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Ireland: Characterizing Mechanisms of Metallic 3D Printing Powder Recycling

In order to cut down on material waste, and save money, laboratories will often reuse leftover metal AM powder. A trio of researchers from the I-Form Advanced Manufacturing Research Centre in Ireland published a paper, “X-ray Tomography, AFM and Nanoindentation Measurements for Recyclability Analysis of 316L Powders in 3D Printing Process,” focusing on better understanding and characterizing the mechanisms of metallic powder recycling, and evaluating ” the extent of porosity in the powder particles,” in order to optimize how many times recycled powder can actually be reused in the powder bed fusion process.

Many “risk-tolerant applications,” like in the aviation and biomedical industries, will not use recycled powder, because any part abnormalities that can be traced back to the material can be unsafe and expensive. Parts 3D printed out of recycled powder need to have mechanical properties, like hardness and effective modulus, that are comparable to those of fresh powder parts.

“In order to reuse the recycled powders in the secondary manufacturing cycles, a thorough characterization is essential to monitor the surface quality and microstructure variation of the powders affected by the laser heat within the 3D printer. Most powders are at risk of surface oxidation, clustering and porosity formation during the AM process and it’s environment [1,2],” they explained. “Our latest analysis confirms the oxidation and the population of porous particles increase in recycled powders as the major risky changes in stainless steel 316L powder [3,4].”

A common practice before reusing recycled powders is sieving, but this doesn’t lower the porosity or surface oxidation of the particles. Additionally, “the subsequent use of recycled powder” can change the final part’s mechanical strength, and not for the better.

“Here, we report our latest effort to measure the distribution of porosity formed in the recycled powders using the X-ray computing technique and correlate those analyses to the mechanical properties of the powders (hardness and effective modulus) obtained through AFM roughness measurements and nanoindentation technique,” the researchers wrote.

They used stainless steel 316L powder, and printed nine 5 x 5 x 5 mm test cubes on an EOSINT M 280 SLM 3D printer. They removed the recycled powder from the powder bed with a vacuum, and then sieved it before use; after the prints were complete, they collected sample powders again and labeled them as recycled powders.

“Both virgin and recycled powders were analyzed by number of techniques including XCT and Nanoindentation. XCT was performed by X-ray computed tomography (XCT) measurements were performed with a Xradia 500 Versa X-ray microscope with 80 KV, 7 W accelerating voltage and 2 µm threshold for 3D scan,” they wrote.

“To measure the roughness of the virgin and recycled powder particles, we performed Atomic Force Microscopy (AFM) and confocal microscopy using the Bruker Dimension ICON AFM. The average roughness was calculated using the Gwyddion software to remove the noise and applying the Median Filter on the images as a non-linear digital filtering technique.”

The researchers also ran nanoindentation on multiple powder particles, under a force of 250 µN for no more than ten seconds, in order to determine “the impact of porosity on the hardness and effective modulus of the recycled powders,” and used an optical microscope to identify pore areas on the powder.

XCT imaging of powder. (a) 3D rendered image of 900 recorded CT images, (b) region of interest, (c) internal pores in particles indicated in a 2D slice, (d) identified pores inside particles after image processing.

The XCT images were analyzed, and “a region of interest” was chosen, seen above, from which pore size and interior particle distribution were extracted.

AFM image on a particle showing the boundary of mold and steel and the area where surface roughness was measured.

Software was used to process the AFM topography images of both the virgin and recycled powders, and the team applied nanoindentation on different locations of the particles, with a force of 250 µm.

(a) powder particles placed on hardening mold for nanoindentation, and (b) an indent applied on a particle surface.

They determined that the reused powder particles had about 10% more porosity than the virgin powder, and the average roughness of the powder particle surfaces was 4.29 nm for the virgin powder and 5.49 nm for the recycled; this means that 3D printing “may increase the surface roughness of the recycled particles.” Nanoindentation measurements show that the recycled powder has an average hardness of 207 GPa, and an average effective modulus of 9.60 GPa, compared to an average of 236 GPa and 9.87 GPa for the virgin powder, “which can be correlated to porosities created beneath the surface.”

Pore size distribution in virgin and recycled powders extracted from image processing on XCT measurements.

