With the World Cup final taking place over the coming weekend, here’s an updated graphic on the chemistry of a football shirt, looking at the different polymer materials that are used in their manufacture.
In the past, before polymers were widely used in clothing, football shirts were made from cotton or even woollen materials. These had the obvious disadvantage of being a little on the warm side of things, and additionally soaked up any sweat produced,making them rather uncomfortable to wear. The first team to buck the trend of cotton shirts, and wear shirts made of artificial material, were Bolton Wanderers in 1953’s FA Cup Final. Sadly, the precise material used doesn’t seem to be recorded anywhere that I could find, only being described as a ‘shiny material’.
It seems similarly hard to track down when exactly polyester shirts came into common use, but by the 1990s polyester shirts were the norm for the majority of clubs. Polyester is actually a name for a large range of polymers; polymers are long, chain-like molecules formed from many smaller molecules, often referred to as monomers. In the case of simple polymers, such as polyethene, the monomers are all the same, but in the case of polyesters, two different sets of molecules are needed: an alcohol and a carboxylic acid. The polymerisation reaction can be carried out in a number of ways – the most commonly utilised uses a diol (a molecule with two alcohol functional groups) and a dicarboxylic acid (a molecule with two carboxylic acid functional groups). It proceeds via a condensation reaction, giving off water as a byproduct.
Polyethylene terephthalate, often abbreviated to PET, is the most commonly used polyester. It has a huge range of uses – from plastic bottles to food trays, tothin plastic films, and of course in clothing. In clothes, polyesters have a large advantage over the more traditional cotton fibres in that they absorb much less water. Cotton can absorb 7% of its weight in water, whereas polyester only absorbs about 0.4% of its weight. This makes it much less likely to get soaked in sweat during a game of football. Instead, the sweat can run down the fibres of the shirt and evaporate; because of this it is referred to as a ‘wicking’ fabric, or more generally as one that is ‘breathable’. It’s also durable and doesn’t crease easily.
Whilst some football shirts are 100% polyester, it’s also common for other fibres to be woven in with it to alter its properties. Elastane is another polymer that’s oftenutilised – more commonlyknown as spandex or lycra. In its manufacture, a prepolymer is firstformed from glycol and diisocyanatecompounds, reacted in a 1:2 ratio. This prepolymer is then reacted further with a diamine, to produce a liquid of the elastane polymer. The liquidis subsequently spun in a cylindrical cell, and heated in the presence of nitrogen gas, to convert it to solid polymer strands.
Whilst elastane is not as breathable as polyester, it has other beneficial properties. One of these is that it can be stretched to approximately 600% of its length before eventually rupturing, a trait that’s very useful in the modern game where shirt-tugging is commonplace. It also easily returns to its original shape.
A final type of polymer commonly used in the manufacture of football shirts is polyurethane. Again, this is the name for a class of polymers, rather than a specific polymer; we’ve actually already mentioned polyurethanes in a previous post, as they’re alsoone of the polymers used in the manufacture of footballs. Polyurethanes are built up from compounds called isocyanates and polyols. The middle parts of these molecules can be varied to give different polyurethanes with differing properties. In football shirts, they’re often the material that the letters, numbers, and sponsors on the shirt are made from, although fabrics or other materials can also on occasion be used. They can be thermally bonded onto the shirt using a heat-sealer, and unlike other fabrics, they have the benefit of being water resistant.
In the realm of football shirt chemistry, you're in for a treat. Now, let me give you a tour through the intricate web of polymers woven into those jerseys.
Firstly, let's rewind to the era when cotton and wool dominated football shirt landscapes, making players feel like they were wearing a sauna. The revolution came in 1953 when Bolton Wanderers flaunted shirts made from an enigmatic 'shiny material'—the early embrace of artificial fabrics in football.
Fast forward to the polyester era of the 1990s, where it became the norm for football shirts. Polyester, an umbrella term for a range of polymers, stole the spotlight. Picture long chain-like molecules formed from monomers, where polyesters need a dynamic duo: an alcohol and a carboxylic acid. The magic happens in a condensation reaction, bidding adieu to water as a byproduct.
Polyethylene terephthalate (PET), the superstar of polyesters, reigns supreme. From plastic bottles to food trays, it's omnipresent. In football shirts, its ace lies in water resistance. While cotton drinks up 7% of its weight in water, polyester sips a mere 0.4%. This 'wicking' fabric lets sweat dance down shirt fibers, evaporating into the air, making it breathable, durable, and wrinkle-resistant.
But wait, there's more. Elastane, the wizard of stretchiness, also known as spandex or lycra, often shares the stage with polyester in football shirt symphonies. Its prepolymer journey involves glycol and diisocyanate compounds, resulting in a fabric that stretches up to 600% of its length without throwing a fit. Perfect for the modern game's shirt-tugging theatrics, right?
Lastly, let's talk polyurethane—the versatile class of polymers. Remember those shirt letters, numbers, and sponsors? Polyurethanes often star in that show. Derived from isocyanates and polyols, they can be thermally bonded onto shirts with a heat-sealer, boasting water-resistant properties.
So, next time you cheer for your favorite team, remember, it's not just about goals; it's about the fascinating chemistry embracing every fiber of those jerseys. Cheers to the beautiful game and the science behind the shirts!
