generally processed following specific heat treatments involving up to three steps (to get complete graphitization), one of these being stabilization, during which PAN fibers are oxidized and stretched in the 200–300 °C temperature range. The effect of stabilization temperature on the chemical structure of the carbon nanofibers is investigated herein to ascertain the possible implication of incomplete conversion/condensation of nitrile groups to form pyridine moieties on the CO2 adsorption capacity. The materials were tested in the pure CO2 atmosphere at 20 °C achieving 18.3% of maximum weight increase (equivalent to an uptake of 4.16 mmol g−1), proving the effectiveness of a high stabilization temperature as route for the improvement of CO2 uptake.

PI/NCC- based carbon molecular sieve membranes for Hydrogen purification: Effect of aging times

In this study, the effect of stabilization temperature on the performance of tubular carbon Upgrade the gas separation performance of the resultant carbon molecular sieve (CMS) membrane, a synthesized nanocrystalline cellulose (NCC) utilizing tissue paper as an added substance was included into the simpleton arrangement at pyrolysis temperatures of 800°C. This paper shows the inference of CMSs from BTDA-TDI/MDI polyimide (PI) arranged by means of a dip-coating strategy on an inorganic cylindrical help surface, trailed by a heat treatment (adjustment and carbonization) under Ar gas stream. Extraordinary consideration was given to the physicochemical attributes of the subsequent PI/NCC-based CMS and its comparing gas permeation properties. Pure gas permeation tests were performed utilizing H2, and N2 at room temperature. The gas permeation information showed that the CMS displayed an amazing performance contrasted with the polymeric membrane. Upgrade in the two gas permeance and selectivity were watched arranged with fresh CMS membrane, with H2N2 selectivity of 434.68±1.39, regarding the neat CMS. By controlling different aging times (fresh, 1 day, multi week, and 3 months), CMSs with various structures and properties were gotten.

CO2 Selective Carbon Tubular Membrane: The Effect of Stabilization Temperature on BTDA-TDI/MDI P84 co-polyimide

Membranes offer remarkable attributes such as possessing small equipment footprints, having high efficiency and are environmentally friendly, with carbon membranes progressively investigated for gas separation applications. In this study, carbon tubular membranes for CO2 separationare prepared via the dip-coating method with P84 co-polyimide as the carbon precursor. The prepared membranes were characterized using Thermogravimetric Analysis (TGA), pore structure analysis Brunauer-Emmett-Teller (BET), Fourier Transform Infrared Spectroscopy (FTIR) and pure gas permeation system. The permeation properties of the carbon membranes are measured and analyzed by using CO2, CH4 and N2 gases. The P84-based carbon tubular membrane stabilized at 300°C and featured excellent permeation properties with permeance range of 2.97±2.18, 3.12±4.32 and 206.09±3.24 GPU for CH4, N2 and CO2 gases, respectively. This membrane exhibited the highest CO2/CH4 and CO2/N2 selectivity of 69.48±1.83 and 65.97±2.87, respectively.

Effect of stabilization temperature during pyrolysis process of P84 co-polyimide-based tubular carbon membrane for H2/N2 and He/N2 separations

In this study, the effect of stabilization temperature on the performance of tubular carbon membrane was being investigated. P84 co-polyimide-based tubular carbon membrane will be fabricated through the dip-coating technique. The tubular carbon membrane performance can be controlled by manipulating the pyrolysis conditions which was conducted at different stabilization temperatures of 250, 300, 350, 400, and 450°C under N2 environment (200 ml/min). The prepared membranes were characterized by using scanning electron microscopy (SEM), x-ray diffraction (XRD), and pure gas permeation system. The pure gas of H2, He, and N2 were used to determine the permeation properties of the carbon membrane. The P84 co-polyimide-based tubular carbon membrane stabilized at 300°C demonstrated an excellent permeation property with H2, He, and N2 gas permeance of 1134.51±2.87, 1287.22±2.86 and 2.98±1.28GPU, respectively. The highest H2/N2 and He/N2 selectivity of 380.71±2.34 and 431.95±2.61 was obtained when the stabilization temperature of 450°C was applied. It is concluded that the stabilization temperatures have protrusive effect on the carbon membrane properties specifically their pore structure, and eventually their gas separation properties.

