Sunday, May 29, 2016

Sand Castle Holds Up A Car! - Mechanically Stabilized Earth

I wouldn't want to build my house on a sand castle foundation, admittedly. In fact, I posted something about the dangers of that before

Reinforced sand, on the other hand, looks like it might be something a little different. Just adding in some fabric - or screening - between layers of packed sand makes for a far stronger product. It's almost like it's a composite.

(It is a composite, by the way, gaining new-found strength from the combination of strengths of the materials comprising the composite.)

Sunday, May 22, 2016

Mitch Anthamatten Explains a Shape-Memory Cycle Involving Strain Induced Crystallization

Wait, a shape memory polymer?

There's a bunch of good connections here to what we teach in our material science course.

  • The polymer switches from being largely amorphous to largely crystalline on addition of strain.
  • The addition of heat energy then causes the polymer to shift back to amorphism.
  • The phase change happens around body temperature, like the stints we talk about.
  • We have a solid-state phase change.
  • At 0:55, the professor says the energy is 'enough to melt those crystals.' I'm way less knowledgeable and more a neophyte about all this than he is, but that sounds wrong to me. I don't think of a crystalline solid changing to an amorphous solid as 'melting.'
All that in less than two minutes time...

That's better than watching the Kentucky Derby.

Condensation Polymerisation | Chemistry for All | The Fuse School

Great animation for condensation polymerization here, folks.

The standard color codings are used - black=carbon, red=oxygen, blue=nitrogen, white=hydrogen. The animations are simplified to focus on the functional groups. And they show the by-products clearly and cleanly.

I do wish they would have suggested that the by-product could be something other than water (like in our preferred nylon demonstration from summer camp), but I'll happily take a great visual of the by-product first.

And we get applications of a couple of condensation polymers.

Overall, a winning, quick video.

Saltwater Brewery “Edible Six Pack Rings”

Saltwater Brewery "Edible Six Pack Rings" from We Believers on Vimeo.

I watched most of this video, though I will warn you that there are some pretty horrific images of ocean animals being girdled by traditional, plastic six-pack rings. Those, I might've watched out of the corner of my eye while glancing at the NBA playoffs.

The idea of using industrial byproducts - here barley and wheat leftovers - for useful products makes sense environmentally as well as economically. Less waste into the landfill, lower cost of waste handling, fewer environmental hazards for marine life?

Sign me up, folks.

Sunday, May 1, 2016

Color: a spectrum of possibilities for your ring

I desperately want a titanium ring, and I'm really curious to get one that's anodized in some gorgeous color(s).

I just can't figure out which ring I want. There are tons of choices.

The titanium, then, can be oxidized to produce gorgeous colors. The process of creating an oxide coating on a metal via application of electrical current is called anodizing.

One of these years I'll get around to trying to do some anodizing myself, but I'm going to have to get a steady supply of titanium before I can use it as a class lab. Titanium's kinda expensive and really, really hard to cut - something that I need to consider, too.

When I do get around to it, though, I'll check back on these instruction pages.

As a warning, there isn't really any color to the oxide layer. It's caused by light wave interference. Check the science out if you really want to know.

If you were thinking of a gift for your favorite material science blogger, I'll need to measure my ring size first, but this one's the current choice.