Matrix in reinforced plastics

These resins are primarily used as a resin matrix in reinforced plastic composites and in structural adhesives. 

The matrix in reinforced plastics may be either a thermosetting or thermoplastic resin. The major thermosetting resins used in conjunction with glass-fiber reinforcement are unsaturated polyester resins and, to a lesser extent, epoxy resins. These resins have the advantage that they can be cured (cross-linked) at room temperature, and no volatiles are liberated during curing. 

Among thermoplastic resins used as the matrix in reinforced plastics, the largest tonnage group is the polyolefins, followed by nylon, polystyrene, thermoplastic polyesters, acetal, polycarbonate, and polysulfone. The choice of any thermoplastic is dictated by the type of application, the service environment, and the cost. 

In practice, the terms plastics , polymer , resin and matrix mean very similar things and are used almost interchangeably in reinforced plastics circles without much confusion, although there are minor differences of interest mainly to the specialist. 

Metal matrix composites (MMC) consisting of fibers embedded in a metal ceramic matrix. Fiber-reinforced plastics (FRP) made of a polymer matrix reinforced with fibers. 

All polymer materials used in reinforced plastics display some viscoelastic or time-dependent properties. The origins of creep in composites stem from the behaviour of polymers under load together with local stress redistributions between fibre and matrix as a function of time. There is little creep at normal temperatures in the reinforcing fibres. The origin of the creep mechanisms is related to the nature and levels of internal bonding forces between the chains of the polymer, which are influenced by temperature and moisture. 

Rich MJ, Drzal LT, Interfacial properties of some high strain carbon fibers in an epoxy matrix, J. Reinforced Plastics and Composites, 4, 145-154, March 1988. 

In reinforced plastics, the material used to bind together the reinforcement material the matrix. 

Reinforced plastics form an important area of structural application of plastics since the modulus and strength of plastics can be increased significantly through reinforcement. In reinforced plastics, the polymer (popularly called the resin) forms the matrix and a filler (mostly used in the form of fibers, hut particles, for example glass spheres, are also used) provides the reinforcing effect. In view of then-distinctive nature and extensive use as materials of construction in load-hearing applications, a special focus has been on analysis of properties of reinforced plastics, especially those reinforced by continuous or discontinuous fibers, as well as their deformation, fi-acture, fatigue, and impact behaviors. 

In the recent past considerable research and development have been expanded in natural fibers as reinforcement in thermoplastic resin matrix. These reinforced plastics serve as an inexpensive, biodegradable, renewable, and nontoxic alternative to glass or carbon fibers. The various advantages of natural fibers over man-made glass and carbon fibers are low cost, low density, competitive specific mechanical properties, reduced energy consumption and biodegradability. Natural fiber reinforced composites with thermoplastic matrices have successfully proven their qualities in... 

Thermosetting unsaturated polyester resins constitute the most common fiber-reinforced composite matrix today. According to the Committee on Resin Statistics of the Society of Plastics Industry (SPl), 454,000 t of unsaturated polyester were used in fiber-reinforced plastics in 1990. These materials are popular because of thek low price, ease of use, and excellent mechanical and chemical resistance properties. Over 227 t of phenoHc resins were used in fiber-reinforced plastics in 1990 (1 3). PhenoHc resins (qv) are used when thek inherent flame retardance, high temperature resistance, or low cost overcome the problems of processing difficulties and lower mechanical properties. 

The matrix in a reinforced plastic may be either thermosetting or thermoplastic, (a) Thermosets... 

The viscoelastic nature of the matrix in many fibre reinforced plastics causes their properties to be time and temperature dependent. Under a constant stress they exhibit creep which will be more pronounced as the temperature increases. However, since fibres exhibit negligible creep, the time dependence of the properties of fibre reinforced plastics is very much less than that for the unreinforced matrix. 

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