One of the beauties of polymers is that they can be designed to fit particular uses.
So some ingenious guy decided that combining nylon and PTFE would produce a breathable AND waterproof material.
Nylon being tough, lightweight and hydrophobic (that is water repelling) means that using it for a waterproof jacket, sweat is going to build up inside it.
Some of us can remember this happening in the kind of outdoor kit we bought in the 60's and 70's!!
But if the nylon could be made to breathe, that is: be both water repellent and allow sweat to escape, then that would help those of us who engage in active outdoor activities because we'd be better able to cope with perspiration wetness.
GORE-TEX is a laminated membrane, i.e. it is a two layer material, that claims to do just that help us cope with perspiration wetness.
Below is a microphotograph of a GORE-TEX membrane.
GORE-TEX is a specially engineered hydrophobic material encasing a microporous expanded polytetrafluoroethene membrane.
This membrane has pores, as you can see in the microphoto, that are engineered small enough to keep soil particles and water droplets from entering but molecules of water, that are about 1000 times smaller than the pores, are unimpeded in their path out to the air through the material.
This expended PTFE membrane is too fragile to exist on its own without support so it is laminated to a nylon support.
So some ingenious guy decided that combining nylon and PTFE would produce a breathable AND waterproof material.
Nylon being tough, lightweight and hydrophobic (that is water repelling) means that using it for a waterproof jacket, sweat is going to build up inside it.
Some of us can remember this happening in the kind of outdoor kit we bought in the 60's and 70's!!
But if the nylon could be made to breathe, that is: be both water repellent and allow sweat to escape, then that would help those of us who engage in active outdoor activities because we'd be better able to cope with perspiration wetness.
GORE-TEX is a laminated membrane, i.e. it is a two layer material, that claims to do just that help us cope with perspiration wetness.
Below is a microphotograph of a GORE-TEX membrane.
GORE-TEX is a specially engineered hydrophobic material encasing a microporous expanded polytetrafluoroethene membrane.
This membrane has pores, as you can see in the microphoto, that are engineered small enough to keep soil particles and water droplets from entering but molecules of water, that are about 1000 times smaller than the pores, are unimpeded in their path out to the air through the material.
Here is a GORE-TEX promotional diagram showing how it works at keeping people dry from perspiration wetness in wet conditions.
The differences between the types of nylon arise because the group in the oblong in the diagram can be a hydrocarbon chain of different lengths.
Thing is, this fragile PTFE membrane is just that - fragile, and collapses readily and loses its performance characteristics because the pores clog up with dirt and close in on themselves.
PTFE stands for polytetrafluoroethene.
It is an addition polymer.
Here is its structure:
Fluorine atoms give the polymer its inert/unreactive properties because the C-F bond is so strong and difficult to break.
Nylon is of a different class of polymer called condensation polyamides.
Nylons have several different structures so here is a typical example:
The differences between the types of nylon arise because the group in the oblong in the diagram can be a hydrocarbon chain of different lengths.
For example, Nylon 6:6 has a (CH2)6 group in each box whereas nylon 6:10 has a (CH2)10 group in the diamine.
Pages on the "Mole" and "Using the Mole" in chemical calculations are here
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