Looking for breakthrough ideas for innovation challenges? Try Patsnap Eureka!

Shaped part of an ultra high molecular weight polyethylene

a polyethylene and ultra-high molecular weight technology, applied in the field of shaped parts of ultra-high molecular weight polyethylene, can solve the problems of inability to meet the requirements of high molecular mass polymers, and insufficient product performance, so as to achieve good processability below the melting point

Inactive Publication Date: 2010-04-08
STICHTING DUTCH POLYMER INST
View PDF2 Cites 6 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a process for making a shaped part of UHMWPE that has good processability below its melting point and maintains a state of disentanglement long enough to process it as an only partly entangled melt. This process involves heating the UHMWPE to a temperature above its melting point, shaping it, and cooling it back down to a temperature below its melting point. The resulting shaped part has improved processability and can be used in demanding applications.

Problems solved by technology

This difference in viscosity of the two molecular mass regimes is due to the ability of long chains to entangle, which imposes a restriction on the flowability of a melt.
These fundamental restrictions make high molecular mass polymers rather intractable via conventional processing routes.
The discrepancy between intrinsic properties related to high values of molecular mass and insufficient product performance due to difficulties in processing is encountered in UHMWPE as well as in other polymers of very high molecular mass.
In the case of melt crystallised UHMWPE, entanglements are trapped upon crystallisation and limit the extent to which the chains can be drawn.
Experimental results however showed that highly disentangled solution crystallised films of UHMWPE, which are drawable below the melting temperature lose their drawability immediately upon melting.
Consequently the chains entangle immediately upon melting, which causes the sudden loss in processability and drawability once the sample has been molten.
These results showed that the fundamental restrictions resulting from the strong dependence of the zero-shear viscosity on molecular mass cannot be easily overcome.
Simple disentanglement of the chains prior to melting will not lead to a less entangled melt and accordingly it cannot be used to improve the melt processability of UHMWPE.

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • Shaped part of an ultra high molecular weight polyethylene

Examples

Experimental program
Comparison scheme
Effect test

examples v

and VI

Catalyst is (C5Me5)2Sm(THF)2

[0040]The polymerizations were carried out at −10 and 0° C., respectively, under atmospheric pressure using a 2000 ml round bottom flask, equipped with a thermocouple and a mechanical stirrer. Petroleum ether (1000 ml) was introduced to the argon-purged reactor after which the solvent was saturated by bubbling ethylene into the solution for 45 minutes at −10° C. and 0° C. resp. The polymerization was initiated by addition of a toluene solution of catalyst (2.8 μmol) into the reactor while stirring vigorously. The same amount of catalyst was added ten times at an interval of one minute. The polymerization was quenched after 15 min with methanol. The solid UHMWPE was recovered by filtration, washed with water and acetone and dried (vacuum oven 60° C., overnight).

examples vii

and VIII

Catalyst is [3-tBu-2-O—C6H3CH═N(C6F5)]2TiCl2

[0041]The polymerizations were carried out under atmospheric pressure using a 2000 ml round bottom flask, equipped with a thermocouple and a mechanical stirrer. Petroleum ether (1000 nil) was introduced to the argon-purged reactor after which the solvent was saturated by bubbling ethylene into the solution for 30 minutes at −10° C. and +20° C., respectively. The polymerization was initiated by addition of a toluene solution of methylalumoxane (20 ml) after which a toluene solution of the catalyst (1 μmol) was introduced into the reactor while stirring vigorously. After 20 minutes the ethylene feed was stopped and isobutyl alcohol was added to terminate the polymerization. HCl and water were added to the resulting mixture. The solid UHMWPE was recovered by filtration, washed with water and acetone and dried (vacuum oven 60° C., overnight).

SynthesisExampleCatalysttemp (° C.)MwMnMWDVSm−101,225,500607,7002.0VI02,040,500832,8562.5VIITi...

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

PUM

PropertyMeasurementUnit
temperatureaaaaaaaaaa
temperatureaaaaaaaaaa
temperatureaaaaaaaaaa
Login to View More

Abstract

Shaped parts of ultra high molecular weight polyethylene (UHMWPE) are made by a process comprising melt processing, wherein a) the UHMWPE has a weight average molecular weight (Mw) of at least 1*106 g / mol, b) during the shaping the storage plateau modulus of the UHMWPE (G*) is kept at a value of at most 1.5 MPa, c) whereafter, before the cooling, the G* is raised to its final value. The shaped parts may advantageously be used in medical applications, e.g., as an element of a hip or knee prosthesis.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a divisional of U.S. application Ser. No. 10 / 561,290 filed on Jan. 25, 2006, which in turn is the US national phase of international application PCT / NL2003 / 000473 filed Jun. 26, 2003 which designated the U.S., the entire content of each being hereby incorporated by reference.FIELD OF INVENTION[0002]The present invention relates to a process for the preparation of a shaped part of an ultrahigh molecular weight polyethylene (UHMWPE) by heating the UHMWPE to a temperature above the melting temperature, shaping the resulting melt, and cooling the melt to a temperature below the melting temperature. The invention further relates to a shaped part obtainable with this process, and to the use thereof, especially in medical applications.BACKGROUND AND SUMMARY OF INVENTION[0003]Such a process is known from WO 03 / 037590. In this publication a shaped part of UHMWPE is prepared wherein the UHMWPE is annealed for at least one hour a...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

Application Information

Patent Timeline
no application Login to View More
Patent Type & Authority Applications(United States)
IPC IPC(8): A61F2/32C08F10/02A61F2/38B29C67/24C08F110/02
CPCB29C67/24B29K2023/0683C08F110/02C08F2500/03
Inventor RASTOGI, SANJAY E.GARKHAIL, KIRTIDUCHATEAU, ROBERTGRUTER, GERARDUS JOHANNES MARIALIPPITS, DIRK REINIER
Owner STICHTING DUTCH POLYMER INST
Who we serve
  • R&D Engineer
  • R&D Manager
  • IP Professional
Why Patsnap Eureka
  • Industry Leading Data Capabilities
  • Powerful AI technology
  • Patent DNA Extraction
Social media
Patsnap Eureka Blog
Learn More
PatSnap group products

Browse by: Latest US Patents, China's latest patents, Technical Efficacy Thesaurus, Application Domain, Technology Topic, Popular Technical Reports.

© 2024 PatSnap. All rights reserved.Legal|Privacy policy|Modern Slavery Act Transparency Statement|Sitemap|About US| Contact US: help@patsnap.com