Plastic waste is, we should by now be all well-aware, one of the biggest man-made ecological problems facing the planet and, by default, us – the source of the issue. One of the most common kinds of plastic is polyethylene terephthalate, or PET. Derived from oil (plastics can also be made from cellulose, coal, natural gas and salt), PET is what most single-use plastic bottles are made from.
It’s so popular because of its lightweight strength, water resistance and shatterproof qualities. PET’s drawback is that while it is recyclable, it can be repurposed just once or twice and doing so is energy intensive and economically unattractive. Which is an environmental problem with 26 million tonnes of PET produced every year.
Recycled PET currently mainly ends up as cheap fibres used in synthetic materials for clothing or carpets. But the questionable economics of ‘downcycling’ PET in this way means that only around 15% of the plastic is actually repurposed. These rest goes into landfills, with a decomposition period of centuries, or is burnt for energy in modern waste-fuelled power plants.
However, new bio-technology detailed in science journal Joule, has resulted in a much more efficient way to potentially recycle PET in the future. The study, carried out by scientists from the U.S. Department of Energy, found a way to ‘upcycle’ PET into valuable composite plastics strong enough to be used for things such as turbine blades. The re-sale value of this kind of reinforced plastic has the potential to completely upend the economic rationale and business incentive to recycle more PET.
The science behind the new ‘upcycling’ technology discovered relies on first breaking used PET down into its basic chemical blocks, called ‘monomers’. These monomers are then blended with renewable materials such as waste biomass and thickeners added. The resulting material is a ultra-strong kind of ‘fibreglass’ plastic.
Not only is the end product of this ‘upcycling’ technology many times more valuable than the cheap fibres produced by most current recycling of PET, producing it is also less energy intensive. The energy required to convert PET into fibre-reinforced plastic is around 57% less than current processes and also produces 40% lower emissions.
Further research will be carried out to determine if the process can be refined to allow for PET to be ‘upcycled’ on an industrial scale. The huge volumes of PET manufactured and the comparatively limited market for composite plastics means this new technology will not completely negate the one-use plastic problem. However, it will make an impact and there is hope that other ‘upcycling’ techniques might mean popular plastics such as PET with low current repurposing value will be convertible into higher value secondary products.