Researchers turned superglue into a recyclable, low-cost, oil-free plastic alternative

The Research Brief is a short summary of interesting academic work.

The big idea

Our team superglue as starting material develop a cheap, recyclable and easy to produce transparent plastic called polyethyl cyanoacrylate, which has properties similar to those of plastics used for single-use products such as cutlery, cups and packaging. Unlike most traditional plastics, this new plastic can be easily converted into its starting materials, even when combined with unwashed municipal plastic waste.

To turn superglue into plastic, we first had to address the problem that makes superglue so “super”: it sticks to just about anything. If superglue is used to stick something together, it is react with moisture in the air or on the surface of what is glued together. This reaction forms molecular chains of repeating superglue units called polymers. The polymers that form when something is glued together are short and don’t bond well, making the glue brittle and easy to break.

While short polymers are good for glue, long polymers have more bonding sites and result in stronger materials. Our team realized that if we could make longer versions of the same type of polymers made from superglue, maybe we could produce a strong plastic.

The way we make these plastics is relatively simple compared to how other types of plastics are made – we just mixed acetone and a little bit of an environmentally friendly catalyst into commercial superglue. Once this mixture dries, it produces a tough, glassy plastic made up of long polymer chains.

In our lab, we can easily produce up to 10 pounds of this material in a matter of days and turn it into usable products. By pouring the mixture into molds before it dries, we can make plastic items in many shapes, such as bowls and cutlery. We also found that heating the plastic after it dried allowed us not only to shape the material into other products, but also to strengthen the plastic.

Why it matters

When manufacturers need to produce a rigid plastic object, such as cutlery, disposable razors, CD cases or plastic models, they often choose polystyrene. Polystyrene is one of the most most produced and least recycled types of plastic.

Because our super glue plastic has properties similar to polystyrene – it is light, durable, inexpensive and easy to mass-produce – it could replace polystyrene in many products. But there are two clear advantages of our superglue-based material: it is not made from oil and is easy to recycle.

When our material is heated to 410 degrees Fahrenheit (210 C), the long molecular chains made of repeating superglue units break apart into their small, individual superglue molecules. At this point the superglue molecules turn into a vapor that is easy to separate from a mixed waste stream of other plastic, paper, food scraps, aluminum and other waste often found in recycling waste streams. Once you’ve captured the superglue vapor, you can cool it down and turn it back into our new plastic with an efficiency of over 90%.

What’s next?

Since superglue is cheap and already produced on an industrial scale, we envision our method of making superglue plastics could easily be scaled up. Finally, the machines used to make super glue can also be used to recycle the super glue plastics and can be easily adapted to existing industrial processes.

Find one substitute for polystyrene is a big step towards sustainable plastics, but polystyrene is just one of them thousands of plastics used today. Our team is now designing super glue-based plastics with properties similar to other types of standard plastics, while being easy to produce and recycle.