Today's KNOWLEDGE Share : New techniques clarify recycled plastic, increasing their value

Today's KNOWLEDGE Share

Mellow the yellow : New techniques clarify recycled plastic, increasing their value

A team of University of Wisconsin-Madison engineers has developed a new solvent-based technique for removing stubborn pigments from recycled multilayer plastic packaging. The advance makes recycled plastic more commercially appealing—increasing its market value and moving the industry closer to “closing the loop” for recycled plastic.

The research, published in the March 14, 2025, issue of Science Advances, was led by postdoctoral fellow Tianwei Yan and PhD student Charles Granger, who work in the lab of George Huber, a professor of chemical and biological engineering at UW-Madison.

Plastic pollution is a major environmental and sustainability issue, with millions of tons of plastic produced from petroleum products entering landfills, waterways and oceans each year. Despite decades of research, plastic recycling is still very limited; only about 9% of plastic is recycled globally, with much of it downcycled into less valuable products.

New technologies, however, may help close the loop on recycling, producing high-quality recycled plastic just as good as fresh, “virgin” plastic. Since 2020, researchers at UW-Madison have made great strides in chemical recycling through a pioneering process called solvent-targeted recovery and precipitation (STRAPTM).

STRAP is particularly good at recycling colored multilayer, flexible plastics, which include food packaging like bags, pouches, wrappers and films. These types of plastic often incorporate multiple specialized layers that prevent moisture, seal out oxygen and improve strength. STRAP uses a series of solvent washes to dissolve each layer of plastic, which is then recovered and processed into near-virgin plastic. These films also contain a variety of color bodies that are put in by brand owners to market their products.

In recent years, Huber’s team has refined STRAP. However, the researchers found that the final plastic films they produced often had a yellowish hue to them. That tinge makes the recycled end product much less appealing to manufacturers, reducing the value of the plastic by more than half.

“To consumers, yellow might be a sign of age or degradation,” says Granger. “In these recycled plastics, that’s not the case. It’s just from pigments. But either way, it looks gross.”

That’s why Granger and Yan set out to discover why recycled plastic film produced via STRAP looked yellow, and what they could do about it. They first tested dozens of pigments, adding them individually to polyethylene, the plastic most used in flexible packaging, running them through the STRAP process to see if they caused the yellowing. Soon, they narrowed the culprit down to Yellow 12, a common organic pigment used to print packaging.

Most other pigments break down during STRAP processing and are removed by solvents or filtering. But elements of Yellow 12 survive the process, remaining in the solvents used to dissolve the plastic. In the final processing step, in which the recycled plastic is dried, the researchers found that evaporating solvents left behind the pigment in the plastic, causing a yellow sheen in the final product.

Armed with that knowledge, the team was able to come up with a method to get rid of the color. “The yellow pigment has a higher solubility in STRAP solvents than other types of plastic pigments due to its chemical structure,” says Huber. “So the first thing was to pick a solvent that has a lower solubility of that pigment. Then there are a couple of extra steps that really make that plastic come out crystal clear.”

Working with Chemical and Biological Engineering Associate Professor Reid van Lehn and his students, who have developed a sophisticated database of solvent-polymer solubility called SolventNet, the team found a solvent that minimized the solubility of the yellow pigment. Then, Yan and Granger added activated charcoal to the process to bind the color bodies and remove even more of the yellow before using a press to squeeze as much solvent as possible out of the recycled plastic. All of this resulted in clear plastic with no yellow detectable to the naked eye.

While making recycled plastic clearer might seem like it’s just fixing a cosmetic problem, Huber says it is a critical step in making plastics recycling economically feasible. “One of the biggest challenges with plastics recycling is contaminants, and one of the biggest issues is dealing with color,” he says. “Clear plastic is worth two to 10 times more than colored plastic. That’s because every company wants to have their special color or logo on their packaging. With clear plastic you can add that color. But color also makes it harder to recycle.”

