On Habitats: Part 4 Non-Plant Based Synthetic Fibers

It’s been a while since I’ve posted about “On habitats” — the series designed to help me (us) take a moment and reflect on where the fiber in our yarn comes from. Part One of this series looked at Natural Plant Fibers, Part two: Synthetic Plant Fibers took a look at tencel, bamboo and corn, and Part three finished off synthetic plant fibers with soy, rayon, and modal. This week will focus on non-plant based synthetic fibers, namely nylon, acrylic, and spandex.

Close up photo of a large nylon fishing net piled on top of itself.
https://pixabay.com/photos/net-fishing-net-fishing-fish-cord-3428088/

Nylon is a polymer, or a plastic constructed of short repeating sections of atoms (think chain link construction) and is created by reacting two molecules with heat and pressure. This then produces a ribbon of nylon that is shredded into chips that can be used for many different types of everyday plastic.

Nylon yarn, or strands of nylon to be blended with other yarns, are created by melting these chips and drawing them through a spinneret. The length and thickness of the strands are determined by the hole size and the speed of the spinneret.

Nylon was the first created in the spring of 1930 by Julian Hill, by accident, and became a replacement for silk in wartime parachutes. Today, nylon is in almost everything, from toothbrushes and umbrellas to machine gears due to its durable nature and natural waterproofing.

While it’s in everything, nylon is not free from environmental impacts. For starters, nylon is not biodegradable, two of the largest sources of microplastic pollution are fishing nets and synthetic textile fibers that wear off during washing (now I feel a little guilty about washing my tights). The bright side to this is that nylon is also infinitely recyclable — we could probably stop producing new nylon, reuse what we’ve made and still have enough nylon for all our nylon needs.

Additionally, nylon is not suited to natural or low impact chemical dyes. This means that the process of dying nylon creates significant water pollution and the emissions from a single power plant are high. The flexibility of nylon does come with a cost.

A bunch of acrylic fibers, some of which have been dyed a dull blue.
https://commons.wikimedia.org/wiki/File:M%C3%A9lange_de_fibres_de_polyester_et_de_soies_pour_pinceaux.jpg

Acrylic yarns are made from a poly compound called acryonile, which is a type of plastic. The compound is first dissolved in a solution then put through one of two spinning methods.

The first method is known as dry spinning. During dry spinning, the compound solution is run through a spinneret to dissolve the solvent (liquid) so that continuous filaments are created. These filaments can then be cut to the desired length and added to other fibers.

The second method, or wet spinning, sets the compound solution into a coagulating bath until filaments are formed. Once the filaments are formed, they are then drawn, dried and processed.

The problem with acrylic yarns is that the process used to turn the plastic into a yarn requires a large amount of fossil fuel and it releases toxic fumes into the air. Additionally, each time that acrylic yarn is washed in a standard in-home washing machine microplastics are released into the water. While you can’t see microplastics due to their size, they add up fast. An estimated 85% of man-made waste on shorelines are made up of microplastics, a substance that will take up to 200 years to fully biodegrade.

Acrylic seems to be used for a variety of reasons. For starters, they are stretchy while also being durable, machine washable, don’t shrink and are moth resistant. Many claim that they’re perfect for baby knits, but I’m not convinced. Plastic melts when it gets hot! Don’t wrap your baby in a plastic blanket!

Opaque spandex fiber spun around a hollow cylinder
https://commons.wikimedia.org/wiki/File:Spandex_fiber.jpg

Spandex, a lightweight fiber often used to make clothing incredibly stretchable (spandex fibers can stretch up to 500% their length! Hello crazy math!), was developed during World War II as a replacement for rubber.

The first step in creating spandex fibers is to create a pre-polymer (unlike nylon and acrylic the polymers do not exist in nature already). Compounds are mixed in a reaction vessel and then added to a solvent to make the solution thinner and easier to handle. The solution is then pumped into a spinning cell (a spinneret in the presence of heat, nitrogen and solvent gas) and converted into fibers. Once the fibers leave the cell, they are bundled together to produce the desired thickness using a compressed air device that twists the fibers together. Finally, the fibers are treated with a finishing agent to prevent them from sticking together during textile manufacturing.

As with the other synthetic fibers, the creation of spandex comes with the repercussions of toxic chemical usage and a lot of energy required to produce them. They’re also created from polyurethane, which is a known carcinogen, and are not biodegradable (which is really bad when you consider how often you need to invest in new tights, sports bras etc).

My verdict on these fibers? It’s hard to say. Specifically, because it would be hard to completely give them up. I know I benefit from the spandex in my sports bras and the socks I knit out of yarns that contain a small percentage of nylon really do hold up better than the ones that don’t (perhaps there is a way to encourage the market to use recycled nylon!). Finally, I love my fleece jackets, they’re perfect for running and keep me warm even when I’m running in the rain (if fleece wasn’t made out of acrylic this would have been the easiest to dump down the drain).

