Need Strength? It’s Modified Wood You Want!

Wood is surely one of the most versatile materials available. It can be found in a huge variety of colours and physical properties depending on the variety of the tree that grew it, and it has been fashioned into all conceivable devices, products, and structures over millenia. It’s not without shortcomings though, and one of the most obvious is that it can’t match the strength of some other materials. To carry large forces with a piece of wood that piece has to be made much larger than a corresponding piece of steel, something which is not a problem in a roof truss, but significantly difficult in a car body.

There have been a variety of attempts to strengthen the structure of wood in the past, and the latest has recently been published as a Nature paper. In it is described a process of first treating natural wood in a chemical bath to remove lignin and leave only the cellulose structure, followed by sustained compression at high temperature. This causes the cellulose fibres to interlock, and leaves a much denser wooden board with an equivalent strength that is described as near that of steel. They’ve posted a video which we’ve placed below the break, showing some ballistic tests on their material.

All new materials are of interest, but assuming that this one can be commercialised it makes for a particularly exciting set of possibilities. Wooden motor vehicles for example, new techniques for wooden aircraft or boats, or as an alternative in some applications where carbon fibre might currently find an application.

We’ve looked at a very similar process in the past for producing transparent wood. The good news for Hackaday readers that takes this from esoteric scientific paper to fascinating possibility though is that it can be done at home. Can any of you replicate the pressing step to take it to the next level?

Woodland scene: Willow [CC BY-SA 2.5].

29 thoughts on “Need Strength? It’s Modified Wood You Want!

  1. Certain strains of wood even have properties which make them work well as self-lubricating plain bearings, Lignum Vitae being a good example. Back in the days when roller bearings were too complex / expensive / needed too much precision, people used oil-laden wood or babbitt metal to make sliding surfaces which would last long under heavy load.

  2. seriously? soo basically they reinvented paper? a good analogy to wood is reinforced concrete whereas the lignin is the concrete and cellulose fibers are the metal reinforcement. so they tried to make a harder material by taking out the harder material? tell me the logic here……. pretty sure steaming and pressing would do exactly the same thing with much less effort….

    1. Lignin is not the harder material. The cellulose fibers are kinda like carbon fibers, and the lignin is like plastic resin. The fibers are what give the material its rigidity, while the resin holds it together. The lignin is subject to plastic deformation and creep. It’s much like if you had concrete rebar, but instead of concrete, hard rubber.

      The point of the method is to remove (most) lignin, and chemically empty the cellulose cells, so they collapse under pressure and leave very little material that has any plastic properties.

    2. That was my take on it, having read about wood and paper making chemistry not so long ago. Taking out the lignin seems…odd, though it’s valuable stuff on its own if I read my wood chemistry book correctly – it’s a long chain of all sorts of aromatics and other hydrocarbons – looks like if you broke that up you’d have racing fuel (toluene and benzene and highly branched HCs) – and most of the cool junk in coal too (remembering where coal comes from, maybe not too surprising).
      In paper making, the stuff they pull out – lignin, while still mixed with the lye and sulfite, is often burned for process heat and to regenerate the original chemicals. Waste of lignin perhaps, but in paper making, it was a waste product, so it makes that highly optimized (well, used to be, anyway) industry have less waste.

      These days, even if they didn’t care about being “green” – most large materials processing plants have a rule – if it comes in – it goes back out as product…”we” just add value by processing things. Turns out, once you know what you’re doing – and have this nice info about what’s going on in the world, you can find a buyer for almost anything. It’s more profitable to be green, more often than not – which is why you see it happening more – else, like other stuff, they’d just buy “better” laws…

      I myself am off-grid solar, and do quite a lot of other things free of the grid – and that resulting property taxes…it’s cheaper!

  3. I think this is really cool research, but I’d like to get some more details. From the _Nature_ article, they’re claiming it improves the strength by 11.5x. American White Oak has a tensile strength of 5.3MPa, and 1010 steel, about the weakest steel you can get, has a tensile strength of 365MPa, so I feel like this is more comparable to magnesium as regards structural materials.
    There have been a fair number of wood-based cars. The Marcos GT was a sportscar with largely plywood-based structure, and Morgans have traditionally used classic woodworking to form the bodywork of their cars. If you see pictures of Morgans being built, you almost feel cheated that the final product is covered in steel or aluminum bodywork.

    1. “Our processed wood has a specific strength higher than that of most structural metals and alloys”

      The claim isn’t about absolute tensile strength, but the press keeps distorting the message as usual. The material is very strong relative to its mass, so even though you need more of it, you end up with a stronger part for the same weight.

    1. but its just marketing isnt it?

      Can the material be recycled?
      What is the power consumption to create this material?
      How does that power consumption compare to the power consumption with creating metals?
      In creating the raw materials for such a product, how much deforestation is needed for the industrial harvesting of wood used in same product?
      How does all that compare to the energy required for recycling metals?

      The problem is that there are alot of unanswered questions about the environmental impact of industrializing the process to create this material and the only thing green about it is that it uses wood as a base.

        1. What passes for science? Come on. It’s a simple process that no one in all the time we’ve been using wood thought of. The guy thought of it because the guy worked with carbon nano tubes and then saw wood micro structure and came up with this. What have you invented?

          1. you might want to chill out there meatpopcycle (love the name, pun intended)

            I think the point that was trying to be made is that the entire article is missing key numbers that should be known if actually doing the science. Numbers such as energy consumption of the process, actual stress values, you know the things you would need to repeat this experiment. After all, science isnt just about the experiments or creating new processes, its about the repeatability of the experiment as well as the data required in order to judge whether this is a good idea going forward. If someone makes a comment that this is a “green” process with out showing that the environmental impact is less than existing material technology then it is just marketing as “green” really refers to nothing more than using wood as the base material. So until I start seeing actual numbers that shows me that the net impact of this process is more efficient than recycling metals It is not science but just marketing hype.

          2. @Mike The article linked above is a Nature advert for the actual paper where you will find things like time, temp, pressure, and concentrations to repeat the process. It also has multiple test for mechanical properties. You could even request data from the authors.
            It’s kind of a big deal. Please try harder.

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