In 1984 PP had become one of the world's five most common plastics. The main raw material is propylene, and the high molecular weight polymer of propylene is polypropylene.
The degree of crystallinity of PP is related to its isotacticity. It is highly isotactic and easy to crystallize. Its crystallinity is 30 to 70%, crystallinity is high, density is high, and melt index is small. Its melting index was measured at a temperature of 23 degrees, the density of the PP non-crystalline part was 0.851 g/cm3, and the crystal part was 0.935 g/cm3. The crystallization directly affected the density. PP has an average molecular weight of more than 80,000 and a melting point of 164 to 170 degrees.
PP aggregation:
The propylene monomer is derived from petroleum, natural gas cracking or dehydration of propanol, followed by polymerization or solvent polymerization using a Ziegler catalyst; that is, using titanium trichloride and molten aluminum as the composite catalyst, with heptane or Gasoline is a solvent, and the polymerization is carried out at a pressure of 0.3~1Mpa, and the temperature is 60~80 degrees. The feed is to and from the separation kettle. The propylene of this reaction is ejected from the kettle, and is recycled for use in compression. The PP suspension is separated by a centrifuge. The solvent was removed and washed with methanol to remove the catalyst residue, followed by washing and drying to obtain PP.
PP identification:
PP is a colorless, odorless, non-toxic, white wax-like granular material that looks like PE (polyethylene) but is more transparent and lighter than PE and has a specific gravity of 0.89 to 0.91. Is the lightest plastic variety, it is basically a linear high crystalline polymer that floats on water.
PP is easy to burn, and it is burned away from the fire. The top of the flame is yellow, and there is a small amount of black smoke at the bottom, and the melt stretchability is excellent. The molten drips after burning, and the oil smells.
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