Polyolefins, exemplified by polyethylene (PE) and polypropylene (PP), exhibit many useful properties. They are lightweight and possess excellent mechanical strength, flexibility, processability, chemical inertness, and recyclability. Polyolefins, therefore, are cost effective. They are used in the manufacture of numerous products, such as toys, plastic shopping bags, food packages, shampoo and detergent bottles, storage boxes, disposable diapers, sneakers, and car bumpers.