A new, fossil-free bioplastic is emerging and, according to experiments conducted at Lund University, Sweden, it is more durable than both regular plastic and other bioplastics, and is potentially better suited for recycling.
Chemical Engineering doctoral student Ping Wang
Chemical Engineering doctoral student Ping Wang
Almost all plastic is made from crude oil, and plastic production currently accounts for 4-6% of global oil consumption. The development of renewable bioplastics is progressing, but relatively few are actually being used.
A strong candidate among bioplastics is polyethylene furanoate (PEF), which contains the furan hydrocarbon and can be extracted from maize, wood and certain types of grain, rather than from oil. The success of PEF has inspired researchers to consider other renewable materials that could potentially be used for plastic production.
The main market for PEF is packaging. Experiments have shown that PEF is superior to standard polyethylene terephthalate (PET) in protecting against oxygen, carbon dioxide and water, which gives products enclosed in plastic greater durability.
Passing with solid results
Lund University Chemical Engineering doctoral student Ping Wang has produced a plastic based on indole with all of the aforementioned environmental benefits – the only downside is that indole is present in human faeces and smells accordingly.
Associate Professor Baozhong Zhang, who is supervising the research team, said: “These are preliminary results, but we have seen that polyester plastic has better mechanical properties, which makes it more sustainable. This can lead to better recycling in the future. At present, PET bottles can only be recycled once, then they must be used for something else such as textiles.”indole is only produced on a small scale and used mainly in perfumes and drugs, but nobody is ruling out the possibility of bioengineering methods to produce indole from sugar through fermentation.
Zhang’s team is thought to be the only one researching indole polyesters, and the results continue to be promising. For example, a regular PET bottle’s glass-liquid transition temperature – i.e. when the material softens and deforms – is 70 degrees, and the most successful PEF experiments withstand about 86 degrees. However, one of Ping Wang’s indole plastics is stable up to 99 degrees.
“We obtained good results,” Wang said, “but are not satisfied. Now we are trying to find methods for making higher quality indole polymers that can be used in more ways, not just for plastic bottles.”