Materials

Tough new pineapple leather is 60X stronger than other materials

View 4 Images
The leather produced with pineapple leaf fibers outperformed other plant-based materials
The leather produced with pineapple leaf fibers outperformed other plant-based materials
Leather from pineapple leaves
Mahidol University
The various applications and stains for 'tanning' the material and achieving texture
Ornwipa Mongkondaw

Mechanical properties of PALF leather compared with other leather alternatives
 Amornsakchai et al

View gallery - 4 images

In a breakthrough for bio-based materials, scientists have made leather from the fibers of discarded pineapple leaves that's comparable to the real thing and also outperforms other existing plant products. The strong and sustainable material, which comprehensively outperformed mushroom-based leather, has great potential to be produced at much larger scale for everything from clothing to bags and shoes.

Using natural rubber for adhesion, researchers from Thailand's Mahidol University created this 100% bio-based pineapple leaf fiber (PALF) leather through a simple process that does away with chemical treatment or additional plastics, which they say is a "significant" step forward.

"This research showcases a sustainable and economically viable alternative to traditional leather, with the potential to revolutionize the leather industry and contribute to a more environmentally friendly future," the team noted.

Leather from pineapple leaves
Mahidol University

While animal leather alternatives are not new, they have so far come with significant challenges. 'Vegan leather,' which relies heavily on plastics in production, may be better for animals but not necessarily the planet, and has been shown to have a much shorter lifespan. There have been major steps forward in using other natural fibers, such as those found in fungi, but their mechanical properties (toughness, tear resistance) have been an ongoing issue.

So what makes pineapple a more likely source for a leather that's produced sustainably and holds its own when it comes to wear and tear? It all comes down to the extraction and preparation of the tiny fibers. The leaves – a plentiful byproduct – were cleaned and chopped into 6-mm-wide pieces. These were then ground into a thick green paste and dried, then sieved to separate non-fibrous material from the pineapple leaf fibers (PALF). The researchers then prepared both untreated PALF (UPALF) and fibers that were mixed with sodium hydroxide and washed (TPALF), to create different leather properties, and spread out on a silkscreen, similar to paper-making processes. Finally, a thin coat of natural latex was applied to the unwoven, flattened fiber sheets, which were then exposed to 70 °C (158 °F) for 24 hours and later compressed.

The researchers landed on a treatment that, when analyzed using a scanning electron microscope, had a structure that performed best in tensile and tear strength tests and optimal hardness. These leather sheets were also treated with a variety of natural stains, from carrot to coffee, to demonstrate how a variety of tones could be achieved without needing any of the toxic chemicals used in commercial tanning.

The various applications and stains for 'tanning' the material and achieving texture
Ornwipa Mongkondaw

While the PALF leather had lower tensile strength and tear resistance to what is expected of animal leathers, they were comparable when the researchers performed their own tests, suggesting natural variability in traditional materials. PALF, however, was especially impressive when measured up against existing commercial leather alternatives, showing to have a tensile strength of 12.3 MPa, more than 60 times tougher than MuSkin (made from Phellinus ellipsoideus mushrooms) at 0.2 MPa. This poor 'wear and tear' factor has been one of the large concerns with mushroom and some other plant-based leather alternatives.

PALF was nearly three times stronger and had a tear resistance of almost double that of existing pineapple leaf leather Pinatex.

Mechanical properties of PALF leather compared with other leather alternatives
 Amornsakchai et al

The research team, led by Professor Taweechai Amornsakchai, plans to now work on adjusting the material's feel, to have it more closely resemble the softness typical of animal leather.

The research was published in the journal Sustainability and Amornsakchai explains the leather-making process in this 2019 video.

Source: Mahidol University via Asia Research News

View gallery - 4 images
  • Facebook
  • Twitter
  • Flipboard
  • LinkedIn
6 comments
windykites
Good luck with that. It does look labour intensive. Some shredding machines would help production. There is certainly plenty of raw material!
paul314
it sounds as if a lot of the strength question has to do with how much of the original fiber remains unchopped. But I would worry a little about the use of latex in the longer term, because that has a tendency to oxidize and become brittle. Perhaps if you oiled it regularly (as people used to do with animal leather).
Karmudjun
Thanks Bronwyn, but I'll stick with traditional leather. Until this is durable enough to make a saddle and can stand up to cactus and barbed wire, I'm not going to search it out. But it is nice to think that one byproduct of the cattle industry may be redundant means there could be less reason to put up with methane rich cow burps all over. But I find the Thai approach of adding the Zupper waste to plastics unacceptable for any environmentalist. The idea is to take nature and manipulate it so we don't need cows or petroleum in the production of any of this!
CDE
How does this affect someone who is allergic to latex?
ljaques
That's pretty cool. And think of the millions of little Naugas who won't be killed and stripped of their hides if this goes mainstream!
CitizenOfEarth
@Karmudjun "The idea is to take nature and manipulate it so we don't need cows" but cows are a part of nature, and tradition leather is a perfectly good natural resource