Carbon Resin Research Articles

Influence of oxidation upon the CO2 capture performance of a phenolic-resin-derived carbon

The effect of oxidation upon the CO2 capture performance has been studied taking a phenolic resin carbon as the base material. Oxygen surface groups were introduced through liquid and gas phase oxidation treatments, using ammonium persulfate, nitric acid and air, respectively. The surface chemistry of the final carbon is strongly affected by the type of oxidation treatment: liquid phase oxidation introduces a greater amount of oxygen, mostly as carboxylic groups; these are absent in the gas phase oxidised sample that contains mainly ether and carbonyl functionalities. The porous texture of the samples is also affected by the oxidation treatment: through liquid phase oxidation the pore volume is somewhat reduced, while this is slightly developed by air treatment at 693K. Despite the reduction in the porous volume and the acidic surface, liquid-phase oxidised samples present greater CO2 adsorption capacity than the starting carbon due to Lewis acid–base interactions with the CO2 molecule. Moreover: oxidised samples are easily regenerated, and observed heats of adsorption are typical from physisorption processes, which will facilitate the adsorbent regeneration in cyclic adsorption processes. Oxidation is therefore proposed as a plausible modification technique for developing easy-to-regenerate carbon adsorbents with enhanced CO2 capture performance.

A SIMPLE METHOD OF APPLYING CARBON FOAM COATING FOR CARBON/CARBON COMPOSITES TO MODULATE CELL COMPATIBILITY

A simple slurry method was used to prepare carbon foam coatings on biomedical carbon/carbon composites to modulate the cell compatibility. The surface morphology and microstructure of the coatings were characterized and the effect of applying carbon foam coatings on cell morphology and cell proliferation was investigated. The results showed that the carbon foam coatings, consisting of carbon microspheres, resin carbon matrices and pores, covered the carbon/carbon composites entirely and uniformly with amorphous structures. There were large numbers of pores with a size ranging from submicron to tens of micrometers being found for the coatings. The cell culture experiments exhibited that both the cell spreading and the cell proliferation were improved after the preparation of the carbon foam coatings. It could be demonstrated that applying carbon foam coatings by a simple slurry method was an effective way to improve the cell compatibility of carbon/carbon composites.

Fiber/matrix interfacial shear strength of C/C composites with PyC–TaC–PyC and PyC–SiC–TaC–PyC multi-interlayers

The fiber/matrix (F/M) interfacial shear strength (IFSS) of carbon/carbon (C/C) composites with PyC–TaC–PyC and PyC–SiC–TaC–PyC multi-interlayers was investigated. To obtain C/C composites with PyC–TaC–PyC and PyC–SiC–TaC–PyC multi-interlayers, a thin layer of PyC was deposited on carbon fibers. After this, TaC and SiC–TaC layer(s) were uniformly deposited on the PyC coated carbon fibers. As an outer-layer, a PyC layer was deposited on these TaC and/or SiC–TaC coated carbon fibers by isothermal chemical vapour infiltration (CVI) and then densified with resin carbon by impregnation and carbonization. Finally, C/C composites with PyC–TaC–PyC and PyC–SiC–TaC–PyC multi-interlayers were obtained. The effects of PyC–TaC–PyC and PyC–SiC–TaC–PyC multi-interlayers on interfacial shear strength (IFSS) of C/C composites were investigated. Single fiber push-out tests were conducted on the fibers aligned perpendicularly on the thin slices specimen surface using nano-indentation. Results showed that the IFSS of C/C composites decreased with the introduction of PyC–TaC–PyC and PyC–SiC–TaC–PyC multi-interlayers. After heat treatment (at temperatures ranging from 1400 to 2500 °C) of C/C composites with PyC–TaC–PyC multi-interlayers, it was found that the IFSS decreased with the increase in temperature. This decrease in IFSS is explained by taking into account the microstructural variations on heat treatment.

