Tech Taps into Recyclable Plastics

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Our vision is that waste plastics will become a renewable resource on a global scale.

In five years, polymer-based components in a range of high-tech components from cord coverings to packaging could be made from recycled plastic. By working with plastics recycling and manufacturing companies, high-tech designers and manufacturers can make trash into something useful again. And the plastic components can be continuously recyclable.

This transition will be powered by innovations like VolCat — a catalytic chemical process recently discovered by my team at IBM Research – Almaden — that digests certain plastics (called polyesters) into a substance which can be fed directly back into plastic manufacturing machines in order to make new products.

VolCat works with a polymer called PET, one of the most commonly manufactured plastic polymers (~10% of total plastics produced per year) and a key ingredient in product packaging and components. Historically, most PET has not been recycled, a primary reason that 8 million metric tons of PET plastics are estimated to go into the ocean each year.

Advancements in plastics recycling like VolCat—short for volatile catalyst—can change that. In the VolCat process, plastic bottles, containers, and PET-based fabrics are collected, ground up, and combined with ethylene glycol and a chemical catalyst in a reactor. The reactor is a lot like a pressure cooker: it’s pressurized and heated (to above 200 degrees Celsius).  The ground-up plastic is digested and cleaned, and contaminants (e.g., food residue, glue, dirt, dyes, and pigments) are separated from material that is useable for new PET.

The catalyst is recovered by distillation using the heat of the reaction. The solution is filtered, purified, and then cooled. The useable matter (called a monomer) takes the form of a white powder, which can be fed directly into a polyester reactor to make brand new plastics. The recovered liquid, along with the catalyst, is then reintroduced into the depolymerization reactor in an energy-efficient, closed-loop cycle.

Other materials such as metals and other polymers can be recycled further down the line.

IBM Research-Almaden has been exploring catalytic chemistry on polymers for several decades. Back in the 1980s, we developed a process called chemical amplification. This catalytic imaging mechanism uses deep UV light and polymeric photoresists to print semiconductor circuits.

This technology had a profound impact on the semiconductor industry’s ability to continually increase transistor density of integrated circuits. Nearly all microelectronics fabrication today is built on chemically amplified photoresists and has been since the 1990s.

Chemically amplified photoresists use customized polymers that undergo a cataclysmic solubility change when light reacts with a formulated compound to produce a powerful catalyst. A catalytic chain reaction occurs that leads to a high-fidelity pattern.

Our exploration of catalysts interacting with polymers led to the realization that the most important commodity plastic, PET, could be rapidly degraded back to monomer by a class of organic catalysts. And our large computer simulations led to enhanced understanding of the role of the catalyst in this depolymerization. This insight led directly to our use of volatile, recyclable catalysts–VolCat was born.

We imagine the VolCat system being used at recycling and polyester manufacturing plants worldwide and creating a circular economy for waste plastics. Currently, polyester reactors are fed ingredients derived from petroleum. With VolCat, new PET can be made from waste PET, turning plastics from pollutants into a renewable resource.

In the future, we anticipate more plastic recycling advancements like VolCat will be discovered and adopted around the globe to combat plastic waste. Electronics suppliers, manufacturers, and consumer electronics companies will be able to cite the use of recycled plastic in their products. Buyers will look for the use of recycled and recyclable materials. And the economics of recycling plastic will drive both demand for and supply of recycled and recyclable polymer-based components and product materials throughout the electronics industry.

— Bob Allen is a distinguished researcher and department head for materials innovation at IBM Research-Almaden.




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