Biodegradable Fibers As Strong As Steel Made From Wood Cellulose 82
Zothecula writes "A team of researchers working at Stockholm's KTH Royal Institute of Technology claim to have developed a way to make cellulose fibers stronger than steel on a strength-to-weight basis. In what is touted as a world first, the team from the institute's Wallenberg Wood Science Center claim that the new fiber could be used as a biodegradable replacement for many filament materials made today from imperishable substances such as fiberglass, plastic, and metal. And all this from a substance that requires only water, wood cellulose, and common table salt to create it. The full academic paper is available from Nature Communications."
Re:Biodegradable? (Score:2, Informative)
When was the last time someone made a bridge out of fibreglass?
http://www.scsolutions.com/fib... [scsolutions.com]
http://www.ettechtonics.com/ [ettechtonics.com]
Re:Stronger than steel (Score:5, Informative)
Most materials have advantages and disadvantages. Wood is an excellent material for many things and steel is a bad material for many things.
Unlike what many people believe carbon fiber (or other synthetic fibers like kevlar/aramid, dyneema, zylon) while stronger than steel are a bad material for many constructions as they often have a higher flexibility, higher sensitivity to things like UV radiation, abrasion etc. that have to be compensated for. This results in many products being worse than e.g. a steel construction but still being sold to the people that think it must be superior. Designing and using composites properly often is a very expensive process.
But again wood is an excellent material - it is flexible, strong (with natural fiber reinforcement), easy to form, renewable and reasonable priced. Even the above mentioned sensitivity of wet environments is easy to circumvent. There are a lot of natural wood which are naturally protected against water and other woods can easily be impregnated.
Re:Stronger than steel made from wood! (Score:4, Informative)
"Stronger than steel" or "stronger than x", by either absolute measure or ratio of strength to weight, doesn't mean shit. There are a million factors.
1) What kind of steel? Tensile yield strength (MPa) is all over the place:
ASTM A36 structural steel: 250
API 5L X65: 448
AISI 4130, water quenched 855C (1570F), 480C (900F) temper: 951
Aermet 340: 2160
2800 maraging steel: 2617
Micro-Melt 10 Tough Treated Tool Steel (AISI A11): 5171
Usually when someone says "stronger than steel" they mean stronger than crappy A36 or the like. If you're going to build a fabric-covered fuselage, you use the 4130. If you've got a building or bridge to erect, you use something closer to A36. For a cutting bit, tool steel. It is brittle as hell but harder than any steel you can use structurally; takes and keeps a wicket edge when ground.
2) Do you care about anything besides tensile yield strength? Just say yes. It matters. Such properties as the following:
Elastic modules
Compressive strength
Hardness
Toughness
Elongation
Endurance limit / fatigue properties
Resistance to corrosion and other degradation
Many of these properties play off against each other. Want hard or tough? Pick one. They are inversely related. Want something that is mechanically workable? It better have decent elongation, which limits achievable strength. On the other hand, piano wire doesn't need to be very workable at all. It has fantastic strength.
3) What safety factor will you require? Depends on a number of factors, and one of these factors is material chosen. Balsa needs a much higher safety factor than steel or aluminum alloy. Its mechanical properties are much more variable, and it tends to have imperfections.
These are just some of the factors that make the simplified table you reference horse shit. Bottom line, if you are building a bridge or airplane to highly optimized requirements, suitable steel or aluminum alloy is going to give you a lot less weight for the same safety-factored strength as balsa - completely aside from temperature/humidity limits, flammability, and liability to rot.