Short carbon fibres

Example 3.17 Short carbon fibres with a diameter of 10 fim are to be used to reinforce nylon 66. If the design stress for the composite is 300 MN/m and the following data is available on the fibres and nylon, calculate the load transfer length for the fibres and also the critical fibre length. The volume fraction of the fibres is to be 0.3. 

In a short carbon fibre reinforced nylon moulding the volume ffacdon of the fibres is 0.2. Assuming the fibre length is much greater that the critical fibre length, calculate the modulus of the moulding. The modulus values for the fibres and nylon are 230 GN/m and 2.8 GN/m respectively. 

As for glass fibres, reinforcement with continuous fibres leads to the highest performances. Compared to short glass fibres, short carbon fibres yield higher reinforcement ratios for the modulus and tensile strength but the impact strength decreases. 

Enhancement ratios obtained with short carbon fibre instead of glass fibre in ... 

Table 6.34 shows some basic property examples of short carbon fibre reinforced thermoplastics. 

Let us consider one final example the application of atomic force microscopy (AFM) relating to nanoscale scratch and indentation tests on short carbon-fibre-reinforced PEEK/polytetrafluoroethylene (PTFE) composite blends (Han et al, 1999). In the scratch test, the tip was moved across the surface at constant velocity and fixed applied force to produce grooves with nanometre scale dimensions on the PEEK matrix surfaces. The grooves consisted of a central trough with pile-ups on each side. These grooves provide information about the deformation mechanisms and scratch resistance of the individual phases. In the nanoscale, indentation and... 

Most carbon fibre reinforced plastics (CFRP) used and investigated to date are produced from preimpregnated continuous carbon fibre prepregs. Polymers reinforced with aligned short carbon fibres have certain advantages as materials for structural components, because they can easily be formed into complicated shapes with satisfactory mechanical properties. Woven fabrics produced from carbon fibres find increasing application in the aerospace and many other industries, because they are easy to handle, they have the ability to conform to complicated shapes and the in-plane properties are more isotropic than those of equivalent unidirectional materials. 

K Friedrich, K Schulte, G Horstenkamp and T W Chou, Fatigue behaviour of aligned short carbon-fibre reinforced PI and PES composites ,/Mafer5 ci 1985 20 3353-3364. 

Mas Mason, J. J., Brown, S. A., Moet, A. An evaluation of the use of infrared heating for contouring 30 % short carbon-fibre-reinforced PEEK. J. Mater. Sci. Medicine 3 (1992) 88-94. 

An injection-moulded bar contains 20% (by volume) of short carbon fibres (high strength form) in a matrix of nylon 6.6. A tensile strain of 10 is applied along the axis of the bar. Determine the mean tensile stress carried by the fibres and the overall stress carried by the bar. Assume that the fibres are all of length 400 pim and diameter 6 fim, and are perfect aligned along the axis of the bar and perfectly bonded to the matrix. Take the axial tensile modulus of the carbon fibres to be 230 GPa, and the tensile and shear moduli of nylon 6.6 to be 2.7 GPa and 1.015 GPa, respectively. 

Ibarra L, Macias A, Palma E, Mechanical properties of composite materials consisting of short carbon fibre and thermoplastic elastomers, Kautschuk Gummi Kunstoffe, 48(3), 180-184, 1995. Jacobsen RL, Tritt TM, Guth JR, Ehrlich AC, Gillespie DJ, Carbon, 33(9), 1217-1221, 1995. Tibbetts GG, Doll GL, Gorkiewicz DW, Moleski JJ, Perry TA, Dasch CJ, Balogh MJ, Physical properties of vapour grown carbon fibres, Carbon, 31(7), 1039-1047, 1993. 

Hitchen SA, Ogin SL, Smith PA, Soutis C, The effect of fibre length on fracture-toughness and notched strength of short carbon-fibre epoxy composites. Composites, 25(6), 407-413, 1994. Kishimoto K, Notomi M, Koizumi T, Fracture toughness of short carbon-fibre-reinforced thermoplastic pol5mide. Engineering Fracture Mechanics, 49(6), 943 et seq, 1994. 

Hitchen SA, Ogin SL, Smith PA, Effect of fibre length on fatigue of short carbon-fibre epoxy composite. Composites, 26(4), 303-308, 1995. 

