6 ms·

Wood pulp extract stronger than carbon fiber or Kevlar (2012)

146 points by jtraffic 9y ago

JonRB 9y ago
I'm delighted by how in-depth and detailed this is! I'd be interested in seeing the numbers for how much the final product weighs in comparison to Kevlar/Carbon Fibre... I'd also love to know if this research went anywhere since 2012
- Scaevolus 9y ago
  > CNCs... bulk density is low at 1.6 g/cc, but they exhibit incredible strength. An elastic modulus of nearly 150 GPa, and a tensile strength of nearly 10 GPa. This is the same as carbon fiber (1.57-1.7g/cc), and slightly higher than kevlar (1.44g/cc).
eutectic 9y ago
Carbon fiber works so well in composites because it is possible to create long, continuous fibers which can be woven into cloth for directional reinforcement. Maybe it is possible to use the strengths of each by adding CNCs to carbon composites.
- chroem- 9y ago
  Nitpick: fabric lay-ups are rarely used in industry because the weave exerts shear stresses on the fibers, making them weaker under load. Aerospace composites are all unidirectional. But fiber blends are very common. It's typical to mix CF, glass, and aramids to get the price and properties you want, though I don't think it would make much sense to mix chopped and continuous fibers.
  - eutectic 9y ago
    Thanks for the correction, my bad. The technical term for the kind of thing I was thinking of is 'multiscale composites', and there already seems to be a lot written about carbon fiber/carbon nanotube mixed composites which would presumably be similar to carbon fiber/nano-cellulose composites. I obviously can't claim to be an expert, but there at least seems to be some precedent.
slackingoff2017 9y ago
Im not too surprised. The strength of plywood is well known in aero and racing circles. For parts like stringers plywood is used instead of fiberglass when higher stiffness is required. Plywood is similar strength/weight as fiberglass which isn't too far off from carbon fiber. The issue with all popular composite materials like fiberglass, carbon fiber, and plywood is that their strength is highly directional. It takes a lot of skill and testing to make sure your part is strong enough in all directions force will be applied. There's some omnidirectional "mat" type materials you can get easily for fiberglass but you exchange the directional strength of weave for a non-directional but overall inferior strength of randomly oriented strands.
omarforgotpwd 9y ago
Stronger at 10% of the price of carbon fiber. So why haven't we seen more people using this material in the last five years?
- kbart 9y ago
  Yes, I often wonder too where all these new inventions are gone after the initial enthusiasm and media attention fades. Probably every weeks you can find articles about 'breakthrough' in material science, battery, memory technologies etc. Yet when I try to Google them after few years, >90% has no follow ups nor these technologies reach market. I guess this is like startups -- good idea is not enough, execution and financing is what matters.
  - omarforgotpwd 9y ago
    Yes. I feel like cancer has been cured every few weeks since Reddit first went live.
    - malka 9y ago
      Cancer is easy to kill. The hard part is not killing the human around the cancer as well.
      - KGIII 9y ago
        Add to this that there are many, many different types of cancer. There won't ever be a cure for cancer. We may find a cure for a cancer, but there are many types of cancer. A good friend is an oncologist. He kinda hates it when people talk about a cure for cancer. I guess it just doesn't work that way.
  - noir_lord 9y ago
    To an extent, also a lot of these processes are incremental rather than revolutionary (despite the press releases) and do eventually make it through to production after an upgrade cycle or two. Hell a carbon fiber (partially) plane flew around the world non-stop in 1986 but it wasn't until 2012 that carbon fiber road bikes got good enough/cheap enough for me to buy one. I think people underestimate incremental improvements, 4% (arbitrarily) a year, year on year adds up eventually. Look at the improvements to Li-Ion battery technology as a good example. Recently I've been doing research on a programming problem that has come up at the new job, I pulled the related research and the canonical first representation of the problem on a computer was formulated in 1966 and the issues it addressed in the paper are identical to the way the processes are run at new employer, almost word for word. 51 years that research has existed and they are still doing things the way they did then.
pacaro 9y ago
Strip planking is popular amongst canoe builders. A 1/4inch thick core of cedar has fiberglass on either side. The glass provides tensile strength and the wood provides both compression strength and a useful offset between the fiber layers. I can lift the bare hull of an 18 foot long sailing canoe with one hand. The downside is in maintenance/repairs, and the critical requirement to keep through holes absolutely watertight. If water gets into the core it's a total PITA Also, strips of cedar that are 3/4" by 1/4" by 18' are really weird to handle.
- Yaggo 9y ago
  Also bigger (sail)boats have been home-built using strip blanking technique. The downside is weight penalty over balsa/foam core.
- doikor 9y ago
  Snowboards are kinda similar with usually having a wooden core for tensile strength with plastic bottom for gliding, plastic top for protecting the wood and metal edges to cut into snow/ice. Get a hole all the way to the wood (usually by hitting some rocks on the rather soft/porous plastic bottom) without keeping it dry and patching quickly will destroy the board very fast. Also modern boards have multiple different kinds of wood in fancy layers/placements inside to give the correct amount of "pop" in the correct spots for the wanted ride. Some of the more expensive/extreme boards have started to replace parts of the wood core with carbon fiber in the cases where weight is very important and a very stiff board is preferred (mainly backcountry/split boards)
- jdietrich 9y ago
  End-grain balsa wood is a surprisingly common core material in high-performance composite structures.
- coredog64 9y ago
  GM used balsa wrapped in carbon fiber for a previous version of the Z06 'Vette for similar reasons [0]. It's light, it's strong, and it's cheap. [0] http://www.autonews.com/article/20050912/SUB/509120708/balsa-wood-helps-put-the-zip-in-the-z06 http://www.autonews.com/article/20050912/SUB/509120708/balsa...
mixedbit 9y ago
Also take a look how strong and abuse-resistant cross laminated timber is: https://alexschreyer.net/engineering/much-abuse-can-cross-laminated-timber-clt-take/ https://alexschreyer.net/engineering/much-abuse-can-cross-la...
imaginenore 9y ago
I think it since got surpassed by UHMWPE, which has a tensile strength of ~20GPa. They make cheap body armor out of it. https://en.wikipedia.org/wiki/Ultra-high-molecular-weight_polyethylene https://en.wikipedia.org/wiki/Ultra-high-molecular-weight_po...
- Gravityloss 9y ago
  One problem with UHMWPE is it's slippery, so hard to glue to a rigid composite. Also, don't count out the path dependence of even very competitive industries. They know carbon fiber, so that's what they use, and they then make small increments from their known territory.
- owenversteeg 9y ago
  UHMWPE is a beautiful thing. As easy to cut as wood, you can bend and mold it at temperatures over 300F, and it's strong enough that a 0.9" thick plate can stop bullets. Specifically, by "bullets", I mean a NIJ-0101.06 level III threat. That could be up to 24 shots from an AK-47, FN FAL, or AR-15.
dsfyu404ed 9y ago
Hmmmm. I wonder how its material properties change in the -40 to +300F range and if the chemicals involved can tolerate immersion in oils. With the weigh/strength characteristics and requirement that it not see water I can see this material being used in indoor (or sealed inside a gearbox somewhere) applications to reduce rotating mass.
AdmiralAsshat 9y ago
No wonder it's so popular as a binding agent for fake cheese.

