Hardened wood as a renewable alternative to steel and plastic • Hacker News Board

Re: Hardened wood as a renewable alternative to steel and plastic

#241

Post by tjmc » Fri, Oct 22, 2021, 4:33 AM UTC

sixstringtheory wrote: post #231

tjmc wrote: post #225

Mechanical engineer here. This article is very light on a lot of detail which would allow you to reasonably compare this material to steel, plastic or any other material. Just a few that come to mind: Hard materials are usually brittle materials that fail suddenly. How tough is it? ie. Can it accept some deformation without significant weakening and will it stretch or crack prior to failure? What is its compressive s…

I’d been interested to know your thoughts on pykrete! https://en.m.wikipedia.org/wiki/Pykrete

"Plausible, but ludicrous"

Re: Hardened wood as a renewable alternative to steel and plastic

#242

Post by ashtonkem » Fri, Oct 22, 2021, 4:35 AM UTC

tomrod wrote: post #152

svachalek wrote: post #66

Earlier quoted context omitted.

Soft bamboo (which is useless for products like these) grows incredibly fast.

Why can they not be hardened? Or otherwise used?

Different species. Bamboo is actually a family of 1,400 individual species, not one individual plant. The grassy and woody varieties are just different plants with different material properties.

As a general rule, the structural properties of wood can’t really be changed without just injecting a shit load of petroleum products[0], which isn’t really what we’re after here. If a type of wood, bamboo or otherwise is too soft for an application, then there really isn’t a way to “harden” it. This is the reason we tend to use hard species for flooring, such as oak, as you need to rely on the natural characteristics of the wood for strength and hardness.

0 - For example OSB, which is basically 5% oil by weight. Even still, our ability to adjust some properties is limited. OSB is strong and cheap, but it’s not that much harder than the wood species it was made from, and hardness is a desirable property for flooring to resist dents. Also, OSB is ugly.

Re: Hardened wood as a renewable alternative to steel and plastic

#243

Post by drjasonharrison » Fri, Oct 22, 2021, 5:11 AM UTC

jml7c5 wrote: post #238

adolph wrote: post #132

Earlier quoted context omitted.

Well, the glue is a renewable resource, old livestock and milk. That's why Borden used mascot Elsie's spouse Elmer as a glue mascot. https://en.wikipedia.org/wiki/Animal_glue https://americacomesalive.com/elmers-glue-the-surprising-sto...

I'd be very surprised if animal glue was used in any engineered wood. Even in fine woodworking it's a niche product; it's expensive and generally doesn't work as well as other glues.

On the other hand, it is reversible. https://woodworkingparts.wordpress.com/2010/08/17/hide-glue-...

"The significant disadvantages of hide glue – its thermal limitations, short open time, poor gap filling capability and vulnerability to micro-organisms – are offset by several advantages. Hide glue joints are reversible and repairable. Recently glued joints will release easily with the application of heat and steam. Hide glue sticks to itself, so the repairer can apply new hide glue to the joint and reclamp it. In contrast, PVA glues do not adhere to themselves once they are cured, so a successful repair requires removal of the old glue first – which usually requires removing some of the material being glued."

Re: Hardened wood as a renewable alternative to steel and plastic

#244

Post by hulitu » Fri, Oct 22, 2021, 5:13 AM UTC

agumonkey wrote: post #59

sfink wrote: post #12

I've been intrigued for a while about various modified wood technologies (eg hardened wood, transparent wood), but I'm always disappointed because it usually ends up just being a minor support structure for a very non-wood material (generally epoxy). This one shows a compression step, so maybe it's different, but I'd really like more info on whether this is actually renewable or sustainable in any interesting sense.…

I, too, would like to see "green" engineering. How to nicely tap in biosphere / organic material to make whatever we need. One old trick was hemp plastic.. I'm not sure what was bad about it since nobody tried it again since Ford made a prototype car body with it.

They even made a film with this car. It's called: Up in Smoke.

Re: Hardened wood as a renewable alternative to steel and plastic

#245

Post by tgtweak » Fri, Oct 22, 2021, 5:19 AM UTC

oliwarner wrote: post #134

dreamlayers wrote: post #118

Earlier quoted context omitted.

It is possible to make a knife out of lignum vitae: https://www.solidsmack.com/fabrication/lignum-vitae-ironwood... So I guess the achievement here is that commonly available inexpensive wood can be made as hard as rare expensive wood.

It's not cheap though, all the bloody carvers get it. Not that any wood is cheap at the moment. I think they might have just been highlighting basswood because it's so soft —softer than many softwoods— and so the outcome shows a much bigger improvement. Show me pine/spruce, poplar and oak.

That was my first thought too - maybe basswood is cheating. It does look though after some research that it seems that the process can be applied to other woods as well, since the process consists essentially of removing the non-cellulose component of the wood (hemicellulose and lignin) with heated chemical solution, then heat-pressing the resulting cellulose-only matter into hard block material.

Naturally, the harder of the hardwoods (IPE, Brazilian Teak, Ebony) are also relatively low-lignin wood types (that also grow relatively slowly, sensitively or in unfavorable geographical regions for logging and transport) and the result of removing the non-lignin would logically yield a lower improvement factor (and possibly take longer).

In general, the difference between softest readily-available lumber (such as basswood/spruce) and hardest (IPE) is about one order of magnitude. The result of this study at 23x means basswood can be made more than twice as hard as the hardest hardwood that is reasonably available. It would likely take a lot of lumber weight input though (explained below).

To your comment: Most common timber/lumber woods (softer: spruce, red pine, fir, chestnut, tamarack/larch and medium: cedar, maple, oak, birch) are rapid-growing and have established forestry industry around them. If you were to take white pine or spruce it should yield similar results to the study since you're basically condensing it to cellulose and they have similar weight densities. You would need to also factor the density of the wood since yield would be ratio of cellulose * weight of the source wood.

