Phenolic Carbon Research Articles

Preparation of a Hierarchically Porous Lead/Carbon Composite and Its Application in Lead‐Carbon Batteries

A novel and scalable lead-modified phenolic resin-based carbon material (Pb/PRC) has been successfully prepared by using lead-modified phenolic resin (Pb/PR) as a precursor, toluene as a pore-forming agent, and KOH as an activating agent. The Pb/PRC composite presents a hierarchically porous nanosphere structure, and this structure contributes to prolong its cycling life under high-rate partial state-of-charge (HRPSoC) operation. Pb/PRC with nano-lead can effectively inhibit hydrogen evolution and provide pseudocapacitance. Compared with a blank negative plate, a lead-carbon battery with Pb/PRC displays 18 000 cycles under HRPSoC operation and exhibits a capacity of 100 mA h g-1 at 2 C discharge rate.

Preparation of Si-SiOx nanoparticles from volatile residue produced by refining of silicon

Residual Si was produced on a furnace wall when upgraded metallurgical grade Si was refined by electron beam melting. It was then recycled to prepare Si-SiOx nanoparticles with an average size of 100 nm by planetary ball milling. The obtained Si-SiOx nanoparticles mainly consist of amorphous Si, crystalline Si and amorphous SiOx, which was confirmed by XRD, FTIR, XPS and TEM. SiOx is mainly composed of SiO2 and SiO1.35. Distilled water used as a grinding aid not only enhances milling efficiency, but also plays a key role in obtaining SiOx. During refining of upgraded metallurgical grade Si, the deposition pattern of residual Si on furnace wall agrees with model of three-dimension growth. Growth of Si-SiOx nanoparticles is the mutual effect of distilled water and ball milling. Si-SiOx nanoparticles were doped into phenolic resin pyrolysis carbon as anode materials for lithium ion batteries, and 10% doping was observed to improve the specific capacity. After 500 cycles, specific capacity of delithiation remained around 550 mA h/g. It suggests the residual Si is a value-added by-product, and it can be recycled as anode materials for lithium ion batteries.

Lightweight, high electrical and thermal conducting carbon-rGO composites foam for superior electromagnetic interference shielding

Lightweight and high strength carbon-rGO composite foams were inventively fabricated by simple sacrificial template technique using reduced graphene oxide (rGO) and phenolic resin as a carbon source. The carbon-rGO composite foams were fabricated by two different routes. In one case, rGO was incorporated in phenolic resin and carbon foam developed by several heat treatments. In the other case, graphene oxide (GO) was decorated over carbon foam and converted into rGO decorated carbon foam by heat treatment. The EMI shielding of carbon-rGO composite foams was measured in the X-band frequency range (8.2–12.4 GHz) and mechanisms were systematically studied with respect to the rGO and porous structure. The EMI SE of carbon foams was increased from −23.2 to −50.7 dB by the decoration of 1.0 wt % rGO. The thermal conductivity achieves as high as 1.4 W/(m K) by incorporation of 4.0 wt % rGO in carbon foam. All the results indicated that this effort provided a novel, simple, low-cost concept for fabricating lightweight, high electrical and thermal conducting carbon-rGO composite foam for high-performance EMI shielding applications.

Thermal behavior of gradient charring materials with improved iterative method

ABSTRACTThe lightweight material of the thermal protection system for a reentry vehicle has become a trend in order to maximize the payload. To explore the effect of gradient density on the thermal behavior of charring materials, a pyrolysis layer model considering of variable density is developed and discretized with the central difference method. An iterative method is improved to look for the locations of the moving interfaces and boundary in each time step. Taken different gradient phenolic impregnated carbon ablator under a return trajectory heat flux for the Orion vehicle as example, their thermal behavior and effective heat capacities are simulated using the code written. Numerical results indicate that the gradient designs can improve the thermal protection performance of charring materials effectively. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47076.