Interface characteristics of nanorope reinforced polymer composites

A shear-lag model is proposed to obtain interface characteristics of nanorope reinforced polymer composites using representative volume element (RVE) concept. In the axisymmetric RVE, the nanorope is modelled as a closed-packed cylindrical lattice consisting seven single-walled carbon nanotubes. In the model, rope is considered to be perfectly bonded with the polymer resin where the nanotubes are assumed to be chemically non-bonded with each other in the rope system. Since, nanotubes are considered to be non-bonded in the nanorope there must exist a van der Waals interaction in terms of Lennard-Jones potential. A separate model is also proposed to determine the cohesive stress caused by this interaction. Closed form analytical solutions are derived for stress components of rope, resin and individual carbon nanotubes in the rope system. Parametric study has also been conducted to investigate the influences of key composite factors involved at both perfectly bonded and non-bonded interfaces.

Hierarchical porous carbon spheres as an anode material for lithium ion batteries

Hierarchical porous carbon spheres are prepared by the carbonization of a D201 anion-exchange resin. These carbon spheres are characterized by X-ray diffraction, Raman spectroscopy, nitrogen adsorption–desorption and electron microscopy. The lithium ion storage capacity of these carbon spheres is evaluated by galvanostatic measurements. The initial discharge–charge capacities of the material are 1213 and 798 mA h g−1 at a current density of 0.1 A g−1, respectively. A discharge capacity of 506 mA h g−1 is still retained when charge–discharged at 1.0 A g−1 for 50 cycles. The large reversible capacity, high rate performance and good cycleability are attributed to the unique hierarchical porous structure featured by large surface area, readily accessed porous channels and the highly graphitized carbon shells. The carbonization of a cheap anion-exchange resin can be easily scaled-up, making the hierarchical porous carbon spheres a promising low-cost anode material for high performance lithium ion batteries.

Nanocasting synthesis of graphitized ordered mesoporous carbon using Fe-coated SBA-15 template

Ordered mesoporous carbons with high porosities and graphitized structures were synthesized by a template-catalysis method using low-molecular-weight phenolic resin as carbon precursor and Fe-coated SBA-15 as both template and catalyst. The synthesis route involves the following steps: (a) the synthesis of mesoporous Fe-coated SBA-15 through a one-pot method, (b) the infiltration of a low-molecular-weight phenolic resin into the porosity of the Fe-coated SBA-15, (c) the carbonization and catalytic graphitization of the infiltrated phenolic resin at 900 °C, and (d) the removal of the Fe-coated SBA-15 template. The X-ray diffraction, nitrogen sorption, transmission electron microscopy and scanning electron microscopy were used to characterize the materials, and the results indicate that the prepared carbon materials have well-ordered mesoporous structures replicated from the templates, and graphitized structures can be observed on the carbon frameworks, depending on the iron content in the templates.

Tribological Characteristics of Different Components on C/C-SiC Composites Fabricated by Warm Compacted <i>In Situ</i> Reaction

C/C-SiC brake composites, based on reinforcement of carbon fiber and dual matrix of carbon and silicon carbide, were fabricated by warm compacted-in situ reacted process. Rules about the influence of different components on the friction and wear characteristics of the C/C-SiC composites are ascertained. As hard particle, the SiC has the function to the formation of friction film, which is in favor of increasing the coefficient of friction (COF) and decreasing the wear rate. The resin carbon plays the role of enhancing the COF, but they are easy to be cut and increase the wear rate. The graphite plays the lubrication function, and right volume content of graphite is helpful to forming friction film to reduce the wear rate. The C/C-SiC composite fabricated by the warm compacted-in situ reaction can with best tribological performance when the components volume fraction of carbon fibre, SiC, graphite and resin carbon are 15.5%, 37.0%, 22.1% and 20.8%, respectively, which the COF and the wear rate can reach the maximum and the minimun value of 0.44 and 1.1μm/cycle respectively.

