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Epoxy resin and glass fiber both are the most widely used constituents of the composite industries. Epoxy resin, due to its excellent adhesion to many reinforcements, high hardness, and excellent resistance to humidity, good mechanical and thermal properties coupled with process ability (Wang, Zheng & Zheng, 2011) has become popular among the polymers. Properties that have made glass fibers so acceptable include low cost, high production rates, high strength, high stiffness, relatively low density, non-flammable, good chemical resistance, relatively insensitive to moisture, able to maintain strength properties over a wide range of conditions, good electrical insulation (Wallenberger, Watson & Li, 2001). In general, glass fiber reinforced epoxy matrix composites have been increasingly used for numerous engineering purpose such as seals, gears, rollers, cams, wheel, clutches and bearings due to high specific strength and high modulus, better tribological properties, wide varieties of availability and design flexibility as compared to metal based counterparts. In particular, the woven fabric composites are getting acceptance in many engineering applications such as in circuit board, marine, aerospace, transportation and other industries for several reasons. They are commonly used in industry to manufacture composite components due to their ease of use, improve structural performance and reduction in cost. They provide better resistance to impact than unidirectional composites and display behavior that is closer to that of a fully isotropic material (Abot, Yasmin, Jacobsen & Daniel, 2004; Park & Jang, 1998; Bijwe & Rattan, 2007).
Glass fiber reinforced polymeric composites traditionally show poor wear resistance and high friction due to the brittle nature of the reinforcing fibers. Modification of woven fabric reinforced composites by incorporation of fillers has been a popular research activity in the plastics industry since the properties of resultant materials may be significantly changed by the introduction of fillers and fabrics (Zaini, Fuad, Ismail, Mansor & Mustafah, 1996). Addition of abrasive fillers, however, enhances not only wear resistance, but, also coefficient of friction of glass/epoxy composites. If coefficient of friction increases, it may lead to heat buildup, which, in turn, might cause thermal degradation/aging of the polymer matrix. Hence, it is essential to reduce coefficient of friction by judicious choice of filler(s). The reason to incorporate filler into a polymer is two-fold; (a) first to improve the wear resistance, mechanical and thermal properties and (b) to reduce the cost of the final product. In the last two decades, various filler and fiber materials have emerged as a subject of extensive research. A good amount of research has already been conducted with organic or inorganic particles filled glass epoxy composites (Suresha, Chandramohan, Prakash, Balusamy & Sankaranarayanasamy, 2006; Debnath, Sampathkumaran, Seetharamu, Thomas & Janardhana, 2005; Suresha et al., 2006; Shivamurthya, Siddaramaiah & Prabhuswamy, 2009; Raju, Suresha, Swamy & Kanthraju, 2013; Mohan, Mahesha & Raja, 2014; Debnath, Singh & Dvivedi, 2013) to improve the tribological as well as mechanical properties based on the continuous sliding (pin and disc) mode of contact. In a comparison of reciprocating and continuous sliding wear, Ward (1970) has shown that under similar conditions of load, speed and nominal area of contact, a higher wear rate is obtained during reciprocating sliding. In most of the cases fiber orientation relative to the rubbing surfaces has not been considered. From tribological aspects of composites as end product, its behavior depends on the types of contact between the mating surfaces and on the fiber orientation relative to the surface of action (Sung & Suh, 1979; Chang, 1983; Cirino, Friedrich & Pipes, 1998).