Synthesis and carbonization of nickel-modified thermoplastic phenolic resin

The use of formaldehyde and phenol as raw materials, under the acidic catalyst, the high temperature polymerization produces a thermoplastic phenolic resin. At low temperatures, modified nickel sulfate is added to synthesize Ni-modified thermoplastic phenolic resin, and carbonization is carried out at high temperature. The effects of carbonization temperature, carbonization heating rate and nickel doping amount on the carbonization product are investigated. Experiments have shown that the optimal conditions for the Ni-modified thermoplastic phenolic resin. The molar ratio of formaldehyde to phenol is 0.85, oxalic acid accounts for 2% of the mass of phenol. The reaction temperature is 100° C. The reaction time is 2 h. The molar ratio of iminodiacetic acid to phenol is 0.03, and the molar ratio of nickel sulfate to phenol is 0.04. The combined temperature is 60°C and the chelating time is 40 minutes. The pyrolytic carbon of the nickel modified phenolic resin is characterized by field emission electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results show that the best carbonization temperature is 10 °C/min at 1100°C for 3 h, and a large number of carbon nanotubes are formed in the pyrolytic carbon.

Effect of Carbon Nanotubes on the Microstructure and Thermal Property of Phenolic/Graphite Composite

In this work, composites based on phenolic resin (P), graphite powder (G), carbon fibers (CFs), and carbon nanotubes (CNTs) were prepared by using hot compression molding. The effect of CNTs on the microstructure and thermal property of these composites was investigated. FESEM analysis indicated that the surface structure of phenolic/graphite composites became more dense and homogeneous with the presence of CNTs. The carbonization behavior of composites was characterized by using thermal gravimetric analyses (TGAs). TGA data showed that the presence of CNTs in phenolic/graphite composites enhanced their thermal stability, by increasing the temperature of maximum weight loss rate (Tm) during pyrolysis and decreasing the weight loss after pyrolysis. In addition, incorporation of CNTs into phenolic/graphite composites reduced significantly their open porosity.

X-ray diffraction analysis of the crystallinity of phenolic resin-derived carbon as a function of the heating rate during the carbonization process

X-ray diffraction analysis of the crystallinity of phenolic resin-derived carbon as a function of the heating rate during the carbonization process

Hierarchical N- and O-Doped Porous Carbon Composites for High-Performance Supercapacitors

Hierarchical N- and O-doped porous carbon composites were prepared by hydrothermally assembling of silk fibers with low molecular weight phenolic resin, followed by carbonization and KOH activation process. Silk fibroin is expected to provide nitrogen and oxygen functionalities for the final composite carbon. The introduction of thin layer graphitic structures of low molecular weight phenolic resin-derived carbon offers more abundant structures, low resistance, and hierarchical porosity with a high BET surface area of 1927 m2·g−1. The composition and electrochemical properties of the composite carbon have been studied as a function of the annealing temperature for KOH activation process. The obtained carbon composite exhibits high specific capacitance as high as 330 F·g−1 (1000 mF·cm−2) at 0.5 A·g−1, good rate capability, and excellent cycling stability (91% of capacitance retention after 10000 cycles) in 6 M KOH electrolyte.

A novel method for analysing the thermal behaviour of charring ablator

Full comprehension of the thermal behavior of the charring ablator is of great importance in designing the thermal protection system (TPS) of a reentry vehicle. To analyze the thermal response of the charring composites under aerodynamic heating, we have improved one-dimensional coupled pyrolysis layer model, in which the transfer of the heat and mass, the moving interfaces and the ablation surface are coupled. A new iterative method is proposed to determine the moving distances of the two moving interfaces and the ablation surface in each time step. The implicit finite difference formulas are derived from the governing equations, and programmed in MATLAB. The iterative method is validated with the arcjet test data in NASA Ames Research Center, and then the thermal response of the phenolic impregnated carbon ablator (PICA) in the Orion vehicle during a lunar return is predicted. This study will be helpful for the optimization of the TPS in reentry vehicles.

