Polystyrene (PS) is an important commodity plastic; however, it is not known as a suitable material for tribological applications. It has a relatively high friction coefficient in contact with metallic surfaces and high abrasion loss factor. Polytetrafluoroethylene (PTFE) is a known friction modifier, has a low friction coefficient, and is extensively used to reduce the friction coefficient and wear rate (with engineering plastics to improve tribological properties). It is known for fluoroelastomers and engineering plastics that fine particles of PTFE have the greatest effect on improving the specified properties. Here, oriented, fibrillated network morphology of PTFE in PS matrix was prepared. The wear studies show a large reduction in both the friction coefficient (45% reduction) and the wear rate (2% incorporation of PTFE leads to a 49% reduction). But the friction coefficients do not show any significant change on increasing PTFE. A similar observation was made for the wear rate. Scanning electron microscope (SEM) images of the worn surfaces show a crack tip bridging mechanism, and it was observed that with the increase in PTFE content, the extent of crack tip bridging increases. This extensive improvement may be attributed to the unique morphology of the blend system. 1. Introduction Blending of polymers is mixing of two or more polymers or copolymers to modify the material property to suit any desired end application in a fast and inexpensive route. There are mainly three different routes of making polymer blends: solution casting, emulsion mixing, and melt mixing. Of the three routes, solution casting is practiced nearly exclusively in laboratory scale processes, due to the difficulties in scale-ups. Melt mixing is the most widely used method of polymer blending and can be done in different equipment, namely, static batch mixing equipment, static kneading equipment, and mixing in extruders. Polymer blends can be homogeneous or heterogeneous mixtures depending on the miscibility and compatibility of the components. The properties of polymer blends depend not only on their individual properties or amount but also, in the case of heterogeneous systems on the nature of the interphase, which in turn is dependent on the morphology of the blend system. Morphology development in blends is a process of evolution of spatial geometry or arrangement of the phases of the constituent polymers. Thus, it would be very desirable if the morphology could be controlled by the blending operation, since that would impart a higher degree of control over the final
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