Polypropylene

Polypropylene, propylene prepared by the polymerization of a thermoplastic resin. Methyl-arranged position into isotactic polypropylene (isotactic polypropylene), random polypropylene (atactic polypropylene) and syndiotactic polypropylene (syndiotactic polypropylene) three.

Methyl arranged in the main chain of the same side of said isotactic polypropylene, if methyl disorderly arranged on both sides of the main chain, said random polypropylene, methyl alternately arranged in the main chain between the two sides, said isotactic polypropylene. General industrial production of polypropylene resins, the isotactic structure content of about 95%, the remainder being atactic or syndiotactic polypropylene. Industrial products isotactic thereof as a main component. Polypropylene also includes small amount of propylene copolymers, including ethylene. Usually translucent colorless solid, odorless and non-toxic. Due to regular and highly crystalline structure, so the melting point of up to 167 ℃. Heat-resistant, corrosion-resistant products available steam sterilization is its advantage. Density, is the lightest general-purpose plastics. The disadvantage is poor low temperature impact resistance, easier to aging, but can be overcome by modifying respectively.

Copolymer PP materials have a lower heat distortion temperature (100 ℃), low transparency, low gloss, low rigidity, but there is a stronger impact strength, impact strength of PP increased with increasing ethylene content . PP Vicat softening temperature of 150 ℃. Due to the high degree of crystallinity, surface rigidity and scratch resistance properties of this material is very good. PP environmental stress cracking problem does not exist.

PP melt mass flow rate (MFR) is usually 1 to 100. Low MFR PP material better impact properties, but the extension of lower intensity. MFR for the same material, copolymer impact strength than homo-type is higher. Crystal, PP contraction rate is very high, typically 1.6 to 2.0%.