Polypropylene (PP) is one of the most widely used and cost-effective general-purpose plastics in injection molding. Its processing is efficient and stable, and the material features excellent chemical resistance, good heat resistance, high resistance to flexural fatigue, low cost, and ease of recyclability. As it is the lightest among common plastics, it is particularly well-suited for weight-sensitive applications; furthermore, various additives can be incorporated to meet specific requirements regarding strength, stiffness, and impact performance. It is extensively utilized across the automotive, home appliance, packaging, and daily consumer goods sectors.