1. Basic nature
1. Polypropylene (PP) Polypropylene is a semi-crystalline polymer made from the polymerization of propylene monomer. Its molecular chains are tightly arranged, with good mechanical properties and chemical resistance. PP has a higher melting point of about 167°C.
2. Polyethylene (PE) Polyethylene is a crystalline or amorphous polymer formed by polymerization of ethylene monomer. The molecular chains of PE are relatively loosely arranged, so its mechanical properties and chemical resistance are slightly inferior to PP. PE has a low melting point of about 130°C.
Second, the production process
1. Polypropylene (PP) The production of PP mainly adopts the gas phase method or bulk method. The gas phase method is to polymerize propylene monomer under the action of a catalyst to generate polypropylene powder. The ontology rule is to polymerize in liquid propylene to generate liquid polypropylene, and then obtain PP particles through cooling, solidification, granulation and other processes.
2. Polyethylene (PE) The production process of PE mainly includes three methods: high pressure, medium pressure and low pressure. The high-pressure method is formed by polymerizing ethylene monomer at higher pressure, and the molecular weight of PE obtained is low; The medium pressure method was polymerized under medium pressure, and the PE molecular weight obtained was high. The low-pressure method is polymerization at lower pressures and is mainly used to produce high molecular weight PE.
3. Differences in use and performance
1. Polypropylene (PP) PP has high heat resistance and mechanical strength, and is widely used in the manufacture of home appliance shells, auto parts, packaging materials, pipes, etc. Due to its good impact resistance and chemical resistance, PP has replaced metal materials in many fields.
2. Polyethylene (PE) PE is widely used in wires and cables, films, pipes and other fields because of its excellent electrical insulation and cold resistance. PE is flexible and can adapt to various temperature changes, so it performs well in low temperature environments. In addition, PE also has the advantages of non-toxic, light weight and low price.
Fourth, summary and outlook
Polypropylene and polyethylene, as the two giants in the plastic family, have a wide range of applications in many fields. With its high heat resistance, mechanical strength and good impact resistance, PP has become an ideal choice for home appliances, automobiles and other industries; PE dominates the fields of wires and cables and films with its excellent electrical insulation, cold resistance and flexibility.
With the continuous development of science and technology, the application fields of polypropylene and polyethylene are also expanding. The new modification technology is:
These two polymers offer many more possibilities, such as enhancing their wear resistance and improving their barrier properties. In addition, increased environmental awareness has also prompted the plastics industry to move in the direction of sustainable development. In the future development, how to use the advantages of polypropylene and polyethylene to develop more environmentally friendly and high-performance plastic products will be an important issue in front of us.
Post time: Mar-14-2025