New Research Could Revolutionize Plastic Recycling

As author Rachel Nuwer noted in her New York Times article, “Polymers: Why Some Recyclable Items Just Don’t Mix,” “not all plastics are equal,” and many plastics cannot be recycled together. However, thanks to researchers at the University of Minnesota (UMN) and Cornell’s Tisch University, this might change.

On February 24, 2017, UMN and Tisch researchers published an article in Science, explaining how they have created a new additive that should make it possible to combine two of the most popular types of plastic: Polyethylene (PE) and Polypropylene (PP). According to an article on the subject, by Helen Tunnicliffe, “PE and [PP] account for two thirds of global plastic use.” However, as is the case with many different plastic types, these materials are too dissimilar on a molecular level to be recycled together. Not only do different plastics have different melting points, but once these materials are in their liquid form, like oil and water, they don’t mix well. To attempt manufacturing anything from such a mixture would be like trying to bake a cake without mixing the ingredients together. You will get lumps where only one ingredient exists, and ultimately your entire cake could fall apart.

About the Research

The idea behind the UMS and Tisch team’s research is to find a method where PE and PP will mix together well. Their idea was to create some form of additive that could be combined with PE and PP to act as a binding agent between the molecules of both. They discovered that by making a new type of block copolymer, or a new type of molecular structure made of small parts of both PE and PP, they could use these small sections of each to attract larger amounts of PE and PP to bind to them.  According to one of the team’s lead researchers, Geoffrey Coates, “People have done things like this before, but they’ll typically put 10 percent of a soft material, so you don’t get the nice plastic properties.” In contrast, Coates says his team’s research only requires “as low as 1% of [their] additive, and you get a plastic alloy that really has super-great properties.”

What this Could Mean for Plastic Recycling

If this research proves successful, it could eventually change the way companies recycle plastic (or at least PE and PP).

  • Less Sorting – Instead of needing to separate PE and PP items for recycling, these materials could be commingled. Also, for those difficult to recycle item that are made from multiple layers of different types of plastic, this could mean easier recycling opportunities. This simplified collection requirement could in turn increase the amount of plastic companies recover for recycling.
  • Higher Strength – The Chemical Engineer notes Coates’ belief that the new hybrid PE-PP polymer is actually stronger than each type of plastic when used separately. In years to come, this could encourage manufacturers to switch from traditional plastics to using the new PE-PP hybrid for making things like jugs and bottles.
  • Higher Value – If the PE-PP hybrid proves a successful manufacturing ingredient, this may result in a high demand for collection of the two together, which could eventually make commingled PE and PP more valuable.
  • More Environmentally Friendly – The combined PE-PP plastic made from this method is also lighter and uses less oil. This not only means less material is required to make the item, but less fossil fuels are also necessary for transporting it.

Our team at Northstar is excited to see what comes of the UMN and Tisch team’s research, and we are hopeful this discovery can be effectively applied to improving plastic recycling. Be sure to check other articles in our Trash Talk blog for more recycling industry news and best practices.