Viscose the Regenerated Fiber
In our previous post “The Fiber Diet” , we’ve discussed the organic make up of the various fibers we used as carbs, proteins and fats (oils / lipids). Here, we'll dive deeper into an interesting semi-natural, semi-synthetic fiber known as viscose, and in the US often called Rayon.
How it's made:
Viscose has been made since the late 1800s actually, and is often referred to as the first man-made fiber. Sometimes referred to as "synthetic silk” it actually has organic origins and has evolved since then to become stronger, softer and cleaner. Here’s how it’s made:
Shortened Cellulose Chains: If you'll recall, viscose is derived from the cellulose from trees, and the same found in cotton- a type of carbohydrate sugar that is found in very long chains usually 700-5000 sugar units long. Viscose is much shorter at about 300-500 units long.
Breaking Cellulose up: The 700-5000 unit-long sugar chains from wood are then dissolved in a solution of alkali (a salt) and carbon disulfide, creating a viscous syrup-like liquid
Building it back up in the shape we want: Now as an individual or smaller chains of sugar, an acid is added that causes the cellulose to reassemble, while it can be extruded (like pasta) into desirable shapes. Cotton, for example, has U-shaped fibers, but viscose can be flat or any shape.
The Structure:
Here is a comparison of viscose yarns vs cotton yarns. Viscose has high surface bulk filaments with irregularity, whereas cotton has smooth, U-shaped yarns which affect surface transport of water.
Electron microscope view of viscose. Credit N. Singh.
Electron microscope view of cotton. Credit N. Singh.
Properties of Viscose:
Very breathable and Hygroscopic: Because it is made of cellulose which is a carbohydrate, the water molecules on the sugar attract moisture vapor. The surface area of the viscose fiber, however, means that Viscose has a moisture regain (see Innovation Thursdays - 05.18.18 - Engineer's Notes: Moisture Wicking ) - a measure of breathability -of 13% which is between cotton (8.5%) and wool (17%).
Soft: The shorter chain length of Viscose results in lots of micro-fibrils when spun leading to softer yarn. The trade-off is that shorter fibers aren't as strong. That's why we blend the Fusion products with synthetics for strength.
Moisture-Wicking: Moisture management is largely a function of the shape of the fiber - because Viscose can be made into flat, rigged fibers - because of capillary action moisture travels easily along those channels.
Anti-microbial: A recent study confirmed that compared to cotton and polyester - bacterial growth is about 1000x less (this doesn't necessarily translate to 1000x less odor though). One hypothesis is that due to the very dry nature of the yarn (it sucks up the moisture) - that it makes it difficult for bacteria to grow.
Products that use Viscose:
We've been using viscose in a few products to date but will be going deeper into it in our Fusion line of viscose blended knits. We blend viscose with polyester or acrylic, in particular, to give it two main properties, wrinkle-resistance and strength.
Ms Fusion Overshirt (35% Viscose)
Ms Fusion Pant (70% Viscose)
Velocity Suit (33% Viscose)
3DPK Blazer & Dress (72% Viscose)
Sustainability:
There's been a lot of discussion regarding the sustainability of Viscose. On the one hand, it uses significantly less water than cotton when growing trees or bamboo on the other, the process for making viscose includes carbon disulfide, which can be harmful to the environment if not properly filtered out. There has been a significant evolution in the viscose process over the years, and the factories to create closed-loop systems for production to ensure those chemicals stay within the plant and out of the water supply and our products. This year we are introducing our latest blends that contain certified fabrics such as Viloft - a German viscose that is sustainably produced.
Viscose is an exciting yarn, one which when blended is becoming a pillar of our Scientifically Natural approach to products - and it itself is a blend of science and nature.