In this book the reader can explore how additives and fillers have been employed as a mean to improve polypropylene properties: mechanical,fluid and resistance to photodegradation. This book explores common properties, advantages and drawbacks of polypropylene, and the means that researchers have been studying as a manner of solve the main disadvantages of polypropylene by the use of additives such as nanoparticles, blend compatibilizers, hindered amine light stabilizers (HALS). These materials have been proved succesful to mantain polypropylene as a top choice in the field of thermoplastics.