Difference Between Polypropylene and Polyethylene

Main Difference

The main difference between Polypropylene and Polyethylene is that Polypropylene is the monomer of propylene whereas Polyethylene is a monomer of ethylene.

Polypropylene vs. Polyethylene

Polypropylene and Polyethylene are both thermoplastic polymers. Both of these polymers are used extensively in a wide array of industrial and household applications. Polypropylene is made from a combination of monomers of propylene while polyethylene is made from a combination of monomers of polyethylene. Polypropylene is highly modifiable, adaptable and moldable while Polyethylene is very sturdy and not easily pliable. Polypropylene is abbreviated as PP and polypropylene are known as PE. Polypropylene is known for its adaptability and its ability to be molded through the heat while propylene is known for its ability to withstand cold temperatures. Polypropylene is not as stable as polyethylene. Polypropylene has a high static charge than polyethylene. Polypropylene is only modifiable into translucent and polyethylene can always be manufactured as optically clear. Polypropylene is a bad insulator while polyethylene is a good electrical insulator. PP has a higher melting point and a lesser cost than PE. PP weighs lighter than a PE. Polypropene is also more resistant to organic solvents and chemicals than polythene. PP can be made into fibers but PE cannot be made into fibers. Both have different chemical formulae as well.

Comparison Chart

PolypropylenePolyethylene
Monomer of propyleneMonomer of ethylene
Chemical Properties
Semi-crystallineInert, translucent
Electrical Properties
High static charge
Bad insulator
Low static charge
Good insulator
Melting Point
130 to 171 °C (266 to 340 °F; 403 to 444 K)115–135 °C (239–275 °F; 388–408 K)
Chemical Formula
(C3H6)n(C2H4)n
Uses
Fibers, films, caps, hinges, synthetic paper, and for production of various chemicals like acrylonitrile, acrylic acid, propylene oxide, cumene, and butyraldehyde.Plastic bags, bottles, food containers, pallets, geomembranes, films made of plastic, food crates, etc.
Density
0.855 g/cm3 amorphous, 0.946 g/cm3 crystalline0.88–0.96 g/cm3
Discovery
J. Paul Hogan and Robert Banks (1951) and Giulio Natta, Karl Rehn (1954).Hans von Pechmann (1898).
Abbreviation
PPPE
Alternate Names
PolypropenePolythene
Cost
CheapExpensive

What is Polypropylene?

A polymer, polypropylene is also known as Polypropene. It is abbreviated to PP. And has a chemical designation of (C3H6)n. It is a polymer that is thermoplastic but can also be adapted to different fabrication procedures. It is produced mainly from a monomer of propylene through the process called chain-growth polymerization. It is a versatile plastic commodity, which also functions as a fiber. In 1954, it was first polymerized by an Italian chemist and Professor Giulio Natta but originally created by the German Karl Rehn. Polypropylene’s ability to semi-crystallize created a lot of stir and it became widely popular in commercial production all across Europe by 1957. Polypropylene has a very unique ability. It can be manufactured via various methods and be utilized in many applications like packaging, injection molding, and fiber. This plastic commodity is the second most popular in the world, preceded by polythene, which is on number one. Propylene is of two kinds namely Homopolymers and copolymers. It is highly modifiable and moldable, and its properties make it a very resourceful material for many industries, especially the plastic industry. Polypropene’s ability to adapt is a vital property. Compared with other plastics, this one has a higher melting point but the same weight as them. It has elasticity without any softness and is very cheap. It is resistant to chemicals like water-based acids and bases. This also keeps its original shape even after it has been flexed or bent, so it has a fatigue resistance. Apart from that, polypropylene is highly useful for components of electronics because of its resistant nature towards electricity. It is quite valuable in the making of fibers, carpets, ropes, clothing, and upholstery, with the packaging industry utilizing it majorly. Automotive industry and household appliances also consume ten percent of this thermoplastic. Toys, house wears also make use of it. However, it is not heat resistant, is highly flammable and tends to deform easily with heat.

What is Polyethylene?

Polyethylene or polythene is also a polymer but is made from a monomer of ethylene. It has a chemical formula of (C2H4)n. The first synthesis of this occurred as an accident in 1898 by the German scientist Hans von Pechmann. Like PP, it is also a thermoplastic in its very nature. Its abbreviated form is PE. PE stands on number one as the most used plastic worldwide. Not all plastics are PE, though. Polythene is not much easily pliable because it is very stable. It’s a good electrical insulator. It has a very low melting point and is used massively in automobile industries as well as in food packaging industries. Approximately 70 percent of it is utilized in food packages, food containers, pallets, and even crates and bottles.

Types

  • Ultra-High-Molecular-Weight Polyethylene (UHMWPE)
  • Ultra-Low-Molecular-Weight Polyethylene (ULMWPE or PE-WAX)
  • High-Molecular-Weight Polyethylene (HMWPE)
  • High-Density Polyethylene (HDPE)
  • High-Density Cross-Linked Polyethylene (HDXLPE)
  • Cross-Linked Polyethylene (PEX or XLPE)
  • Medium-Density Polyethylene (MDPE)
  • Linear Low-Density Polyethylene (LLDPE)
  • Low-Density Polyethylene (LDPE)
  • Very-Low-Density Polyethylene (VLDPE)
  • Chlorinated Polyethylene (CPE)

Key Differences

  1. Polypropylene is abbreviated as PP and polyethylene is commonly referred to as PE.
  2. Polypropylene is the second most used plastic commodity in the world and polythene is the first.
  3. PP is very much cheap and PE is very expensive.
  4. Polypropene has a higher melting point than polyethylene.
  5. Polypropylene is less sturdy than polyethylene.
  6. Polypropylene has less weight than PE.
  7. Polypropene is a bad electrical insulator as compared to polyethylene.
  8. Polypropylene is made from a mixture of propylene monomers and polyethylene is made from a mixture of ethylene monomers.
  9. Polypropylene is mostly used in automobile and packaging industries, hinges, household appliances, and toys, carpets, fibers, caps, synthetic papers, etc., and polythene is used in plastic bags, food containers, and bottles, films, food crates, and pallets, etc.
  10. Polypropylene has the chemical formula (C3H6)n and polyethylene is (C2H4)

Comparison Video

YouTube video

Conclusion

All in all, although polypropylene and polyethylene do share a few physical properties, but are totally different in nature and the way they are used. PP is more pliable and PE has more sturdiness. PP is also elastic in nature but PE is stable. They also are made from the polymerization of different monomers like propylene and ethylene. But both are equally important commodities of plastic in the world.

Harlon Moss

Harlon currently works as a quality moderator and content writer for Difference Wiki. He graduated from the University of California in 2010 with a degree in Computer Science. Follow him on Twitter @HarlonMoss

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