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Recycled Wood and Wood Products

06/13/2011 2:19 PM

Hey everyone, I was thinking recently about recycled wood. Well first off, most recycled wood products aren't very good or at least aren't as good as their original. Particle board (the saw dust/powder stuff) has it's uses, but most recycled wood products aren't as strong as the original and need the use of glues and binding agents.

Wood is composed of mainly cellulose and lignin. There are processes that can separate these two products from any wood, paper or fiber source. Cellulose and lignin are used in other products but require lots of binding agents or chemical processes. Cellulose acetate is known by everyone. From buttons to film to fibers in clothing are made from it. As far as lignin goes, I have no idea what it could be used for or is used for. I couldn't find any mechanical properties of it but all I know is that wood is technically a composite of cellulose and lignin and that lignin is an important structural component of it. There are a lot of things that use wood powder, like bakelite and I'm pretty sure that "plastic lumber" for decks and outdoor structures use a recycled plastic/wood fiber composite. I'm not talking about that kind of use.

As far as I know, there aren't any composites that try to recombine cellulose and lignin into some usable material. Clearly it's an effective combination, but what could be done to duplicate it? I figure the reason is there isn't a way to bond the two materials at the molecular level in the same way that nature does in it's self organizing ways.

So I was wondering if there is any possibility of using raw recycled cellulose and lignin for an engineered biomaterial that is as good as other materials. I figure trying to make "artificial wood" would be really stupid because wood kind of grows on it's own and is quite cheap. The only beneficial aspect I was thinking of was using waste and recycled wood products (from demolished homes, yard waste, paper etc) to make something else that's good enough to be used again.

So it's just a thought and I wanted to know if there were any people with some additional insights!

Thanks!

Nick

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#1

Re: Recycled Wood and Wood Products

06/13/2011 10:36 PM

great idea. I work in a kitchen factory... dispose of a lot of wood products that could fit your scheme...

We also have a farmer that uses the sawdust from the tower to be put into the soil. so there is that use too. (to help grow more things)

Chris

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#2

Re: Recycled Wood and Wood Products

06/13/2011 11:24 PM

There is a world shortage of lignin (for those that know what it is) as a soil conditioner. Farming practices of stubble burning have depleted the lignin stores in the soils. It has an extremely long "half life", but is difficult to re-introduce.

However at a closer level to your question, (and I'm sure that Dell could pass some more educated insight into this) the waste wood will become "plastic" (think of steam shaping of boards) and then at some higher temperature, with applied pressure will re-bond with minimal adhesives.

Other uses researched in WWII were that addition of H2SO4 each Ton of wood produced half ton of sugar (proposed use to make ethanol for fuel), celulose (for explosives) and other useful by products that could be used as stock feeds and fertilisers. (The source of this info is a "propaganda" book (Publised by USA military) called something like "Science Year Book", where they talked about the amazing discoveries in blood transfusion, rockets, food preservation and othere things that would make the home front proud of their achievements.)

Keep up the search. There are many ways that wood can be re-cycled.

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#10
In reply to #2

Re: Recycled Wood and Wood Products

06/15/2011 3:50 AM

So do you mean Del the cat? Yeah I've seen him over the years. I'm a long time reader but not so much a poster. He does seem to be the jack of all trades and master of everything

And thank you for your input

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#3

Re: Recycled Wood and Wood Products

06/13/2011 11:54 PM

your interest in using used wood to create superior properties or at least equivalent properties to virgin wood intriques me. its got to boil down to fibres and binder fused together to emulate the real thing. the thing i don't see done enough is the continuous fibre part from one end to the other that is bound in position or fused in position and impermeable to water - etc - what costs the time and money are the forms that receive the raw materials and add the necessary compressive and thermal energy to set the binder in a timely fashion. i believe that a lot of objects that are made from metals and plastics could be made from a wood/binder composite to make things from house hold objects to automobiles.

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#4

Re: Recycled Wood and Wood Products

06/14/2011 2:59 AM

Thanks everyone for the quick replies. It is an interesting topic, as nature makes so many things that are so useful. When you look at tree wood cells under an electron microscope you can find that the lignin and cellulose are organized like we try to make composites with fibers. Wood is surprisingly interesting because of the composite nature. It not only has a nano scale structure like in the picture below but a macro scale as well (i.e. the grain and veins). I imagine that the veins and air cavities are why wood is quite strong for the weight.

I guess I don't know exactly where the lignin is but my guess is that it's in the middle lamella. I wish I understood the structure more. I've read that certain fungi can eat all of the cellulose and sugars out of wood leaving basically nothing but lignin.

