Fiber-reinforced organic matrix

A carbon-carbon composite is a carbon fiber reinforced earbon matrix material, where the earbon matrix phase is typically formed by the pyrolysis of a solid, liquid or gaseous organic precursor material. The matrix can be either a graphitizable or a non-graphitizable earbon and the carbonaceous reinforcement is in fibrous form. The composite may also eontain other eomponents in particulate or fibrous forms. 

It should be noted that biological structural materials occurring in nature are typically composites. Common examples are wood, bamboo, bone, teeth, and shell. Furthermore, use of artificial composite materials is not new. Bricks made from straw-reinforced mud were employed in biblical times. This material also has been widely used in the American Southwest for centuries, where it is known as adobe. In current terminology, it would be called an organic fiber-reinforced ceramic matrix composite. 

As with organic-matrix composites, the orientation of the reinforcing material determines whether the properties will be isotropic or oriented in a preferential direction so that the strength and stiffness are greater in the direction of the fiber orientation. 

The crosslinking copolymerization of unsaturated polyesters with styrene is utilized industrially for the production of surface coatings. More extensive are applications in fiber-reinforced plastics where the unsaturated polyesters are used as a matrix for inorganic and organic fibers (see Example 5-20). Areas of application are (large) parts in boats, vehicles, and sport equipment construction. 

The matrix resins for foamed composites include rigid pol)ruretha-nes, unsaturated polyesters, vinyl esters, and their hybrid resins, such as, unsaturated polyester-urethane hybrid resins and vinyl ester-urethane hybrid resins. The reinforcing fibers include glass fibers, carbon fibers, and organic fibers such as polyamide fiber (Kevlar, DuPont), polyamide-... 

The composites can be classified on the basis of the form of their structural components fibrous (composed of fibers in a matrix), laminar (composed of layers of materials), and particulate (composed of particles in a matrix). The particulate class can be further subdivided into flake (flat flakes in a matrix) or skeletal (composed of a continuous skeletal matrix filled by a second material). In general, the reinforcing agent can be either fibrous, powdered, spherical, crystalline, or whiskered and either an organic, inorganic, metallic, or ceramic material. 

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