The Ingenious Design Behind the Recyclable Two-Liter Plastic Soda Bottle

Bill Hammack, the Engineer Guy. explained the ingenious design behind the recyclable two-liter lightweight plastic soda bottle, which is made out of polyethylene terephthalate (PET), noting how its formation shaped tube balances the pressure of carbonated beverages without exploding.

Bill explains how the two-liter plastic soda bottle begins as a plastic tube, called a preform, which is heated and inflated with air in a bottle-shaped mold. He explains how the stretching of the preform creates a crystalline regions in the bottle's plastic (polyethylene terephthalate) that create a bottle with great strength, low permeability to carbon dioxide, but which is also lightweight-some 35 times lighter than a glass bottle of the same size.

Hammack specifically spoke about the unique shape of the bottle's bottom, the distance between the threads on the neck of the bottle, its tamper-proof rings, and the needed to be done for non-carbonated drinks.

Bill explains key features of the bottles design, including: why the bottle looks like it does, why the neck has gaps in its threads, and how the tamper-proof ring works. He also discusses hot-fill bottles" used for sports drinks and plastic juice bottles, noting the panels molded into the bottles to accommodate temperature changes.

He also talked about the recycling of PET bottles, what percent ends up in landfills, and how these bottles are upcycled into other products.

Approximately 500 billion PET bottles are manufactured yearly; about 75% end up in landfills or are incinerated. Yet, PET is recyclable and can be converted into fibers for fabrics used in sports jerseys and car upholstery.

Hammack previously talked about the ingenious design of the aluminum can.

The Remarkably Clever Engineering Behind the Aluminum Can