Polypropylene (PP) is a large molecule made by polymerizing propylene, and has three types of isotactic PP, syndiotactic PP and atactic PP according to molecular configuration. Among them, Isotactic PP has a commercially useful structure, which has high crystallinity, and excellent mechanical/thermal properties. Thus, 'PP resin' commonly indicate isotactic PP.
Currently, GS-Caltex produces superior-quality homo, random, and impact polypropylene "hiprene"(which all basically belongs to isotactic structure) and is striving to reinforce the PP Compound business.
Homo polypropylene is a resin polymerized by only propylene monomers, and has a fine stereoregularity, featuring a high crystallinity. It thus shows excellent rigidity and thermal resistance. Its main uses are film, yarn, and many commodity applications.
Impact polypropylene is a co-polymer of propylene and ethylene(It is polymerized differently from Random polypropylene). Impact polypropylene has no much smaller rigidity compared to the homo polymer, and greatly improved on impact resistance. It is used mainly in making impact-resistant materials for automotives and electronic appliances, and industrial vessels, etc.
Random polypropylene is a co-polymer made by adding a small amount of ethylene in polymerizing polypropylene, which lowers molecular stereoregularity. Compared to homo polypropylene, It has structurally more atypical parts in molecular chains, so it has a little weaker rigidity. However, It has better impact-strength and flexibility. Also, It has excellent transparency with little light scattering, compared to homo and impact polypropylene. Random polypropylene is used mainly in making transparent airtight vessels and transparent bottles, energy absorber for autos(foam) as well as impact-resistant packaging materials.
PP Compounds are made by adding other chemicals such as inorganic fillers (like talc, mica, and glass fiber) and rubber, as well as functional additives such as flame retardants and nucleating agents, to homo, random and impact polymers. Through this, PP Componds have greatly enhanced properties over ordinary polypropylene. There are many grades according to purposes and properties such as rigidity, conductivity, thermal resistance, glossiness, softness, paintability, and flame retardation. They are widely used in making interior and exterior materials for automotives, and electric appliances' parts, and the like.