Effect of nanosilica on characteristics of carbonizates of phenol-formaldehyde resin – Fe(acac)3

A series of carbon–iron–silica (CIS) composites (carbonizates) were prepared by carbonization of phenol-formaldehyde resin – Fe(III) acetylacetonate mixtures with addition of different amount of nanosilica A380 and compared with a composite prepared without silica (CFe composite). The characteristics of the composites differ because two type iron silicates were formed at a surface of silica nanoparticles and affected structure of carbon–iron phases. The textural characteristics of the CIS composites show a decrease in meso- and macroporosity and an increase in nanoporosity because new nanoparticles are formed in voids between silica nanoparticles. The CFe particles, including graphite-like structures, metallic iron nanoparticles and Fe3C, are larger than the CIS particles, which also include iron silicates, amorphous and crystalline silica. The presence of metallic α-Fe nanoparticles can provide the magnetic properties of the composites.

Bipolar plates made of carbon fabric/phenolic composite reinforced with carbon black for PEMFC

Polymer electrolyte membrane fuel cell or proton exchange membrane fuel cell (PEMFC) is composed of bipolar plates, end plates, membrane electrode assemblies (MEAs) and gas diffusion layers (GDLs). Among the constituents of PEMFCs, the bipolar plates are major components, which make up a large portion of the stack volume and cost.In this study, the bipolar plate has been fabricated using carbon fabric/phenolic composite for mass production because the phenolic resin cures much faster than epoxy resin. Because the phenolic resin becomes brittle after being fully cured, it is mixed with carbon black to increase the ductility. The surface of the carbon fabric/phenolic composite bipolar plates has been treated with flame to reduce the interfacial contact resistance.The experimental results show that the contact resistance of the carbon fabric/phenolic composites bipolar plate decreases as the flame-treatment temperature and time increase due to the degree of carbonization of the phenolic resin, while the flexural strength decreases because the carbonization of phenolic resin increases its brittleness. Therefore, the optimum flame surface treatment temperature and processing time for the carbon fabric/phenolic composite bipolar plates are investigated to optimize the electrical conductivities and mechanical properties.

Ordered nanoporous carbon for increasing CO2 capture

Ordered nanoporous carbons (ONCs) were prepared using a soft-templating method. The prepared ONCs materials were subjected to a controlled carbonization temperature over the temperature range, 700–1000°C, to increase the specific surface area and total pore volume of ordered nanoporous carbon followed by carbonization of the phenolic resin. ONCs materials synthesized at various carbonization temperatures were used as adsorbents to improve the CO2 adsorption efficiency. The surface properties of the ONCs materials were examined by X-ray photoelectron spectroscopy. The structural properties of the ONCs materials were analyzed by X-ray diffraction. The textural properties of the ONCs materials were examined using the N2/77K adsorption isotherms according to the Brunauer–Emmett–Teller equation. The CO2 adsorption capacity was measured by CO2 isothermal adsorption at 298K/30bar and 298K/1bar. The carbonization temperature was found to have a major effect on the CO2 adsorption capacity, resulting from the specific surface area and total pore volumes of the ONCs materials.

Conversion of diatomite to porous Si/C composites as promising anode materials for lithium-ion batteries

Diatomite, a natural clay mineral, is mainly composed of silica and contains a large number of fine microscopic pores. In the present work, a series of porous Si/C composites are successfully synthesized by employing diatomite as a raw material, followed by low temperature magnesiothermic reduction, impregnation and carbonization of phenolic resin. The obtained Si/C composites are consisted of porous Si coated with a 15 nm thick amorphous layer of carbon. Porous Si/C composites with different ratios of Si and C are investigated as anode materials for Li-ion batteries. The porous Si/C composite containing 33% carbon exhibits the highest reversible capacity of about 1628 mAh g−1 at the first cycle with excellent capacity retention in the following cycles. Moreover, the porous Si/C composites display the excellent rate performance at high current densities such as 1 and 2 A g−1. The optimum electrochemical performance could also be tuned by varying the proportions of porous Si and carbon precursors during the preparation process. The results indicate that the natural pore structures of Si and C are conducive to the electrochemical performance and clay mineral diatomite could be considered as a promising raw material for Si/C composites for lithium-ion batteries.

