Making ULTRA-BRIGHT GLOWING GOO

Barnaby Dixon is an impressive puppeteer that I first heard about probably ten years ago. If you haven't checked out some of his work, do yourself a favor and spend a few minutes there first.

In this instructional video, Barnaby explains how he uses a thermoplastic polymer - a polymer that becomes flexible when it's heated above some temperature but is rigid below that same temperature. It's a great example of the polymer's glass transition phase change. Because polymers are mixtures, they don't necessarily have definite melting temperatures as pure substances like elements or compounds do. Instead they have ranges of temperatures during which they aren't quite solid or liquid but are flexible and moldable - think of hot glass being shapeable but not liquid.

I have some of this at school. It used to be available from Educational Innovations. That's where I bought it, but they sadly don't carry it anymore. Of course, just about anything is available at Amazon if you search for pcl moldeable plastic.

The Controversy Behind Nike’s Vaporfly Running Shoe, Explained | WSJ

Anything more than totally naked sporting competition is essentially a materials question.

Wooden tennis racquets gave way (briefly) to aluminum and then to composite racquets.

Wooden baseball bats became aluminum then composites.

Similar progressions took place for pole vaulting and nearly every other sport.

In running, however, the materials question mostly shows up in the running shoes, and Nike's Vaporfly is the current materials leader in that realm.

More videos after the jump...

How To Make Skulls Using Old Milk Jugs And A Heat Gun

You can get a way cheaper heat gun from Harbor Freight if you need one.

This project is just a different application of our in-class demonstration of inflating a milk jug using that same heat gun, but here once the HDPE jug is softened, it gets molded around a somewhat-heat-resistant skull and cooled to hold that new shape

Sound like a fun idea - and very appropriate for the spooky season that we find ourselves in.

chemed 2013 diy chemistry

Alfredo Mateus is apparently pretty cool - or at least has some pretty cool ideas.

Through the Prezi above first, largely without words...

• The bottle tops - hacksawed off just below the screw top collar - become flexible in hot water and can be turned into keychains. The distorted bottle tops then can show the thermoplasticity when returned to hot water.
• The inflation of the preforms is a bit trickier, and the method hinted at in the Prezi is far tougher to pull off. Check out my other post about a way to successfully inflate the preforms.
• Carving a can with chemistry is a variation on the aluminum can demo using a solution of either sodium hydroxide or copper (II) sulfate to react away the aluminum can. Here Mateus has used this to produce some nice lights.
• The hydrophobic toys need a whole lot more explanation. The carbon compounds in soot are apparently hydrophobic and can make for a very cool 'maze' by letting the droplets roll around rather freely.
• The PET molecules, though, are pretty spectacular, and they're the ones I desperately want to recreate for my classroom. I just need to figure out how to throw around a few pop rivets. And sadly, they're the only ones that are NOT covered in the related pdf of instructions.

Any chance anybody can find better instructions for the 2L bottle molecules?

♡DIY: School Pride Plastic Cuffs {Back To School}

Our students love the shrinky dinks. The success rate is pretty high (not 100% because of the curling and touching that the video maker above mentions), and it's a simple project. There are lots of fun creations that can be made (even entire books about the projects).

I've never tried to twist or bend the shrinky dink when it first comes out of the toaster oven, admittedly. Usually I'm trying to flatten it down as much as possible.

DIY Fashion ♥ Toothbrush Bracelets

How cute are those?

It took me a while to get the different between thermoplastic and thermoset polymers down. Then I realized it's nothing but word origins.

• thermoplastic...thermo = heat...plastic = change shape...so thermoplastics are things that, when heated, change shape...
• thermoset...thermo = heat...set = not changing shape...so thermosets are things that, when heated, don't change shape...

Clearly, whatever cheap, pretty, translucent polymer these toothbrushes are made of are thermoplastic.

Now I just need to find the absolute cheapest way to buy a few hundred of these for my classes.

Thanks, by the way, to Jen Donaldson for sending in today's project video.

Blowing step by step

I think it's a longshot that I ever get my hands on a blow-molding machine like those we see up there. The prices for even used machines are a little out of my school budget. I can certainly afford the preforms, though.

I've tried warming up the preforms in boiling water, but that appears not to be hot enough to allow the plastic to be inflated.

Luckily, Ed Escudero, one of our ASM master teachers and a fellow Cincinnatian, recently came up with a way that we can model the injection molding of the preforms in the classroom.

Ed uses soda bottle caps with tire stems glued through them (available from Flinn Scientific individually or in bulk) and a bicycle pump to generate pressure inside the bottle. He wraps the bottle in a flameless ration heater (FRH) (available from military surplus stores or from ZestoTherm here in Cincinnati - developed at the University of Cincinnati, by the way - or simply given out to ASM camp attendees every summer) with a corner cut off to allow water to be poured in but hopefully not to pour back out. The FRH is held horizontal long enough to allow water to thoroughly soak the magnesium powder before being secured by rubber bands around the preform.

Once the preform is hot enough - something that takes a couple of minutes, the bicycle pump is pumped to increase the internal pressure and inflate the 'bottle'. The procedure doesn't produce anything really resembling a traditional 2L bottle, but it works pretty well as a proof of concept for the students.

Check out Ed's set-up below...

What is Plastimake?

I will readily admit to having a weak spot for things that change and can change back. I buy pretty much every color-changing, plastic cup that I find and have them all lined up in the window of my classroom. So the sight of this thermoplastic changing from rigid and opaque to pliable and translucent and back again is just too much for me.

I'm sending my money to the Land Down Under to get me some Plastimake.

Does anybody know the conversion from US dollars into whatever the Australians use as money? Barbie shrimp, I think?

Update: turns out that these things are available from Educational Innovations, too. They've been in the goodie boxes that we give away each of the past few years. Sign up for a workshop, and you might win this stuff.

Shrink! Shrank! Shrunk! Make Stylish Shrink Plastic Jewelry

One of the great attractions of materials science as a course and subject is the number of non-science connections that our students can make. There are hooks for the sport kid (composite baseball bats and hockey sticks), the builder kid (galvanizing deck hangers), the destroyer kid (dropping cement 'hockey pucks'), the art kid (glass making), and most definitely the craft kid (shrinky dinks and lots more).

Sometimes, though, I feel that I'm far out of my depth in that last area. Sure, I can explain to most student - at least to a depth of understanding with which they are comfortable - the concepts of a thermoplastic returning to its original structure/size/shape when heat is applied. I can even demonstrate it a few different ways (2L bottles, shrinky dinks).

What I can't do, though, is to show them anything really neat that I've made with a shrinky dink. I was a pretty linear, geometric kid. When the teachers gave me a blank piece of paper, crayons, and the instructions to 'make something', I invariably went in for a random bunch of geometric figures colored in all the crayon colors - sort of a stained glass mosaic with no planning at all. I do sometimes like how these look on the shrinky dinks because the colors get so dark and rich, but it's not exactly something that's going to hook the artsy-crafty kid into the neatness of shrinky dinks. That's why I was happy to stumble upon this book when looking at the 741s (comic books) at my local library.

This book is filled with ways to turn shrinky dinks into earrings, necklaces, even rings. There are techniques in ink jet printing, plastic sanding, and shaping that are far more crafty than I could ever have thought on my own. It's going to make a nice addition to my classroom library and just might open up a whole new section.

You can check out some of the interior pages and download pdfs of some of the designs from the book at the publisher's site or on the blog of one of the contributors. The book is available from Amazon. Here are a few others in the shrink plastic realm.

And in the interest of going multimedia, here's a video review of the book...