Since this is a high-waste process (only 40% of the weight is kept in the final product which is then compressed to the target density of 10000lbf or so) it would probably make most sense when using waste-wood as input (wood chips, sawdust, offcuts, recycled wood) and not on viable timber. This is similar to LVL and OSB (although it uses glue for binder)

Some composition comparisons:

Nordic Spruce: 39.5% Cellulose [1], 0.43 kg/m3 [5] (the poster child for engineered lumber construction in europe)

Black Walnut: 47.7% Cellulose [2], 0.63 kg/m3 [5]

Brazilian Teak: 53.0% Cellulose [3], 1.05 kg/m3 [5]

Basswood: 42.7% Cellulose [4], 0.41 kg/m3 [5]

[1] https://www.mdpi.com/2073-4360/13/10/1619/pdf#:~:text=Sjostr....

[2] https://yadda.icm.edu.pl/yadda/element/bwmeta1.element.agro-...

[3] https://bioresources.cnr.ncsu.edu/resources/color-and-chemic...

[4] https://www.fpl.fs.fed.us/documnts/pdf2019/fpl_2019_jia001.p... (pretty cool that they can make the basswood transparent to a significant extent also).

[5] https://cedarstripkayak.wordpress.com/lumber-selection/162-2...

Re: Hardened wood as a renewable alternative to steel and plastic

#246

Post by gremloni » Fri, Oct 22, 2021, 6:12 AM UTC

politician wrote: post #223

potatoman22 wrote: post #212

Earlier quoted context omitted.

Plastic doesn't radiate.

NIMBY neighbors don’t compromise.

There shouldn’t be any neighbors in the middle of nowhere.

Re: Hardened wood as a renewable alternative to steel and plastic

#247

Post by pySSK » Fri, Oct 22, 2021, 6:36 AM UTC

logical_proof wrote: post #211

contravariant wrote: post #198

Earlier quoted context omitted.

The amount of effort required for 10 million trees a day would require everyone in the US to plant a tree each month. This would likely also require people to care for enough saplings to plant a new tree each month. It's not an insurmountable level of effort per person, but if you try to do it on a large scale you inevitably end up with logistical problems, and it would require quite a lot of space.

I am not sure I understand your math here. Let’s say every adult in the US, 300M, plants a tree each month for 12 months, 3.6B trees planted in a year. Or are you factoring in saplings that fail to grow or something? Is it that bad that for every 160 trees planted only one survives? Edit: strike that I see what you meant there with the a day. I just should have actually read what you wrote before I commented.

US adult population is around 200 million.

Also, they can't even get people to wear a mask or take a shot. Getting all these people to plant trees seems like an insurmountable task.

Re: Hardened wood as a renewable alternative to steel and plastic

#248

Post by dx034 » Fri, Oct 22, 2021, 6:38 AM UTC

gbrown wrote: post #199

CodeGlitch wrote: post #173

Earlier quoted context omitted.

I wonder if there's any legs in algae or seaweed. Wouldn't take up valuable land to grow and is fast growing.

Seaweed is great - it also pulls excess nitrogen out of the water, can be co-cropped with bivalves, can be fed to cows for decreased methane production, can be eaten directly in many forms… If we had an actual price on carbon seaweed production would be a boom industry.

Couldn't you use it in large tanks to suck out CO² directly from the air? What makes this more expensive than currently proposed alternatives? Even if you don't use the seaweed in the end, you could just dry and bury it I guess?

EDIT: After some research I found an interesting article addressing this: https://www.technologyreview.com/2021/09/19/1035889/kelp-car...

Re: Hardened wood as a renewable alternative to steel and plastic

#249

Post by Ma8ee » Fri, Oct 22, 2021, 7:01 AM UTC

bumby wrote: post #227

Ma8ee wrote: post #146

Earlier quoted context omitted.

Or build houses and bridges and stuff with them instead of concrete.

The US can’t keep up with infrastructure maintenance as it is, let alone moving to materials with shorter lifespans and more maintenance

I don't think that the economy of wood is worse in the long run. It is quite much faster and cheaper to build with, and as long as it isn't allowed to be wet for long periods of time it also lasts indefinitely (there are wooden temples that are 1300 years old), and repairs are usually faster and easier than similar in concrete.

Re: Hardened wood as a renewable alternative to steel and plastic

#250

Post by jillesvangurp » Fri, Oct 22, 2021, 7:38 AM UTC

KennyBlanken wrote: post #68

jillesvangurp wrote: post #19

Earlier quoted context omitted.

Not sure if this is exactly the same but cross laminated timber (CLT) is already being used for constructing all kinds of buildings. Executive summary of its qualities: - Stronger and lighter than concrete. Think thinner floors and walls but with similar strength and load-bearing capability; less tonnes of material to move around. That alone is a big advantage. - Several buildings across the world already exist; more…

The biggest problem with CLT and other engineered wood beams is that it fails extremely quickly in a fire. I've heard firefighters talk about how their departments are considering scaling back entries on newer homes because those beams can fail so early in a fire when the binder fails.

It's not that black and white. CLT is more of a group of materials with different characteristics than a single thing. Fire rated versions of it exist and are commonly used depending on the requirements and building codes. This article has a nice overview: https://constructionexec.com/article/fire-safety-of-clt-and-...

Using cheaper materials for low rise might indeed be an issue. Also, living in houses that are mostly low quality plywood and other flammable materials is of course not great for fire safety. It's a tradeoff between cost, requirements, and regulations.

Even concrete buildings sometimes collapse when fire gets hot enough. Metal loses its strength when it gets warm enough. The collapse of the Twin Towers in New York are a pretty grim example of that.