Electrical conductive and structural characterization of electrospun aligned carbon nanofibers membrane

In the paper, the membrane with aligned carbon nanofibers (CNFs) was prepared by electrospinning, stabilization and carbonization. The electrical conductivity of the membrane was examined. The effect of stabilization temperature and drum rotating speed on the conductivity of aligned CNFs membrane was discussed. The study on stabilization temperature showed that 250 °C was optimum parameter for preparing fibrous aligned CNFs membrane with uniform diameter, but 270 °C was benefit to fiber conglutination which could improve the electrical conductivity of the final CNFs membrane. The study on drum rotating speed showed that when drum rotating speed reached 2500 rpm, graphitic structures with parallel graphene sheets could be observed and 1000, 1500 and 2000 rpm CNFs membranes presented desirable conductivity with only 1.3 Ω·cm in the parallel directions and 2.0 Ω·cm in the perpendicular direction.

Effects of Stabilization Temperature on the Chemical and the Physical Properties of Polyacrylonitrile Stabilized Fibers

The present work dealt with the preparation of carbon fibers from Polyacrylonitrile (PAN)/ acrylamide (AM) fibers via a solvent-free coagulation process. The PAN/AM fibers were stabilized in an oxidizing atmosphere at various temperatures (200, 250, 275, and 300 °C), while the stabilization time was fixed at thirty minutes. The effects of stabilization temperature on the chemical and the physical properties of the prepared stabilized fibers were studied. The chemical structure evolutions of stabilized fibers (SFs) from the precursor fiber were observed with FTIR studies, whereas the microstructure properties were thoroughly characterized with SEM studies. The mechanical strengths of the SFs were obtained from the Young Modulus and the tensile strength analyses. Stabilization temperature at 275°C had been identified as the optimum stabilization temperature for the PAN/AM fibers.

Effects of the stabilization temperature on the structure and properties of polyacrylonitrile-based stabilized electrospun nanofiber microyarns

Polyacrylonitrile (PAN) precursor nanofiber microyarns were successfully synthesized using a modified electrospinning method, and then were stabilized at different stabilization temperatures. Effects of stabilization temperature on the structure, thermal, and mechanical properties of stabilized microyarns were studied by FTIR, XRD, DSC, TG, and mechanical behavior test. It was found that when the stabilization temperature was above 250 °C, cyclization and dehydrogenation reactions were basically completed, and PAN crystal microstructure was almost completely destroyed, as well as the thermally stable ladder structure was formed. The results also showed that the strength of the stabilized microyarns increased to a threshold value and started to reduce thereafter as the stabilization temperature increased.

Effect of stabilization temperature on gas permeation properties of carbon hollow fiber membrane

AbstractCarbon hollow fiber membranes (CHFMs) derived from polymer blend of polyetherimide (PEI) and polyvinylpyrrolidone (PVP) were extensively prepared through stabilization under air atmosphere followed by carbonization under N2 atmosphere. The effects of the stabilization temperature on the morphological structure, chemical structure, and gas permeation properties were investigated thoroughly by means of scanning electron microscopy, Fourier transform infrared spectroscopy, and single gas permeation system. The experiment results indicate that the transport mechanism of small gas molecules of N2, CO2, and CH4 is dominated by the molecular sieving effect. Based on morphological structure and gas permeation properties, an optimum stabilization condition for the preparation of CHFM derived from PEI/PVP was found at 300°C under air atmosphere. The selectivity of ˜55 and 41 for CO2/CH4 and CO2/N2, respectively, were obtained for CHFMs prepared at stabilization temperature of 300°C. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Effects of Stabilization Temperature on Structures and Properties of Polyacrylonitrile (PAN)-Based Stabilized Electrospun Nanofiber Mats

