The Influence of Sample Preparation on the Strength Results of a Pan-Based Carbon Fiber (original) (raw)
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Effects of preoxidation and carbonization technologies on tensile strength of PAN-based carbon fiber
Journal of Applied Polymer Science, 2008
Dependence of the tensile strength of resulting carbon fiber (CF) on the preparation technologies during preoxidation and carbonization were studied systematically by a series of pilot experiments. The proper preoxidation time, preoxidation temperature, and preoxidation stretching ratio are the base of preparing highquality CF. During precarbonization, the enhancement of the precarbonization temperature and the application of the precarbonization stretching are helpful to increase the tensile strength of CF, but the stretching ratio should be controlled carefully by on-line tension values. The tensile strength of CF increases quickly below 12008C and then slowly above 12008C as the carbonization temperature raises. Even though during carbonization, a proper relaxation should also be explored in order to prepare optimal CF.
EXPERIMENTAL INVESTIGATION ON MECHANICAL CHARACTERIZATION OF PAN CARBON
The main factors that derive the use of composites are weight reduction, corrosion resistance, specific strength and stiffness, when compared to traditional materials or conventional materials. Characterization of each composite material is done before its application in product development. In the present work, the mechanical characteristic properties of Carbon as reinforcement will be studied. Laminates will be made with fabric of PAN, based Carbon and sample pieces are tested as per ASTM standards. The quality of laminates is verified and further tested for their mechanical properties like tensile, compression, flexure & ILSS. Fiber volume fraction is also determined from resin content and density.
Analysis of failure in ‘Recoil from tension’ of pan-based carbon fibers
Carbon, 1993
Results from a study of the "recoil from tension" method for estimating the compressive strength of the poiyacrylonitrile (PAN)-based carbon fibers are reported here. Analysis of the effect of different gauge lengths on the recoil strength distribution and the fracture morphological features of cross sections of the tested filaments imply that both axial recoil and bending influence the recoil failure of PAN-based carbon fibers. The experimental recoil strength distributions have been compared to logistic and weibull models. A universal logistic model that incorporates a dependence on gauge length has been found to provide a good fit to the distributions obtained at different gauge lengths. This analytical expression can be used to obtain a physically meaningful extrapolated average "zero gauge length" recoil strength. which might be appropriate for estimating the true axial compressive strength of fibers.
Fibers
The aim of this work is to review a possible correlation of composition, thermal processing, and recent alternative stabilization technologies to the mechanical properties. The chemical microstructure of polyacrylonitrile (PAN) is discussed in detail to understand the influence in thermomechanical properties during stabilization by observing transformation from thermoplastic to ladder polymer. In addition, relevant literature data are used to understand the comonomer composition effect on mechanical properties. Technologies of direct fiber heating by irradiation have been recently involved and hold promise to enhance performance, reduce processing time and energy consumption. Carbon fiber manufacturing can provide benefits by using higher comonomer ratios, similar to textile grade or melt-spun PAN, in order to cut costs derived from an acrylonitrile precursor, without suffering in regard to mechanical properties. Energy intensive processes of stabilization and carbonization remain a...
Tensile Strength of Carbon Fiber
Tehnički glasnik
Carbon fiber is a material with a vast area of utilization. When combined with a resin, we get a composite, which provides great mechanical properties, has low mass and can be utilized in many different applications. Carbon fiber cloth can be found in a wide range of forms and shapes, differing from weight to the shape of their weave. Manufacturing a composite part can be achieved with a variety of techniques and processes, each of them having advantages and disadvantages over the other. One of the most common process for producing composite parts is the open moulded hand lay-up process. This process is economically viable, has low cost for equipment, and can produce parts with satisfactory results. A composite sheet is manufactured using the hand lay-up process. Three testing samples are taken out from the composite sheet, and their tensile strength is determined using the ASTM D3039 standard.
Factors controlling the strength of carbon fibres in tension
Composites Part A: Applied Science and Manufacturing, 2014
We have investigated the fracture mechanisms of different types of carbon fibres, in terms of skin-core differences in single fibres, flaw size and fracture toughness. The fibre strength distribution was measured precisely using the fragmentation test for single-fibre composites. The failure probability for intermediate/high modulus types fibres was found to be constant with fibre strength in the range 2-4 GPa, but in contrast the strength scatter for high modulus type fibres was reduced. The fracture toughness of the carbon fibres, determined by introducing notches with lengths in range 60-200 nm, was found to be about 1.1 MPa m 1/2. The average flaw size of the carbon fibres increased with increasing fibre modulus, suggesting that the crack growth of surface flaws on the tens-of-nm scale occurred. This appears to be the main reason for the reduction in tensile strength during the carbonisation treatment.
Mechanical, surface and interfacial characterisation of pitch and PAN-based carbon fibres
Carbon, 2000
The mechanical and surface characteristics of pitch and PAN-based carbon fibres were studied by tensile testing, XPS, SEM analysis and wetting measurements. The pitch-based fibres had two different geometries, with circular and ellipsoidal (ribbon-shaped) cross sections. Plasma oxidation was used to treat the surface of the fibres. The interfacial characteristics of untreated and treated fibres were measured by fragmentation tests of single filament composites. The effect of the surface treatment on the mechanical, surface and interfacial properties of the fibres was determined and correlated. It was shown that a relationship exists between the ability of the surface to transfer loads and its oxygen content. Finally, the influence of the non-axisymmetry on the interfacial parameters obtained in the fragmentation tests was assessed.
Carbon, 2001
The present work reports a comparative study of alternative models to describe the tensile strength of carbon fibers. The theoretical models were validated using data determined for a wide range of materials. Fibers derived from PAN and pitch, with different geometries (circular and ellipsoidal cross section), with and without surface treatment, were tensile tested. A mixed-mode Weibull distribution function, adapted for the length dependence of fiber strength, was used to model the tensile data, assuming the weakest link approximation. This function is capable of describing the effect of flaws and crystalline misalignment on fiber tensile strength. Additionally, the 'end-effect' model was employed to distinguish between these failures and those that result from the test method itself, namely the influence of the machine clamps. It was observed that the relative importance of end-effects increases as the length or the aspect ratio of the fiber decreases. For most fibers studied at longer gauge lengths, a two-parameter Weibull distribution could adequately fit the strength data. Thus, in these cases, a dominant flaw population may be responsible for fiber failure. Based on the results of this study, criteria are proposed for selecting the most appropriate statistical models to predict the tensile strength of carbon fibers at small gauge lengths.