Commercial isotactic PP has a melting point that ranges from 160 to 166 ☌ (320 to 331 ☏), depending on atactic material and crystallinity. Perfectly isotactic PP has a melting point of 171 ☌ (340 ☏). 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. Polypropylene has good resistance to fatigue. This allows polypropylene to be used as an engineering plastic, competing with materials such as acrylonitrile butadiene styrene (ABS). Polypropylene is normally tough and flexible, especially when copolymerized with ethylene. The Young's modulus of PP is between 13 N/mm². However, the density of polyethylene can significantly change with fillers. Unlike polyethylene, crystalline and amorphous regions differ only slightly in their density. With lower density, moldings parts with lower weight and more parts of a certain mass of plastic can be produced. Therefore, PP is the commodity plastic with the lowest density. The density of PP is between 0.895 and 0.93 g/cm 3. 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. In isotactic polypropylene, for example, the methyl groups are oriented on one side of the carbon backbone.
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: 19 The properties of polypropylene depend on the molecular weight and molecular weight distribution, crystallinity, type and proportion of comonomer (if used) and the iso tacticity. The methyl group improves mechanical properties and thermal resistance, although the chemical resistance decreases. Polypropylene is in many aspects similar to polyethylene, especially in solution behaviour and electrical properties. Syndiotactic polypropylene was also first synthesized by Natta.Ĭhemical and physical properties This pioneering discovery led to large-scale commercial production of isotactic polypropylene by the Italian firm Montecatini from 1957 onwards.
The stereoselective polymerization to the isotactic was discovered by Giulio Natta and Karl Rehn in March 1954. Paul Hogan and Robert Banks first demonstrated the polymerization of propylene in 1951. Polypropylene is the second-most widely produced commodity plastic (after polyethylene). īio-PP is the bio-based counterpart of polypropylene (PP). It is a white, mechanically rugged material and has a high chemical resistance. Its properties are similar to polyethylene, but it is slightly harder and more heat-resistant. Polypropylene belongs to the group of polyolefins and is partially crystalline and non-polar. It is produced via chain-growth polymerization from the monomer propylene.
Polypropylene ( PP), also known as polypropene, is a thermoplastic polymer used in a wide variety of applications.
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