146 points by jtraffic 9y ago

I'm delighted by how in-depth and detailed this is! I'd be interested in seeing the numbers for how much the final product weighs in comparison to Kevlar/Carbon Fibre... I'd also love to know if this research went anywhere since 2012

Scaevolus 9y ago
> CNCs... bulk density is low at 1.6 g/cc, but they exhibit incredible strength. An elastic modulus of nearly 150 GPa, and a tensile strength of nearly 10 GPa. This is the same as carbon fiber (1.57-1.7g/cc), and slightly higher than kevlar (1.44g/cc).

eutectic 9y ago

Carbon fiber works so well in composites because it is possible to create long, continuous fibers which can be woven into cloth for directional reinforcement. Maybe it is possible to use the strengths of each by adding CNCs to carbon composites.

chroem- 9y ago
Nitpick: fabric lay-ups are rarely used in industry because the weave exerts shear stresses on the fibers, making them weaker under load. Aerospace composites are all unidirectional. But fiber blends are very common. It's typical to mix CF, glass, and aramids to get the price and properties you want, though I don't think it would make much sense to mix chopped and continuous fibers.
- eutectic 9y ago
  Thanks for the correction, my bad. The technical term for the kind of thing I was thinking of is 'multiscale composites', and there already seems to be a lot written about carbon fiber/carbon nanotube mixed composites which would presumably be similar to carbon fiber/nano-cellulose composites. I obviously can't claim to be an expert, but there at least seems to be some precedent.

slackingoff2017 9y ago

Im not too surprised. The strength of plywood is well known in aero and racing circles. For parts like stringers plywood is used instead of fiberglass when higher stiffness is required. Plywood is similar strength/weight as fiberglass which isn't too far off from carbon fiber. The issue with all popular composite materials like fiberglass, carbon fiber, and plywood is that their strength is highly directional. It takes a lot of skill and testing to make sure your part is strong enough in all directions force will be applied. There's some omnidirectional "mat" type materials you can get easily for fiberglass but you exchange the directional strength of weave for a non-directional but overall inferior strength of randomly oriented strands.

omarforgotpwd 9y ago

Stronger at 10% of the price of carbon fiber. So why haven't we seen more people using this material in the last five years?

