Marine-biodegradable plastic decomposes by 92% in just one year

Nylon-based products such as clothing and fishing nets are notoriously slow to degrade, especially in marine environments, contributing significantly to global ocean pollution. 

A Korean research team has now developed an innovative material that can be produced using existing manufacturing infrastructure and effectively addresses this problem.

They have developed a high-performance polyester-amide (PEA) polymer that decomposes by over 92 percent in one year under real marine conditions, while maintaining strength and flexibility comparable to nylon. 

This material is not only scalable and
recyclable, but also applicable to a wide range of uses such as textiles, fishing nets, and food packaging.

Unlike conventional biodegradable plastics that suffer from low durability and heat resistance, the PEA polymer combines ester (for biodegradability) and amide (for toughness) linkages in an optimal ratio. This design offers both high degradability and mechanical durability.

Traditionally, the synthesis of polymers with both ester and amide groups required toxic organic solvents. 

However, the team developed a new two-step melt polymerisation process that eliminates the
need for solvents and enables industrial-scale production (up to 4kg) in a 10l reactor. 

Importantly, this method is compatible with existing polyester manufacturing facilities with only minor modifications, enhancing its industrial scalability.

Marine biodegradability tests conducted off the coast of Pohang showed that the new PEA achieved up to 92.1 percent degradation within one year, significantly outperforming existing biodegradable plastics such as PLA (0.1 percent), PBS (35.9 percent), and PBAT (21.1 percent). Even more complete biodegradation occurs under composting conditions, where microbial populations are
higher.

The tensile strength of the PEA reached up to 110 MPa, surpassing that of nylon 6 and PET. In practical experiments, a single PEA fibre strand was able to lift a 10kg object without breaking. When woven into fabrics, it also withstood ironing at 150°C, confirming its high thermal resistance.

In addition to performance, sustainability was a key focus of the research. The PEA was synthesised using long-chain dicarboxylic acids derived from castor oil (a non-edible crop), and caprolactam derivatives recovered from
recycled nylon 6 waste. 

This upcycling approach reduced CO2 emissions to just one-third that of conventional nylon 6, lowering emissions from 8-11 kg CO2eq/kg to 2.3 to 2.6kg CO2eq/kg.

The team is currently evaluating the material for commercialisation, with expectations for industrial adoption within two years.

Dr Sungbae Park stated, “The key achievement is that this material overcomes the limitations of conventional biodegradable plastics while offering nylon-level performance.” 

“This technology marks a pivotal step toward the commercialisation of biodegradable engineering plastics and will significantly contribute to solving the global marine plastic pollution crisis,” KRICT President Young-Kuk Lee added.