“The pore size in recycled powders has a wider distribution compared to virgin counterpart. The main population of pore size is around 1-5 µm in virgin powder which slightly reduces to bigger size but for a smaller population. There are also bigger pores in recycled powder but with a smaller population,” they noted. “On the other hand, looking at higher pore population in virgin powder (around 10 µm size), we believe that the out-diffusion of metallic elements to the surface occurs during laser irradiation.”

Surface roughness plots from AFM measurements on powder particles. Average roughness calculated by Gwyiddion software.

The recycled powder hardness, which is smaller than in the virgin powder, “could be attributed to higher pore density in recycled particles,” since porosity causes the powder to be “more vulnerable to the applied force resulted in smaller hardness.”

While change in grain size of the powder particles can lead to reduced mechanical properties, the team’s AFM and SEM results did not show much grain redistribution in the recycled powder. But, their nanoindentation and XCT results did find that higher powder porosity can decrease both the hardness and modulus of the particles, which “will damage the mechanical properties of the manufactured parts.”

Hardness and effective modulus of fresh and virgin particles by nanoindentation.

“We have previously presented our achievement on surface and size analysis using SEM and XPS analysis. Here, we focused on pore distribution in both powders and correlated that to surface roughness, hardness and effective modulus obtained from nanoindentation analysis of the powder particles,” the researchers concluded. “The results indicate that pores population is about 10% more in recycled powders affected by the laser heat and oxygen inclusion/trap in the powder, which in turn, increases the surface roughness but reduces the hardness and modulus of the recycled powders. The pores are filled with gases (such as Argon or Oxygen) since these gases are not able to skip the melt and have a lower solubility in the melt throughout the solidification process.”

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Climate Disrupted: The State of Recycling

In our already-climate-disrupted world, we are inundated with petro-based plastics. We could rehash the numerous statistics that we probably already know, like the fact that only 9 percent of plastic waste in the U.S. actually gets recycled or that we all have microplastics in our stomachs or that making plastic products from recycled plastics actually uses 66 percent less energy than using virgin polymers. But we all know most of these stats. The question is “what are we going to do about it?”

Obviously, the recycling system in the U.S. isn’t adequate. How might it be improved?

Improving U.S. Recycling Rates

The entire industrialized world doesn’t suck at recycling; German, for instance, has a municipal solid waste (MSW) recycling rate of 68 percent. However, one of the most powerful nations in the industrialized world does. Though the U.S. represents just 4 percent of the global population, it generates 35 percent of the planet’s waste.

Image courtesy of the EPA.

The good news is that the U.S. is better at it than it was in the past. As of 2017, the U.S. was recycling over 35 percent of its MSW, compared to just 6 percent in the 1960s. While about 50 percent of the waste that gets recycled is paper and paperboard, only 3.4 percent is plastic. (Worth noting is that, in 2010, over 50 percent of U.S. MSW consisted of compostable materials. Though these materials could be composted at home or through municipal programs, their decomposition in landfills leads to methane emissions, in part causing landfills to represent 20 percent of the country’s methane production. Aerobic composting does not result in methane release, so just by composting food waste, you can reduce GHG emissions.)

To get up to the levels achieved by Germany and Austria (another leader in the recycling race), it has been suggested that the U.S. make very clearly demarcated waste receptacles with a wider range of categories easily accessible by the public across the country, as well as in individual homes. Germany has bottle recycling machines located at most grocery stores throughout the country. South Korea and Hong Kong have battery and electronic disposal bins at train stations and other public locations.

Greater education about what can and cannot be recycled (e.g., cereal boxes vs. greasy hamburger wrappers) and how to prepare items for recycling (e.g., thorough cleaning of food debris) can improve recycling rates by causing less issues at the recycling plant. According to Waste Management, the largest processor of residential recycling in North America, 25 percent of items sent for recycling should actually be trashed. However, China’s Green Fence policy now requires only 0.5 percent contamination, leading the country to reject many more recycling shipments than historically accepted.

In addition to improved education and public waste sorting options, there are policy options that can be utilized to increase recycling rates. In many European countries, such as Switzerland, recycling is free, but garbage disposal costs money. In Germany, retailers and manufacturers have to pay for a green dot on their packaging with more packaging leading to more fees, incentivizing businesses to reduce the amount of packaging they use.

New Methods of Recycling

In addition to improving the rates of recycling in arguably the most consumer-driven country on the planet, there are new ways of recycling that can reduce waste overall. For instance, faster and more accurate sorting technology could make the process more efficient. This is one technology that claims to do just that, though we cannot vouch for its efficacy.

