textile blends

 When you look at the labels in your garments, you will see that the current textiles are composed of a variety of materials.

nowadays current textiles are composed of many different types of fibres, why does this makes post-consumer textile recycling very challenging.

 If you were to burn a piece of textile, you would see large differences, based on the fibre composition. hundred percent cotton. It burns readily without melting, like burning paper, a material also consisting of cellulose. There is no distinct smell, and the residue is a small amount of light grey ash 

a piece of hundred percent polyester however, burns slowly and melts, and it smells like burning plastic. The residue consists of black, hard matter

a blend of thirty percent acryl, forty percent of polyester and thirty percent of wool burning. when burnt The burning is very intense and smells very bad. We have no explanation, based on the fibre composition, why this burns so readily. Most of the textiles nowadays are composed of many different types of fibres. As you can understand, this also means that processing of these post-consumer textiles through recycling can be very challenging. So why do we use textile blends at all?

 To understand why we use textile blends, we first need to know a little bit about the properties of each fibre. Tenacity says something about the strength of the fibre. Elongation is the ability of a fibre to recover its original length when stretched and released. And moisture regain is the ability of a dry fibre to absorb moisture under humid conditions.

cotton is a strong fibre and becomes even stronger in a wet state. It is comfortable to wear due to high moisture regain. Viscose is not so strong but also very comfortable due to high moisture regain. Polyester is a strong fibre, but is not so comfortable as it does not absorb moisture. Elastane is a very stretchy fibre providing a lot of comfort.

therefore its easy to understand why a single-component textile such as 100% polyester or 100% cotton, often does not fulfil the requirements of today’s fashion. Fibre blending, by combining two or more fibres to a new yarn, can combine the best qualities of each fibre. Selection of fibres for blending is often based on achieving several objectives. One is to improve functionality of the fabric. A well-known example is the presence of a few percent of elastane in jeans to improve wear comfort. Another example is a blend of polyester and cotton, to combine strength and comfort. But also to reduce the price as polyester fibres are cheaper than cotton fibres. A third reason can be ease of processing, as synthetic fibres can be produced in a wide range of fibre lengths compared to the relatively short length of natural fibres, making spinning easier.

a well-known combination is a 50/50 blend of cotton and polyester, but other fibre combinations are also used. Elastane is not only added to cotton in jeans, but also to polyester, polyamide, wool or other fibre combinations to create clothing that stretches with your body. In the end, you get complex textiles, often based on 2 or 3 fibres, but also combinations of 4 or 5 fibres are not unusual  However, for sustainability and end-of-life options blending might not be such a good idea. There are good recycling options for 100% polyester and 100% cotton fabrics. Chemical recycling of polyester leads to virgin quality and cotton can be processed to regenerated cellulose fibres like viscose or lyocell. But what happens when fibre blends are used instead of only cotton or polyester? And when in each garment a few percent elastane is present? Then the current recycling technologies do not fit anymore as each textile fibre has its own optimal recycling process and elastane amongst others acts as a contaminant.In this case, recycling becomes technically complicated, energy-consuming and expensive and will most likely not become a profitable business.To change this, we need to start at the beginning of the value chain,with design for circularity as the focus area.Recycling options for monomaterials, like 100% cotton, are much more promising than recycling of multimaterials like textile blends.We can also work on alternatives to elastane made from fully recyclable biobased polyesters. Another option is improving the strength of regenerated cellulosic fibres. In that case, blending will not be requird anymore.Textile recycling of post-consumer goods is still in its infancy,and we should learn from mature recycling industries, like paper and glass.

 In particular, we should also follow developments of plastic recycling closely, as it has large similarities with the current textiles for fashion in terms of material use and complexity.If we do this,we will stand a much better chance of making fashion truly sustainable.