Polyethylene or Polythene 8/9/2008 1 PE - An Over View Muralimanohar.D Density – 0.9 g / mm.

Polyethylene or Polythene

8/9/2008 1PE - An Over View

Muralimanohar.D

Density – 0.9 g / mm

Polyethylene

8/9/2008 2PE - An Over View

Polyethylene or polythene is a thermoplastic commodity heavily

used in consumer products . Over 60 million tons of the material

are produced worldwide every year

In the polymer industry the name is sometimes shortened to PE

Classification of Polyethylene

8/9/2008 3PE - An Over View

Polyethylene is classified into several different categories

based mostly on its density and branching. The mechanical

properties of PE depend significantly on variables such as the

extent and type of branching, the crystal structure and the

Molecular weight.

Polyethylene Classification Cont’d

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Ultra high molecular weight polyethylene(UHMWPE)

Ultra low molecular weight polyethylene(ULMWPE - PE-WAX)

High molecular weight polyethylene(HMWPE)

High density polyethylene(HDPE)

High density cross-linked polyethylene (HDXLPE)

Cross-linked polyethylene(PEX)

Medium density polyethylene(MDPE)

Low density polyethylene(LDPE)

Linear low density polyethylene(LLDPE)

Very low density polyethylene(VLDPE)

Polyethylene Classification Cont’d

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Physical properties

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 130 °C ((250 to 265 °F). The melting

point for average, commercial, low-density polyethylene is typically 105 to

115 °C (220 to 240 °F).

Polyethylene Classification Cont’d

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Physical properties cont’d

Most LDPE, MDPE and HDPE grades have excellent chemical resistance and

do not dissolve at room temperature because of their crystallinity.

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 trichloroethane or

Trichlorobenzene.

Ultra high molecular weight polyethylene

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Ultra high molecular weight polyethylene (UHMWPE), also known as high-

modulus polyethylene (HMPE) or high-performance polyethylene (HPPE),

is a subset of the thermoplastic polyethylene. It has extremely long chains,

with molecular weight numbering in the millions, usually between 2 and 6

million. The longer chain serves to transfer load more effectively to the

polymer backbone by strengthening intermolecular interactions.

n greater than 100,000

Ultra high molecular weight polyethylene Cont’d

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This results in a very tough material, with the highest impact strength of any

thermoplastic presently made. It is highly resistant to corrosive chemicals,

with exception of oxidizing acids. It has extremely low moisture absorption,

has a very low coefficient of friction, is self-lubricating, and is highly

resistant to abrasion (15 times more resistant to abrasion than carbon steel).

Its coefficient of friction is significantly lower than that of nylon and acetal,

and is comparable to that of Teflon, but UHMWPE has better abrasion

resistance than Teflon. It is odorless, tasteless, and nontoxic.

Ultra high molecular weight polyethylene Cont’d

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Trade names

Dyneema is a registered trademark of Royal DSM N.V. (The Netherlands).

Honeywell developed a product identical in chemical structure, which is

sold under the brand name Spectra

Other trade names for consolidated UHMWPE materials include TIVAR by

Quadrant EPP Inc., Polystone-M by Röchling Engineering Plastics, Tensylon

by Integrated Textile Systems, and GARDUR by Garland Manufacturing

Ultra high molecular weight polyethylene Cont’d

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Usage

Fiber applications

Ballistic vests, ballistic helmets and ballistic vehicle protection, bow strings, climbing equipment, fishing line, spear lines for spearguns, high-performance sails, suspension lines on sport parachutes, rigging in yachting

Medical Applications in Total Joint Replacement

UHMWPE has over 40 years of clinical history as a successful biomaterial for use in hip, knee, and for spine implants

Skis and snowboards

The bottom of most modern skis — the surface that contacts the snow — is coated with UHMWPE, treated for compatibility with waxes and with epoxy base material

Ultra high molecular weight polyethylene Cont’d

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Hockey

Ice hockey and field hockey sticks use Dyneema as a material to reinforce the body of the stick.

High-density polyethylene (HDPE) forth coming week……………

8/9/2008 12PE - An Over View

Thank you