Onward and Upwards in Shrinkwrap Innovation
Next time you tuck into a freshly roasted turkey, give thanks to high-energy physics. The Butterball thawing in your fridge the week before Thanksgiving wouldn’t be possible without it.
Heat-shrinkable film, or shrink wrap, is made from polyethylene plastic, which consists of long polymers strung together. The carbon atoms in the plastic are saturated, having bonded with two hydrogen atoms. Heated to the boiling point of water, the plastic melts.
But when they are zapped with a beam of electrons from a particle accelerator, the polymer chains are desaturated.
The hydrogen atoms get kicked out, and carbon atoms form bonds with other carbon atoms. Carbon chains are really strong, and can withstand extreme heat without breaking down.
Once it cools down, the new, stronger plastic retains its expanded shape, and will accommodate anything from a turkey to a new CD to a Sea Knight Navy helicopter. Once heat is applied, it shrinks again, creating an air-tight, durable wrapping.