Is it a Microwave or a Shrink Ray?

I’ll be honest: This one blew me away the first time I saw it! What is going on here? It all has to do with polymers, which are basically long chains of repeated molecules, which you can learn more about here.

Just to re-iterate: This is not dangerous to you, but it is dangerous to the microwave!

Microwave Magic

These polymers have some interesting properties that we need to understand, and then this will become much simpler. As we have seen before, temperature can be an important part of chemistry. That is also important here! Let’s start by talking about something a more familiar polymer: protein!

We all have lots of protein in our bodies which perform many different functions. These functions are determined by their shapes, which are in turn determined by the specific molecules that make them up. However, if proteins are exposed to high temperatures or acidic conditions, they lose their shape and just uncoil into a big mess. This is called denaturation, is actually a good thing for us. Human stomachs are highly acidic, and when you eat food with protein in it, this allows the protein to be broken down so that it can be used.

image002

A similar thing happens with the polymers in the bag*. When these huge chains are hot, they become very flexible. Left to their own devices, they will tangle up and clump into a polymer mess. Alternatively, in this flexible state they can be easily manipulated a different shape. When they are cooled down, they maintain this shape.

This gives us all the tools we need to understand the behavior of these bags in the microwave. These bags contain a polymer skeleton surrounded with foil and paint. When the bags are manufactured, they are heated up and stretched out before being cooled off. The result is that the long polymers in the bag are locked into long straight lines forming the structure of the bag.

In the microwave, they get HOT. Without anything to hold them in position, they collapse into their natural shape: a big clump. As the bag’s polymer skeleton collapses, the bag itself shrinks dramatically. The results are astounding!

Written By: Scott Alton

Microwave Magic Display

*Note: If you are reading carefully, it may seem like this is the exact opposite of the protein. This is because proteins are heated up to the point where they collapse to the appropriate shape at body temperature, whereas for these polymers that temperature is much higher. If these polymers were to get even hotter, they would exhibit similar denaturation behavior. Similarly, cooling the protein well below body temperature would lock them into their current shape. The same thing is happening, it is just on different temperature scales.

WELCOME TO OUR ASTROCAMP BLOG

We would like to thank you for visiting our blog. AstroCamp is a hands-on physical science program with an emphasis on astronomy and space exploration. Our classes and activities are designed to inspire students toward future success in their academic and personal pursuits. This blog is intended to provide you with up-to-date news and information about our camp programs, as well as current science and astronomical happenings. This blog has been created by our staff who have at least a Bachelors Degree in Physics or Astronomy, however it is not uncommon for them to have a Masters Degree or PhD. We encourage you to also follow us on Facebook, Instagram, Google+, Twitter, and Vine to see even more of our interesting science, space and astronomy information. Feel free to leave comments, questions, or share our blog with others. Please visit www.astrocampschool.org for additional information. Happy Reading!

Categories

Archives

Tags