Fibre reinforced composite

Silicon carbide has attracted considerable interest because of its good mechanical and physical properties and chemical inertness. One of the most important applications of SiC is to produce a matrix reinforced by fibres, forming ceramic-matrix composites. These composite materials exhibit much better fracture toughness than monolithic ceramics. Compared with carbon/carbon composites, fibre-reinforced SiC matrix composites possess superior oxidation resistance and mechanical properties. The Si-C-H-Cl system (e.g. methyltrichlorosilane, CH3SiCl3) has been used for SiC deposition because it is easy to produce stoichiometric SiC deposits. 

M. Schmiicker, P. Mechnich, All-Oxide Ceramic Matrix Composites with Porous Matrices, in W. Krenkel (ed.) "Ceramic Matrix Composites, Fibre-Reinforced Ceramics and their application" Wiley-VCH, Weinheim, 2008, 205-229... 

Key words vinylester resin, polymer matrix composites, fibre-reinforced... 

A. R. BunseU, ed.. Fibre Reinforcements for Composite Materials, Elsevier Science Publishing Co. Inc., New York, 1988. 

B. L. Riley, 2nd Int Conf. on Fibre Reinforced Composites, Proceedings, University of Liverpool, UK, 1986, p. 153. 

There is a simple way to estimate the modulus of a fibre-reinforced composite. Suppose we stress a composite, containing a volume fraction Vfo( fibres, parallel to the fibres (see Fig. 6.3(a)). Loaded in this direction, the strain, e , in the fibres and the matrix is the same. The stress carried by the composite is... 

Fig. 6.3. A fibre-reinforced composite loaded in the direction in which the modulus is (a) a maximum, (b) a minimum.

This gives us an upper estimate for the modulus of our fibre-reinforced composite. The modulus cannot be greater than this, since the strain in the stiff fibres can never be greater than that in the matrix. 

The two estimates, if plotted, look as shown in Fig. 6.4. This explains why fibre-reinforced composites like wood and GFRP are so stiff along the reinforced direction (the upper line of the figure) and yet so floppy at right angles to the direction of reinforcement (the lower line), that is, it explains their anisotropy. Anisotropy is sometimes what you want - as in the shaft of a squash racquet or a vaulting pole. Sometimes it is not, and then the layers of fibres can be laminated in a criss-cross way, as they are in the body shell of a Formula 1 racing car. 

There are less exotic ways of increasing the strength of cement and concrete. One is to impregnate it with a polymer, which fills the pores and increases the fracture toughness a little. Another is by fibre reinforcement (Chapter 25). Steel-reinforced concrete is a sort of fibre-reinforced composite the reinforcement carries tensile loads and, if prestressed, keeps the concrete in compression. Cement can be reinforced with fine steel wire, or with glass fibres. But these refinements, though simple, greatly increase the cost and mean that they are only viable in special applications. Plain Portland cement is probably the world s cheapest and most successful material. 

Fig. 26.3. The molecular structure of a cell wall. It is a fibre-reinforced composite (cellulose fibres in o matrix of hemicellulose and lignin).

Epoxide resins reinforced with carbon and Aramid fibres have been used in small boats, where it is claimed that products of equal stiffness and more useable space may be produced with a 40% saving in weight over traditional polyester/ glass fibre composites. Aramid fibre-reinforced epoxide resins have been developed in the United States to replace steel helmets for military purposes. Printed circuit board bases also provide a substantial outlet for epoxide resins. One recent survey indicates that over one-quarter of epoxide resin production in Western Europe is used for this application. The laminates also find some use in chermical engineering plant and in tooling. 

Jones, F.R., Interfacial aspects of glass fibre reinforced plastics. In Jones, F.R. (Ed.), Interfacial Phenomena in Composite Materials. Butterworths, London, 1989, pp. 25-32. Chaudhury, M.K., Gentle, T.M. and Plueddemann, E., Adhesion mechanism of poly(vinyl chloride) to silane primed metal surfaces. J. Adhes. Sci. Technol, 1(1), 29-38 (1987). Gellman, A.J., Naasz, B.M., Schmidt, R.G., Chaudhury, M.K, and Gentle, T.M., Secondary neutral mass spectrometry studies of germanium-silane coupling agent-polymer interphases. J. Adhes. Sci. Technol., 4(7), 597-601 (1990). 

One of the key factors which make plastics attractive for engineering applications is the possibility of property enhancement through fibre reinforcement. Composites produced in this way have enabled plastics to become acceptable in, for example, the demanding aerospace and automobile industries. Currently in the USA these industries utilise over 1(X),000 tonnes of reinforced plastics out of a total consumption of over one million tonnes. 

Tsai, S.W. and Hahn, H.T. Introduction to Composite Materials, Technomic Westport, CT (1980). Folkes, M.J. Short Fibre Reinforced Thermoplastics, Research Studies E ress, Somerset (1982). Mathews, F.L. and Rawlings, R.D. Composite Materials Engineering and Science, Chapman and Hall, London (1993). 

Ashbee, K. Fibre Reinforced Composites, Technomic Lancaster, PA (1993). 

A single ply unidirectional carbon fibre reinforced PEEK material has a volume fraction of fibres of 0.58. Use the data given below to calculate the Poisson s Ratio for the composite in the fibre and transverse directions. 

Other types of compression moulding and stamp forming used for continuous fibre reinforced composites are illustrated in Fig. 4.73. 

Meng Hou, Lin Ye and Yiu-Wing Mai, Advances in processing of continuous fibre reinforced composites Plastics, Rubber and Composites Proc. ondAppL, 23, 5 (1995) pp. 279-292. Mitchell, P. (ed.) Tool and Manufacturing Engineers Handltook, Vol 8, 4th ition, Soc. Man. Eng., Michigan (1996). 

Access of air and water will also affect the corrosion rate. Metal inserts in corrosive plastics are most actively attacked at the plastic/metal/air interfaces with certain metals, notably aluminium titaniumand stainless steel, crevice effects (oxygen shielding and entrapment of water) frequently accelerate attack. Acceleration of corrosion by bimetallic couples between carbon-fibre-reinforced plastics and metals presents a problem in the use of these composites. 

A pyrolysis technique was investigated as a method for the chemical recycling of glass fibre-reinforced unsaturated polyester SMC composites. The proeess yielded liquid products and gases and also a solid residue formed in the pyrolysis of glass fibres and fillers. The solid residue was used as a reinforeement/filler in unsaturated polyester BMC composites, and the influenee on mechanical properties was studied in comparison with BMC prepared entirely from virgin materials. 

Currently, scrap fibre-reinforced composite materials and prepregs are landfilled, although these materials represent... 

Recycling of glass fibre-reinforced plastics is reviewed, with special emphasis on remelting of thermoplastic composites, mechanical recycling of thermoset composites, depolymerisation and dissolution of thermosets and thermoplastics, closed loop recycling of glass, and the use of glass as a mechanical compatibiliser. 32 refs. 

Journal of Thermoplastic Composite Materials 7, No.l, Jan.l994,p.64-74 NEW DEVELOPMENTS IN CHEMICAL RECYCLING AS A SINK FOR PROBLEMATIC WASTE FROM FIBRE-REINFORCED PLASTICS Menges G... 

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