5 - Glass fibers

Abstract

Glass fibers are formed from melts and manufactured in various compositions by changing the amount of raw materials like sand for silica, clay for alumina, calcite for calcium oxide, and colemanite for boron oxide. Therefore, different types of glass fibers show different performances like alkali resistance or high mechanical properties using various amounts of silica or other sources. Glass fiber products are classified according to the type of composite at which they are utilized. Moreover, chopped strands, direct draw rovings, assembled rovings, and mats are the most important products that are used in the injection molding, filament winding, pultrusion, sheet molding, and hand layup processes to form glass fiber-reinforced composites. Protection of the glass fiber filaments from breakage or disintegration is an important issue either during manufacturing of glass fiber or during composite production. Applying sizing agent to the glass fiber during manufacturing of fibers causes lubrication of the glass fiber filaments in addition to inhibit static electricity accumulation, adhesion of the fiber filaments together, and adhesion between fiber filaments and polymer matrix of the composites. During manufacturing of composites, an interphase layer, at which interpenetration of the sizing to the matrix or diffusion of the matrix polymer to the sizing, is formed. The resultant interphase layer can either increase or decrease the performance of the composite considering harmony between sizing components and matrix polymer. Compatibility between sizing and matrix polymer enhances high mechanical properties and on the contrary incompatible sizing results poor mechanical properties. From energy point of view, reduction in the weight of vehicles is the main reason to save energy in the transportation industry, and in this regard growth in the production of lightweight cars to about 50% indicates importance of the glass fiber-reinforced composites. Consequently, growth in the glass fiber production is what that happened and will be continued in the future.