Is Teflon Absorbent?

Not my subject but go to google , type" Is Teflon Absorbent" & enter.

You will find following site "Teflon let life happen". Download the PDF. Very interesting.

http://www2.dupont.com/Products_and_Services/en_AU/assets/downloads/dcse%20msds/carpet/Teflon(R)%20Let%20Life%20Happen%20Technical%20Presentation.pdf

"Coating Teflon over fabrics for stain protection."

This indicates Teflon will not allow staining materials to reach fabric, which means Teflon, is impermeable.

Well, may be to a grater extent compared to most of the commercial polymers.

I like to share my experience on usage of Teflon.

As pilot plant engineer my job was to assist scientists and transform formulas to equipment/plants. We were handling harsh chemicals like Silicon tetrachloride and using Teflon tubes extensively. These tubes exhibited blisters of Silica on the outer surface of tubes. This means the fluid seeped through the wall of the tube pores.

My colleague scientist explained that Teflon is not thermosetting polymer and needs to be sintered to achieve shapes. Possibly sintering process leave some pores if not well made.

If used for hydrocarbon service some molecules may sit in these pores, which you want clean perhaps.

Solvents may help. If the hydrocarbons you are using is of heavy ends, lighter hydrocarbons like Naphtha might help. Ethyl tetrachloride (Carbon tetrachloride? – hazard chemical) dissolves most of the hydrocarbons and these solvents vaporize spontaneously without any trace behind.

Hi,

Assuming you are speaking about teflon PTFE, not the other products like FEP, .....

PTFE Teflon is among the most nonporous among all 'moulded' or 'extruded' plastics, with porosity being a fraction of a percent, so it will not absorb hydrocarbons .....

....with three notable riders:

1. During processing of teflon rods, hydrocarbon lubricants are used. These stick to the outside surface, and during subsequent machining, spread to the surface area of the machined component. If you are using teflon in oxygen service, you need to tell the supplier to tell the manufacturer of the rods to give oil-free rods.This problem is less severe if your teflon supplier is machining the components from moulded bush or rod, yet you need to due-diligence this aspect. Also, to use water as cutting-cooling fluid during machining, not the usual emulsions of water and hydrocarbon oils.

2. Teflon thread seal tape manufacture uses hydrocarbon to a greater extent, again the manufacturer will supply oilfree on demand.

3. Teflon is moulded in porous form, by design, for filters and other components. Some unscrupulous moulders mould lower densities to save cost, in which case the teflon will be porous. This probability will need to be eliminated.

A more precise reply is possible after knowing your exact situation, either in this forum or bilaterally.

Navroze Havewala
Mazda Manufacturers
India.
skype NMHavewala havewala@gmail.com mazda@vsnl.com +91 22 28211859.

absorb or not is NOT the correct question. Solid PTFE ,well formed, is impervious to hydrocarbons and hydrocarbons do not dissolve into the PTFE solid. Poorly formed PTFE is full of mechanical voids and hydrocarbon molecules will permeate the matrix to some degree, the magnitude being a function of pore size and hydrocarbon molecule size and shape. Some hydrocarbon molecules will remain 'adsorbed' onto the surface of solid (well formed) PTFE. A 'perfectly smooth' surface on PTFE is not possible of course.

Heat, detergents, vacuum drying all will 'encourage' the clinging hydrocarbons to migrate off the TFE surface. The term 'free of all', taken literally, is not feasible for usable PTFE specimens. If your requirement is ' hydrocarbon molecule level so low that it is not significant to the intended use' is a much different objective.

For example, in the manufacture of semiconductors, absolute cleanliness of surfaces touched by the reactants is essential to avoid even unmeasurable levels of contamination, since even a single molecule of contamination will cause an imperfection usually resulting in a 'bad chip.' It is essentially impossible to clean-up contaminated surfaces to the levels required if they are ever contaminated with anything other than clean air.