polystyrene waste

A Look at a Canadian Company’s Process to Recycle Polystyrene

GreenMantra currently converts waste polyethylene and polypropylene plastics, such as film, bottle caps and food containers, into specialty synthetic waxes.

GreenMantra Technologies, a technology company that produces polymers from waste plastics, has been chosen to receive a $2.2 million from Sustainable Development Technology Canada (SDTC) to be used toward construction of a demonstration plant that will convert waste polystyrene into modified styrenic polymers for use in inks, foam insulation and other applications.

Construction will begin on the demonstration plant in 2018 at GreenMantra's existing manufacturing complex in Brantford, Ontario, Canada, with commissioning slated for first half of 2019. This timeline can be expedited if required by the market.

Polystyrene plastic in foam and solid form is commonly used in consumer products, food and product packaging and many other applications. It is one of the world's fastest growing solid wastes, yet has one of the lowest recycling rates of all plastics with an estimated 95 percent either disposed of in landfills or incinerated, according to the company.

GreenMantra currently converts waste polyethylene and polypropylene plastics, such as film, bottle caps and food containers, into specialty synthetic waxes. These waxes are used in various applications in the coatings, plastics processing, adhesives, roofing and paving industries.

In 2014, SDTC provided GreenMantra with $2 million to help fund construction of the plant that produces these waxes.

The company’s newest technology is an offshoot of its polyolefin process and targets waste polystyrene.

Waste360 recently sat down with Domenic Di Mondo, senior director of research and business development for GreenMantra Technologies, to discuss the company latest developments in converting waste polystyrene into modified styrenic polymers.

Waste360: Please explain how GreenMantra obtained the grant from Sustainable Development Technology Canada (SDTC)?

Domenic Di Mondo: SDTC is aware of GreenMantra’s role in clean technology and provided support in the past to help us scale up our polyolefin waste conversion process. We have successfully demonstrated our polystyrene-based technology in the laboratory, and now are ready for scale up.

The grant in support of our polystyrene demonstration plant is the result of our ongoing relationship with SDTC and their strong support to drive growth of clean technology companies in the region.

Waste360: What is the technology behind converting waste polystyrene into modified styrenic polymers and how does it work?

Domenic Di Mondo: It is a thermo-catalytic depolymerization process, similar to the process we use for polyolefin plastic waste, but tailored to styrenic plastics.  

GreenMantra has developed an extension to its initial technology that converts waste polyolefin (#2, 4, and 5) plastic to synthetic waxes. The new process utilizes very different feedstock (#6, waste PS) and process parameters while utilizing similar proprietary catalysts to produce a new portfolio of styrenic polymer products. 

The process for chemical up-cycling of the waste polystyrene involves a thermo-catalytic depolymerization that targets the final product in high yields with minimal secondary products formed. This new process and technology was developed and validated by the scientists at GreenMantra on a lab scale over the last 2 years and is now ready for scale up. 

Waste360: What is the outcome of this process?

Domenic Di Mondo: The end product is a range of modified styrenic polymers that can provide unique physical properties and performance benefits tailored to various end product formulations including inks and insulation.

Waste360: How will the plant obtain the waste polystyrene and, once complete, how much waste polystyrene will be recycled, on average?

Domenic Di Mondo: GreenMantra has ongoing relationships with various leading plastics recyclers and will be working to source polystyrene regionally.

The plant will have an operating capacity that will enable it to utilize up to 1,000 metric tons annually, on an initial basis. Future commercial scale modular facilities would be closer to 10,000 metric ton annual capacity.

Waste360: How is this conversion process beneficial for the waste stream?

Domenic Di Mondo: Polystyrene is one of the world’s fastest growing solid wastes, yet has one of the lowest recycling rates of all plastics. Our technology holds the promise of converting and upcycling this waste into valuable styrenic polymer products with uses in various long-life end products such as ink and insulation. Our technology opens the pathway to products and markets not previously accessible to the waste polystyrene feedstocks.

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