Wettability Of Carbon Fibers Research Articles

Effect of surface treatment on surface characteristics of carbon fibers and interfacial bonding of epoxy resin composites

This paper aims to study the effect of aqueous ammonia etching, nitric acid oxidation and aqueous ammonia/nitric acid combined treatment on surface characteristics of carbon fibers (CFs) and interfacial bonding properties of CF/epoxy resin composites. The morphologies and chemical compositions of pristine CFs and treated CFs were characterized using a Scanning Electron Microscope (SEM), Atomic Force Microscopy (AFM), and X-ray Photoelectron Spectroscopy (XPS). It was found that the surface of treated CFs has greater roughness compared with the surface of pristine CFs; moreover, the surface roughness is at maximum with the aqueous ammonia/nitric acid combined treatment. No obvious change in chemical composition takes place with aqueous ammonia etching of CFs. On the other hand, the oxygen content on the surface of CFs increases with nitric acid oxidation and aqueous ammonia/nitric acid combined treatments. The effect of surface treatment on the wettability, single filament tension strength, and interfacial shear strength (IFSS) of CF/epoxy resin composites was measured. Results show that the wettability of CFs against distilled water improves with the surface treatment. The wettability optimum with the aqueous ammonia/nitric acid combined treatment. Compared with pristine CFs, there is only a slight loss in tension strength with the treated CFs. In addition, the IFSS value of composites increased greatly. The IFSS of aqueous ammonia/nitric acid treated carbon fibers reinforced with epoxy resin composites increases by 46.36 % compared with pristine ones, This resulted from the combined action of the increase in the carbon fiber surface roughness and surface oxygen containing functional groups.

New method for interfacial evaluation of carbon fiber/thermosetting composites by wetting and electrical resistance measurements

Interfacial properties were evaluated for carbon fiber (CF) with different thermosetting polymeric matrices in composites. CF tow was wet by phenolic or epoxies, and the interfacial adhesion evaluated by electrical resistance changes. The interfaces between two types of CF tows with phenolic resin and three types of epoxies were investigated. The change in electrical resistance was found to depend on the wettability of CF by the polymer resins, with the more obvious resistance changes being associated with better wettability. The electrical resistance changes were measured 20 min after the polymer resin was dropped on the CF tow. To confirm the relationship between changes in resistance and interfacial properties, both interfacial shear stress (IFSS) and interlaminar shear stress (ILSS) were also measured. The results of these mechanical measurements were generally consistent with the electrical resistance measurements in that the materials with high electrical resistance also exhibited high IFSS and ILSS.

Partially reduced graphene oxide as a multi-functional sizing agent for carbon fiber composites by electrophoretic deposition

Partially reduced graphene oxide (pRGO) was coated on carbon fibers by an anodic electrophoretic deposition (EPD). Coated-pRGO increased surface energy and wettability of carbon fiber. As a multi-functional sizing agent, pRGO enhanced both mechanical and electrical properties of the carbon fiber composite in spite of introducing a very small amount of less than 0.001 wt%.

Wetting of carbon fibers by coal-tar pitch melts

The wettability of carbon fibers from different manufacturers with finish, rinsed of finish, and heat treated at 2000°C by the model liquids water and octane was studied comprehensively. The polar and dispersion components of the carbon-fiber surface free energy were calculated. It was shown that finished fiber had a polar nature whereas removal of the finish could increase or decrease the surface polarity. This could be related to the fiber preparation method. The surface tension of pitch melts was measured and factored into its components. It was shown that the contribution of the polar component to the pitch surface tension was always at least 50% for the studied pitches. The surface tension correlated well with the pitch viscosity but was not related to the softening temperature. Edge wetting angles of the carbon fibers by pitch were calculated based on the experimental results. Fibers for which the contribution of the surface-energy polar component was greater demonstrated better wettability.

Optimum dispersion conditions and interfacial modification of carbon fiber and CNT–phenolic composites by atmospheric pressure plasma treatment

Electric resistance measurements were used to determine the optimal dispersion conditions for carbon nanotubes (CNTs) in phenolic resins. Plasma treatment is frequently used to modify carbon fiber surfaces to improve adhesion of the fibers to matrices. Such treatment might also influence carbon fiber tensile strength. In order to determine the effect of atmospheric pressure plasma treatment on carbon fiber tensile strength and interfacial bonding strength, change in tensile strength of the fiber was studied at different gage lengths before and after the plasma treatment. The wettability of carbon fibers was improved significantly after only 10s of plasma treatment. Such plasma treatment resulted in a decrease in the advancing contact angle from 65° to 28°. Surface energies of carbon fiber and CNT–phenolic composites were measured using the Wilhelmy plate technique, indicating that the work of adhesion between plasma treated carbon fibers and CNT–phenolic composites was higher than it before plasma modification. The interfacial shear strength (IFSS) and apparent modulus were also increased by plasma treatment of the carbon fibers.

