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Melt-processible, wear resistant polyethylene

a technology of polyethylene and wear resistance, which is applied in the field of melt-processing and wear-resistant polyethylene, can solve the problems of inability to melt-process, the introduction of this polymer, and the general economic cost of the method, and achieve the effects of good wear resistance, high wear resistance, and good wear resistan

Inactive Publication Date: 2009-10-08
ETH ZZURICH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The resulting polyethylenes exhibit improved thermoplastic flow behavior and high wear resistance, enabling the production of articles with desired mechanical properties and wear resistance through melt-processing, expanding the range of products that can be manufactured.

Problems solved by technology

Equally well-known, however, is the intractability of this polymer, which is due to the fact that UHMW PE, above its crystalline melting temperature, does not form a fluid phase that is of a viscosity that permits melt-processing techniques used with many thermoplastic polymers.
Rods, sheets, blocks, slabs and profiles of UHMW PE are produced by cumbersome methods such as, for example, ram-extrusion, pre-forming and sintering of compressed powder, optionally followed by machining or skiving, high isostatic pressure processing, and the like.
Unfortunately, these methods generally are less economical than common melt-processing, and, in addition, severely limit the types and characteristics of objects and products that can be manufactured with this polymer.
The aforementioned additions of lubricants, plasticizers, and processing aids or lower molecular weight polyethylenes, however, do not yield melt-processible PE compositions with a desired combination of properties.

Method used

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  • Melt-processible, wear resistant polyethylene
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Examples

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examples

[0033]The following examples are given as particular embodiments of the invention and to demonstrate the practice and advantages thereof. It is understood that the examples are given by way of illustration and are not intended to limit the specification or the claims that follow in any manner.

General Methods and Materials

[0034]Viscosity. The absolute values of the complex viscosities of different Polyethylenes were measured from small amplitude oscillatory shear experiments (Rheometrics Dynamic Spectrometer RDS-II) at 180° C., and are given here for those viscosity values determined at a frequency of 10−1 rad / s using standard plate-plate geometry.

[0035]Molecular Weight Distribution. The molecular weight distributions of the various materials used were determined by high temperature gel permeation chromatography with a Waters 150C ALC / GPC instrument with the following specifications: column type: TSK GMHXL-HT (13 μm), mobile phase flow rate: 0.5 ml min−1, solvent and mobile phase ant...

examples 1-5

[0046]The following Table III presents an overview of the viscosities, number- and weight average molecular weights (Mn, Mw), polydispersities (Mw / Mn) and crystallinities and wear coefficients of another set of different polyethylenes that are not of ultrahigh molecular weight.

TABLE IIIViscosity at 10−1MnMwCrystallinityWear coefficient,Samplerad / s (Pa · s)(kg / mol)(kg / mol)Mw / Mn(%)104 ·κ (mm3 / mN)PE 1484a,4.0 · 1031021201.260.92.80N.I.S.T.Fraction,1.1 · 1052673291.249.72.57S.N.P.A.Fraction,3.1 · 1053604481.249.52.56S.N.P.A.Fraction,4.2 · 1054504901.154.32.44S.N.P.A.LLDPE,4.6 · 103nd125nd44.42.47Aldrichnd: not determined

[0047]The data in this table lists polyethylenes that are not of ultrahigh molecular weight, have viscosities of less than 106 Pa·s, and exhibit a wear coefficient of less than 3.2·10−4 mm3 / mN.

example 6

[0048]A polyethylene is prepared having the following properties:

Mw about 350,000 g / mol;

Polydispersity about 2.5; and

1-Hexene co-monomer content of about 4 wt %.

[0049]The wear coefficient is determined to be about 1.9·10−4 mm3 / mN.

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Abstract

Melt-processible, thermoplastic polyethylene compositions of high resistance against wear are disclosed and methods for making and processing same. Additionally, products comprising these compositions are described.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application claims the benefit of U.S. provisional application 60 / 251,395 filed Dec. 6, 2000, the entire disclosure of which is hereby incorporated by reference.FIELD OF THE INVENTION[0002]This invention relates to melt-processible, wear resistant polyethylene, compositions thereof, articles formed therefrom, and methods for making the same.BACKGROUND OF THE INVENTION[0003]Ultrahigh molecular weight polyethylene (“UHMW PE”) is well-known for, among other properties, its chemical resistance, low friction coefficient, high toughness and in particular its excellent resistance against wear. As a result, it has found numerous applications in environments where abrasion and friction may occur, such as in the chemical industry, mining, mechanical engineering, the field of biomedical implants and the textile industry. Equally well-known, however, is the intractability of this polymer, which is due to the fact that UHMW PE, above its crystalli...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C08F110/02C08J5/16C08L23/02C08L51/06
CPCC08F110/02C08L23/02C08L51/06C08L2666/24C08F2500/03C08F2500/17C08F10/02
Inventor SMITH, PAULVISJAGER, JEROENTERVOORT, THEO
Owner ETH ZZURICH