Scientists Unveil Cost-Effective Solution for Mixed Plastic Recycling

Jakarta – Scientists from Nanyang Technological University (NTU) Singapore have developed a new method to recycle mixed plastic packaging without the use of hazardous chemical solvents, offering a potential breakthrough in tackling one of the most challenging forms of plastic waste.

The technology, which targets multilayer plastic packaging that is typically difficult to recycle, could significantly reduce the amount of waste sent to landfills or incinerators.

A research team from NTU’s School of Materials Science and Engineering and the Nanyang Environment and Water Research Institute (NEWRI) introduced a method known as depolymerisation-induced polymer separation (DIPS). The approach works by selectively breaking down specific types of plastic within mixed packaging, while preserving recyclable materials, making them easier to recover and reuse.

Multilayer plastic packaging is widely used in food products such as snacks and instant noodles due to its durability and ability to maintain product quality. However, the combination of different plastics bonded together makes it notoriously difficult to separate and recycle.

Hu Xiao, director of programs at NEWRI and the lead researcher, said the use of mixed plastic packaging continues to grow, while efficient and safe recycling technologies remain limited.

“We are seeing an increasing use of mixed plastic packaging in everyday food products, yet recycling them efficiently and safely remains a major challenge. Our team aims to address this by developing a practical and scalable method to separate these materials without hazardous solvents,” Hu said in a statement on Wednesday.

Another researcher, Lian Yen Nan, noted that one of the recycling industry’s biggest challenges is the lack of viable technologies for processing mixed plastics. The study, therefore, focused on developing a solution that could be realistically adopted by industry players.

The DIPS method utilizes reactive extrusion, a process that uses an extruder machine typically employed to melt and shape plastics. In this case, the machine functions as a chemical reactor.

During the process, polyethylene terephthalate (PET) reacts with glycerol, a relatively inexpensive and widely available chemical. This reaction breaks PET down into smaller molecules, altering its physical and chemical properties.

As a result, PET naturally separates from polypropylene (PP), another commonly used plastic in packaging. The separation occurs due to differences in polarity and viscosity between the materials during processing.

The entire process operates under normal pressure and does not require chemical solvents, making DIPS safer and potentially more cost-effective than conventional chemical recycling methods.

In laboratory tests, the recovered polypropylene retained up to 90 percent of its original tensile strength compared to virgin material. When applied to industrial waste samples, the resulting material quality was also reported to surpass that of conventional mechanical recycling.

Meanwhile, the processed PET is not immediately reused as packaging material but still holds economic value. It can be utilized as a raw material for higher-value products, including epoxy substitutes for wind turbine blades, or further processed into monomers for new polymers.

The research team believes the DIPS method can be adapted for various combinations of mixed plastics and scaled up for industrial use using existing extrusion machinery already common in manufacturing facilities.

Kathirvel Periasamy, the study’s lead author and a doctoral student at NTU, said the technology is designed to bridge the gap between laboratory research and industrial application.

“Our process aims to bridge the gap between laboratory research and real-world industrial use. By simplifying separation and eliminating solvents, we hope to make plastic recycling more economically viable and environmentally sustainable,” he said.

The researchers estimate that if mixed plastic waste can be efficiently recycled on a large scale, it could unlock a global economic potential exceeding US$250 billion, or around Rp4,000 trillion annually.

As a next step, the team plans to collaborate with industry partners to test the technology at a larger production scale.

Indonesianpost.com | Republika