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  • Writer's pictureNed Patton

All About Natural Fibers

In this post I am going to talk a bit about natural fibers, their uses, and how they are changing the overall composites market. To get started I need to talk about where natural fibers come from and which natural fibers are useful and are being used in composites today.

Natural fibers are fibers from plants, so they are primarily cellulose. All plants of course are made primarily of this stuff. And as you might expect, some plants are better fiber producers than others. Hemp has been used for rope for millennia, and coconut fibers and flax fibers have also been used for a very long time. Flax fibers are actually the fiber used to make linen. And, of course, there is always cotton which is the clothing fabric fiber of choice for many people.

Composites made from plant fibers (or plant strings if you will) are usually made using hemp, flax, and even forest wood waste. Flax is the most prevalent fiber in the newer natural fiber composites, and has found significant inroads into the automotive industry. The interior door panels of your new car may be made using flax fiber, as may your trunk liner and seat backs. And if you’re lucky enough to have bought a Mercedes E-Class with a sunroof lately, the frame for your sunroof is a natural fiber composite.

The largest hurdle that had to be overcome to adopt natural fibers in composites is the fact that all of the natural fibers that would make good composites – hemp, flax, and wood waste – have a high water content. So, the typical polyester, vinyl ester, and epoxy resins don’t stick to them very well. The traditional resins are hydrophobic – they don’t like water – so they don’t stick to fibers with high water content.

However, several companies recently have gotten around that problem by formulating new resins and hardeners. One such company is Nouryon ( which has developed a hydrophilic (likes water) hardener for standard polyester and vinyl ester resins. They developed this as part of SSUCHY – a four year long public-private partnership project in Europe that was formed in September 2017 to develop renewable precursors for composites. That means biopolymers and plant fiber reinforcements.

That being said, the business of natural fiber composites is still somewhat in its infancy, with mostly startup companies producing products for the automotive industry. Bcomp in Europe uses mostly flax fiber in their composite panels that they make for Polestar (jointly owned by Volve and Greely), the race version of the Tesla P100DL (in the pic above), and the Gillet Vertigo which was entered into the Pikes Peak Hill Climb in 2018.

UFP Technologies ( uses natural fibers in a polypropylene matrix to make door panels, seat backs, bolsters, and trunk liners and load floors. These are the same people that make your paper egg cartons out of recycled paper, so they have been in the natural fiber business for a long time, and have recently branched out into low cost, high production rate natural fiber composite panels for the automotive industry.

Natural fibers have gotten so much traction in industry that the International Organization for Standards (ISO) has developed standard testing methods for natural fiber composites. ISO 16616:2015 is just such a standard. The title of this standard is “Test methods for natural fiber-reinforced plastic composite (NFC) deck boards”. And there is a European standard (CSN EN 15534-5) for composites made from cellulose-based materials or natural fibers.

So, natural fibers have not only gained traction, they are beginning to take over industries that are trying to become or have been legislated to become carbon neutral. Since the fibers are made by plants, at least the string portion of natural fiber composites is carbon negative – they actually sequester carbon from the atmosphere.

That’s an introduction to natural fibers. In other posts, I delve more into natural fibers and bio-based or plant-based resin systems and how they are displacing some more traditional composite materials. And of course, sustainability efforts that are underway are adopting natural fibers and natural resins as well. But all of that is for other posts in this blog. Stay tuned!


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