In this study, effects of surface modification of calcium carbonate (CaCO3) nanoparticles with a single-layer of stearic acid were investigated on dispersion in polypropylene (PP) matrix. Two kinds of CaCO3 nanoparticles (monolayer-coated and uncoated) were used to investigate this effect. All combinations were mixed in a co-rotating twin screw extruder and then were injection molded. After breaking the injection molded parts in liquid nitrogen, effect of surface modification of nanoparticles on their dispersion in the PP matrix was investigated using a field emission scanning electron microscope (FESEM). The results showed good agreement between the measurements made with the TGA analysis and the existing theories. The surface modification of calcium carbonate nanoparticles using a single layer of stearic acid also had an effective influence on improving distribution and dispersion of nanoparticles in the PP matrix.
To find the possible error sources of manufacturing systems, the important operational characteristics of different body elements should be investigated. Stiffness is one of the most important characteristics of a machine tool's guiding system, influencing their performance and accuracy. This paper concerns with some analytical and experimental investigations on static stiffness of linear motion guides. The analytical studies are conducted using Hertzian theory. Then, we have carried out some experiments to investigate the static stiffness of industrial ball bearing linear motion guides in normal, lateral and angular directions. A maximum force of 10 kN has been applied to measure it for three preload levels of carriages and in compression and tensile directions. The results of analytical and experimental investigations have been compared. Then, the guide is driven with different velocities to find the influence of movement on the stiffness. The backlash and three different angular deflections in roll, pitch and yaw directions are measured.
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