Release and flammability evaluation of pyrolysis gases from carbon-based composite materials undergoing fire conditions

In the event of fire, composite materials can be exposed to high heat flux leading to a significant release of smoke and toxic fumes that can contribute to the growth of the fire. This can be problematic in the aerospace industry where strict fire regulations are imposed for designated fire zones. Research has therefore been carried out in recent years to estimate the volatile emissions and self-ignition risk during the development phase of composite parts. In the present study, gaseous emissions and lower flammability limits (LFL) were evaluated during the degradation of three carbon-reinforced composites. The thermoplastic polyetherketoneketone (PEKK), belonging to the polyaryletherketone (PAEK) family, which is known for its high-temperature stability, was compared with two thermosetting resins: a classic phenolic resin and a fire improved epoxy. The former is well known and already used as thermal protection whereas the latter could be used as ablative protection for internal thermal insulation. Gaseous emissions were measured using an analytical pyrolyser (heated platinum filament) coupled with a gas chromatograph and a mass spectrometer (Py-GC–MS) for four different temperatures: 360, 450, 590 and 750 °C. From the suspected species given by the pyrolysis experiments, the LFLs were determined by means of a Quantitative Structure-Property Relationship. The classification of the three materials in terms of combustibility (degradation temperature and mass loss) and ignitability (gaseous emissions and lower flammability limit) revealed superior performances of PEKK composites. The benefit of the fire treatment on the carbon-epoxy was demonstrated by a higher value of LFL whereas the carbon-phenolic resin had a lower mass loss even if it presented a lower degradation temperature.

In Situ Ablation Recession and Thermal Sensor for Thermal Protection Systems

In this research, a break-wire-like ablation recession and thermal sensor based on commercial, affordable thermocouples was designed, fabricated, and tested. The objective of this paper was to demonstrate the capability of this technique to provide real-time measurement of in-depth temperature and recession rates. The in situ ablation recession and thermal sensors were assembled on ablatives ranging from low to high densities (). The different types of ablatives adapted for this study were phenolic impregnated carbon ablator, AVCOAT, carbon/phenolic, and carbon/carbon composites. These ablation recession and thermal sensors were tested under an oxidative hyperthermal environment at a heat flux in the range of created by an oxyacetylene test bed. The results were very promising, demonstrating that the proposed approach can provide accurate recession rate data of a variety of ablatives. The sensing technology developed is very versatile and can be applied to the thermal protection systems of spacecraft, and can also be exploited on rocket nozzles. The key features of this sensor system are the use of inexpensive, commercially available thermocouples and industry-standard drilling techniques demonstrated on different ablatives.

Multiwall carbon nanotube embedded phenolic resin-based carbon foam for the removal of As (V) from contaminated water

It is well proposed that micron or nano size filters requires to separate adsorbent from water after removal of adsorbate. However, even after filtration trace quantity of adsorbent remains in purified water, which deteriorates the quality of water for potability. To overcome these problems, multi walled carbon nanotube (MWCNT) loaded Carbon Foam (CF) was fabricated by a sacrificial template process. In this process, multi walled carbon nanotubes (MWCNTs) and phenolic resin mixture was used for the impregnation of the polyurethane (PU) template. Impregnated PU Foam stabilized and carbonized to get MWCNTs embedded Carbon Foam (CF). The MWCNT loaded CF (MWCNTs-CF) was used for the removal of As (V) species from water. The proposed foam efficiently removes arsenic (As (V)) from water and it can be easily separated from water after purification without any sophisticated tools. The adsorption capacity of the proposed material was found to be 90.5 μg*g−1 at optimized condition of pH, time and concentration, which is excellent in comparison to several other materials utilized for removal of As (V). Kinetic and isotherm studies reveal that the multilayer adsorption over heterogeneous surface follows pseudo second order kinetics. The adsorption phenomena were further confirmed by several characterization techniques like scanning electron microscope (SEM), x-ray diffraction (XRD) spectroscopy and x-ray photoelectron spectroscopy (XPS).

