Claims
- 1. An irradiated crosslinked polyethylene composition made by the process comprising steps of:
a) irradiating at a temperature that is below the melting point of the polyethylene; and b) mechanically deforming the polyethylene below the melting point of the irradiated polyethylene in order to reduce the concentration of residual free radicals.
- 2. The polyethylene of claim 1, wherein the deformed polyethylene is crystallized at the deformed state.
- 3. The polyethylene of claim 2, wherein the polyethylene is annealed below the melting point following crystallization.
- 4. The polyethylene of claim 1, wherein the polyethylene has substantially no trapped residual free radical detectable by electron spin resonance.
- 5. The polyethylene of claim 1, wherein crystallinity of the polyethylene is about equal to or higher than that of the starting unirradiated polyethylene.
- 6. The polyethylene of claim 1, wherein crystallinity of the polyethylene is about equal to or higher than that of the starting irradiated polyethylene that has been melted.
- 7. The polyethylene of claim 1, wherein crystallinity of the polyethylene is at least about 51%.
- 8. The polyethylene of claim 1, wherein elastic modulus of the polyethylene is about the same as or higher than that of the starting unirradiated polyethylene.
- 9. The polyethylene of claim 1, wherein elastic modulus of the polyethylene is about the same as or higher than that of the starting irradiated polyethylene that has been melted.
- 10. The polyethylene of claim 1, wherein starting polyethylene material is in the form of a consolidated stock.
- 11. The polyethylene of claim 1, wherein starting polyethylene material is a finished product.
- 12. The polyethylene of claim 11, wherein the finished product is a medical prosthesis.
- 13. The polyethylene of claim 1, wherein the polyethylene is a polyolefin.
- 14. The polyolefin of claim 13 is selected from a group consisting of a low-density polyethylene, high-density polyethylene, linear low-density polyethylene, ultra-high molecular weight polyethylene (UHMWPE), or mixtures thereof.
- 15. The polyethylene of claim 1, wherein the polyethylene is in intimate contact with a metal piece.
- 16. The metal piece of claim 15 is a cobalt chrome alloy, stainless steel, titanium, titanium alloy or nickel cobalt alloy.
- 17. The polyethylene of claim 1, wherein the polyethylene is in functional relation with another polyethylene or a metal piece, thereby forming an interface.
- 18. The polyethylene of claim 17, wherein the interface is not accessible to ethylene oxide gas or gas plasma.
- 19. The polyethylene of claim 1, wherein the mechanical deformation is uniaxial, channel flow, uniaxial compression, biaxial compression, oscillatory compression, tension, uniaxial tension, biaxial tension, ultra-sonic oscillation, bending, plane stress compression (channel die) or a combination thereof.
- 20. The polyethylene of claim 1, wherein the mechanical deformation is performed by ultra-sonic oscillation at an elevated temperature that is below the melting point of the irradiated polyethylene.
- 21. The polyethylene of claim 1, wherein the mechanical deformation is performed by ultra-sonic oscillation at an elevated temperature that is below the melting point of the polyethylene in presence of a sensitizing gas.
- 22. The polyethylene of claim 1, wherein the deforming temperature is less than about 140° C.
- 23. An irradiated crosslinked polyethylene composition made by the process comprising steps of:
a) contacting the polyethylene composition with a sensitizing environment; b) irradiating by gamma or electron beam radiation; and c) subjecting the composition to a temperature that is below the melting point of the polyethylene composition while in the presence of a sensitizing environment in order to reduce the content of free radicals.
- 24. The polyethylene of claim 23, wherein the polyethylene is contacted with a sensitizing environment prior to irradiation.
- 25. The polyethylene of claim 23, wherein the sensitizing environment is acetylene, chloro-trifluoro ethylene (CTFE), trichlorofluoroethylene, ethylene gas, or mixtures containing noble gases thereof.
- 26. The noble gas according to claim 25, is selected from a group consisting of nitrogen, argon, helium, neon, and any inert gas known in the art.
- 27. The environment according to claim 25, wherein the gas is a mixture of acetylene and nitrogen.
- 28. The environment according to claim 25, wherein the mixture comprising about 5% by volume acetylene and about 95% by volume nitrogen.
- 29. The polyethylene of claim 23, wherein the sensitizing environment is dienes with different number of carbons, or mixtures of liquids thereof.
- 30. The polyethylene of claim 23, wherein crystallinity of the polyethylene is at least about 51%.
- 31. An irradiated crosslinked polyethylene composition having reduced free radical content, and wherein crystallinity of the polyethylene is at least about 51%.
- 32. A method of making an irradiated crosslinked polyethylene composition comprising steps of:
a) irradiating at a temperature that is below the melting point of the polyethylene; and b) mechanically deforming the polyethylene below the melting point of the irradiated polyethylene in order to reduce the concentration of residual free radicals.
- 33. The method of claim 32, wherein the deformed polyethylene is crystallized at the deformed state.
- 34. The method according to claim 32, wherein annealing temperature is below the melting point of the polyethylene.
