Plastic waste is increasingly found in the environment due to the growing production and demand for plastics. Its degradation leads to the formation of microplastics (MPs), plastic fragments smaller than five millimeters. Microplastics are easily transported through nature via wind and water, and they can also enter the food chain, posing a threat to the non-living environment, flora, fauna, and ultimately, humans. The aim of this study was to investigate the impact of multiple extrusion processes on the properties of polypropylene, a thermoplastic polymer material. Mechanical recycling of polypropylene was carried out using a twin-screw laboratory extruder, and the pellets were extruded at an extruder temperature profile of T = 170/190/190/195/200/200 °C with a screw rotation speed of 50 rpm in four cycles. Samples obtained through extrusion were characterized using infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Infrared spectroscopy provided information about the degradation of the samples, including the appearance and/or disappearance of characteristic functional groups in the polypropylene molecule. X-ray diffraction was used to determine the structural and the fraction of crystallinity (homogeneity, crystallinity). Multiple recycling cycles of polypropylene samples resulted in the emergence of new oxygen-containing degradation groups, which combined and/or disappeared with an increasing number of extrusion cycles. Additionally, as the number of extrusion cycles increased, the concentration of degradation groups and the crystallinity of the samples that remained homogeneous during the process decreased.