POLY ETHYLENE
LEKHRAJ MEENA
MDM14B016
MONOMER OF POLY ETHYLENE
• The ingredient
or monomer is ethylene (IUPAC name ethene),
a gaseous hydrocarbon with the formu...
MONOMER OF POLYETHYLENE
STRUCTURE OF POLYETHYLENE
CHEMICAL PROPERTIES
# Most LDPE, MDPE, and HDPE grades have excellent chemical
resistance, meaning that it is not attacked...
PHYSICAL PROPERTIES
Polyethylene is a thermoplastic polymer consisting of
long hydrocarbon chains.
Depending on the crysta...
POLYMERIZATION
• Ethylene is a rather stable molecule that polymerizes only
upon contact with catalysts.
• The conversion ...
SIMPLE MECHANISM
•
SIMPLE MECHANISM
CLASSIFICATION OF POLYETHYLENE
• Polyethylene is classified into several different categories based mostly on
its density ...
BRIEF HISTORY ABOUT POLYETHYLENE
Polyethylene was first synthesized by the
German chemist Hans von Pechmann who
prepared i...
MKHKH
• #The first industrially practical polyethylene synthesis (diazomethane is a notoriously
unstable substance that is...
#
• The breakthrough landmark in the commercial production of polyethylene began with the
development of catalyst that pro...
SOME PRODUCT OF POLYETHYLENE
•
•
•
•
•
•
THANKS
…….
Poly ethylene
of 16

Poly ethylene

lekh
Published on: Mar 4, 2016
Published in: Engineering      
Source: www.slideshare.net


Transcripts - Poly ethylene

  • 1. POLY ETHYLENE LEKHRAJ MEENA MDM14B016
  • 2. MONOMER OF POLY ETHYLENE • The ingredient or monomer is ethylene (IUPAC name ethene), a gaseous hydrocarbon with the formula C2H4, which can be viewed as a pair of methylene groups (=CH2) connected to each other. • Because the compound is highly reactive, the ethylene must be of high purity.
  • 3. MONOMER OF POLYETHYLENE
  • 4. STRUCTURE OF POLYETHYLENE
  • 5. CHEMICAL PROPERTIES # Most LDPE, MDPE, and HDPE grades have excellent chemical resistance, meaning that it is not attacked by strong acids or strong bases. # It is also resistant to gentle oxidants and reducing agents. Polyethylene burns slowly with a blue flame having a yellow tip and gives off an odour of paraffin. # The material continues burning on removal of the flame source and produces a drip. # Crystalline samples do not dissolve at room temperature. Polyethylene (other than cross-linked polyethylene) usually can be dissolved at elevated temperatures in aromatic hydrocarbons such as toluene or xylene, or in chlorinated solvents such as tri-chloroethane or tri-chlorobenzen.
  • 6. PHYSICAL PROPERTIES Polyethylene is a thermoplastic polymer consisting of long hydrocarbon chains. Depending on the crystallinity and molecular weight, a melting point and glass transition may or may not be observable. The temperature at which these occur varies strongly with the type of polyethylene. For common commercial grades of medium- and high- density polyethylene the melting point is typically in the range 120 to 180 °C (248 to 356 °F). The melting point for average, commercial, low-density polyethylene is typically 105 to 115 °C (221 to 239 °F)
  • 7. POLYMERIZATION • Ethylene is a rather stable molecule that polymerizes only upon contact with catalysts. • The conversion is highly exothermic. • Coordination polymerization is the most pervasive technology, which means that metal chlorides or metal oxides are used. • The most common catalysts consist of titanium(III) chloride, the so-called Ziegler-Natta catalysts. • Another common catalyst is the Phillips catalyst, prepared by depositing chromium(VI) oxide on silica. • Ethylene can be produced through radical polymerization, but this route has only limited utility and typically requires high pressure apparatus
  • 8. SIMPLE MECHANISM •
  • 9. SIMPLE MECHANISM
  • 10. CLASSIFICATION OF POLYETHYLENE • Polyethylene is classified into several different categories based mostly on its density and branching. Its mechanical properties depend significantly on variables such as the extent and type of branching, the crystal structure and the molecular weight. With regard to sold volumes, the most important polyethylene grades are HDPE, LLDPE and LDPE. • 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)
  • 11. BRIEF HISTORY ABOUT POLYETHYLENE Polyethylene was first synthesized by the German chemist Hans von Pechmann who prepared it by accident in 1898 while investigating diazomethane. When his colleagues Eugen Bamberger and FriedricH Tschirner characterized the white, waxy substance that he had created, they recognized that it contained long -CH2- chains and termed it poly methylene.
  • 12. MKHKH • #The first industrially practical polyethylene synthesis (diazomethane is a notoriously unstable substance that is generally avoided in industrial application) was discovered in 1933 by Eric Fawcett and Reginald Gibson, again by accident, at the Imperial Chemical Industries (ICI) works in North wHich, England . Upon applying extremely high pressure (several hundred atmospheres) to a mixture of ethylene and benz aldehyde they again produced a white, waxy, material. Because the reaction had been initiated by trace oxygen contamination in their apparatus, the experiment was, at first, difficult to reproduce. It was not until 1935 that another ICI chemist, Michael Perrin, developed this accident into a reproducible high-pressure synthesis for polyethylene that became the basis for industrial LDPE production beginning in 1939. Because polyethylene was found to have very low-loss properties at very high frequency radio waves, commercial distribution in Britain was suspended on the outbreak of World War II, secrecy imposed and the new process was used to produce insulation for UHF and SHF coaxial cables of radar sets. During World War II, further research was done on the ICI process and in 1944 Bakelite Corporation at Sabine, Texas and Du Pont at Charleston, West Virginia, began large scale commercial production under license from ICI.
  • 13. # • The breakthrough landmark in the commercial production of polyethylene began with the development of catalyst that promote the polymerization at mild temperatures and pressures. • The first of these was a chromium trioxide–based catalyst discovered in 1951 by Robert Banks andJ. Paul Hogan at Phillips Petroleum. • In 1953 the German chemist Karl Ziegler developed a catalytic system based on titanium halides and organoaluminium compounds that worked at even milder conditions than the Phillips catalyst. • The Phillips catalyst is less expensive and easier to work with, however, and both methods are heavily used industrially. By the end of the 1950s both the Phillips- and Ziegler-type catalysts were being used for HDPE production. • In the 1970s, the Ziegler system was improved by the incorporation of magnesiuM chloride. • Catalytic systems based on soluble catalysts, the metallocenes, were reported in 1976 by Walter Kaminsky and Hansjörg Sinn. The Ziegler- and metallocene-based catalysts families have proven to be very flexible at copolymerizing ethylene with other olefins and have become the basis for the wide range of polyethylene resins available today, including very low density polyethylene and linear low-density polyethylene. • Such resins, in the form of UHMWPE fibers, have (as of 2005) begun to replace aramids in many high-strength applications.
  • 14. SOME PRODUCT OF POLYETHYLENE • • • • • •
  • 15. THANKS …….

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