Porous fibers from natural/synthetic polymer blends

• US 6,765,028 B2
• Filed: 12/16/2002
• Issued: 07/20/2004
• Est. Priority Date: 12/14/2001
• Status: Expired due to Fees

• Current Assignee: North Carolina State University (University of North Carolina System)
• Original Assignee: North Carolina State University (University of North Carolina System)
• Inventors: Kubo, Satoshi, Kadla, John F., Venditti, Richard A., Gilbert, Richard D.
• Primary Examiner(s): Foelak, Morton
• Application Number:
  US10/321,939
• Publication Number:
  US 20030212157A1
• Time in Patent Office: 582 Days
• Field of Search: 521/61, 521/77, 264/45.9, 264/46.1, 264/59
• US Class Current: 521/61
• CPC Class Codes: B01D 2323/12 Specific ratios of components used
• CPC Class Codes: B01D 67/002 from melts
• CPC Class Codes: B01D 67/003 by selective elimination of components, e.g. by leaching
• CPC Class Codes: B01D 69/08 Hollow fibre membranes manufacture of hollow fibres D01D5/24, D01F1/08
• CPC Class Codes: B01D 69/085 Details relating to the spinneret
• CPC Class Codes: B01D 69/141 Heterogeneous membranes, e.g. containing dispersed material; Mixed matrix membranes
• CPC Class Codes: B01D 69/1411 containing dispersed material in a continuous matrix
• CPC Class Codes: B01D 71/10 Cellulose; Modified cellulose
• CPC Class Codes: B01D 71/74 Natural macromolecular material or derivatives thereof B01D71/08, B01D71/24 take precedence
• CPC Class Codes: D01D 5/247 Discontinuous hollow structure or microporous structure
• CPC Class Codes: D01F 6/46 of polyolefins
• CPC Class Codes: D01F 9/00 Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments

Abstract

A method of preparing a porous fiber, the method including blending a natural polymer having a thermal stability with a synthetic polymer having a thermal stability, wherein the thermal stability of the natural polymer is different from the thermal stability of the synthetic polymer, and wherein the natural polymer and synthetic polymer from immiscible phases; extruding the blended polymers while heating at a predetermined heating rate to the fiber spinning temperature; spinning the fibers while maintaining the temperature; and heating the fibers at a heating rate that maintains the natural polymer in a fiber form and that removes the synthetic polymer, whereby a porous fiber is formed.

Claims

1. A method of preparing a porous fiber, the method comprising:

(a) blending a natural polymer having a thermal stability with a synthetic polymer having a thermal stability, wherein the thermal stability of the natural polymer is different from the thermal stability of the synthetic polymer, and wherein the natural polymer and synthetic polymer form immiscible phases;

(b) extruding the blended polymers while heating at a predetermined heating rate to a fiber spinning temperature;

(c) spinning the fibers while maintaining the temperature; and

(d) heating the fibers at a heating rate that maintains the natural polymer in a fiber form and that removes the synthetic polymer, whereby a porous fiber is formed.

2. The method of claim 1, wherein the natural polymer is lignin.

3. The method of claim 1, wherein the synthetic polymer is a polyolefin.

4. The method of claim 3, wherein the synthetic polymer is polyethylene or polypropylene.

5. The method of claim 1, wherein:

(a) the natural polymer is present in an amount ranging from about 25% to about 99% by weight; and

(b) the synthetic polymer is present in an amount ranging from about 1% to about 75% by weight.

6. The method of claim 5, wherein the natural polymer is lignin.

7. The method of claim 5, wherein the synthetic polymer is a polyolefin.

8. The method of claim 7, wherein the synthetic polymer is one of polypropylene and polyethylene.

9. A porous fiber produced by the method of claim 1.