Yan and Granger say they would like to use their methodology to remove other contaminants found in recycled plastics, including other problematic pigments, dirt and debris, and chemical contaminants like bromine and PFAS.

George Huber is the Richard L. Antoine Professor in chemical and biological engineering at UW-Madison. Reid Van Lehn is the Hunt-Hougen Associate Professor in chemical and biological engineering. This work was partially supported by a gift from Ross Annable.

Other UW-Madison authors include Kevin L. Sánchez-Rivera, Panzheng Zhou, and Styliani Avraamidou. Other authors include Steven Grey and Kevin Nelson of Amcor in Neenah, Wisconsin, and Fei Long and Ezra Bar-Ziv of Michigan Technological University in Houghton, Michigan.

This work was funded by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Bioenergy Technologies Office under Award Number DE-EE0009285 to G.W.H and DE-EE0010294.

Top image caption: Tianwei Yan (left) and Charles Granger have developed a method for removing yellow pigments from recycled plastic film, like the one Yan holds, greatly increasing their marketability.

source:University of Wisconsin-Madison

Today's KNOWLEDGE Share :Compression on steel will lead to changes in the mold cavity

Today's KNOWLEDGE Share

Based on consulting requests, I realize that a lot of people forget that huge forces are developed during the molding process, as a result of pressure levels exceeding often 1000 bar/100MPa.

That amounts to 1 metric Ton of equivalent force applied to each square cm of tool surface.

That is why clamp tonnage numbers are what they are of course.

But, no matter how good your steel or tool design is, metal will bend significantly when subjected to huge unbalanced forces.

And, even more surprisingly, for balanced forces, the cavity will expand by "compressing" the steel by quite a few microns !

You can run a quick FEA to check that, by applying 1000-2000 bar on a piece of steel.

Of course tubular shaped parts will readily see significant core shift problems as soon as flow is slightly unbalanced, since a differential of a few Tons-force can quickly appear if flow is not perfectly balanced. The problem here is, of course, that the more the core deflects, the more the unbalance grows. So it is a bad case of positive feedback leading to catastrophic results (unexpected weldlines in the thinned side towards which the core has been bent/pushed).

Don't underestimate the importance of these effects in molding.

While coupling Flow Analysis with stress analysis on the steel structure can supposedly model this, it is very challenging to describe the complex tool assembly. And such coupled approaches can be very challenging numerically. So, while core-shifting predictions are now quite standard, full tool deflections are usually neglected in simulations. And the clear tendency of steel compressibility to lead to overpack is never accounted for.

source:Vito Leo

#polymers #injectionmolding

Orion S.A. signs supply agreement for tire pyrolysis oil with Contec S.A.

Orion S.A, a global specialty chemicals company, announced today it has signed a long-term supply agreement with Contec S.A., which will provide Orion tire pyrolysis oil to produce circular carbon black for tire and rubber goods customers.

The agreement with Warsaw, Poland-based Contec further enables Orion to diversify its sources of tire pyrolysis oil, commonly known as TPO.

“With the ConPyro® TPO supplied by Contec, Orion will be able to make large-scale volumes of circular grades of carbon black that will supply growing demand from the world’s leading tire and rubber goods producers,” Orion CEO Corning Painter said. “This is yet another way that Orion is accelerating the transition to a circular economy.”

TPO-based manufacturing is the only circular technology that is moving into industrial production to produce high-quality active carbon black. The process takes discarded end-of-life tires and exposes them to high temperatures to produce a feedstock Orion can convert into virgin carbon black.

Orion is the only company that has made circular carbon black from 100% TPO as a feedstock. The company has also demonstrated that its circular products can replace virgin carbon black in many applications.

“At Contec, sustainability is one of our core values. This partnership is a clear confirmation to the market that the industry is continuously evolving, and the circular economy is no longer just a vision for the future - thanks to collaboration with Orion, it is becoming a tangible reality today,” said Krzysztof Wróblewski, CEO of Contec S.A.

source: Orion S.A.

