Fibres that come through fire
Yes there are such things: the real tough guys of the fibre world, who fear neither fire nor brimstone. They are the reason that workers, who are up there when the blast furnaces are opened and are exposed to temperatures of up to 1,000 degrees Celsius for up to 20 seconds at a time, remain on their feet instead of melting. And their name is Aramid!
Okay, the word aramid isn’t really written with a capital letter – that was just for effect! Strictly speaking, it is, moreover, an abbreviation for “aromatic polyamide”. Polyamides, which are synthetic fibres, are used, amongst other things, for strainers in industrial liquid filtration, but also – some fibres clearly like it ‘hot’ in all senses of the word – for nylon stockings (to give here just a very brief impression of their scope). “Aromatic” here, doesn’t mean that the heat-resistant aramid fibres have a particularly pungent, flame-repelling smell, it simply serves to place them in the appropriate materials classification in organic chemistry, that of the aromatic compounds, of which the first to be discovered did, indeed, have an aromatic smell – hence the name.
However – before this blog entry turns into a chemical treatise, let’s get back to the aramid fibres, which contain such a high proportion of aromatics, that the fibres can absorb a particularly large amount of energy – energy … heat … and lo and behold… the jigsaw falls into place! (heat is a form of energy, also often called ‘thermal energy’). “A worker at the blast furnace is regularly exposed to temperatures of up to 400 degrees Celsius,” says graduate engineer, Stefan Griesbach, Quality Manager at TTI Technische Textilien International GmbH, who create a textile fabric from the heat-resistant fibres, from which, in turn, clothing manufacturers (‘off-the-peg producers’ and other apparel and garment makers) make protective clothing for high-temperature applications.
But TTI will also finish its fabric as required, with an appropriate coating for instance. One possible way of coating the material involves the aluminisation of the aramid fibres (see photo). Because they then acquire protection against radiation, as a result, and reflect a major portion of the insupportable heat. The heat that remains and works its way through to the wearer is then trapped by the cool aramid fibres, which absorb the thermal energy and, in contrast to other types of fibre, do not subsequently melt themselves, when life gets really hot for them. And they continue to be eminently wearable: whilst, according to Griesbach, glass fibres, say, exhibit much greater resistance to heat – up to 1,200 degrees Celsius – they are not comfortable to wear.
Whether the TTI team really have built a blast furnace on their stand for effect, or whether we have just reproduced a picture, is something to be discovered only by those who brave the path to the fiery furnace, ready to cast the ring…