Ultrahigh molecular weight linear polyethylene and articles thereof
AssigneeE. I. Du Pont de Nemours and Company
InventorEdward G. Howard, Jr.
Life of this patent
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Abstract
Novel ultrahigh molecular weight linear polyethylene (UHMWLPE) in the form of a shaped article, exhibiting a unique combination of properties making the material useful as a bearing surface, in general, but particularly useful as a prosthetic hip joint cup and as other prosthetic shapes for replacement of other joints of the human body, A novel process for preparing this article is also disclosed.
Claims15
An ultrahigh molecular weight linear polyethylene having a molecular weight of at least 800,000, two crystalline DSC melting points, the higher of which is greater than 144.degree. C., said higher melting point decreasing by at least 11.degree. C. upon remelting;
- a homoeomerous morphology;
- said polyethylene being substantially free of internal stresses as measured by the absence of distortion in a shaped article of said polyethylene after being subjected for at least 30 minutes at a temperature 100.degree. to 132.degree. C. in a heat transfer medium that is chemically and physically inert to polyethlyene.
An improved folded chain ultrahigh molecular weight linear polyethylene having a molecular weight of at least 800,000, and exhibiting a flexural modulus of 50-300 kpsi, a tensile stress at yield of 3.5-4.3 kpsi, a tensile stress at break of 4-6 kpsi, a tensile modulus of 150-300 kpsi, a notched Izod impact resistance of 15-25 ft. lb per in. of notch, an elongation at break of 200-1400%, a creep at a compression of 1 kpsi of less than 2% after 24 hours at a temperature of 23.degree. C. and relative humidity of 50%;
- and an infrared crystalliniity index of at least about 0.35.
Dependencies are inferred from the claim text.