Synthetics - Derived from Nature?
I’ve written this article because I have read a number of posts recently on LinkedIn likening bio based synthetics to petroleum based synthetics, with sweeping statements being made about them being one and the same. While there are certainly a number of similarities, there are certainly plenty of differences that make bio based options a stepping stone to more sustainable fabrics.
It’s worth saying at this point that we are far from finding good, environmental and socially sustainable fabrics for sportswear. While it could be argued that wool, typically merino wool, is the original sustainable sports fabric (and that is largely true), there are some considerable drawbacks in terms of it’s performance; it can hold up to twice it’s weight in water, it is more difficult to care for, both price and quality can be inconsistent year on year, and it isn’t always sustainably or ethically farmed. Mulesed wool is still widely available (see here for definition: https://kb.rspca.org.au/knowledge-base/what-is-the-rspcas-view-on-mulesing-and-flystrike-prevention-in-sheep/) and the environment in which sheep are reared can be environmentally damaging unless they follow a regenerative farming system (another good article here: https://www.woolmark.com/environment/regenerative-agriculture/).
Photo by Sam Carter on Unsplash
Petrolum based synthetics, such as nylon, polyester and elastane, have taken over as the sportswear yarn of choice due to a number of factors; price, consistency of quality and the many ways in which it can be mechanically altered to enhance certain qualities, as well as it’s durable nature (its so durable that most polyester fabrics in your wardrobe will outlive your great, great grandchildren). What makes these yarns unsustainable is that they are made from non renewable resources, the threat to biodiversity through oil extraction, the high energy and emissions during the process of turning oil into monofilaments and that they take hundreds of years to degrade.
In 2018 it was estimated that synthetics make up 51% of our fabric production. This has been a dramatic increase in just the last 10 years, and given the exponential rate there are a number of solutions that have been bought to the table, and the one I want to talk about here is bio-based synthetics. There are two types of bio-based synthetics, partially and fully bio based. Personally, I am not a fan of anything that has different fibre compositions within the fabric as these make the end of life particularly tricky as there are currently no ways to separate fibres out.
Photo by Charlie Hang on Unsplash
The fully bio based synthetics I’m referring to are often called polyamide 10,10 or polyamide 11 (the partially bio based ones are called polyamide 6,10) and these are currently the only ones commercially available bio based options. Those of you with a keen eye will notice that they have the same chemical name as nylon, which is often referred to as polyamide 6 or 6,6. And this is where many arguments are made by chemists as to the viability of bio based as a sustainable option. The term ‘plastic’, under which both oil and bio based synthetics sit, refers to how the polymers react under heat and pressure, also known as thermoplastic. It is not, as popular opinion would suggest, and indication of its feedstock.
So what makes bio based a more sustainable option; first it’s often derived from renewable resources, some come from a natural waste product such as sugar molasses, others from castor beans. Castor beans can’t be used as a food for either humans or animals and they are grown in areas of drought, not requiring fertiliser or other farming methods for increasing yields, so they don’t take away land from food sources and they provide people with an income for land where they can’t grow much to generate income. Where we do have to be cautious as businesses is to ensure our demand does not exceed what can be produced without effecting other areas of farming, we also need to ensure farmers are being paid an amount they can live on and if grown under regenerative systems then this can contribute to a reduction of carbon within our atmosphere. In addition to this, because these are farmed rather than extracted from oil fields, the environmental impact is further reduced.
Castor Bean Plant - Britannica
Bio based synthetics also have a reduced carbon footprint compared to petroleum based fibres; partially bio based polyamide 6,10 has a carbon footprint 49% lower than polyamide 6, and polyamide 10,10 having the lowest carbon footprint of all commercially available options of 58% lower than polyamide 6.
The production of bio based monofilaments is similar to it’s petroleum based counterparts which involve a number of chemical transformations. While this doesn’t make for an ideal scenario, it is these production methods that make the bio based fibres more commercially available and financially viable. How this may change as we develop new resins is yet to be seen.
Another aspect for consideration is end of life, while we can alter the resins to make them biodegradable, this is something that can also be done to petroleum based synthetics with an additive at the resin production stage and this is often what is used for Cradle to Cradle synthetics. Unlike branding a fabric or a garment compostable, which is required to have testing standards applied to it, stating a product is biodegradable doesn’t require any lab based testing. It also depends on the additive used in the creation, I have spoken to a number of yarn suppliers who have said their petroleum based products can biodegrade in 5, 10 or 20 years, and even then this is also effected by dyes and any other additives used. And as this is a relatively new category, there are a lot of unknowns for the benefits or potential downsides of biodegradable synthetics, covering both petroleum based and bio based.
The good news is that the monomers and polymers that make up bio based synthetics are similar to petroleum based synthetics, so they should be able to be recycled in the same way. Again, the problem with this is that as a new category this is a relatively unknown, particularly when we look at fibre to fibre recycling (which only makes up a small section of synthetic recycling in the first place). Ultimately recycling centres, whether mechanical or chemical, require a large volume in order to recycle to the maximum efficiency. This is where having a supplier that manages end of life for you is going to be important in the future, where brands can incorporate sustainable decisions as part of their merchandising strategies without having to produce more products in one particular fibre just to achieve end of life recycling.
While there is no doubt that bio based synthetics are not the answer to our problems, neither are virgin or recycled petroleum based synthetics. As we drive up demand for more sustainable options we will see more funding being made available as well as new products coming to market quicker. Only by taking the first step can we continue on our journey to becoming sustainable businesses.
