Composite polymer matrix

Materials that are classified as fibers are either polycrystalline or amorphous and have small diameters fibrous materials are generally either polymers or ceramics (e.g., the polymer aramids, glass, carbon, boron, aluminum oxide, and silicon carbide). Table 16.4 also presents some data on a few materials that are used in fiber form. 

Fine wires have relatively large diameters typical materials include steel, molybde-nmn, and timgsten. Wires are used as a radial steel reinforcement in automobile tires, in fUament-woimd rocket casings, and in wire-wound high-pressure hoses. 

The matrix phase of fibrous composites may be a metal, polymer, or ceramic. In general, metals and polymers are used as matrix materials because some ductility is desirable for ceramic-matrix composites (Section 16.10), the reinforcing component is added to improve fracture toughness. The discussion of this section focuses on polymer and metal matrices. 

Glass Fiber-Reinforced Polymer (GFRP) Composites 

Fiberglass is simply a composite consisting of glass fibers, either continuous or discontinuous, contained within a polymer matrix this type of composite is produced in the largest quantities. The composition of the glass that is most commonly drawn into fibers (sometimes 

Polymers are well-suited as matrix materials due to their low density and their low processing temperatures. Accordingly, composites with a polymer matrix are of extreme technical importance. They are indispensable in aerospace industry and many other areas, for example in sports equipment. Polymer matrix composites can be used with long and short fibres. We will start this section by discussing long-fibre polymer matrix composites and then study short-fibred ones. 

Long-fibre reinforced polymer matrix composites 

Because the strength and elastic stiffness of the fibres used in polymer matrix composites is frequently more than a hundred times larger than that of the 

This variation in the mechanical properties is due to the fibre microstructure. There are two different structures (so-called allotropes ) of carbon The diamond structure, shown in figure 1.13, only forms at high temperatures and pressures and is in fact metastable at room temperature. The stable conformation of carbon is graphite. In graphite, the carbon atoms are ordered in a 

The microstructure of the high-stiffness carbon fibres is similar to that sketched in figure 9.13(a), with the sheets arranged almost perfectly along the 

Aligned continuous fiber PMC tubes combine strength and rigidity to make very light structural members and trusses. Porsche and other automobile manufacturers are experimenting with carbon fiber PMC tubular frames to lighten their cars. The Porsche Carrera GT is built with a carbon fiber panel monocoque body on a carbon PMC subframe with practically no metal parts in the structure. 

It is possible to fabricate graphite fibers with thermal conductivities as high as 1200 W/m-deg. These fibers are available in a polymer prepreg that can be cured by 

Recent developments in s5mthesis and assembling CNTs into continuous fibers have opened the doors to more widespread research in the effort to develop the ultimate fiber (see Section 5.4.7). When subjected to high pressrue, some of the bonds can convert to sp bonds, which may provide a means for cross-linking the CNT fibers into a super-strong fabric—carbon threads joined by diamonds. 

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O Brien, T.K., Characterization of Delamination Onset and Growth in a Composite Laminate in Damage in Composite Materials, ASTM STP 775, p. 140-167,1982 Poursartip, A. Ashby, M. F., Beaumont P.W.R., The Fatigue Damage Mechanics of Fibrous Laminates in Proceedings of the European Workshop on Nondestructive Evaluation of Polymers and Polymer Matrix Composites, Polymer NDE (edited by Khg. Ashbee), Technomic Publishing, p. 250-260, 1984... 

W. J. Beranek, Proceedings of the European Workshop on NDE of Polymer and Polymer Matrix Composition, Terniar do Vimeko, Sept. 1984, pp. 222—236. 

Polymer-matrix composites for aerospace and transport are made by laying up glass, carbon or Kevlar fibres (Table 25.1) in an uncured mixture of resin and hardener. The resin cures, taking up the shape of the mould and bonding to the fibres. Many composites are based on epoxies, though there is now a trend to using the cheaper polyesters. 

