Spider silk is hundreds of time stronger than the best synthetic fibers?

[astro]

I know spider silk is good stuff, but I thought some stuff like Kevlar might come close. Is spider silk really hundreds of times stronger than existing materials, or is the author just being sloppy? Being a chemistry professor it seems he should know what he’s talking about. Is this spider silk claim BS or not?

The material world By James M. Pethokoukis

In the new book Why Things Break: Understanding the World by the Way It Comes Apart (Harmony Books, $24), Mark Eberhart, a chemistry professor at the Colorado School of Mines, explores the fascinating question of what holds things together, what breaks them apart, and why we should care. His interest in the topic started early. When he was growing up in the 1960s, Eberhart learned that splitting an atom leads to an awfully big boom. That prompted him to fret that when he cut into a stick of butter, he would inadvertently cause an atomic explosion. In a recent E-chat, the professor talked about the sinking of the Titanic, the fragility of bike locks, and the feasibility of superhero costumes.

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Eberhart: The great mysteries of materials science remain the full elucidation of the relationships between structure of materials and properties. From observations of natural materials, we know that ultimate properties are far beyond anything we have obtained. Spider silk is hundreds of time stronger than the best synthetic fibers. Though we know this to be true, the reasons remain hidden. Once these relationships are exposed, it will be possible to design materials with phenomenal properties.

[Tuckerfan]

Somewhere, I’ve read a report that debunks the whole spider silk business. IIRC, said that while a steel wire the size of spider silk would break before the silk would, if you scaled the spider silk up to the size of ordinary steel cable (for example), it would retain the same breaking point that it has now, thus making it orders of magnatude weaker than steel.

[Xema]

*Originally posted by Tuckerfan *
if you scaled the spider silk up to the size of ordinary steel cable (for example), it would retain the same breaking point that it has now, thus making it orders of magnatude weaker than steel.

Well, you don’t use thin, strong fibers by “scaling them up” - you make strands consisting of multiple fibers, and cables consisting of multiple strands.

[DarrenS]

Related thread. (pun unavoidable)

[Derleth]

Tuckerfan: How would you scale it up anyway? Somehow make a single strand the same size as a steel I-beam? Why would you do that instead of spinning those strands into threads, and thence into cabling?

[GusNSpot]

I seem to recall that it is not size / size but pound / pound, the strongest NATURAL substance… or some such.

Also, sometimes scale is a deal breaker because of the problems with scaling every variable.

For instance, full scale aircraft / model aircraft.

YMMV

[DreadCthulhu]

http://en.wikipedia.org/wiki/Spider_silk

says that spider silk is roughly 5 times stronger than steel for a given mass, with a tensile strength of ~1.3 GPa. A decent steel has a tensile strength of 1.65 GPa, but of course is considerably denser than spider silk. In comparison, http://en2.wikipedia.org/wiki/Kevlar Kevlar is also listed at 5 times stronger than steel for a a given weight.

And of course, the strength spider silk pales in comparison to carbon nanotubes, which come in at around 200 GPa for tensile strength. Though we can’t make very long carbon nanotubes. Yet.