Polyethylene from Ethanol: Difference between revisions
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=Introduction – Polyethylene= | =Introduction – Polyethylene= | ||
Polyethylene (PE) is a polymer of long chains of the monomer [http://en.wikipedia.org/wiki/Ethylene ethylene] (IUPAC name "''ethene''"). It is one of the world’s most common plastics, with a wide range of uses and over 60 million tons produced worldwide every year. Several different categories exist, based mostly on density and branching. Common ones are high-density PE ([http:// | Polyethylene (PE) is a polymer of long chains of the monomer [http://en.wikipedia.org/wiki/Ethylene ethylene] (IUPAC name "''ethene''"). It is one of the world’s most common plastics, with a wide range of uses and over 60 million tons produced worldwide every year. Several different categories exist, based mostly on density and branching. Common ones are high-density PE ([http://en.wikipedia.org/wiki/HDPE HDPE]; plastic # 2) and low-density PE ([http://en.wikipedia.org/wiki/Low-density_polyethylene LDPE]; plastic # 4). Polyethylene is created through polymerization of ethylene, a simple two-carbon molecule. Polyethylene is not biodegradable, therefore significant environmental issues are associated with its use. When disposables are involved, every effort should be made to replace PE with biodegradable alternatives. However, resistance to biodegradation can also be a desired effect in some applications. For example, [http://en.wikipedia.org/wiki/Geomembranes geomembranes] are often made of HDPE and are widely used as liners for fish ponds, constructed wetlands and biogas digesters. Excellent chemical resistance of PE allows for widespread use in storage applications. PE is also a useful starting material for digital fabrication. | ||
=Polyethylene – the current situation= | =Polyethylene – the current situation= | ||
Revision as of 13:54, 14 January 2009
Introduction – Polyethylene
Polyethylene (PE) is a polymer of long chains of the monomer ethylene (IUPAC name "ethene"). It is one of the world’s most common plastics, with a wide range of uses and over 60 million tons produced worldwide every year. Several different categories exist, based mostly on density and branching. Common ones are high-density PE (HDPE; plastic # 2) and low-density PE (LDPE; plastic # 4). Polyethylene is created through polymerization of ethylene, a simple two-carbon molecule. Polyethylene is not biodegradable, therefore significant environmental issues are associated with its use. When disposables are involved, every effort should be made to replace PE with biodegradable alternatives. However, resistance to biodegradation can also be a desired effect in some applications. For example, geomembranes are often made of HDPE and are widely used as liners for fish ponds, constructed wetlands and biogas digesters. Excellent chemical resistance of PE allows for widespread use in storage applications. PE is also a useful starting material for digital fabrication.
Polyethylene – the current situation
Almost all PE today is derived from petroleum. In a very energy-intensive process, a petroleum feedstock is cracked at high temperatures. After distillation and purification in large, capital-intensive facilities, ethylene is produced. This is then polymerized to polyethylene, a process that again involves high temperatures, high pressures and often toxic organic solvents. Clearly not an ideal situation.
Polyethylene from ethanol
Ethene is a very simple organic molecule (C2H4) that does not have to be derived from petroleum. In fact, it can easily be produced from ethanol in a dehydration reaction. This has been known for many decades, but was not cost-competitive at low oil prices. Recently, a Brazilan-Japanese joint venture announced the "Green Polyethylene Project", with sugarcane as the feedstock. Commercial-scale introduction of this "BIO-polyethylene" is planned for 2011. We welcome PE to the club of bioplastics and believe that it can be produced on a small scale from ethanol.
Links
Wikipedia entry on polyethylene [1]
Wikipedia entry on High-density polyethylene (HDPE) [2]
Wikipedia entry on Low-density polyethylene (LDPE) [3]
Patents: Production of [4] and process for obtaining [5] ethylene from ethanol
News: Brazilian company to make renewable polyethylene [6]