Gore-Tex is a waterproof, breathable fabric membrane invented in 1969 by Wilbert L. Gore and his son, Robert W. Gore[1]. It is manufactured by W. L. Gore & Associates and is composed of expanded polytetrafluoroethylene (ePTFE), a stretched form of the PFAS compound polytetrafluoroethylene (PTFE)[1].
Invention and History
The invention of Gore-Tex was a result of a serendipitous discovery. In 1969, Bob Gore stretched heated rods of PTFE and found that under the right conditions, it could be expanded to form a microporous structure that was about 70% air[1]. This discovery led to several patents:
- U.S. patent 3,953,566 (1976-1993)
- U.S. patent 4,187,390 (1980-1997)
- U.S. patent 4,194,041 (1980-1998)
Gore-Tex’s invention was followed by legal battles, including the famous Gore v. Garlock case, which established Gore as the legal inventor of ePTFE[1].
Structure and Properties
Gore-Tex has a unique microstructure:
- Composed of long, narrow fibrils intersecting at nodes
- Porosity can be tuned based on processing conditions
- Impermeable to most liquids, including water, but permeable to certain vapors and gases
- High ultimate tensile strength (50-800 MPa) compared to full-density PTFE (20-30 MPa)
- Exhibits negative Poisson’s ratio
Processing
The production of Gore-Tex involves a tape stretching process:
- PTFE powder is mixed with a lubricating agent to form a paste
- The paste is extruded into a sheet and calendered
- The sheet is heated and stretched
- The expanded material is sintered to increase strength
Applications
Gore-Tex is used in various applications:
- High-performance fabrics (especially rainwear)
- Medical implants
- Filter media
- Insulation for wires and cables
- Gaskets and sealants
- Space suits
- Conservation of illuminated manuscripts
- Explosive sensors in clothing
- Bagpipe bags
Use in Rainwear
Gore-Tex revolutionized rainwear by providing a waterproof yet breathable material. Its key features include:
- A porous fluoropolymer membrane with about 9 billion pores per square inch
- Pores small enough to block water droplets but allow water vapor to pass
- An outer layer coated with Durable Water Repellent (DWR) treatment
Medical Applications
In the medical field, Gore-Tex is used for:
- Sutures
- Vascular grafts
- Heart patches
- Synthetic knee ligaments
- Nasal dorsal interruption treatment
- Glaucoma surgery membrane implants
Environmental and Health Concerns
Gore-Tex production has raised environmental and health concerns:
- PTFE is made using PFOA, a persistent environmental contaminant classified as carcinogenic to humans
- Gore pledged to eliminate PFCs by 2023
- The company plans to replace ePTFE with expanded polyethylene by 2025 in consumer fabrics
- Two lawsuits have been filed against Gore regarding PFAS-related water pollution
Comparison with Other Materials
| Feature | Gore-Tex | Traditional Rainwear | Windstopper |
|---|---|---|---|
| Waterproof | Yes | Yes | No |
| Breathable | Yes | No | Yes |
| Windproof | Yes | Yes | Yes |
| Stretchable | No | No | Yes |
Gore-Tex continues to be a widely used material in various industries due to its unique properties, despite ongoing environmental concerns and legal challenges.
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