Numerical Study on Density Gradient Carbon–Carbon Composite for Vertical Launching System

This study presents new carbon–carbon (C/C) composite that has a density gradient within single material, and estimates its heat conduction performance by a numerical method. To address the high heat conduction of a high-density C/C, which can cause adhesion separation in the steel structures of vertical launching systems, density gradient carbon–carbon (DGCC) composite is proposed due to its exhibiting low thermal conductivity as well as excellent ablative resistance. DGCC is manufactured by hybridizing two different carbonization processes into a single carbon preform. One part exhibits a low density using phenolic resin carbonization to reduce heat conduction, and the other exhibits a high density using thermal gradient-chemical vapor infiltration for excellent ablative resistance. Numerical analysis for DGCC is performed with a heat conduction problem, and internal temperature distributions are estimated by the forward finite difference method. Material properties of the transition density layer, which is inevitably formed during DGCC manufacturing, are assumed to a combination of two density layers for numerical analysis. By comparing numerical results with experimental data, we validate that DGCC exhibits a low thermal conductivity, and it can serve as highly effective ablative material for vertical launching systems.

Sandwich-type electrochemical immunosensor based on Au@Ag supported on functionalized phenolic resin microporous carbon spheres for ultrasensitive analysis of α-fetoprotein

Signal amplification is crucial for obtaining low detection limits in electrochemical immunosensor. In this work, we developed a novel signal amplification strategy using Au@Ag nanoparticles loaded by polydopamine functionalized phenolic resin microporous carbon spheres (Au@Ag/PDA-PR-MCS). Phenolic resin microporous carbon spheres (PR-MCS) possesses uniform size and a large surface area (1656.8 m2 g−1). Polydopamine (PDA) functionalized phenolic resin microporous carbon spheres (PDA-PR-MCS) retains the advantages of PR-MCS and possesses strong adsorption ability. With the unique structure of PDA-PR-MCS, it not only improves the loading capacity and dispersity of Au@Ag nanoparticles (Au@Ag NPs), but also enhances the stability for the combination of the Au@Ag NPs by chemical absorption between Au@Ag NPs and -NH2 of PDA. The Au@Ag/PDA-PR-MCS exhibits extraordinary electrocatalytic activity towards reduction of hydrogen peroxide (H2O2) to make the electrochemical response more sensitive. Furthermore, Au NPs with good biocompatibility and excellent conductivity were electrodeposited on the surface of electrode, which was used as a sensing platform to immobilize primary antibody (Ab1) and accelerate the electron transfer on the electrode interface. Herein, the designed immunosensor provided a broad linear range from 20 fg/mL to 100 ng/mL for alpha fetoprotein (AFP) detection and a low detection limit of 6.7 fg/mL (signal-to-noise ratio of 3) under optimal experimental conditions. Moreover, the excellent performance in detection of human serum samples indicated that the proposed immunosensor will provide promising applications in clinical monitoring of AFP.

A Molecular Investigation of Soil Organic Carbon Composition across a Subalpine Catchment

The dynamics of soil organic carbon (SOC) storage and turnover are a critical component of the global carbon cycle. Mechanistic models seeking to represent these complex dynamics require detailed SOC compositions, which are currently difficult to characterize quantitatively. Here, we address this challenge by using a novel approach that combines Fourier transform infrared spectroscopy (FT-IR) and bulk carbon X-ray absorption spectroscopy (XAS) to determine the abundance of SOC functional groups, using elemental analysis (EA) to constrain the total amount of SOC. We used this SOC functional group abundance (SOC-fga) method to compare variability in SOC compositions as a function of depth across a subalpine watershed (East River, Colorado, USA) and found a large degree of variability in SOC functional group abundances between sites at different elevations. Soils at a lower elevation are predominantly composed of polysaccharides, while soils at a higher elevation have more substantial portions of carbonyl, phenolic, or aromatic carbon. We discuss the potential drivers of differences in SOC composition between these sites, including vegetation inputs, internal processing and losses, and elevation-driven environmental factors. Although numerical models would facilitate the understanding and evaluation of the observed SOC distributions, quantitative and meaningful measurements of SOC molecular compositions are required to guide such models. Comparison among commonly used characterization techniques on shared reference materials is a critical next step for advancing our understanding of the complex processes controlling SOC compositions.

