Presentation on theme: "Polyethylene or Polythene 8/9/2008 1 PE - An Over View Muralimanohar.D Density – 0.9 g / mm."— Presentation transcript:
Polyethylene or Polythene 8/9/ PE - An Over View Muralimanohar.D Density – 0.9 g / mm
Polyethylene 8/9/ PE - 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/ PE - 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 8/9/ PE - An Over View 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 8/9/ PE - An Over View 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 8/9/ PE - An Over View 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 8/9/ PE - An Over View 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 8/9/ PE - An Over View 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 8/9/ PE - An Over View 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 8/9/ PE - An Over View 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 materialskis
Ultra high molecular weight polyethylene Cont’d 8/9/ PE - An Over View 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……………