I thought this was kind of an interesting article about the fungi.

http://www.cfans.umn.edu/Solutions/Winter2009/FungiAttack/index.htm

But what I was really interested in was the prospect of using raw cellulose and lignin to recombine and make another product. I liked the comment that with just heat it could be recombined to at least make some kind of mass. I imagine that if it's mixed in the right way or arranged in sheets (I don't know ) it would probably make something really strong. Wood has a fair amount of other not so strong components such as hemicellulose. I think that it's just not as strong and that if someone found a way to make a fake wood without it, you'd have a stronger product that is very dense.

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#5

Re: Recycled Wood and Wood Products

06/14/2011 7:36 AM

The Lawrence Berkley National Lab is doing extensive research in this area.

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#6

Re: Recycled Wood and Wood Products

06/14/2011 10:23 AM

How about something completely out of the box...as you noted yourself that it is foolish to think you can make a product as good as wood for as low a price as wood. But there is plenty of wood which goes to waste...sawdust from mills comes to mind.

I like the sugar made from wood waste in the above post. Experiments have been done with making ships out of sawdust and ice. (good for the arctic...), but that is really old news. Such a ship would be useful as a cheap and very stable drilling platform, but perhaps with global warming becoming a reality, it might suffer from melt. I know you can't sink that ship!

Suzanne Lee is growing clothing from the raw materials found in waste wood.

Paul Stamets is using mycillium to create an environment that eats oil spills and trash.

(and on a related note...mushrooms can be used for insulation in buildings...Not too sure I like that idea as much, but you didn't come here for the usual code book answers now did you?)

And of course, there are many other "cutting edge" answers to the very questions you have asked. And many internet resources available. Check this out. Especially number three on the list....a use for lignin. Arboform. (hope I am not breaking the rules by mentioning a trade name there...but it IS a fascinating article on a totally new technology.)

So....you wanted a more conventional answer? Well, here is a good article on using fiber resin...the fiber being wood fibre. Not really news, but still, a different take on an old idea.

Are these the sorts of idea you are looking for?

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#7
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Re: Recycled Wood and Wood Products

06/14/2011 12:27 PM

The use of lignin in the thermoplastic material is like what I was looking for. But you gave some really interesting links. The use of the fungus is really a biomimetic approach I think. Using something from nature like that is really interesting.

But that is exactly what I was thinking about. Sawdust, old paper, waste lignin etc could all be used for something. I was also trying to find the properties of raw cellulose and lignin. I remember from my materials science course that you can do calculations of composite material given the elastic modulus and the yield strength. Assuming an even mix of the two (and with the previously mentioned thought that they bond with heat) it would be interesting to see what the properties would be.

I what I really like is the idea of being able to create something without the use of large amounts of petroleum based products.

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#8
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Re: Recycled Wood and Wood Products

06/14/2011 5:25 PM

Yousef maybe in Ottawa sawdust is going to waste but out here in BC most sawdust ends up as wood pellets and exported to Europe probably also to Austria.

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#9
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Re: Recycled Wood and Wood Products

06/15/2011 3:44 AM

You're right, Europe does import from Canada as far as I know. Did you know Sweden is the top producer in the world, even higher than Canada? :)

I doubt that anywhere in the developed world that large quantities of sawdust is wasted.

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#12
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Re: Recycled Wood and Wood Products

06/15/2011 7:28 AM

The big mills have a waste stream, or so I have heard. There is no economic way to gather and dispose of sawdust from cabinet shops or smaller operations such as pallet making shops, pre-built truss operations or job sites. When you consider shipping and handling, wood is cheaper than anything you could make from it, including scrap! More wood is thrown away than is ever recovered downstream.

There is hope of course. Construction firms have bins reserved for wood waste now, and the Springhill landfill site hammers wooden items like crates and pallets and construction waste into tiny shreds, and recovers the metal. The wood chips are pelletized if it is reasonably clean (free of plastic parts) , otherwise it becomes part of the road. The operation does not pay for itself, but rather is part of a program to stream recyclable materials aside in a successful attempt to extend the life of the landfill. It makes sense when you consider the cost of a landfill.

Lignin is an overlooked material...it is like a thermo plastic. There is also hay, small twigs and other formerly alive materials which are a source of lignin. Good luck with that...I don't think this technology has matured yet. I don't think I'll be recovering it in my backyard any time soon though.

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#13
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Re: Recycled Wood and Wood Products

06/15/2011 9:14 AM

Yeah, it's certainly true, unless it's a big plant, in order to even get a small truckload of sawdust it's not worth it for them to make $20 from whatever they do to get it.

Do you know anything about lignin aside that it's a termoplastic? I can't find really any information on it's properties.

