Polypropylene is a thermoplastic polymer with a wide variety of applications. Researchers are continually finding new opportunities for the use of polypropylene, as discussed in the five chapters of this book. Chapter One aims to show the feasibility of post-consumer polypropylene recycling to obtain 3D printer filaments and presents some necessary characteristics of the materials used in FDM technology to ensure final parts with good properties. Chapter Two provides an overview of polypropylene nanocomposites, types of nanofiller, and their applications in the industry. Chapter Three explores the potential of polypropylene-based composites as an alternative to conventional radiation shielding materials. Chapter Four reviews polymer monoliths' recent environmental and bioanalytical application in several polypropylene tubes, such as pipette tips, syringe barrels, spin columns, and ink-pen tubes. Lastly, Chapter Five investigates the effects of calcium, aluminum and zinc stearates as pro-oxidant agents on the degradation of polypropylene bags under natural weathering.