What is UHMW-PE?

UHMW-PE stands for Ultra High Molecular Weight Polyethylene. It is the highest quality PE available, engineered for tough jobs and a wide range of applications. It delivers savings in a number of difficult applications.

Ultra High Molecular Weight is the secret of this polymer's unique properties. Its high-density polyethylene resin has a molecular weight range of 3 to 6 million, compared to 300,000 to 500,000 for HMW resins. That difference is what ensures that this material is strong enough to withstand abrasion and impact better than lower level poly products.

UHMW-PE's high molecular weight means it will not melt or flow as a molten liquid. Processing methods are therefore derived from those of powder metal technology. UHMW-PE cannot be transformed and molded by conventional plastic processing techniques (injection molding, blow molding or thermoforming). Compression molding is the most common conversion process used with this resin, producing a stronger, more consistent product.

There are three levels of PE:

• Level One - includes LD-PE, MD-PE, HD-PE
  Low density polyethylene (< 0.930 g cm-3 /<0.0334 lb/in3)
  Medium density polyethylene (0.930 to 0.940 g cm-3 /0.0334 to 0.0338 lb/in3)
  High density polyethylene (>0.940 g cm -3 >0.0338 lb/in3 , MW approx. 100,000)
  
  
• Level Two - HD-HMW, VHMW
  High density high molecular weight polyethylene (MW 200,000 to 500,000). Manufactured by two methods distinguished by the catalyst system involved: the Ziegler method, which uses titanium halides, titanium esters and aluminum alkyls as catalysts, and the Phillips method, using a chromium oxide catalyst.
  
  In all cases, the pressure is low, compared with the high-pressure methods. In the Ziegler method, the working pressures and temperatures are in the ranges 1 to 50 bar/14.2 to 711 psi and 20 to 150 degrees C/68 to 302 degrees F, while the Phillips method uses 30 to 40 bar/427 to 569 psi and 85 to 180 degree C/185 to 356 degrees F. Techniques involve suspension, solution, gas-phase and bulk methods [4] with correspondingly different pressures and temperatures. Under these conditions, ethylene molecules are anionically polymerized to predominantly linear macromolecules (i.e. non-branched). The low degree of branching of PE-HD leads to a high degree of crystallinity (60 to 80%) and correspondingly high density of 0.942 to 0.965 g cm-3 /0.0341 to 0.0349 lb/in3.
  
  
• Level Three - (ULTRA III™) HD-UHMW-PE
  High density ultra high molecular weight polyethylene (>0.940 g cm -3 >0.0338 lb/in3 , MW> 106 to 6 x 106). This is our trademarked polymer that is used in all of our applications.

ULTRA III™ Properties

The charts here detail the mechanical and electrical properties of ULTRA III polymer.