Today's KNOWLEDGE Share : The Stache Lab discovers startling mechanism to promote depolymerization

The Stache Lab discovers startling mechanism to promote depolymerization

Turns out that the black plastic lid atop your coffee cup has a superpower. And the Stache Lab, which uncovered it, is exploiting that property to recycle at least two major types of plastic.

Their startling mechanism for promoting depolymerization relies on an additive that many plastics already contain: a pigment called carbon black that gives plastic its black color. Through a process called photothermal conversion, intense light is focused on plastic containing the pigment to jumpstart the degradation.

So far, researchers have shown that carbon black can depolymerize polystyrene and polyvinyl chloride (PVC), two of the least recycled plastics in the planet’s waste stream. The lab’s most recent pair of papers showcases the potential.

First, in ACS Central Science at the end of last year, there was a proof-of concept for the depolymerization of polystyrene using a common Fresnel lens to focus photonic energy. Then, earlier this month, the lab published their method to upcycle PVC in the Journal of the American Chemical Society (JACS).

In both cases, carbon black serves as the trigger of the breakdown, a quality Assistant Professor of Chemistry Erin Stache discovered recently and that even industrial partners she has spoken with were unaware of. The lab’s method has since been tried out on such post-consumer waste as PVC pipes, black construction pipes, trash bags, credit cards, even those ubiquitous yellow rubber duckies.

“The surprising thing, especially with the black polystyrene depolymerization, is that they’ve been manufacturing these materials for decades and it seems no one recognized that this was possible,” said Stache. “Under ambient sunlight, the energy is not sufficient to break down these polymers. But if you increase the light intensity enough, then you start seeing the depolymerization.

“Plastics are facing a lot of criticism right now, and we are starting to learn the consequences of it building up in the environment. We can certainly change our habits to help alleviate the amount of plastic we use. But we’re not going to get rid of our dependence on plastic. So can we think of it instead as a resource? Can we turn it into other commodity chemicals that we have to make anyway? We have found that we can.

A good yield

In their ACS paper, researchers showed that unmodified post-consumer black polystyrene samples were successfully depolymerized to a styrene monomer without adding catalysts or solvent. Simple, focused radiation on the plastic provided monomer yields of up to 80% in just five minutes.

“I think this marriage between photothermal and depolymerization strategies is really groundbreaking. Black colored plastic accounts for ~15% of all plastics, and we found that 10-weight percent of black polystyrene in plastic mixture is enough to give good yield,” said Hanning Jiang, co-first author on the paper.

Carbon black absorbs all the way from UV to IR, and that’s great because what we want is for this agent to take as much light as possible and transform light into heat.”

Jiang noted that the lab’s mechanistic studies on the process are continuing.Co-first author and graduate student Sewon Oh emphasized: “Carbon black is an additive here. In industry, a lot of products like tires and inks have carbon black. We take advantage of what is already incorporated in plastics to depolymerize back to monomer.

“In this paper,” he added, “we primarily focused on depolymerizing polystyrene. However, we envision and also expect that our method can be extended to other types of polymers.”

In short order, researchers adapted their method to PVC and received strong results. They extended the process by adding polystyrene into the PVC-carbon black mixture—“We basically spatula it in,” said Stache—and were able to upcycle the material and then derivatize it into a couple of common consumer products: a fragrance precursor and a heart disease drug.

Part of the challenge of recycling PVC is that the material has carbon-chlorine bonds that generate hydrochloric acid (HCl) whether it’s being recycled mechanically or chemically. Hydrochloric acid is very corrosive and highly toxic.

“We used carbon black to initiate the thermal degradation of PVC, generate HCl with an acceptor for HCl that reacts to make an adduct,” Stache explained. “So you can basically access a new commodity chemical from the process. We take advantage of what is normally a bad process – the HCl – and add it to another commodity chemical and then we get a new product.

