News Categories
PP resin polypropylene is in many aspects similar to polyethylene, especially in solution behavior and electrical properties. The methyl group improves mechanical properties and thermal resistance, although the chemical resistance decreases.
The properties of pp resin polypropylene depend on the molecular weight and molecular weight distribution, crystallinity, type and proportion of comonomer (if used), and the isotacticity. In isotactic polypropylene, for example, the methyl groups are oriented on one side of the carbon backbone. This arrangement creates a greater degree of crystallinity and results in a stiffer material that is more resistant to creep than both atactic polypropylene and polyethylene.
The density of (PP) is between 0.895 and 0.92 g/cm3. Therefore, PP is the commodity plastic with the lowest density. With lower density, moldings parts with lower weight and more parts of a certain mass of plastic can be produced. Unlike polyethylene, crystalline and amorphous regions differ only slightly in their density. However, the density of polyethylene can significantly change with fillers. Young's modulus of PP is between 1300 and 1800 N/mm². Polypropylene is normally tough and flexible, especially when copolymerized with ethylene. This allows polypropylene to be used as an engineering plastic, competing with materials such as acrylonitrile butadiene styrene (ABS). Polypropylene is reasonably economical. |
The melting point of polypropylene occurs in a range, so the melting point is determined by finding the highest temperature of a differential scanning calorimetry chart. Perfectly isotactic PP has a melting point of 171 °C (340 °F). Commercial isotactic PP has a melting point that ranges from 160 to 166 °C (320 to 331 °F), depending on atactic material and crystallinity. Syndiotactic PP with a crystallinity of 30% has a melting point of 130 °C (266 °F). Below 0 °C, PP becomes brittle. The thermal expansion of PP is very large but somewhat less than that of polyethylene. Chemical properties Polypropylene at room temperature is resistant to fats and almost all organic solvents, apart from strong oxidants. Non-oxidizing acids and bases can be stored in containers made of PP. At elevated temperatures, PP can be dissolved in nonpolar solvents such as xylene, tetralin, and decalin. Due to the tertiary carbon atom, PP is chemically less resistant than PE (see Markovnikov rule). |
There are three general types of pp resin polypropylene: homopolymer, random copolymer, and block copolymer. The comonomer is typically used with ethylene. Ethylene-propylene rubber or EPDM added to polypropylene homopolymer increases its low-temperature impact strength. Randomly polymerized ethylene monomer added to polypropylene homopolymer decreases the polymer crystallinity, lowers the melting point, and makes the polymer more transparent.
Contact us, you'll receive exclusive offers and always be in the know about new product announcements and specials!
Mechanical properties
Thermal properties
