Method for producing porous articles from alternating poly(ethylene tetrafluoroethylene) and articles produced therefrom
Poly(ethylene tetrafluoroethylene) (ETFE) polymers having an average molecular weight of at least 300,000 g/mol and a melt enthalpy of at least 57 J/g are provided. The ETFE polymer may include at least one additional comonomer. The ETFE polymer is used to form a porous tape or membrane that has a node and fibril structure. A porous ETFE tape may be formed by lubricating the ETFE polymer and subjecting the lubricated polymer to pressure at a temperature below the melting point of the ETFE polymer. Optionally, the ETFE tape may be expanded at a temperature below the melting temperature of the ETFE polymer to form an expanded ETFE membrane. Alternatively, the ETFE polymer may subjected to heat and pressure without the addition of a lubricant to form a dense preform. The dense preform may be subsequently slit in a length direction and stretched to form a dense ETFE fiber.
1. A microporous poly(ethylene tetrafluoroethylene) (ETFE) article comprising:
a microporous ETFE tape formed from an ETFE polymer having an average molecular weight of at least about 300,000 g/mol, a melting point from about 260° C. to 300° C., and a melt enthalpy of at least 57 J/g, said tape having a node and fibril structure.
2. The microporous article of claim 1 , wherein, said ETFE polymer includes from about 0.001 mol % to about 10 mol % of an additional monomer.
3. The microporous article of claim 1 , wherein said ETFE tape has a thickness from about 0.01 to about 4 mm.
4. The microporous article of claim 1 , wherein said ETFE tape has a porosity greater than about 10%.
5. The microporous article of claim 1 , wherein said ETFE polymer has an average molecular weight from about 500,000 g/mol and about 20,000,000 g/mol.
6. A microporous polyethylene tetrafluoroethylene) (ETFE) article comprising:
a microporous ETFE membrane formed from an ETFE polymer having an, average molecular weight of at least about 300,000 g/mol, a melting point from about 260° C. to 300° C., and a melt enthalpy of at least 57 J/g, said ETFE membrane having a node and fibril structure.
7. The microporous article of claim 6 , wherein said ETFE polymer includes from about 0,001 mol % to about 10 mol % of an additional comonomer.
8. The microporous article of claim 6 , wherein said ETFE membrane has a thickness less than about 1 mm.
9. The microporous article of claim 6 , wherein said ETFE membrane has a thickness from about 0.08 mm to about 0.5 mm.
10. The microporous article of claim 6 , wherein said FIFE membrane has a porosity greater than about 10%.
11. The microporous article of claim 6 , wherein said ETFE polymer has an average molecular weight from about 500,000 g/mol to about 20,000,000 g/mol.
12. The microporous article of claim 6 , wherein said article is selected from a sheet, membrane, fiber, tube and three dimensional self-supporting structure.