Polypropylene (PP) is produced by the polymerization of propylene. PP has a reputation as a lightweight, versatile polymer with excellent chemical resistance along with relatively high rigidity and a high melting point compared with other polymers such as PE. The high-temperature feature is very important and allows for PP to be under the hood in auto applications and to undergo retort and hot-filled treatments for food packaging. In addition, PP continues to be used in applications ranging from automotive parts, carpet fibers, household and food containers, toys, dog kennels, diapers, water pipe, foam construction materials, and high-clarity films. In addition to inter-material competition with PE, PS, and PET, PP typically competes against other traditional nonpolymer materials.