Applied Sciences, Inc. has, in the past few years, used the fixed catalyst fiber to fabricate and analyze VGCF-reinforced composites which could be candidate materials for thermal management substrates in high density, high power electronic devices and space power system radiator fins and high performance applications such as plasma facing components in experimental nuclear fusion reactors. These composites include carbon/carbon (CC) composites, polymer matrix composites, and metal matrix composites (MMC). Measurements have been made of thermal conductivity, coefficient of thermal expansion (CTE), tensile strength, and tensile modulus. Representative results are described below. 

All VGCF was graphitized prior to composite consolidation. Composites were molded in steel molds lined with fiberglass reinforced, non-porous Teflon release sheets. The finished composite panels were trimmed of resin flash and weighed to determine the fiber fraction. Thermal conductivity and thermal expansion measurements of the various polymer matrix composites are given in Table 6. Table 7 gives results from mechanical property measurements. 

Table 6. Thermal properties of VGCF polymer matrix composites...

Historically, polymer-matrix composite materials such as boron-epoxy and graphite-epoxy first found favor in applications, followed by metal-matrix materials such as boron-aluminum. Ceramic-matrix and carbon-matrix materials are still under development at this writing, but carbon-matrix materials have been applied in the relatively limited areas of reentry vehicle nosetips, rocket nozzles, and the Space Shuttle since the early 1970s. 

E. P. Plueddemann, Interfaces in Polymer Matrix Composites, Academic Press, New York (1974). 

Carbon fiber-PEEK, 26 764 Carbon fiber polymer-matrix composites, properties of, 26 774... 

Polymer liquid crystals, 75 107-111 Polymer matrices, 26 761-765 Polymer-matrix composites, 73 502 26 751, 755-756 fabrication of, 26 765 Polymer melts, 75 108-109 27 730-731 chain fluctuations in, 27 714 viscosity of, 20 99 21 712-714 Polymer metal composites, smart, 22 718 Polymer microspheres, 9 73-75 Polymer microstructure, polychloroprene, 79 836-838... 

Experimental results are presented that show that high doses of electron radiation combined with thermal cycling can significantly change the mechanical and physical properties of graphite fiber-reinforced polymer-matrix composites. Polymeric materials examined have included 121 °C and 177°C cure epoxies, polyimide, amorphous thermoplastic, and semicrystalline thermoplastics. Composite panels fabricated and tested included four-ply unidirectional, four-ply [0,90, 90,0] and eight-ply quasi-isotropic [0/ 45/90]s. Test specimens with fiber orientations of [10] and [45] were cut from the unidirectional panels to determine shear properties. Mechanical and physical property tests were conducted at cold (-157°C), room (24°C) and elevated (121°C) temperatures. 

Brink, A. E. and Owens, J. T., Thermoplastic polyurethane additives for improved polymer matrix composites and methods of making and using therefor, US Patent 6 043 313, 2000. 

Fiber-reinforced polymer matrix composites UD carbon fiber-epoxy matrix ... 

The interface region thus formed has a substantial thickness, and its chemical, physical and mechanical properties are different from those of either the bulk fiber and the matrix (i.e., the interphase as opposed to the interface of zero thickness). The interphase is found to be significantly softer than the bulk matrix material in polymer matrix composites (Williams et al., 1990 Tsai et al., 1990). For example,... 

Other than in polymer matrix composites, the chemical reaction between elements of constituents takes place in different ways. Reaction occurs to form a new compound(s) at the interface region in MMCs, particularly those manufactured by a molten metal infiltration process. Reaction involves transfer of atoms from one or both of the constituents to the reaction site near the interface and these transfer processes are diffusion controlled. Depending on the composite constituents, the atoms of the fiber surface diffuse through the reaction site, (for example, in the boron fiber-titanium matrix system, this causes a significant volume contraction due to void formation in the center of the fiber or at the fiber-compound interface (Blackburn et al., 1966)), or the matrix atoms diffuse through the reaction product. Continued reaction to form a new compound at the interface region is generally harmful to the mechanical properties of composites. 

Scolar, D.A. (1974). In Interfaces in Polymer Matrix Composites, Composite Materials, Vol. 6 (E.P. Plueddemann ed.). Academic Press, New York, pp. 217-284. 

ASTM D 5528 (1994). Mode I interlaminar fracture toughness of unidirectional fiber-reinforced polymer matrix composites. 

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