scholarly journals CATALYSTS OF ACID-BASE PROCESS ON THE BASIS OF THE MODIFIED CARBON FIBER

2019 ◽  
Vol 85 (7) ◽  
pp. 38-48
Author(s):  
Liudmyla Grishchenko ◽  
Tetiana Bezugla ◽  
Alexander Zaderko ◽  
Anna Vakaliuk ◽  
Oleksandr Mischanchuk ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Chemical Analysis ◽  
Carbon Fibers ◽  
Isopropyl Alcohol ◽  
Fiber Surface ◽  
Surface Oxidation ◽  
Complete Conversion ◽  
Acid Base ◽  
Base Process ◽  
Catalytically Active

The functionalization of the carbon fiber based on polyacrylonitrile with sulfur-containing groups of high acidity was carried out in order to obtain the acid-base processes catalysts. Fibers were treated with sulfur vapors in the temperature range of 400-800°C, followed by surface oxidation with 30% hydrogen peroxide solution. Modified samples were investigated by chemical analysis, thermo-programmed desorption with mass spectrometric registration of products, IR spectroscopy and thermogravimetry. It is shown that the obtained materials contain SO3H-functional groups and oxygen-containing groups (carboxyl, lactone, phenolic, etc.) formed in the surface layer during the oxidation of the fiber surface. The chemical analysis showed that the concentration of sulfur in the samples of the modified fiber is 1.6-6.5 mmol/g. The synthesized samples have a satisfactory thermal stability. The synthesized catalysts were investigated in the model reaction - gas phase dehydration of isopropyl alcohol. It was found that obtained SO3H-containing carbon fibers were catalytically active and had high propylene selectivity. For all the samples obtained there is a complete conversion of alcohol into propylene. The activity of modified carbon fiber samples in the reaction indicated is a fairly high, temperatures of the total conversion of alcohol into propylene are in the range of 160-190°C. During the study of synthesized catalysts in  several cycles of catalysis it have been shown that within repeated use (3 cycles) of all modified fiber samples, the yield of propylene does not decrease, the activity remains stable - the temperature of the dehydration reaction remains unchanged or increases  insignificantly (by 5-10ºС). The temperatures of complete conversion of isopropyl alcohol in propylene for synthesized catalysts are lower than the temperatures of destruction maxima of surface sulfogroups. Thus, modified carbon fibers can be used as low-temperature catalysts of acid-base processes, in particular dehydration of alcohols.

Effect of CNT Grafting on Carbon Fibers on Impact Properties of CFRTP Laminate

2018 ◽  
Vol 774 ◽  
pp. 410-415 ◽  
Author(s):  
Kazuto Tanaka ◽  
Ken Uzumasa ◽  
Tsutao Katayama
Keyword(s):  
Mechanical Properties ◽  
Carbon Fiber ◽  
Carbon Fibers ◽  
Interfacial Strength ◽  
Fiber Surface ◽  
Impact Properties ◽  
Specific Strength ◽  
Out Of Plane ◽  
Reinforced Thermoplastics ◽  
The Impact

Carbon fiber reinforced thermoplastics (CFRTP) are expected to be used as a structural material for aircraft and automobiles not only for their mechanical properties such as high specific strength and high specific rigidity but also for their high recyclability and short molding time. Generally, in a composite material having a laminated structure, interlaminar delamination is often caused by an out-of-plane impact, so the interlayer property plays an important role in the mechanical properties. It has been reported that the fiber/matrix interfacial strength increases by grafting carbon nanotubes (CNT) on the carbon fiber surface. In this study, CNT grafted carbon fibers were used for reinforcement of CFRTP laminate for the improvement of impact properties of CFRTP laminates. The impact absorbed energy of the CFRTP laminate using CNT grafted carbon fibers as reinforcing fiber was higher than that using untreated CF.

Liquid-Phase Oxidation Modification of Carbon Fiber Surface

2012 ◽  
Vol 430-432 ◽  
pp. 2008-2012 ◽  
Author(s):  
Wen Bo Lu ◽  
Cheng Guo Wang ◽  
Hua Yuan ◽  
Xiu Ying Hu
Keyword(s):  
Nitric Acid ◽  
Liquid Phase ◽  
Carbon Fiber ◽  
Carbon Fibers ◽  
Fiber Surface ◽  
Oxidation Time ◽  
Liquid Phase Oxidation ◽  
Acid Oxidation ◽  
Oxidation Treatment ◽  
Phase Oxidation

The carbon fibers were subjected to liquid–phase oxidation treatment in 65% nitric acid solution. The relation between liquid-phase oxidation time and structure of carbon fibers had been assessed by LRS, XRD, SEM, and FTIR. The results indicate that smaller surface crystallites obtained by etching and more unsaturated carbon created after treatment, and corrosion enhanced with the increase of oxidation time. But nitric acid oxidation treatment does not change the bulk structure of carbon fibers. After nitric acid treated, the grooves of surface is wider and deeper compared to the original carbon fiber, When the oxidation times reach 12 hours, the surface of carbon fibers is severely damage. When the oxidation times reach 6 hours, there is not any characteristic peek in the FTIR. But after oxidation treatment for 9 hours, -COOH, -OH can be found from FTIR. So the best time for liquid-phase oxidation process is 9 hours.

