Characteristics Of Carbon Foams Research Articles

Investigation of CO2 sequestration performance and statistical analysis of dye removal efficiency of liquefied hornbeam based carbon foams: Effects of biomass/solvent weight ratio, tar contribution, and chemical activation

Investigation of CO2 sequestration performance and statistical analysis of dye removal efficiency of liquefied hornbeam based carbon foams: Effects of biomass/solvent weight ratio, tar contribution, and chemical activation

Altering the characteristics of carbon foams synthesized by biomass liquefaction with bio-oil addition: influence of the surfactant ratio

Carbon and graphite foams have recently been reported to be highly suited to a range of applications, such as high-temperature insulation, fuel cell electrodes, heat exchangers, brake discs, engine parts, and bone surgery materials. In this study, the effect of surfactant amount added during carbon foam synthesis on the structure of the foam produced through the liquefaction of spruce tree sawdust in the presence of pyrolytic oil (bio-oil) was studied. When a mixture of phenol and pyrolytic oil was used as a solvent during synthesis instead of just phenol, the foaming agent could not exit the polymer, leading to the production of a hard polymeric structure. Also, applying the standard amount of surfactant meant that the gas molecules could not overcome the high surface tension at the polymer surface and were therefore trapped within the polymer, causing relatively few pores to be generated during synthesis. Increasing the amount of surfactant led to successful foaming, as gas molecules could dissociate from the structure by overcoming the surface tension of the polymer matrix. When the combination of pyrolytic oil and phenol was utilized, adding extra surfactant caused the porosity to increase by 19–33% due to the 39–61% rise in the surface area, although the compressive strength of the foam decreased by 24–79%. This study, therefore, showed that the surface area, porosity, compressive strength, elemental carbon content, and crystalline structure of the carbon foam could be tailored to the application area of the foam by adjusting the conditions applied during synthesis appropriately.

Effect of chemical activation on the cellular structure of biopitch-derived green carbon foam

Abstract Current researches pay particular attention to cost-effective and abundant raw materials such as biomass as an alternative to fossil-derived-carbonaceous precursors. The aim of this study is to examine the usability of pyrolytic oil as a biopitch source in the foaming process and to investigate the effect of chemical activation on the characteristics of carbon foam. The elemental analysis of the biopitch supported the fact that the H/C and O/C ratios of wood-tar-based-pitch had high oxygenated and aliphatic carbons in contrast to fossil-pitches. Various basic analysis methods such as elemental analysis, X-ray diffraction, nitrogen sorption isotherms, Raman spectroscopy, scanning and transmission electron microscopy, true/bulk density and compressive strength tests were applied to analyze carbon foams. When the results of nitrogen sorption analysis were examined, it was determined that the surface area of carbon foam increased to about 31 times after activation. According to the pore size distribution graphs, the foams had regular pore distribution; additionally, the pore size in the mesopore region was determined to shift to the micropore region with activation. Compressive strength values were in the range of 0.40–1.97 MPa. Moreover, an increase in porosity values and a decrease in compressive strength values were observed due to enhancing porosity as a result of the activation process.

Preparation and Characteristics of Carbon Foam (II)

Properties, surface condition and composition of the carbon foams containing fillers such as the powder of glass and titanium white are investigated.These carbon foams were prepared by the heat-treatment of the phenol resin foam containing filler at heat treatment temperature of1500, 2000, 2500°C for30minutes under an atmosphere of Argon. Further, using the foam heat-treated at2900°C, the influence of the filler on graphitization is examined.The scanning electron microscope (SEM) is used for the observation on the condition of surface of the carbon foams, further the spectroscope attached to SEM and X-ray diffractometer are used for the investigation of the composition of them.The pores of the foam get out of shape as the heat treatment temperature are increased.Bulk density of the foam increases with the elevation of the heat treatment temperature and the increase of the filler contents.Condition of the distribution of the silicon in glass and titanium in titanium white is almost equal to all over the foam.So, the reason of increase of the compressive strength of the carbon foam is not reinforcement of the cell wall of the foam but the thickening of it.Titanium and silicon carbonize at considerably lower temperature than that at which the usual carbide-cristalls are formed.At the heat treatment temperature 2900°C, the graphitization of the carbonized phenol resin foam without filler is bad, therefore, multiple graphitization is shown in this case. But that of the carbon foam containing glass and titanium white are remarkably improved.

Preparation and Characteristics of Carbon Foam

The carbonized plastic foam containing inorganic filler is prepared. The method of preparation of this carbon foam is considerably simple, and it has excellent properties, such as low density, high thermal insulation, high chemical resistance, comparatively high mechanical strength and resistance to air oxydation.The preparation method of this carbon foam is as follows: the mixture of resin, curing agent, surface activating agent, bubbling agent and filler are mixed during hot roll, then the products are pulverized, poured into a covered box and cured at 150 °C. The cured raw foam is carbonized at the desired temperature in the atmosphere of inert gas.The samples of carbonized phenol foam containing glass and titanium white powder heattreated at 1000 °C are described. The physical properties, resistance to air oxydation, compressive strength, and thermal conductivity are measured.Compressive strength of the carbon foam containing glass powder up to 20% in the raw state increases with the elevation of glass content, but that of the carbon foam containing more than 20% of glass powder in the raw foam decreases with the elevation of glass content. In the case of the carbon foam containing titanium white powder, compressive strength increases with the elevation of titanium content.True density of the carbon foam with either glass or titanium filler has the same tendency to compressive strength as a function of filler content. Bulk density and thermal conductivity of the carbon foam containing either filler increase with the elevation of filler content.For the carbon foam containing glass powder, resistance to air oxydation increases with the elevation of glass content; for the carbon foam containing titanium white powder, it is considerably high, but the best resistance to air oxydation in our experiment is obtained in the case of the carbon foam containing about 20% of titanium white.

41. Moisture sorption and desorption characteristics of carbon foam

41. Moisture sorption and desorption characteristics of carbon foam