Polypropylene (PP) is a high-molecular-weight polymer derived from propylene monomers. Depending on the polymerization method, its production can be categorized into five main processes: solution polymerization, slurry polymerization, bulk polymerization, gas-phase polymerization, and combined bulk–gas-phase polymerization. Structurally, polypropylene is primarily divided into isotactic, syndiotactic, and atactic forms. Among them, isotactic polypropylene is the most commonly used, accounting for more than 90% of all applications.

Atactic polypropylene is suitable for use in additives, adhesives, and modifiers. It serves as an effective carrier for modified masterbatches due to its high viscosity, good flow characteristics, and superior coating performance. Syndiotactic polypropylene offers benefits such as clarity, toughness, and flexibility, though its rigidity and hardness are only about half that of isotactic PP. It can undergo vulcanization similar to ethylene-propylene rubber, producing elastomers with mechanical properties surpassing those of conventional rubber.

Although its higher cost currently limits broader use, syndiotactic polypropylene holds strong development potential and is considered a promising new growth area for polypropylene resins, as well as an emerging synthetic resin for advanced material modification.

CHEMICAL PROPERTIES

PRODUCT USAGE

Polypropylene possesses outstanding processing performance and can be formed through multiple techniques to create a wide range of products for diverse applications. Injection-molded polypropylene is especially common, with general-purpose PP serving as the main material in everyday consumer items. In the automotive, home appliance, and industrial sectors, both pure and modified polypropylene are widely utilized. For instance, toughened PP is often used for automobile bumpers and wheel covers, while reinforced PP is applied in dashboards, steering wheels, fan blades, and handles.