Preparation and research of electroless nickel on carbon fiber surfaces

2016 ◽  
Vol 63 (4) ◽  
pp. 256-261 ◽  
Author(s):  
Zhongcai Shao ◽  
Jian Guo ◽  
Pin Liu
Keyword(s):  
Activation Energy ◽  
Carbon Fiber ◽  
Carbon Fibers ◽  
Fiber Surface ◽  
Electroless Nickel ◽  
Transverse Cross Section ◽  
Optical Microscope ◽  
Operating Conditions ◽  
Content Type ◽  
Cold Setting

Purpose The paper aims to introduce the process flow of electroless nickel (EN) plating on carbon fiber surfaces, the effect of former processing on the properties of coating and the dynamics of the process. Design/methodology/approach The coated fibers were mounted in cold-setting epoxy resin, and transverse cross-section of the coated fibers were examined under an optical microscope to ascertain the thickness, uniformity and continuity of the coating over the fiber surface. The coating morphology was studied by using a scanning electron microscope (SEM). This study also determined the activation energy and electrical properties of EN coated on carbon fibers. Findings Activation temperatures have a greater impact on the quality of EN. At a temperature of 80°C, the EN layer prepared was uniform and compact and fully coated the carbon fibers. The optimum components of the EN plating process is NiSO4: 28 g/L; NaH2PO2: 30 g/L; NaAc: 20 g/L; Na3C6H5O7:10 g/L; C4O6H2KNa: 2 g/L; (NH4)2SO4: 18 g/L; thiourea and lead acetate: trace; operating conditions: pH = 8.5, temperature: 70°C; time: 0.5 h). The activation energy of the EN plating on carbon fiber is 12 kJ/mol, and the electrical conductivity of nickel-plated carbon fiber in 80 mL of distilled water is 16.5 μs/cm. Originality/value This paper determined the optimum processing conditions and the activation energy of the EN plating on carbon fiber.

Improving the interfacial properties of carbon fibers/vinyl ester composites by vinyl functionalization on the carbon fiber surface

RSC Advances ◽  
2016 ◽  
Vol 6 (35) ◽  
pp. 29428-29436 ◽  
Author(s):  
Xiuping Zhang ◽  
Liu Liu ◽  
Ming Li ◽  
Yanjie Chang ◽  
Lei Shang ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Carbon Fibers ◽  
Vinyl Ester ◽  
Interfacial Adhesion ◽  
Fiber Surface ◽  
Interfacial Properties ◽  
Resin Composites ◽  
Vinyl Ester Resin ◽  
Adhesion Properties ◽  
Carbon Fiber Surface

APMA functionalized CFs can significantly improve the interfacial adhesion properties of the carbon fiber reinforced vinyl ester resin composites.

Effect of Heat Treatment on Mechanical Properties of Laminated Carbon Fiber Reinforced Polymeric Composites

2016 ◽  
Author(s):  
A. B. M. I. Islam ◽  
Ajit D. Kelkar ◽  
Lifeng Zhang
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Carbon Fiber ◽  
Carbon Fibers ◽  
Fiber Surface ◽  
Fiber Reinforced ◽  
Carbon Fabric ◽  
Carbon Fiber Reinforced ◽  
Fiber Deposition ◽  
Pan Fibers

In recent years use of electrospun nanofibers and nanoparticles to improve the interlaminar properties have increased significantly. In most of the cases the additional interlaminar phase of nanofibers is required to go through various thermal and/or chemical processes. There has been emphasis to optimize the interlaminar nanofiber layers to achieve the optimum desired mechanical properties such as interlaminar strength. One common practice is to disperse nanofibers into the resin and then use the nanofiber enhanced resin to fabricate the laminated composites. However, proper dispersion and fiber filtering out are some of the problems that exist in fabrication using the nanofiber mixed resin approach. To alleviate this problem, an innovative approach of growing PAN (polyacrylnitrile) nano fibers directly on carbon fabric by electrospinning seems to solve the dispersion and fiber filtering problem. However, as PAN fibers require stabilization and carbonization, it is obvious that carbon fabric with PAN fiber deposition will have to undergo stabilization and carbonization process. The effect of stabilization and carbonization heat treatment on the mechanical properties of carbon fiber fabric is not yet fully understood. This paper presents the effects of heat treatment on carbon fabric used for fabricating laminated carbon fiber reinforced composite with epoxy resin. The heat treatment was performed at 280°C in air for six hours, and 1200°C for one hour in nitrogen which are similar to stabilization and carbonization of pure PAN fibers. The effects, due to heat treatment, were mainly characterized in terms of mechanical properties by performing tensile tests and shear tests. Fiber surface topography was observed by SEM to analyze physical changes. Chemical changes, corresponding to the existing groups with carbon fibers, were examined through FTIR. The results obtained are compared with a set of control laminated composite specimens, which were fabricated using heat vacuum assisted resin transfer molding (HVARTM) process and cured at 149°C. The two sets of composite were infused with resin in a single vacuum bag to ensure that both sets of specimens have identical resin infusion and cure cycle. Laminates used for making control specimens were fabricated using carbon fabric which did not undergo any heat treatment. A change in laminate thickness for heat treated carbon fabric was observed indicating a possible bulk up of the carbon fibers due to loss of sizing compounds, which also resulted into significant change in tensile properties.