Optimization of the curing process of phenolic impregnated carbon ablator

ABSTRACTPhenolic impregnated carbon ablator (PICA), which is composed of the phenolic resin (PR) and carbon fiber, is of particular interest to researchers in the aerospace field. In this work, PICA was prepared by the double‐stage isothermal heating curing method and the curing process of PICA was optimized based on non‐isothermal differential scanning calorimetry, extrapolation method and orthogonal experiment. Orthogonal array chose the standard L9 (34). The results show that the optimum curing process of PICA is 120 °C 1 h + 170 °C 1 h, based on considering the better compressive property as the standard. And the results of the Fourier transform infrared spectra indicate that the more dimethylene ether groups result in the higher compressive strength of PICA cured at 120 °C 1 h + 170 °C 1 h. The existence of the more dimethylene ether groups can increase the amount of gases generated and bring off more heat during the ablative process of materials. This may provide a new vision for improve the ablative property of materials. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46230.

Microstructure and mechanical properties of newly developed SiC-C/C composites under atmospheric conditions

The purpose of this study is to investigate the relationship between its microstructure and bending strength of SiC-C/C (carbon-carbon) composites. By using the phenolic resin and carbon fiber bundle, the carbon fiber reinforced plastics (CFRP) precursor was prepared by employing filament winding technique. To modify the phenolic resin, the micro-sized glass fiber was added. The CFRP precursor was charred at high temperature at Argon atmosphere to obtain SiC-C/C composites. The matrix of composites was densified by resin impregnation done by cold isostatic pressing (CIP) method. The detail observation of matrix after charred revealed that when precursor resin was modified with glass fiber, the direction of thermal crack at matrix showed complex manner, while thermal crack at un-modified matrix only appeared along fiber direction. Because of the presence of complex thermal crack, the matrix of SiC-C/C composite showed high porosity at un-densified condition and effectively densified by CIP to promoting resin flow toward thermal crack. The bending and compression test results showed that bending strength and inter-laminar shear strength of SiC-C/C composites was increased by densification. Moreover, the fractured surface observations suggested that the presence of synthesized SiC nano-whisker at inter-laminar enhances the apparent shear strength due to mechanical bridging between laminar.

COMPOSITE MATERIALS APPLICATION EXPERIENCE FOR IMPROVEMENT OF CENTRIFUGAL PUMPS

Background. The use of composite materials in the pump industry is possible for bearings, slotted and face seals, hydraulic discs and lightweight corrosion-resistant impellers manufacturing. Today, usage of all these elements reduces the reliability of pumps and requires improvement. Aims and Objectives. Conduct a comparative analysis of Russian composite materials and consider the possibility of using them to improve centrifugal pumps bearings. Analyze the possibility to use integrated bearings cooled by the pumped medium instead of babbit bearings cooled by an oil system. Results. The examined Russian materials: phenolic carbon fiber (PCF), oxaphen - showed good performance as sliding bearings. At present, the area of their application is expanding both in the pumping industry and in other areas of industry. Replacement of babbitt bearings for built-in ones made of composite materials will completely eliminate leaks of the pumped medium, reduce operating costs, reduce vibration and noise, reduce gas contamination of the room, and prolong the overhaul period.

Electrical and Mechanical Properties of Phenolic Resin and Gigantochloa Apus Carbon Fiber Composites

Electrical and Mechanical Properties of Phenolic Resin and Gigantochloa Apus Carbon Fiber Composites

Preparation and application of N-doped carbon nanotube arrays on graphene fibers

A new kind of carbon hybrid material with a unique structure and outstanding mechanical and functional properties is reported in this article. Nitrogen-doped carbon nanotube (CNT) arrays with inside located Ni particles are in situ grown on the surface of phenolic carbon modified graphene fibers during their conversion from graphene oxide fibers. The carbon hybrid fibers exhibit not only high tensile strength and elongation at the break, but also excellent flexibility since the CNT arrays cover all the surface of the highly strong graphene fiber. This well-constructed carbon material would be suitable for catalysts, polymer composites, hydrogen storage, oxygen reduction reaction etc.