Analysis of PTFE: Why does it seal well?

PTFE tape is commonly used to seal gaps, cracks and gas leaks. By means of gas physisorption and atomic force microscope (AFM), we shed light on why PTFE powder and tape seal so well. This approach can also be used to analyze other flexible materials, thin films/coatings, and novel elastomers.

Polytetrafluoroethylene (PTFE) is a synthetic polymer composed of tetrafluoroethylene chains, discovered in 1938 by Roy Plunkett at DuPont.1 PTFE is hydrophobic, has the third lowest co-efficient of friction among all materials (0.05-0.1) and low thermal conductivity, but high melting point (326 °C) and density (2.2 g/cm3 ).2 Common industrial uses of PTFE include use in anti-friction materials (lubricants, grease, etc.), creating hydrophobic fabrics, use in high temperature membrane filters, dental filings, among others.

This approach makes use of multiple measurement techniques like gas physisorption (surface area information) and atomic force microscopy (AFM, surface morphology) to throw light on why PTFE is able to seal gaps in materials very well. The purpose of this note is also to show how a material (like PTFE) can be analyzed at the textural level to give a complete explanation of its physical, real world performance attributes. When developing novel materials, we typically need information on: a) how the material will behave at the sub-nm level (PTFE powder) by measuring surface area and b) what is the nature of the material when extruded into thin flexible sheets, PTFE sealing tape just being an example.

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