Interfacial Adhesion Of Carbon Research Articles

Effects of microstructure on the internal friction of carbon–carbon composites

Internal friction directly depends on the microstructure of material. For carbon–carbon composites made up of fibers, matrix and interface, internal friction mechanisms involved are more complex. In present work, the effects of microstructure on the internal friction in carbon–carbon composites are studied. During the Chemical Vapor Infiltration (CVI) process, the internal friction in carbon–carbon composites decreases with the increasing of density. The experimental result does not accord with the equation for conventional composites. Considering the porous structure and non-full ideal interfacial adhesion in carbon–carbon composites, we develop a modified equation for the quantitative description of internal friction, which shows good agreement with the experimental results. Furthermore, internal friction related to pyrolytic carbon matrix, fibers and interface are discussed, respectively, which gives us a fundamental understanding on the internal friction in carbon–carbon composites. Among these internal friction mechanisms, interfacial internal friction is of special interest, as it causes some abnormal internal friction phenomena in carbon–carbon composites.

Study of the interaction of carbon fibre surfaces with a monofunctional epoxy resin

X-ray photoelectron spectroscopy (XPS) and static secondary ion mass spectrometry (SIMS) have been used to determine the chemical changes observed as a result of interactions between carbon fibre surfaces and epoxy resins. A comparison has been made between untreated, commercially treated and air plasma treated carbon fibres. Both positive and negative static SIMS results indicated the presence of nitrogen and oxygen containing fragments as a result of air plasma treatment, the spectra from commercially treated fibres were dominated by contaminants. Fibres were then sized in the monofunctional epoxy resin, 1,2-epoxy-3-phenoxypropane, and further analysis carried out to determine the chemical nature of the fibre-resin interface. Angle resolved XPS was used to confirm the presence of a layer of resin. Positive ion fragments from static SIMS data have been identified as species which have been formed as a result of the epoxy molecule chemically reacting with species on the fibre surface. Surface energy measurements have also been recorded and it is shown that the polar component of surface energy is greatly increased as a result of surface treatment. This increase is much greater for air plasma treated fibres than for commercially treated fibres. It is proposed that air plasma treatment of carbon fibres increases the interfacial adhesion in carbon fibre/epoxy composites, by the introduction of functional groups which form chemical bonds with the epoxy resin.

Impact behavior of carbon fiber/ultra‐high modulus polyethylene fiber hybrid composites

AbstractCarbon fiber (CF)/ultra‐high modulus polyethylene (UHMPE) fiber hybrid composites were fabricated using vinyl ester resin as a matrix. Interfacial adhesion of carbon fiber/vinyl ester composites and UHMPE fiber/vinyl ester composites as model composites was optimized using low temperature plasma treatment. Interlaminar shear strengths of carbon fiber/vinyl ester and UHMPE fiber/vinyl ester homocomposite were greatly increased by plasma and silane coupling agent treatment. From the result of the impact test, total absorbed energy of carbon fiber/UHMPE fiber hybrid composites was correlated with laminating sequences at optimized interfacial adhesion between the reinforcing fiber and matrix resin. UHMPE fiber layers of hybrid composites played an important role in absorbing energy. Elastic and plastic deformation of UHMPE fiber layers also played a key role in improving the impact properties of carbon fiber/UHMPE fiber hybrid composites.

Measurement of interfacial adhesion in carbon/ epoxy composite after plasma surface treatment on carbon fibers

After gas plasma treatment with oxygen for 1 min or argon for 2 min at a power of 30 watts, scanning electron microscopy (SEM) showed changes in the surface topography of carbon fibers. Microbond tests showed improvement of the interfacial shear strength (IFSS) between AS4 carbon fibers and bisphenol A based (DGEBA) epoxy resin.