Preparation and characterization of nanocomposites based on amino group-terminated multi-wall carbon nanotubes and bismaleimide resin

In this work, a novel nanocomposite consisting of bismaleimide resin (BMI) and amino group-terminated multi-wall carbon nanotubes (NH2-MWNTs) have been discussed. The fluorinating MWNTs (F-MWNTs) were synthesized by solid-phase method and the NH2-MWNTs were prepared by interaction of the F-MWNTs with 1,2-diaminoethane. The NH2-MWNTs/BMI nanocomposites have been prepared by solution blend method. Their morphology and properties were characterized by transmission electron microscope, fourier transmission infrared, X-ray diffraction, scanning electron microscopy, etc. The results showed that impurities in the MWNTs were removed after the purification treatment and amine groups have been successfully attached to the purified MWNTs. The impact strength of the NH2-MWNTs/BMI nanocomposites increased firstly as the NH2-MWNTs increased and then decreased. When the content of the NH2-MWNTs is 0.6 wt%, the impact strength of nanocomposites is optimal (about 12.57 kJ/m2) which increase by 58.51% compared with the neat BMI resin.

Decomposition of 2,2′,4,4′,5,5′-hexachlorobiphenyl with iron supported on an activated carbon from an ion-exchange resin

An activated carbon (AC) containing a high concentration (374mgg−1) of Fe was prepared by carbonization of an ion-exchange resin. To examine its chemical reactivity as a catalyst to decompose 2,2′,4,4′,5,5′-hexachlorobiphenyl (PCB-153), the decomposition parameters of temperature and time were varied under air or N2. Decomposition at 350°C was achieved within 15min under air and 30min under N2, and the efficiency of PCB-153 decomposition was 99.7% and 98.0%, respectively. An analysis of inorganic chloride ions revealed that PCB-153 was mineralized effectively during the decomposition. The Brunauer–Emmett–Teller (BET) surface area and pore volume of the AC were measured to assess the adsorption capacity before and after the decomposition. The differences between decomposition under air and N2 reflected the differences in the BET surface and pore volume measurements. A decomposition pathway was postulated, and the reactive characteristics of chlorine atoms loaded on the benzene rings followed the order of para>meta>ortho, which agrees with the calculated results from a density functional theory study.

Structural changes in four different precursors with heat treatment at high temperature and resin carbon structural model

Four precursors (mesophase pitch, condensed polynuclear aromatic resin, polyimide resin, and thermo- setting phenolic resin) were heat treated at temperatures from 900 to 3000 C. These products were characterized by X-ray diffraction, transmission electron microscopy, and helium adsorption density instruments. Heterogeneous graphitization was observed above 2200 C in the resin carbons. Various constituents (amorphous, turbostratic, and graphitic) coexisted and transformed from being disordered to ordered with increasing treatment temperature. The molecular structures of the starting materials played important roles in the proportions of various constituents, crystallite sizes, and preferred orientation of the graphitic constituent of the different carbons during high temperature treatment. High-resolution transmission electron micros- copy images showed that the structural features of Jenkins' and Shiraishi's model all existed in three resin carbons. Based on these results, we think that their structures are not belong to Jenkins' model, also do not belong to Shiraishi's model, are a complex of above two models.

Mesua Ferrea L. Seed Oil Modified Sulfone Epoxy Resin and Multi-Walled Carbon Nanotube Nanocomposites and Their Biomedical and Mechanical Properties

<i>Mesua Ferrea</i> L. Seed Oil Modified Sulfone Epoxy Resin and Multi-Walled Carbon Nanotube Nanocomposites and Their Biomedical and Mechanical Properties

Investigation of porous carbon fabricated by polymer blending of phenolic resin and suberic acid

Porous carbons used for electric double-layer capacitors were fabricated by chemical blending and carbonization of phenolic resin (PF) and suberic acid (SA). The reaction of PF with diacid was confirmed by longer wavelength shift of carbonyl stretching peak of diacid in FTIR spectra and higher decomposition temperature of suberic acid in TG curves. The decomposition of suberic acid at high temperature contributed to the formation of micropores in PF resin during carbonization process. The influence of the ratio of PF to SA on pore structure, adsorption behavior and capacity performance was investigated. The specific surface area and total pore volume increase with decrease of ratio of PF to SA at first and then decrease. The maximum specific surface area and total pore volume were obtained at ratio 3, which corresponds to 511 m2 g−1and 0.26 cm3 g−1, respectively. Electrochemical investigation indicates that a satisfactory specific capacitance of 145 Farad g−1 in 30 wt% KOH aqueous electrolytes is obtained. The capacitance maintenance achieves 72% as the current density increases 50 times. Porous carbon with reasonable pore structure was produced by chemical blending of diacid and phenolic resin, which offers a new development direction for preparation of porous carbon materials.

