Shellfish may give us ‘vanishing plastic’

Prototype biodegradable plastics are possibly just months away, spelling good news for the worsening headache of plastic packaging, which accounts for up to 25% of municipal landfill.

Researchers at Swinburne University have been investigating the use of bioplastics - ingredients from renewable sources - and the properties of biopolymers that determine their ‘compostability’.

These projects have brought together PhD students Suchetana Chattopadhyay and Cameron Way, who are examining the properties of plastics biopolymers as part of their PhD studies, under the supervision of Associate Professor Enzo Palombo.

Chattopadhyay is using a respirometer - a composting machine - to test novel, chitin-based polymers.

Chitin is the world’s second most abundant organic compound. It is mostly derived from shellfish waste, but also includes the exoskeletons of crustaceans, insects and spiders.

In collaboration with an industry partner, Chattopadhyay has provided the first direct evidence of true biodegradability in novel, chitin-based polymers.

She has demonstrated that fungi - which plays a key role in degrading the most abundant biopolymers found in nature - grows on the chitin-based biopolymer, proving that the material is biodegradable.

Chattopadhyay’s objective to reduce the growing amount of inorganic landfill has the added aim of finding a biopolymer suitable for food packaging that is derived from raw materials that don’t compete with food crops such as starch from food crops.

In a parallel project, Cameron Way has been examining the composition and mechanical and biodegradation relationships of polylactic acid-lignocellulose (PLA) biocomposites.

“It’s about finding a technical balancing act between a biopolymer’s competing mechanical and biodegradability properties,” Way said. “In other words, ensuring the bioplastic is strong enough to be used in plastic packaging and then compost when discarded.”

Way’s research has led him to use a corn starch-based biopolymer that is reinforced with lignocellulose fibres.

“An ideal balance of the competing mechanical and biodegradable properties in the biocomposite would involve improvements in both areas through finding a key bacterium or enzyme that kicks off biodegradability,” he said.

Way said biodegradable plastics are essential to reducing the mounting dilemma of plastics waste: “From an environmental perspective, both the PLA and wood fibres are 100% sustainable, so they reduce the need to use petrochemical crude oils and conventional plastics, and potentially eliminate long-term waste issues with landfill.

“With very strong uptake into the market and demand outstripping supply in the US, the best use for polylactic plastics is food and beverage packaging because it can be simply thrown into the compost,” he said.