Researchers at Aarhus University have found a better method to recycle polyurethane foam from items like mattresses. This is great news for the budding industry that aims to chemically recover the original components of the material—making their products cheaper and better.

This is where a research team from Aarhus University comes in with a smart idea. They base their method on what the companies in question already use, namely breaking down PUR foam with acid (acidolysis).

But the companies do not separate the broken-down PUR into polyol and isocyanate. This results in a mixture that cannot be directly recycled but requires their customers to use new recipes.

The AU researchers are not only able to break down PUR and separate the two main components—they can do it in one go. They heat flexible PUR foam to 220°C in a reactor with a bit of succinic acid (see fact box). Afterwards, they use a filter that catches one material and lets the other pass through.

It is the polyols that pass through, and they do so in a quality comparable to virgin polyol, making it possible to use them in new production of polyurethane. The solid part of the product mixture that is filtered out is transformed into a so-called diamine in a simple hydrolysis process, which is used in the production of isocyanates and thus PUR.

In this way, the researchers are able to recover up to 82 weight percent of the original material from flexible PUR foam—used in mattresses—as two separate fractions of diamines and polyols. The researchers have recently published their findings in the journal Green Chemistry.

Source: Phys.org