kbart 9y ago
Yes, I often wonder too where all these new inventions are gone after the initial enthusiasm and media attention fades. Probably every weeks you can find articles about 'breakthrough' in material science, battery, memory technologies etc. Yet when I try to Google them after few years, >90% has no follow ups nor these technologies reach market. I guess this is like startups -- good idea is not enough, execution and financing is what matters.
- omarforgotpwd 9y ago
  Yes. I feel like cancer has been cured every few weeks since Reddit first went live.
  - malka 9y ago
    Cancer is easy to kill. The hard part is not killing the human around the cancer as well.
    - KGIII 9y ago
      Add to this that there are many, many different types of cancer. There won't ever be a cure for cancer. We may find a cure for a cancer, but there are many types of cancer. A good friend is an oncologist. He kinda hates it when people talk about a cure for cancer. I guess it just doesn't work that way.
- noir_lord 9y ago
  To an extent, also a lot of these processes are incremental rather than revolutionary (despite the press releases) and do eventually make it through to production after an upgrade cycle or two. Hell a carbon fiber (partially) plane flew around the world non-stop in 1986 but it wasn't until 2012 that carbon fiber road bikes got good enough/cheap enough for me to buy one. I think people underestimate incremental improvements, 4% (arbitrarily) a year, year on year adds up eventually. Look at the improvements to Li-Ion battery technology as a good example. Recently I've been doing research on a programming problem that has come up at the new job, I pulled the related research and the canonical first representation of the problem on a computer was formulated in 1966 and the issues it addressed in the paper are identical to the way the processes are run at new employer, almost word for word. 51 years that research has existed and they are still doing things the way they did then.

pacaro 9y ago

Strip planking is popular amongst canoe builders. A 1/4inch thick core of cedar has fiberglass on either side. The glass provides tensile strength and the wood provides both compression strength and a useful offset between the fiber layers. I can lift the bare hull of an 18 foot long sailing canoe with one hand. The downside is in maintenance/repairs, and the critical requirement to keep through holes absolutely watertight. If water gets into the core it's a total PITA Also, strips of cedar that are 3/4" by 1/4" by 18' are really weird to handle.

Yaggo 9y ago
Also bigger (sail)boats have been home-built using strip blanking technique. The downside is weight penalty over balsa/foam core.
doikor 9y ago
Snowboards are kinda similar with usually having a wooden core for tensile strength with plastic bottom for gliding, plastic top for protecting the wood and metal edges to cut into snow/ice. Get a hole all the way to the wood (usually by hitting some rocks on the rather soft/porous plastic bottom) without keeping it dry and patching quickly will destroy the board very fast. Also modern boards have multiple different kinds of wood in fancy layers/placements inside to give the correct amount of "pop" in the correct spots for the wanted ride. Some of the more expensive/extreme boards have started to replace parts of the wood core with carbon fiber in the cases where weight is very important and a very stiff board is preferred (mainly backcountry/split boards)
jdietrich 9y ago
End-grain balsa wood is a surprisingly common core material in high-performance composite structures.
coredog64 9y ago
GM used balsa wrapped in carbon fiber for a previous version of the Z06 'Vette for similar reasons [0]. It's light, it's strong, and it's cheap. [0] http://www.autonews.com/article/20050912/SUB/509120708/balsa-wood-helps-put-the-zip-in-the-z06 http://www.autonews.com/article/20050912/SUB/509120708/balsa...

mixedbit 9y ago

Also take a look how strong and abuse-resistant cross laminated timber is: https://alexschreyer.net/engineering/much-abuse-can-cross-laminated-timber-clt-take/ https://alexschreyer.net/engineering/much-abuse-can-cross-la...

imaginenore 9y ago

I think it since got surpassed by UHMWPE, which has a tensile strength of ~20GPa. They make cheap body armor out of it. https://en.wikipedia.org/wiki/Ultra-high-molecular-weight_polyethylene https://en.wikipedia.org/wiki/Ultra-high-molecular-weight_po...

Gravityloss 9y ago
One problem with UHMWPE is it's slippery, so hard to glue to a rigid composite. Also, don't count out the path dependence of even very competitive industries. They know carbon fiber, so that's what they use, and they then make small increments from their known territory.
owenversteeg 9y ago
UHMWPE is a beautiful thing. As easy to cut as wood, you can bend and mold it at temperatures over 300F, and it's strong enough that a 0.9" thick plate can stop bullets. Specifically, by "bullets", I mean a NIJ-0101.06 level III threat. That could be up to 24 shots from an AK-47, FN FAL, or AR-15.

dsfyu404ed 9y ago

Hmmmm. I wonder how its material properties change in the -40 to +300F range and if the chemicals involved can tolerate immersion in oils. With the weigh/strength characteristics and requirement that it not see water I can see this material being used in indoor (or sealed inside a gearbox somewhere) applications to reduce rotating mass.

AdmiralAsshat 9y ago

No wonder it's so popular as a binding agent for fake cheese.