Activation-free preparation of porous carbon by carbonizing phenolic resin containing pore-forming substance

This paper describes an activation-free preparation of porous carbon by carbonization of a phenolic resin (PF) containing pore formers such as m-phthalic acid (PA), trimesic acid (TMA), and phloroglucinol (PG). Monitoring of their carbonization behaviors by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) suggested that PA and TMA, which have carboxylic functional groups, decomposed as single components, i.e., they had little interaction with PF. This left pores in the obtained carbon, as shown by N2 adsorption/desorption measurements. PG, which has phenolic groups, can interact strongly with PF, and no porous structure developed in PG/PFC. This strong interaction could prevent PG from decomposing individually and leaving pores in the carbon. It was also suggested that the presence of phenolic groups might cause interactions in the blend; we therefore suggest that pore formers with carboxyl groups would be appropriate in polymer blend carbonization techniques.

Effect of interfacial interaction on free volumes in phenol-formaldehyde resin–carbon nanotube composites: positron annihilation lifetime and age momentum correlation studies

The phenol-formaldehyde-carbon nanotube composites were characterized for their free volume properties and interfacial interactions between nanotubes and the polymer matrix. The base polymeric material was a novolac type phenol-formaldehyde (PF) condensation resin cross-linked with para-toluene sulfonic acid. Multi-wall carbon nanotubes (MWCNTs) were synthesized using a catalytical chemical vapor deposition method and characterized using high-resolution transmission electron microscopy. The PF resin-carbon nanotubes composites having 2, 5, 10 and 20% (w/w%) MWCNTs were prepared. The crystallinity and morphology of the samples were characterized using X-ray diffraction and scanning electron microscopy. The free volume size in the polymer nanocomposites was observed to increase with the increase in nanotube content. Positron age momentum correlation (AMOC) studies revealed the electronic environment around different positron annihilation sites. The studies showed that ortho-positronium principally annihilates from interfacial regions of polymer and nanotubes in the nanocomposite. The positron lifetime studies together with AMOC measurements indicate an increase in the free volumes at the interface of polymer and MWCNTs in the composite. The free positron intensities showed that the polymer and nanotubes are weakly interacting in this system.

Microstructure evolution process of porous silicon carbide ceramics prepared through coat-mix method

Porous silicon carbide ceramics were prepared through the coat-mix method and molding, carbonization and sintering process with silicon powders and phenolic resin as raw materials. The crystalline phase, microstructure, and porosity of samples treated at different stages were characterized. Results showed that the fabricated porous silicon carbide ceramics consist of pure β-SiC phase with a homogeneous structure and porosity of above 60%. Each of the processing stages, including coat-mix, molding, carbonization, and sintering, has certain contribution to the porosity of the final porous silicon carbide ceramics, in which the mole ratio of resin carbon to silicon and the molding temperature are the main factors to affect the porosity. A porosity evolution process of porous silicon carbide ceramics during fabrication process was also proposed.

Interphasial viscoelastic behavior of CNT reinforced nanocomposites studied by means of the concept of the hybrid viscoelastic interphase

AbstractIn this study the effect of carbon nanotubes content as well as of the tensile stress level applied upon the linear viscoelastic creep response of carbon nanotube polymer nanocomposites was investigated. Experimental findings were modeled by means of the newly developed hybrid viscoelastic interphase model, which constitutes an extension of the previously developed hybrid interphase model. According to this model, the viscoelastic interphase thickness has not of constant value but is dependent upon the property considered at the time as well as on the creep time. In addition, the parameter of imperfect bonding is introduced through the degree of adhesion. Experimental findings combined with analytical results gave a better understanding of the viscoelastic response of epoxy resin carbon nanotubes nanocomposites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012