The effect of micron fillers on the mechanical properties of polyurethane shoe soles

In this study, the effects of the polyol/isocyanate ratio, mold temperature, and the size and content of polyol filler material on the mechanical properties in the production of polyurethane shoe outsoles were investigated. Pumice was preferred as the filler material due to its proximity to the density of isocyanate, and 2 different sizes of pumice stone powder were added in four different proportions. To create the inner mold for the shoes, a sports mold was obtained from a PVC inner mold manufacturing company, digitized in the context of this doctoral study, and a sole design was created. A metal mold design was then created to match the sole design and manufacturing was carried out. Samples were obtained using 3 different polyol/isocyanate ratios, 3 different mold temperatures, 2 different sizes of filler material, and 4 different contents of filler material. These samples were subjected to FTIR and EDX analyses, and their densities were calculated. Tensile tests, compression energy tests, wear tests, flexural resistance tests, and water absorption rates were determined, and SEM examination was conducted. As a result of the conducted tests and analyses, it was determined that a 50/50 polyol/isocyanate ratio and a mold temperature of 50 ℃ provided advantages among the studied values. Different contents and sizes of the filler material led to significant variations in the tensile strength, ductility, compression energy, flexural resistance, wear resistance, and water absorption rate of the obtained samples. It was concluded that the filler content and its size have a significant impact on achieving the desired properties in polyurethane shoe outsoles, and these effects have been presented within the scope of this thesis.