That being said, you don’t have to convince me not to use acrylic yarns, I already do my best not to use them at all because like my fleece jackets they:

  • Don’t breath
  • Melt when exposed to heat
  • Are 100% plastic

So at least I can rest a little easy. It also helps that I try to buy my clothing second hand, so at least recycling someone else’s fleece jacket!

On habitats: Part 2 — Synthetic Plant Fibers

Last week I started the “On habitats” series to take a moment and reflect on where the fiber in our yarn comes from. Part One of this series looked at Natural Plant Fibers, which brings us to part two: Synthetic Plant Fibers. These include tencel, bamboo, corn, soy, rayon, and modal. In the interest of keeping these posts readable, I’m going to focus on tencel, bamboo, and corn this week.

wood-647597_960_720
https://pixabay.com/photos/wood-tree-trunks-hardwood-logging-647597/

Tencel (Lyocell): Tencel is derived from the cellulose of hardwood trees. The trees are logged and trucked to a mill where they are cut, debarked and fed to a chipper. The hardwood chips are then turned into a pulp through the assistance of chemical digesters, which is then washed (and sometimes bleached). After the pulp is washed, it’s layed out in a large sheet and left to dry. Once dry, the sheets are rolled onto a large spool.

Next, spools are unrolled and broken into one-inch squares so that they can be loaded into a heated pressurized vessel filled with amine oxide. After a short time in this solvent, the cellulose dissolves into a clear solution and is pumped through a filter to ensure that all of the chips have been dissolved. From here, fibers are pumped through a spinneret, which leads to the creation of long strands of fiber. These strands of fiber are then immersed in a diluted solution of amine oxide (this sets the strands) and washed in demineralized water. Fibers are then lubricated (detangled), allowed to dry, run through a crimper and then carded. Once carded, they are ready to be spun.

The amine oxide solvent is non-toxic and is almost completely recycled during manufacturing, so it is not released into the environment. Additionally, the principal ingredient in this yarn is obtained by managed tree farms (no deforestation), the process uses less water and energy when compared to other manmade fibers and tencel (lyocell) is naturally biodegradable.

bamboo-828703_1280
https://pixabay.com/photos/bamboo-forest-nature-green-plant-828703/

Bamboo: There are two methods that can be used to get bamboo fiber: mechanical and chemical. The mechanical method involves crushing the plants into a mush and using natural enzymes to break it down before spinning it into yarn. This method is labor-intensive (expensive) and the fiber produced is not very soft.

The chemical method, a “chemical cocktail”,  contains primarily sodium hydroxide and carbon disulfide — both are known to be bad for human health and are harmful to aquatic life when released into the water supply — which produces a very soft fiber (ie the fiber used to make bamboo underwear). While companies claim this a minute part of the process, a factory producing a lot of bamboo fiber/fabric will expose their workers and the environment.

Although Bamboo itself is a sustainable resource, there is a lack of transparency and true sustainability — the soil association has not certified bamboo at this time. In addition to the process of turning bamboo into a fiber, there are concerns around it becoming a mono-crop grown only in China. This is leading to a decrease in biodiversity and an increase in pests (more pesticide needs to be used).

corn-4457379_1280
https://pixabay.com/photos/corn-cornfield-corn-on-the-cob-4457379/

Corn: Corn is grown worldwide and used for food and fuel, leaving behind the husks as farm waste. These husks contain a fiber called lignocellulose which is soft and strong. Lignocellulose is separated from the husk via a patented biochemical process. This biochemical process contains common non-toxic chemicals (acetic acid, sodium chloride, sodium hydroxide, surfactants, and softeners) and is combined with water in a rotator for about a half-hour. The clumps of coarse fibers are then washed (with water) and dried before another biochemical treatment is applied to reduce the diameter of the fiber strands. Finally, the fibers are bleached, dyed and spun into yarn.

The downside? A lot of corn is genetically modified, which unfortunately means that something in the pollen is interfering with the monarch butterfly’s breeding cycle. Interesting. Essentially, while the corn fiber itself is not terrible for the environment, there are a lot of aspects (mono crop, etc) of the farming process that is.

Main Takeaways: I poked around and there isn’t a lot of corn yarn on the market yet, it looks like this could be a growing trend if the demand for the fiber increases. In terms of tencel; I don’t mind it in blends, but have not worked with a pure tencel fiber before. That being said, it’s nice to know that even though the fiber is manmade from a tree (which is a little mind-blowing) the process is both sustainable and eco-friendly. As for bamboo… I think I’m going to have to pay attention to what happens in the industry and abstain from using bamboo yarns for a little while. While I enjoy the way bamboo takes dye, I find it hard to support an industry that doesn’t have a problem exposing their employees to harsh conditions.

Stay tuned for synthetic plant fibers part two (soy, rayon, modal, and ramie), coming next week!