I never played with these as a kid, boy did I miss out, they’re amazing! Originaly I had planned to use these thermoplastic sheets for an additional holder on my microscope. Either I am a talentless hack, very possible, or Shrinky-Dinks are not the product for precision instrument construction, also a possibility. This popular toy/craft is made of Polystyrene, a widely used thermoplastic polymer, often seen in styrofoam™, yogurt containers, drinking cups, and computer casings, it is plastic #6.
(Structure complements of The Macrogalleria)
Why does it work though? We’ve discussed Glass Transition temperature previously, so here is a little more detail. There is a specific property that allows for the magical shrinking: biaxial orientation of the polymer. This causes even shrinkage in the x and y direction, through the length and width of the sheet. Also, this study from UC Irvine and 3M creates improved Shrinky-Dinks! Rather than Polystyrene they used Polyolefins. These layered cross-linked thin films have lower levels of distortion than Polystyrene, and have greater “shrinkablity” a reproducable 95% reduction in dimension, while Shrinky-Dinks achieve around 60%.
(image from “Better Shrinkage than Shinky-Dinks”)
In the above images a single layer of ink has been printed onto the polyolefin film, then shrunk with heat to 5% of previous size. Holy micro-scale roughness! SEM’s are sexy, no doubt. So take a trip to the craft store and go get your toaster oven out of the basement; now you too can study microfluidics at home! (Just remember to thank me in your journal article.)
More evidence for me being a talentless hack: check out the microfluidics study using Shrinky-Dinks. Boo me.
Congratulations to our Winner! Kelly will receive a Materials Girl Coffee Mug.
Along with a post about the innovative non-woven product she submitted, and a personal interview. (Coming soon.)