The investigation of mechanical and tribological properties of some thermoplastic composite materials

Poly-butylene-terephtalate (PBT), poly-ethylene-terephtalate and PBT/PET composites filled with up to 30 wt% alumina, were prepared by extrusion and injection molding machine. Alumina filler, with weight percentages varying between 10 and 30 wt%, were added to PBT, PET thermoplastic matrix and PBT/PET blend. In this study, alumina filler was used with three different particle sizes which are 10?m, 45 ?m and 60 ?m. Uniaxial tensile, impact and hardness tests were used to examine the effect of alumina filler addition on the mechanical behavior of PBT, PET thermoplastic materials and PBT/PET blend. Tensile strength, elongation at break, modulus of elasticity, impact energy and hardness were obtained. The results showed that the tensile strength values decreased while modulus of elasticity of PBT, PET composite linearly increased with the increase in alumina filler weight ratio. In addition to this, the impact strength and maximum elongation linearly decreased with the increase in filler weight ratio. In addition, in this wear study, dry sliding wear characteristics of PBT, PET and PBT/PET blends and its composite were investigated using a pin-on-disc ring. Disc materials are AISI 4140 steel disc. Wear tests were carried out at the sliding speeds of 0.5 and 1.0 m/s and applied loads of 50N, 100N and 150N and under atmospheric conditions of temperature and humidity. Friction coefficient and specific wear rate values for different combinations of the materials were obtained and compared. For all material combinations, it was observed that, the coefficient of friction increases linearly with the increase in applied pressure and sliding speed values. Furthermore, their specific wear rate slightly increases with the increase in applied loads and sliding speed values. Moreover, seven impingement angles (0o, 15 o, 30 o, 45 o, 60 o, 75 o, 90 o) were used for erosive wear test. The effect of impingement angles of PBT, PET composites in erosive wear tests was investigated. In addition, wear surface properties of all polymer composites used were investigated by using optical microscope.