Critical Crayons What Does a Materials Scientist Do

Critical Crayons

What Does a Materials Scientist Do? Everything is made of something. For our products to function well, we need to use the best materials.

What’s your cell phone made of? • Glass • Plastic • Copper, Aluminum • Very small amounts of critical metals

Where do metals come from? All metals are mined from the earth

Does the earth continuously make metal? • Metals were imparted to the earth when it was formed billions of years ago. . . • What we have is all we’ve got • Certain metals are abundant (iron, aluminum) • Others are scarce (niobium, vanadium, indium)

Critical Metals • Metals that are very important, but are scarce • Used in cell phones! Also solar panels, TV’s, computers, magnets, lasers, medical technology, fuel cells, motors, fiber optic cables. . • Their supply is not secure • Technology cannot progress without these metals

What do we do?

Recycling • When we throw stuff away, everything gets mixed and we get a useless mess • The mess only becomes useful when we separate the parts • Glass, aluminum, plastic, copper • We separate the parts using differences in properties • Recycling is separation

Difficulties • Once mixed, the parts like to stay mixed due to entropy • You will need to do work for separation • When one material is very dilute, it will be harder to get it out • It’s often impossible to get all the impurities out • The parts are never as good as they were before – downcycling

Design Challenge • Imagine in the future crayon wax is a ‘critical metal’ and is very scarce • Crayons have been thrown away for years and are present in landfills • We have to turn to our trash if we ever want crayons again • I go to the landfill and shred up what I find to recycle them

Design Challenge • Devise a multi-step process (but no hands!) to sort through waste and yield enough shavings to make 1 crayon (about 6 g) • Melt the wax in a foil cup on the hot plate and pour 2 new cool with yield ice water • crayons Iterate to–get a purer - the to speed the curing purer the recycled mixture, the stronger the crayon! • Molten wax may ONLY be used at the hot plate tables – not at your group’s table

Design Challenge • Conduct a 3 -point bend test on the crayons. • Use table-to-table boundary at same height and at least a 1” gap • Use 1 -turn of string over a bucket handle and add water until crayon breaks. Record volume of water for breakage. (Make the string long enough so that the “crash” does not get water everywhere!) • Report results out to larger group!

Design Challenge Hints: • Crayon won’t float in regular water, but will once a certain amount of salt has been added. • You will likely need all sizes of crayon (both flakes and bits) from your mixture to yield enough for 2 crayons (~6 g out of ~12 g in your waste mix) • Pour your measuring water slowly to get an accurate breaking point

Materials • A container with lots of shredded waste including enough crayon shavings to make 2 crayons • Separation Tools (choose 3 max per group at a time) • • • Magnets (ferromagnetic materials? ) Sieves, colanders and slotted spoons (particle size/shape) Water (float? ) Balloons (static? ) Coffee filters

Questions • Does the addition of impurities always make a material weaker? • How did the lab illustrate ‘downcycling’? • If you wanted to scale up your process, could you do it efficiently? (Automate? ) • Is it better if we can sort bigger pieces before shredding? – designing for disassembly

Image Sources • http: //e-wasteregulation. blogspot. com • http: //www. cnet. com/news/iphone-6 -will-adopt-curved-display-claims-latestrumor/ • http: //www. biostockspro. com/7 -advantages-of-precious-metals-investment/ • http: //www. pc 3 mag. com/少年你太年輕了：apple-突然變慢是個陰謀！ • http: //www. colourlovers. com/web/blog/2008/04/22/all-120 -crayon-names-colorcodes-and-fun-facts • http: //www. thomasnet. com/articles/electrical-power-generation/NIB-magnetapplication • http: //www. photo-dictionary. com/phrase/2821/sieve. html • http: //www. seprotech. com/company-profile/