Lin, T., Jia, D., He, R, Wang, M., Liang, D., 2008. Effects of fibre length on mechanical properties and fracture behavior of short carbon fibre reinforced geopolymer matrix composites. Materials Science and Engineering A, 497(1-2), pp. 181-185. 

An injection moulded bar contains 20 % (by volume) of short carbon fibres (high strength form) in a matrix of nylon 6.6. A tensile strain of 10 is applied along the axis of the bar. Determine the mean tensile stress carried by the fibres and the overall stress... 

J. R. Sarasuaand J. Pouyet "Recyclingeffects onmicrostructureand mechanical behaviour of PEEK short carbon-fibre com jx)sites." journal of Materials Science, pp. 533-536,1997. 

An example of the development of materials used in FDM/FFF technologies is that conducted by Tekinalp et al. (2014) where they studied the benefits of short carbon fibre reinforcement on ABS load-bearing 3D printed parts. As observed in Fig. 7.9, carbon fibres were found to exhibit near-perfect alignment with the writing... 

Lithium ions may enter the intercalation structure only from the surrounding sides and edges of the carbon layers. For some products, to enhance the ratio of accessible graphitic edges and sides of the carbon particles total surface, synthetic microscopically small graphite balls are used which may be understood as turned (machined) from the layered graphitic structure. Micro-short carbon fibres are also successfully applied as anode hosts. 

Gao J, Weitsman YJ (1998) Composites in the sea sorption, strength and fatigue. University of Tennessee Reptnt MAES 98-4.0 CM, August 1998 Gebhard A, Bayerl T, Schlarb AK, Friedrich K (2009) Galvanic corrosion of polyacryinitrile (PAN) and pitch based short carbon fibres in polyetheretherketone (PEEK) composites. Corros Sci 51(ll) 2524-2528... 

In a parallel study, the influence of bioactive additives, such as short carbon fibres (CF), HAp nanoparticles and bioglass, on the thermal and mechanical properties of PLGA was examined under in vitro conditions. The presence of bioactive particles affects the process of apatite growth on composite surface, in which a chemical bond between the implant and the bone tissue is formed. Despite the deterioration of mechanical properties after incubation under in vitro conditions, the PLGA/HAp composites still showed advantageous biological behaviour [156]. 

Chang, L., Z. Zhang, H. Zhang, and K. Friedrich. 2005. Effect of nanoparticles on the tribological behaviour of short carbon fibre reinforced poly(etherimide) composites. Tribology International 38 (11-12) (November) 966-973. doi 10.1016/j.triboint.2005.07.026. http //linkinghub.elsevier.eom/retrieve/pu/S0301679X05001957. 

Also, analysis of the kinetics and the glass transition temperature suggested greater interaction between aramid fibres and elastomer matrix. In particular, the degradation of PU or PU composites reinforced with aromatic PA or short carbon fibres followed first-order kinetics. 

Z. Zhang, C. Breidt, L. Chang, F. Haupert, K. Friedrich (2004) Enhancement of the wear resistance of epoxy short carbon fibre, graphite, PTFE and nano-TiOj,... 

L. Chang, Z. Zhang (2004) Tribological properties of epoxy nanocomposites II. A combinative effect of short carbon fibre and nano-TiOj, Wear, submitted. 

Effects to increase thermal conductivity have been less successful. Increases have been modest and linear percolation does not play a major role due to the less dramatic difference in conductivity between filler and matrix. Results are similar to those observed for short carbon fibres in similar systems. ... 

The uniform dispersion of short carbon fibres, particularly at higher fibre volumes, is difficult. The most that can be added using conventional mixing methods and materials is about 1% by volume. The dispersion of the fibres into individual filaments is controlled by the mixing technique. The methods used have included ... 

Short and randomly mixed fibres The effect of mixing short carbon fibres, mainly of the pitch type, has been studied extensively, mostly using fibres... 

Pramanik, P.K. Khastgir, D. De, S.K. Saha, T.N. Pressure-sensitive electrically conductive nitrile rubber composites filled with particulate carbon black and short carbon fibre. J. Mater. Sci. 1990, 25, 3848-3853. 

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