PET (Polyethylene Terephthalate) is the undisputed heavyweight champion of the bottling world. If you are holding a soda, water, or cooking oil bottle, you are likely holding PET. It is a high-performance polyester that offers a rare combination of glass-like transparency and shatter-proof durability.
What makes PET truly special is its “barrier” property. It is incredibly good at keeping oxygen out and $CO_2$ in, which is why your soda stays fizzy and your food stays fresh.
| Property | Typical Value | Unit | Why it Matters |
| Light Transmission | >90% | % | Optical clarity identical to glass |
| Tensile Strength | 50 – 80 | MPa | Handles high internal pressure (carbonation) |
| Glass Transition | 70 – 80 | °C | Maintains shape at room/fridge temps |
| Molding Shrinkage | 0.2 – 0.5 | % | Low shrinkage for precise cap threads |
| Recyclability | #1 (Highest) | – | Most widely recycled plastic globally |
While PET can be injection molded into parts like electronics housings, its true home is Stretch Blow Molding. The process starts with an injection-molded “preform” (which looks like a test tube with threads). This preform is then reheated and literally stretched while air is blown into it. This stretching aligns the molecules, making the bottle incredibly strong despite being paper-thin.
Processing Insight: PET is “hydroscopic” and extremely sensitive to moisture. If the resin isn’t bone-dry before molding, it undergoes “hydrolysis,” which turns the clear plastic yellow and makes it brittle. At the factory, we use high-heat desiccant dryers to ensure every flake of PET is perfectly prepped for a flawless, crystal-clear finish.
Environmental Edge: PET is the most recycled plastic in the world (look for the #1 symbol). Today, we can use rPET (recycled PET) to help brands meet sustainability goals without sacrificing the premium look and feel of their packaging.
Are you designing a new beverage bottle or a high-clarity cosmetic jar? I can help you optimize the “preform” design to ensure your container is lightweight yet strong enough for the shelf.
Contact us to evaluate manufacturability, tolerances, and cost for your specific application.
We will contact you within 24 hrs, please pay attention to the email with the suffix “@dewintech.com”. Your privacy is safe, we won’t use your email for any other purposes. Download NDA
