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In this study, influence of the chemical foaming agent content and talc mineral filler on the microcellular and mechanical properties of pure polypropylene and 20 wt% talc filled polypropylene composite foams was investigated. The chemical foaming agent at 1 wt% and 2 wt% ratios was added to pure polypropylene and talc filled polypropylene composites. Using an injection molding machine, foam materials were produced under a set of process parameters consisting of injection pressure, injection speed, melt temperature, and packing pressure. For each set of process parameters, the cell number, cell size, distance between cells, skin layer thickness, cell density, and the mechanical properties of foam products were recorded. The results indicate that the cell number, cell density, skin layer thickness, tensile strength, and tensile modulus values for microcellular talc filled polypropylene composite foam are higher, while the cell diameter, impact strength, and elongation at break values are lower than that of pure microcellular polypropylene foam.

The friction and wear properties of pure poly-tetra-fluoro-ethylene (PTFE), 35% carbon filled poly-tetra-fluoro-ethylene (PTFEþ35%C), and 17% glass fiber-reinforced polytetra-fluoro-ethylene (PTFEþ17%GFR) sliding against stainless steel under dry sliding conditions were studied by using a pin-on-disc tribometer. The effect of applied pressure and sliding speed on tribological properties of the polymer-stainless steel combination under dry sliding conditions was investigated. Tests were carried out at sliding speeds of 0.32, 0.64, 0.96, 1.0, 1.5, and 2.0 m/s and under applied pressures of 0.17, 0.34, 0.68, 1.02, 1.76, 3.53, 5.30, and 7.07 MPa. Optical microscopy was utilized to examine the worn surfaces of pure PTFE and it's composite. The results indicated that, for pure PTFE, carbon-filled PTFE and glass fiber-reinforced PTFE composites are used in this investigation; the friction coefficient decreases with the increase in applied load values. The maximum reduction in wear rate was obtained by glass fiber-reinforced PTFE composite. The specific wear rate for pure PTFE, carbon filled PTFE composite, and glass fiber-reinforced PTFE composite were in the order of 10 À13 , 10 À14 , and 10 À15 m 2 /N, respectively. The wear mechanism include adhesive and abrasive processes.

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Until now, recycling studies brought to the agenda after the rapid increasing of plastic materials in every area and causing those plastics to environmental pollution after discarding them following the utilization. The purpose of recycling plastic waste is to minimize environmental pollution and to create of new resources. To perform the present study, Recycled Polypropylene Granules (RPP) belonging to Polypropylene (PP) will be used in most particularly in the automotive and in the packaging industry finding application area behind the Low Density Polyethylene (LDPE). To develop the several properties (physical and thermal) of RPP polymer and to get close to or greater value to the original PP features, different rates of micron-sized glass fibers, talc and CaCO 3 are added into the polymer. By recycling waste, demand for natural resources (such as oil, which is plastic's raw materials) will decrease and rapid consumption of energy sources will be prevented while providing the protection of natural resources. Raw materials imports would be reduced due to the usage of recycled products. In this study, Recycled Polypropylene Granules (RPP) were obtained from companies and glass fiber/talc/CaCO 3 additive RPP granules in different ratios were produced with compounding extrusion process. These produced new composite pellets were produced in injection molding machine by means of designed mold to perform tensile and impact tests. In the thermal analysis, the melting temperature and crystallization rate were determined by DSC analysis; the thermal decomposition temperature was determined by TGA analysis. Micro structural examination was done using a Scanning Electron Microscope (SEM).