Influence of Surface Properties of Carbon Fibers Biofilm Carriers on Immobilization of Different Microorganisms

Results of our workgroups have shown that carbon fibers (CFs) are high quality biofilm carriers with well biocompatibility relative to other polymer carriers used in biofilm sewage treatment. In the present study, two kinds of microorganisms, namely, aerobic nitrifier and facultative aerobic denitrifying bacterium, were immobilized on the surface of different CFs, which the effects of specific area, functional groups and wettability on immobilization of these bacteria was studied. Results show that different microorganism require for different surface properties of CFs. Biomass of immobilized aerobic nitrifier increases with increasing specific areas, surface oxygenic functional groups and wettability of CFs. It can be immobilized more facultative aerobic denitrifying bacterium if there are proper specific areas, surface functional oxygenic group and wettability on the surface of CFs

Influence of Surface Properties of Carbon Fibers Biofilm Carriers on Immobilization of Different Microorganisms

Results of our workgroups have shown that carbon fibers (CFs) are high quality biofilm carriers with well biocompatibility relative to other polymer carriers used in biofilm sewage treatment. In the present study, two kinds of microorganisms, namely, aerobic nitrifier and facultative aerobic denitrifying bacterium, were immobilized on the surface of different CFs, which the effects of specific area, functional groups and wettability on immobilization of these bacteria was studied. Results show that different microorganism require for different surface properties of CFs. Biomass of immobilized aerobic nitrifier increases with increasing specific areas, surface oxygenic functional groups and wettability of CFs. It can be immobilized more facultative aerobic denitrifying bacterium if there are proper specific areas, surface functional oxygenic group and wettability on the surface of CFs

Recent advances in electron-beam curing of carbon fiber-reinforced composites

Cross-linking polymerization initiated by high-energy radiation is a very attractive technique for the fabrication of high-performance composite materials. The method offers many advantages compared to conventional energy- and time-consuming thermal curing processes. Free radical and cationic poly-addition chemistries have been investigated in some details by various research groups along the previous years. A high degree of control over curing kinetics and material properties can be exerted by adjusting the composition of matrix precursors as well as by acting on process parameters. However, the comparison with state-of-the-art thermally cured composites revealed the lower transverse mechanical properties of radiation-cured composites and the higher brittleness of the radiation-cured matrix. Improving fiber–matrix adhesion and upgrading polymer network toughness are thus two major challenges in this area. We have investigated several points related to these issues, and particularly the reduction of the matrix shrinkage on curing, the wettability of carbon fibers, the design of fiber–matrix interface and the use of thermoplastic toughening agents. Significant improvements were achieved on transverse strain at break by applying original surface treatments on the fibers so as to induce covalent coupling with the matrix. A drastic enhancement of the K IC value exceeding 2 MPa m 1/2 was also obtained for acrylate-based matrices toughened with high T g thermoplastics.

Aryl Diazonium Salts for Carbon Fiber Surface-Initiated Atom Transfer Radical Polymerization

, +N2-C6H4-CH(CH3)-Br diazonium salt was electrochemically reduced in order to graft phenylethyl bromide groups to carbon fibers. The pretreated fibers (CF-Br) served as macroinitiators of atom transfer radical polymerization (ATRP) of vinylic monomers. This procedure combining a diazonium salt and ATRP permitted the polymerization of butyl, glycidyl and hydroxyethyl methacrylates at the surface of carbon fibers (CF) resulting in CF-PBMA, CF-PGMA, and CF-PHEMA hybrids, respectively. The surface chemistry and wettability of these hybrids were interrogated by XPS and water contact angles. The change in the wettability of carbon fibers reflects the chemical nature of the tethered polymer chains as the wettability decreases in the order CF-PHEMA > CF-PGMA > CF-PBMA > CF. Furthermore, CF-PHEMA was found to resist non-specific adsorption bovine serum albumin (BSA) compared with the more hydrophobic CF-PBMA system. This work shows that the use of diazonium salt is a facile, new surface chemistry option for grafting initiator of ATRP to carbon fiber. This strategy ensures a good carbon fiber-polymer adhesion through covalent bonds.