- 35. The method according to claim 34, wherein the annealing temperature is less than about 145° C.
- 36. The method according to claim 32, wherein irradiation is carried out using gamma radiation or electron beam radiation.
- 37. The method according to claim 32, wherein irradiation is carried out at an elevated temperature that is below the melting temperature.
- 38. The method according to claim 32, wherein radiation dose level is between about 1 and about 10,000 kGy.
- 39. The method according to claim 32, wherein mechanical deformation is performed in presence of a sensitizing environment.
- 40. The method according to claim 32, wherein mechanical deformation is performed at an elevated temperature that is below the melting point of the polyethylene.
- 41. The method according to claim 32, wherein mechanical deformation is performed in presence of a sensitizing gas at an elevated to a temperature that is below the melting point of the polyethylene.
- 42. The method according to claim 32, wherein the mechanical deformation is uniaxial, channel flow, uniaxial compression, biaxial compression, oscillatory compression, tension, uniaxial tension, biaxial tension, ultra-sonic oscillation, bending, plane stress compression (channel die) or a combination thereof.
- 43. The method according to claim 42, wherein the mechanical deformation is performed by ultra-sonic oscillation at an elevated temperature that is below the melting point of the polyethylene.
- 44. The method according to claim 42, wherein the mechanical deformation is performed by ultra-sonic oscillation at an elevated to a temperature that is below the melting point of the polyethylene in presence of a sensitizing gas.
- 45. The method according to claim 32, wherein the mechanical deformation is performed at a temperature that is less than about 135° C.
- 46. A method of making an irradiated crosslinked polyethylene comprising steps of:
a) contacting the polyethylene with a sensitizing environment; b) irradiating by gamma or electron beam radiation; and c) subjecting the composition to a temperature that is below the melting point of the polyethylene composition while in the presence of a sensitizing environment in order to reduce the content of free radicals.
- 47. The method according to claim 46, wherein the polyethylene is contacted with a sensitizing environment prior to irradiation.
- 48. The method according to claim 46, wherein irradiation is carried out in air or inert environment.
- 49. The method according to claim 46, wherein the annealing in presence of sensitizing environment is carried out at above an ambient atmospheric pressure.
- 50. The method according to claim 46, wherein the annealing in the presence of sensitizing environment is carried out at above an ambient atmospheric pressure of at last about 1.0 atm.
- 51. The method according to claim 46, wherein the annealing in the presence of sensitizing environment is carried with high frequency sonication.
- 52. The method according to claim 46, wherein the sensitizing environment is acetylene, trichlorofluoroethylene, ethylene gas, or mixtures of gases thereof.
- 53. The method according to claim 46, wherein the sensitizing environment is dienes with different number of carbons, or mixtures of liquids thereof.
- 54. The method according to claim 46, wherein the sensitizing environment is a mixture of acetylene and nitrogen.
- 55. The method according to claim 46, wherein the sensitizing environment comprising about 5% by volume acetylene and about 95% by volume nitrogen.
- 56. An irradiated crosslinked polyethylene composition made by the process comprising steps of:
a) irradiating at a temperature that is below the melting point of the polyethylene; b) mechanically deforming the polyethylene below the melting point of the irradiated polyethylene in order to reduce the concentration of residual free radicals; c) annealing above the melting point; and d) cooling down to room temperature.
- 57. A method of making an irradiated crosslinked polyethylene composition comprising steps of:
a) mechanically deforming the polyethylene at a solid- or a molten-state; b) crystallizing the polyethylene at the deformed state; c) irradiating the polyethylene that is below the melting point of the polyethylene; and d) heating the irradiated polyethylene below the melting point in order to reduce the concentration of residual free radicals and to recover the original shape.
- 58. The method according to claim 57, wherein the irradiated crosslinked and heated polyethylene contains substantially reduced or no detectable residual free radicals, wherein crystallinity of the polyethylene is about 51% or greater.
- 59. The method according to claim 57, wherein the polyethylene has higher oxidation resistance than irradiated and heated polyethylene.
- 60. An irradiated crosslinked polyethylene composition made by the process comprising steps of:
a) mechanically deforming the polyethylene at a solid- or a molten-state; b) crystallizing the polyethylene at the deformed state; c) irradiating the polyethylene that is below the melting point of the polyethylene; and d) heating the irradiated polyethylene below the melting point in order to reduce the concentration of residual free radicals and to recover the original shape.
- 61. The polyethylene of claim 60, wherein the polyethylene contains substantially reduced or no detectable residual free radicals, wherein crystallinity of the polyethylene is about 51% or greater.
- 62. The method according to claim 60, wherein the polyethylene has higher oxidation resistance than irradiated and heated polyethylene.
Parent Case Info
[0001] This application claims priority to provisional application Serial No. 60/344,354, filed Jan. 4, 2002, the entirety of which is hereby incorporated by reference.
Provisional Applications (1)
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Number |
Date |
Country |
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60344354 |
Jan 2002 |
US |