There are also natural methods for processing waste. For instance, phytoremediation relies on plants to remove, degrade or contain contaminants in soil, sludge, sediments and water. In the Netherlands, one company has used biological treatment to clean water, ultimately reducing water use by 50 percent. Cereol in Germany relies on enzymes to degum vegetable oil as a replacement for potentially dangerous acids or large amounts of water, thus reducing water use by 92 percent and waste sludge by 88 percent.

There is currently research underway to apply similar principles to plastics. A team at Kyoto University, for instance, has isolated a bacteria that can digest PET. Yale researchers have discovered a species of fungi that can digest polyurethane.

As we discussed in our posts on polyhydroxyalkanoates (PHA) and other bioplastics, it’s possible to generate polymers from bacteria. We can even envision the possibility of creating a circular economy in which bacteria are used to digest waste to create new usable biopolymers. In our next post, we will discuss the concept of a circular economy in greater depth, including such possibilities.

[Feature image courtesy of RitaE on Pixabay.]

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3D Printing and Mass Customization, Hand in Glove Part IV

Earlier in this series, we’ve discussed how we’re drunk on consumption, how we use up too much material and that recycling has some constraints. Now we’ll look at how creating and using high valued goods using recycling and sustainable materials is key. Whereas a lot of the especially wasteful waste of today is used on the low end of the cost scale. Plastic bags and plastic packaging survives for only a few days before it is disposed of in landfill. Materials such as PE, HDPE and PP are low cost and versatile. Thermosets can’t even be recycled into anything meaningful but can become perfect forms for a brief time. The lowest value applications also see, typically, the largest volumes and the shortest life of the material in that part. A nice ASA mirror could spend a few decades on a car and a PEI part could live in an aircraft for a decade while polyethylene bags last a day or two. The lest functional materials are also expensive to correctly identify and sort, something that is still often done manually. Due to all of this there is a mismatch between the high value needs of today’s consumers and the low value availability of abundant materials close to them.

Noble and trusted materials such as marble or wood, feel luxurious and long-lasting to the touch. Meanwhile, the feel of a polymer has made myriad inexpensive memories in our lives. There are notable exceptions, some high-value products use polymers well. The polypropylene handles of Wusthof knives, for example, seem very durable and luxurious. The German knife firm has gone further however and now uses “smoked oak” fiber composite materials on its Epicurean line of knives. Instead of an oil-based polymer or a costly wood, these fiber-based materials can give the manufacturer lower cost while maintaining good quality and a great feel. Outdoor retailer Patagonia has used a significant portion of recycled polyester in its recognizable product line. 72% of its collection now uses one recycled material or other and the firm also uses recycled wool, cotton, and cashmere.

One could look at other ways than just recycling materials and turning them into near new ones. Patagonia’s worn wear program patches up your jackets so they look visibly repaired but last longer. Asos’ reclaimed vintage line reportedly uses deadstock and old styles and turns them into new ones while Beyond Retro uses vintage clothing as fabric for new styles. Alternative methods can be found in 3D printing where materials such as hemp fill PLA replace an energy-intensive material with lower intensity hemp used as a filler. I like Wusthofs fiber examples and the 3D printed hemp fill because what you can do as a firm or designer is to craft a new feel, look and process to give people a completely new sensation. Using low impact and recycled materials it is possible to give a wholly contemporary branded material a sense of purpose that showcases its humble recycled origins while making the people using it feel better about themselves. Positioning these products in the higher echelon of branded products elevates the recycling process and makes for good business cases. Yes recycled napkins will elevate and use a vast quantity of material in a “morally superior” way but if we make good recycled materials design the pinnacle of achievement we will position renewed goods as a growing business set to expand across the globe.

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Climate Disrupted: A Circular Economy

In trying to prevent the total collapse of our natural ecosystem, we can work toward building a circular ecosystem of goods production and consumption. The goal of a circular economy is to produce no waste and have no negative impact on our ecosystem.

At the moment, we have very minor hints at a circular economy in the additive manufacturing (AM) space in the form of recycled feedstock and feedstock recyclers.

Recycled Feedstock

On the market, it is already possible to purchase 3D printing filament from a number of brands, including Innofil3D (now a BASF company), 3D Fuel and others. These companies manufacture filaments made from waste products. While ABS is recycled from car parts, PET is recycled from plastic bottles and HIPS can be scavenged from old refrigerators.