An improved heat treatment strategy for electrospun polyacrylonitrile (PAN)-based nanofiber mats is developed. Polyacrylonitrile nanofiber mats were fabricated by electrospining and then were stabilized at different temperatures. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and mechanical testing were used to study the effects of temperature (for times of 1 h) on the structures and properties of PAN-based heat stabilized electrospun nanofiber mats. Results showed that at temperature below 250°C, the structure conversion of PAN nanofibers was not obvious. However, when the stabilization temperature was above 260°C, PAN nanofibers became thermally stable and the aromatization indices increased rapidly to 55.8%, which is preferable for stabilized PAN nanofiber mats. After thermal treatment up to 270°C, most of the C≡N groups in PAN macromolecules change to C˭N groups, implying that the cycling reaction was almost complete at 270°C. The tensile strength of the nanofiber mats revealed that for the highest mechanical properties of the nanofiber mats, the stabilization temperature should be around 260°C.

Effect of Stabilization Temperature on the Degradation of Adriamycin Ik Albumin Microspheres

The effect of stabilization temperature on the degradation of adriamycin HCl during the preparation of albumin microspheres was investigated. The degradation of adriamycin HCl by heating at various temperature with different time interval in dried adriamycin HCl powder, adriamycin HCl aqueous solution, wetted Adriablastina (adriamycin HCl with lactose) powder and Adriablastina aqueous solution was also studied. In the presence of water the degradation of adriamycin HCl was found; whereas, in the absence of water no degradation occurred. The degradation of adriamycin HCl in solution and wetted powder showed a zero order reaction. An increase in temperature increased degradation rate. The rate constant for adriamycin HCl degradation in Adriablastina solution obtained was in good agreement with that in adriamycin HCl solution. It was suggested that the presence of lactose had no interference in the degradation of adriamycin HCl. The zero-order reaction of degradation was attributed to the drug behaved like a suspension. The degradation of adriamycin HCl at various stabilization temperature during the preparation of microspheres had the same tendency as those of the adriamycin HCl solution and the wetted adriamycin HCl powder that were heated by the DSC instrument with the condition similar to the preparation of microspheres.

Factorial design based optimization of the formulation of albumin microspheres containing adriamycin

The use of factorial design in the formulation of adriamycin-associated albumin microspheres, using the heat-stabilization technique, is illustrated. The effect of stabilization temperature, protein concentration and stabilization time on the entrapment and recovery of adriamycin in microspheres have been investigated using a 2 x 4 x 4 factorial design. The associated drug content in unwashed and four times washed microspheres was determined using HPLC. Maximum drug association and drug recovery were obtained from microspheres synthesised using 25 per cent w/v albumin solution and stabilized at 120 degrees C for 2.5 min. Under these conditions, the entrapped and total associated drug content of the microspheres was about 4 per cent and 12 per cent w/w respectively, and the drug recovery was about 75 per cent. The in vitro dissolution study carried out using dynamic dialysis revealed that the release of adriamycin from these particles follows a bi-phasic pattern. The results demonstrate that use of short stabilization time, low protein concentration and low stabilization temperature are required for the formulation of microspheres with high adriamycin content.

Albumin microspheres. II. Effect of stabilization temperature on the release of adriamycin

The effect of stabilization temperature on the rate of release of adriamycin from bovine serum albumin (BSA) microspheres has been evaluated: Microspheres were prepared at 105, 120, 135 and 150°C and washed 1–4 times to remove the surface drug before the release study. Release profiles depend on the number of washing steps employed. Microspheres subjected to two or less washings exhibit a tri-phasic zero-order release of adriamycin, whereas four washings of the carrier shows a bi-phasic zero-order release pattern. The in vitro dissolution results indicate that the rate of release of adriamycin from the microspheres decreases with an increase in stabilization temperature of the carrier and the release of entrapped drug can be controlled.