“You can use plastic waste as a feed stock for commodity chemical production, whether it be to make polystyrene or this adduct which is very versatile and you can make several different products from it.”

source:Princeton University

Today's KNOWLEDGE Share : The Natural Gas vehicle market in India

Today's KNOWLEDGE Share

The Natural Gas vehicle market in India

The natural gas vehicle segment reached 30 million vehicles in 2024 and it seems to be moving ahead of witnessing many CNG variants in the global market in the next 3 years. Asia Pacific is leading with 21 million Natural Gas Vehicles(NGV) followed by Latin America with 6 million NGV’s and Europe with 2 million and North America NGV fill the spots respectively.

The Natural Gas Vehicle market has witnessed continuous improvements in various parts designs, processes and is also imposed by stringent regulations throughout all geographical regions in the global market. The natural gas industry will grow along with the Hydrogen market in the forthcoming years and CNG fuel stations will be available in all Indian cities with its matured technology in all segments.

As far as the Indian NGV market is concerned, the market is driving with opening up new CNG stations in various parts of the country. The infrastructure for the transportation of CNG is in the fast phase with a lot of projects in India in recent years. Maruti Suzuki has a stronghold in the NGV market with its variants like Celerio,Dzire, Brezza, Baleno,Tata Nexon/Punch,Suzuki Eeco, Ertiga,Grand Vitara,Toyota's Urban Cruiser Taisor, Hyundai Grand I10 Nios,Aura etc. Maruti Suzuki has witnessed 15% CAGR for the past 5 consecutive years in the Indian market.

Muthruamalingam Krishnan

#cng #NGV #composites #type4cylinders

Avient Expands Flame Retardant Solutions Portfolio for Wire and Cable with ECCOH™ XL 8054

Avient Corporation, an innovator of materials solutions, announces an expansion of its ECCOH™ XL Cross-Linkable Flame Retardant Solutions with the launch of ECCOH XL 8054. Developed for low smoke and fume wire and cable insulation, this solution can meet stringent electrical and electronic fire safety regulations in Europe.

One of the key advantages of ECCOH XL 8054 is its excellent processability due to its ability to meet the Commission Electrotechnique Internationale (CEI) EN 50363-0:2015 standards, namely G17 and G18, and adhere to the Construction Products Regulation (CPR) for enhanced fire safety. Compared to traditional elastomeric compounds, it can be processed using standard single-screw extrusion equipment, eliminating the need for a continuous vulcanization (CV) line. This streamlined manufacturing process can not only reduce production costs but also increase line speed, offering a cost-effective and efficient solution for manufacturers.

ECCOH XL 8054 also excels in mechanical properties, with high elongation at break and outstanding performance in the Hot Set Test at 250°C. With these attributes, it can be used in a variety of applications, including shipbuilding, railways, building and construction, and solar cables.

"We are dedicated to providing a smooth integration of ECCOH XL 8054 for our customers,” said Hermann Fuechter, Senior Marketing & Product Manager EMEA, Specialty Engineered Materials at Avient. “Our advanced development and technical services teams offer a collaborative strategy to optimize equipment and processes, enabling a seamless transition and enhanced performance." 

source : Avient 

Today's KNOWLEDGE Share : Carbon Fiber Commercial Use

Today's KNOWLEDGE Share

Carbon Fiber Commercial Use:

Commercial adoption of carbon fiber-reinforced composites began to accelerate in the late 1970s and early 1980s with applications in military and commercial aircraft as well as recreational products such as golf club shafts and tennis rackets. The cost/benefit trade-off has been a challenge for carbon fibers since their introduction. In the early days, aircraft designers were eager to gain the weight-savings benefits of carbon fiber composites but were working with composites as “black aluminum,” and the relative higher cost of carbon fiber versus aluminum limited its adoption in commercial aerospace.

Military aircraft and weapon systems as well as recreational products led the growth in demand for carbon fiber while commercial aerospace continued its understanding of the true benefits composites could deliver. With the innovative use of carbon fiber composites on the Boeing 787 and Airbus A350, carbon fiber composites have become an enabling technology for the most advanced commercial aircraft.

source:Tom Haulik (Hexcel)