Composite Materials: Polymer Matrix Composites

POLYMER MATRICES

Composite materials, as we know, are composed of a matrix and a reinforcement. Very commonly polymer matrix are used. PMC’S or polymer matrix composites are made up of a variety of short or continuous fibers bound together by an organic polymer matrix. These are designed so that the mechanical loads to which the structure is subjected in service are supported by the reinforcement. The function of the matrix is to bond the fibers together and to transfer loads between them. Polymer matrix composites are often divided into two categories: reinforced plastics, and “advanced composites. ” The distinction is based on the level of mechanical properties (usually strength and stiffness); however, there is no unambiguous line separating

Advanced composites, which have been in use for only about 15 years, primarily in the aerospace industry, have superior strength and stiffness, and are relatively expensive. Advanced composites are the focus of this assessment. Chief among the advantages of PMCs is their light weight coupled with high stiffness and strength along the direction of the reinforcement. This combination is the basis of their usefulness i n aircraft, automobiles, and other moving structures. Other desirable properties include superior corrosion and fatigue resistance

Sporting goods, such as golf clubs and tennis rackets, account for another 25 percent. The sporting goods market is considered mature, with projected annual growth rates of 3 percent. Automobiles and industrial equipment round out the current list of major users of PMCs, with a 25 percent share. The next major challenge for PMCs will be use in large military and commercial transport aircraft. PMCs currently comprise about 3 percent of the structural weight of commercial aircraft such as the Boeing 757, but could eventually account for more than 65 percent. Because fuel savings are a major reason for the use of PMCs in commercial aircraft, fuel prices must rise to make them competitive. The largest volume opportunity for PMCs is in the automobile. PMCs currently are in limited production in body panels, drive shafts, and leaf springs. By the late 1990s, PMC unibody structures could be introduced in limited production. Additional near-term markets for PMCs include medical implants, reciprocating industrial machinery, storage and transportation of corrosive chemicals, and military vehicles and weapons.

Beyond the turn of the century, PMCs could be used extensively in construction applications such as bridges, buildings, and manufactured housing. Because of their resistance to corrosion, they may also be attractive for marine structures. Realization of these opportunities will depend on