Ultra-high-molecular-weight polyethylene products including vascular prosthesis devices and methods relating thereto and employing pseudo-gel states

A method for making an ultra-high-molecular-weight polyethylene product for use in vascular prostheses and the like, comprising,

• dissolving under slow-stirring conditions ultra-high-molecular-weight polyethylene in a solvent at an elevated temperature in the range of 140.degree.-170.degree. C.,
• cooling the solution at a rate less than 20.degree. C. per minute to a temperature at which polymer crystals grow into an intercrystalline network that produces a pseudo-gel state, and
• extracting the solvent to produce a semicrystalline porous morphology.

A method of making an ultra-high-molecular-weight polyethylene product for use in vascular prostheses and the like, comprising,

• dissolving, under slow-stirring conditions of about 60-600 r.p.m., ultra-high-molecular-weight polyethylene in a non-volatile solvent at an elevated temperature in the range of 140.degree.-170.degree. C.,
• cooling the solution at a rate less than 20.degree. C. per minute to a temperature in the vicinity of 120.degree. to 125.degree. C. at which polymer crystals grow into an intercrystalline network that produces a pseudo-gel state, and
• extracting the non-volatile solvent to produce a semi-crystalline porous morphology.

A method for making a tubular profile of ultra-high-molecular-weight polyethylene with adjustable wall thickness, comprising the successive steps of

• wrapping an ultra-high-molecular-weight polyethylene pseudo-gel containing nonvolatile solvent on a mandrel,
• extracting the solvent from the pseudo-gel with a more volatile solvent, and
• evaporating the volatile solvent from the tubular profile.

A method for making an ultra-high-molecular-weight polymer product for use in vascular prostheses and the like, comprising,

• slowly dissolving ultra-high-molecular-weight polymer in a solvent at an elevated temperature,
• cooling the solution at a rate below 20.degree. C. per minute to a temperature at which polymer crystals grow into an intercrystalline network that produces a pseudo-gel state, and
• extracting the solvent to produce a semi-crystalline porous morphology.

A method for making a tubular profile of ultra-high-molecular-weight polymer with adjustable wall thickness, comprising the successive steps of

• wrapping an ultra-high-molecular-weight polymer pseudo-gel containing nonvolatile solvent on a mandrel,
• extracting the solvent from the pseudo-gel with a more volatile solvent, and
• evaporating the volatile solvent from the tubular profile.

A pseudo-gel comprising a suitable solvent in an amount of 99 to 90 percent by weight and an ultra-high-molecular-weight polyethylene in an amount of 1 to 10 percent by weight, said polyethylene being a semicrystalline network with adjustable crystalline morphology comprising randomly dispersed and oriented chain-folded single crystals, stacks of single crystals, spherulite crystals, and extended-chain shish-kebab-type of fibrils with lengths up to a few millimeters and widths up to 20 .mu.m.

A semicrystalline morphology of ultra-high-molecular-weight polyethylene comprising randomly dispersed and oriented single crystals, stacks of single crystals, spherulitic crystals, and shish-kebab-type of fibrils with lengths up to a few millimeters and widths up to 20 .mu.m, a melting point of 125.degree.-140.degree. C., measured at a heating rate of 5.degree. C./min., a crystallinity of about 70%, measured on the basis that the heat of fusion of a perfect polyethylene crystal is 293 J/g., and a porosity from about 50 to 90%, measured on the basis that the density of polyethylene is 960 Kg/m.sup.3.

A pseudo-gel comprising a suitable solvent in an amount of 99 to 80 percent by weight and an ultra-high-molecular-weight polymer in an amount of 1 to 20 percent by weight, said polymer being a semicrystalline network with adjustable crystalline morphology comprising randomly dispersed and oriented chain-folded single crystals, stacks of single crystals, spherulite crystals, and extended-chain shish-kebab-type of fibrils with lengths up to a few millimeters and widths up to 20 .mu.m.

A semicrystalline morphology of ultra-high-molecular-weight polymer comprising randomly dispersed and oriented single crystals, stacks of single crystals, spherulitic crystals, and shish-kebab-type of fibrils with lengths up to a few millimeters and widths up to 20 .mu.m., a melting point of 125.degree.-270.degree. C., depending on the particular polymer, measured at a heating rate of 5.degree. C./min., a crystallinity of about 50% to about 75%.