| Autor: |
Rastogi, Sanjay, Kurelec, Lada, Cuijpers, Juul, Lippits, Dirk, Wimmer, Markus, Lemstra, Piet J. |
| Zdroj: |
Macromolecular Materials and Engineering; December 2003, Vol. 288 Issue: 12 p964-970, 7p |
| Abstrakt: |
The role of entanglements in obtaining a homogeneous product of ultra high molecular weight polyethylene (UHMW-PE) has been explored. Studies performed in this report show that a disentangled state before melting is a prerequisite to obtain homogeneous products of an intractable polymer like UHMW-PE. The disentangled state is obtained directly from the reactor by controlling the polymerisation conditions or in the solid state when there is enhanced chain mobility along the c-axis of a unit cell. The disentangled state is maintained in the melt over a period of time, invoking implications in polymer rheology. This approach is applicable to polymers in general. The homogeneous fully sintered UHMW-PE, obtained for the first time, shows a considerable decrease in oxygen permeability, and increase in toughness and fatigue resistance. Such homogeneous products of UHMW-PE are of beneficial in highly demanding applications, especially in knee-prosthesis, where the polymer is used as an inlay between the human bone and a metal or ceramic part, which slides against the polyethylene component during normal gait. Phase diagram for the extended chain crystals. |
| Databáze: |
Supplemental Index |
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