A little while ago I was asked to speak on a panel discussing smart fibres at a fabric conference/show. Unfortunately I was unable to attend but I wrote a mini essay on the subject. It’s copied below, and I’ve stuck in some photos to try and illustrate the point.
Fibres which thermoregulate are the dream ticket – we don’t want fibres to keep us warm or cool, but fibres which do both. These are real ‘smart’ fibres. Historically, in technical textiles we have always been trying to protect, be it Gore-Tex, down clothing, or windproof fabrics.
We have been trying to reduce the impact of the surroundings on the wearer. This is borne of the ancient beliefs in the fear of outside, the alien, that the world is a threat.
In spacesuits, deep-sea diving suits, high altitude clothing, and polar expedition gear these assumptions might well be true. But in the everyday, even in potentially hostile environments like the mountains, perhaps we should be shifting to a position where fibres, fabrics and clothing are more about enhancing the interaction with the environment rather than limiting them. In practice, this means enhancing or amplifying the body’s exceptional thermoregulatory capacity, rather than limiting it.
Humans are extremely well adapted to prevent overheating. This is imperative, as while our core temperature can drop by more than 5 °C with no lasting effects, a rise in temperature of 5 °C is often fatal. Yet to survive the cold latitudes in which many of us live we wear clothing. This clothing protects against the cold, but it inhibits our most powerful thermoregulatory response: sweating. In effect we have replaced one evil – being too cold – with another: inhibition of cooling ourselves. And this is why fibres which thermoregulate, or enhance our ability to thermoregulate, are crucial.
We don’t want a barrier, a suit of armour: we want something that allows us to interact with the environment.
If we go back to the early mountaineers they wore clothing which was mainly made from natural fibres such as silk and, particularly, wool. Their clothing allowed basic interaction with the environment. One way a material can interact is to be ‘smart’. Wool in particular seems a pretty smart fibre and adapts constantly to its environment: it has a huge heat of adsorption, greater than many of the manmade fibres which have been developed that boast smart properties. One can sometimes see steam coming from piles of sheared wool as rain falls. When worn, this latent heat is fantastic in that it can keep a user dry in damp conditions, but the problem comes if the user is overheating: they sweat into the wool and it gets hotter! That isn’t smart. Many of the ‘modern’ smart synthetic fibres boast the same properties.
There are plenty of other interesting limitations borne of the current ‘smart’ fibres. For example, wicking can prevent cooling: the body loses heat by sweat evaporating from the skin, and the greater the distance between the site of evaporation and the skin, the greater the reduction in sweating’s efficacy. This effect is magnified as the environmental temperature rises. Thus, wicking fibres which transport sweat far from the skin may well increase comfort by reducing chafing, reducing the feeling of skin wetness, etc., but they don’t necessarily aid thermoregulation. If used correctly, however, they can allow sweat to stay near to the skin, while spreading sweat over a large area and thus maximising cooling. This is an example where the fibre isn’t the key, but the ways that the fibres interact: this is fabric design.
Much of the big talk over the last two years has been about air permeability and the resulting comfort.
This is a huge step in the right direction: it’s no longer about us versus the hostile environment; it’s about us interacting with it.
Air permeability, however, is not so much a fibre property as a fabric property. And fibres and fabrics are only a small part of the answer: a factor that makes textiles and performance clothing so exciting is the number of factors that influence performance. There are more hierarchical steps than in almost any other science. Polymers are the building blocks. There are more possibilities with polymers than we perhaps realise. We can change the polymer, the molecular weight, distribution, blends… there is so much potential. After that is the fibre. Old fibre production techniques still offer new possibilities, and relatively new fields like electrospinning are in such infancy that they offer near-limitless opportunities. Fibres go on to make fabrics, and here again are countless ways to innovate. Fabrics are where brands start to pay attention, and it their job to make sure they use the positive aspects of those fabrics to make garments which enhance those properties. The garments must also allow interaction with their environment and not merely try to barricade against it. Interaction with environment is the key to smart materials.