scholarly journals Wettability of Copper Coated Carbon Fibers

1994 ◽  
Vol 3 (4) ◽  
pp. 096369359400300
Author(s):  
G. Carotenuto ◽  
A. Gallo ◽  
L. Nicolais
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Carbon Fiber ◽  
Carbon Fibers ◽  
Solid Surface ◽  
Fiber Surface ◽  
Wetting Kinetics ◽  
Coated Carbon ◽  
Kinetics Of ◽  
Scanning Electron

The wetting kinetics of a solid surface by a molten metal decrease with increase of its roughness. The topography of the growing copper coating, produced on carbon fiber surface by electroplating from a sulphat bath, has been studied by scanning electron microscopy. The smoothes surface is produced after 200÷300 milliampere-hour of plating.

Improved interfacial and impact properties of carbon fiber/epoxy composites through grafting hyperbranched polyglycerols on a carbon fiber surface

e-Polymers ◽  
2014 ◽  
Vol 14 (2) ◽  
pp. 145-150 ◽  
Author(s):  
Kaiqiang Sui ◽  
Qingbo Zhang ◽  
Yingying Liu ◽  
Lei Tan ◽  
Li Liu
Keyword(s):  
Contact Angle ◽  
Shear Strength ◽  
Carbon Fiber ◽  
Carbon Fibers ◽  
Dynamic Contact Angle ◽  
Fiber Surface ◽  
Dynamic Contact ◽  
Impact Properties ◽  
Carbon Fiber Surface ◽  
Contact Angle Analysis

AbstractGrafting hyperbranched polyglycerols onto a carbon fiber surface is done in an attempt to improve the interfacial and impact properties between carbon fiber and epoxy resin. Scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and dynamic contact angle analysis were performed to characterize the carbon fibers. The TGA result shows that the mass fraction of the hyperbranched polyglycerols grafted onto the carbon fibers surface was 9.03%. The SEM results indicate that the hyperbranched polyglycerols have been grafted onto the carbon surface and that the surface roughness of the carbon fiber significantly increased. The XPS result indicates that oxygen-containing functional groups obviously increased after modification. Dynamic contact angle analysis indicates that the surface energy of modified carbon fibers increased significantly compared with the untreated ones. Results of the mechanical property tests show that interfacial shear strength increased from 59.86 to 80.16 MPa, interlaminar shear strength increased from 57.57 to 73.49 MPa and impact strength simultaneously increased from 2.52 to 3.52 J.

Surface Modification of Recycled Carbon Fibers by Use of Plasma Treatment

2017 ◽  
Vol 742 ◽  
pp. 576-582 ◽  
Author(s):  
Anna Schneller ◽  
Wolfgang M. Mueller ◽  
Ramona Roessle ◽  
Siegfried R. Horn
Keyword(s):  
Carbon Fiber ◽  
Plasma Treatment ◽  
Functional Groups ◽  
Carbon Fibers ◽  
Photoelectron Spectroscopy ◽  
Nitrogen Concentration ◽  
Tensile Modulus ◽  
Fiber Surface ◽  
Plasma Source ◽  
Resin Matrix

In this study, sized and thermally desized virgin carbon fibers (vCF) as well as recycled carbon fibers (rCF) from a thermal recycling process are plasma treated by a plasma-jet. The effect of two different process gases (nitrogen and dinitrogen monoxide) and the influence of the distance between the plasma source and the fiber surface are studied with the aim of increasing the oxygen and nitrogen concentration on the rCF surfaces. Higher surface coverage of oxygen-and nitrogen-containing functional groups is supposed to lead to a better adhesion between the carbon fiber and the epoxy resin matrix. The elemental compositions and functional groups of the treated carbon fiber surfaces are studied by x-ray photoelectron spectroscopy. The effect of plasma treatment on the fiber properties like tensile strength, tensile modulus and surface roughness is investigated.

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