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#11

Re: Recycled Wood and Wood Products

06/15/2011 4:50 AM

Hmmm yes, I agree that trying to make artifical wood is daft, however some products like pywood do have advantages, mind these aren't from scrap/waste.
Not really my field, but I'd guess that the most cost effective uses are as fuel or as raw source of chemical materials, but I'm anything but a chemist.
Sawdust is handy stuff of course unless you have too much of it.
I use my sawdust to sprinkle into the compost caddy in the kitchen, it absorbs and liquid, stops any smell, deters the fruit flies and ends up back on the compost heap.
It's good for mopping up spills of course, I did offer BP a bag full a while back but they never got back to me.
I recall recently seeing a recycled wood product which was waterproof used as cladding, it was in one of the engineering magazines, don't think it was cheap though. When the appropriate timber is used it can last a long time, and it looks so good too. I'm currently working on the prettiest Yew character bow you ever did see, it looks more like burr walnut... dunno if it will explode on me though
Del

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#14
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Re: Recycled Wood and Wood Products

06/15/2011 9:42 AM

I learned a lot about a few things from these few posts, but I'm really hoping to find out about the thermoplastic properties of Lignin and how that would work when mixed with cellulose as a composite. I already know that fairly pure cellulose can be obtained because it's used in insulation for homes and as was previously stated, lignin is a byproduct of the paper industry.

Anyone know of someone who might be able to give some insight into this?

I really don't know if this is a stupid idea or not but I was just thinking of all the paper, wood and plant based waste we produce. There are a lot of composites that use wood as a filler, but they are often expensive. So why not separate the wood waste and make something else out of it?

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#15
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Re: Recycled Wood and Wood Products

06/15/2011 11:50 AM

Nick if anyone is doing research into new uses of wood it would be the universities located in areas where forestry, silviculture and lumbering is the economic mainstay. I'm sure sweden has a large university active in this area if not elsewhere in Europe.

Although not exactly what you wanted to know, there are now cellulose digesters that can produce bio fuel. This was a result of university research.

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#20
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Re: Recycled Wood and Wood Products

06/21/2011 4:17 AM

The International Lignin Institute is the group which you want to talk to. They are based in Switzerland, and they are devoted to finding ways to use lignin in industry. So much so that I was wondering if you are actually a member of the ILI.

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#16

Re: Recycled Wood and Wood Products

06/15/2011 12:44 PM

I see on the WIKI for lignin that there is a product that has been developed from the sulfonate of lignin from the paper industry that is usable as an injection molded plastic. Of course there are many chemicals derived from the lignin that is a waste product of the paper industry like surfactants for cement and artificial vanilla. A few years ago I understand they were trying it out as a soil additive but I don't know how that went.

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#17
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Re: Recycled Wood and Wood Products

06/16/2011 10:20 AM

I spoke with a chemist and he said that it is likely that pure lignin becomes soft and sticky due to the hydrogen bonding but is unlikely to melt like a more normal polymer would. I looked at the wiki as well and I would believe that it could become extrudable. I mean they extrude everything from particle board to steel, so as long as it stays together after the tooling, I don't see any reason why it isn't possible.

It's amazing that something as seemingly simple as wood can have so many byproducts.

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#19
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Re: Recycled Wood and Wood Products

06/20/2011 11:52 PM

When sawdust is compressed under pressure in a wood pelletizing machine, the lignin melts. this is what makes the sawdust into "pellets". Pellets find their uses in compost bins, cat litter, and chicken coops.

I think wood pelletization of scrap wood is a wonderful thing all on its own.

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#18

Re: Recycled Wood and Wood Products

06/20/2011 10:41 PM

Basically, it has the same function as myelin sheath in mammalian cells. It's like an inert binding material.

http://www.ili-lignin.com/aboutlignin.php

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#21

Re: Recycled Wood and Wood Products

06/23/2011 9:21 PM

Breakdown Breakthrough

Lisa D. Chong

Lignin is an organic polymer that binds tightly to cellulose fibers in plant cell walls, imparting rigidity and strength. The conversion of plant biomass into biofuels has been a challenge, in part because lignin hinders the degradation of cellulose into sugars that can be fermented. One approach is to use enzymes that break down lignin. Although such enzymes have been characterized in fungi, these microorganisms have been difficult to exploit commercially. Some bacteria secrete lignin-degrading enzymes, but the details are not well understood. The identification of a bacterial lignin-degrading gene would allow large-scale production of the enzyme in an organism that is easy to genetically manipulate and grow. Ahmad et al. used a bioinformatics approach to identify a gene in the soil bacterium Rhodococcus jostii that encodes a lignin-degrading peroxidase (DypB). In the presence of manganese salts, recombinant DypB expressed and purified from Escherichia coli showed degradation activity toward lignin, lignocelluloses from wheat straw, and synthetic model compounds. It is not clear how DypB is secreted from R. jostii, but the dypB gene is adjacent to a gene that encodes encapsulin, a shell-forming protein. The authors speculate that the genes may be coupled, and that an encapulsin nanocompartment could facilitate secretion.

Biochemistry 50, 5096 (2011).

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