3D Fuel’s Buzzed filament made from waste generated during beer making. Image courtesy of 3D Fuel.

3D Fuel is one of the more notable companies in the space due to the wide range of waste-based plastic it manufactures. This includes waste byproducts from the beer, cotton and coffee industries, as well as biochar derived from the pyrolysis of landfill waste. All of these materials are then combined with NatureWorks PLA to give second lives to what would otherwise rot in giant piles somewhere.

Because many desktop 3D printing filaments are meant for low-cost machines, it might be safe to say that this helps offset the waste produced for prototyping and visual modeling. In general, 3D printing is still used for these applications, even as a shift toward production is taking place. As the technology is deployed for end part manufacturing, however, it is important to understand the reusability of materials in production systems.

HP, for instance, offers several materials that are 70 to 80 percent reusable. In powder bed fusion technologies, not all unprinted powder from a build can be reused due to exposure to the sintering/fusing source. In the case of HP’s materials, that amount is limited to just 20 to 30 percent.

Feedstock Recyclers

The aforementioned materials are obviously a small fraction of the possibilities for manufacturing with recycled feedstocks. A step further is the use of material recyclers that can be used to shred used plastic and remelt it into new, usable filament. Those with access to extrusion 3D printers can build recyclers like Michigan Tech’s RecycleBot at home or purchase a system like the Filabot or Felfil Evo.

A Gigabot X 3D printer modified with a 3D-printed hopper. Image courtesy of Michigan Tech.

There are good arguments to be had about whether or not such a system could even exist in industrialized society because of the destructive nature of recycling. Waste that is recycled can only be put through such a process a given number of times before its quality is too low for continued re-use. According to research from the Michigan Technical University Open Sustainability Technology (MOST) group, recycled plastic filament can only last five recycling cycles before it becomes unusable.

However, the MOST group is trying to overcome these issues. The lab is working to improve the quality of recycled plastic feedstock by replacing a plastic filament extruder with a hopper for processing shredded plastic. The research demonstrated that recycled ABS, PET and PP had similar tensile strength to virgin plastic filaments. PLA, however, was 2.5 percent weaker.

Circular Economy

If we were able to maintain quality throughout recycling, we can imagine how 3D printing could become a manufacturing process of choice for a circular economy. In a form of what the MOST lab refers to as “industrial symbiosis,” waste byproducts from one production site could be used as the material feedstock for another.

While other manufacturing technologies might be deployed in such a scenario, 3D printing has the advantage of producing less material waste than subtractive technologies such as CNC machining. It also has the benefit of cost effectively fabricating objects on-demand, eliminating the need for warehousing extra goods made with mass manufacturing technologies like injection molding.

An eco-industrial park centered on a photovoltaic manufacturing plant. Image courtesy of Renewable Energy.

The MOST group detailed the possibilities of a symbiotic eco-industrial park used to manufacture solar panels in a study. The calculations suggested that raw material use could be cut by 30,000 tons annually and embodied energy use could be cut by 220,000 GJ annually.

For the journal sustainability, a team of UK researchers attempted to conceive of a way to incorporate a number of emerging technologies, including AM, into a circular economic model. Using the production of shoes as an example, the team illustrated the production of shoes in a circular economy in this way:

“The design of this pair of trainers allows new disruptive business models, such as offering trainers as a service through a subscription model. This model provides a personalized service if the trainers need to be repaired, maintained, or parts need to be replaced, as the main body detaches from the sole with a mechanical joint. In addition, trainers will be produced in local stores. The model also includes the use of other technologies such as the ability to scan your foot to produce every trainer to measure and an augmented reality application to virtually try the trainers on. These technologies will allow the custom production of trainers avoiding a surplus of unsold products and utilizing the minimal amount of material.”

This second example in particular (as opposed to the solar park envisioned by the MOST lab) suffers from a lack of imagination, in that it attempts to maintain our current global society as much as possible. Our current economic, social and technological order are what have generated all of the ecological crises we are facing in the first place.

If we are to maintain a society with any level of industrialization that we currently have, it may be necessary to avoid thinking in terms of individual “consumers” purchasing goods as they always have, albeit locally and with a subscription model, and begin thinking about what aspects of this industrial society are necessary and which are merely convenient.

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3D Printing and Mass Customization, Hand in Glove Part III

As discussed in the first and second installments of this series, we are drifting into a consumption-driven stupor and self-medicating our way through lives that, if we live in OECD countries, use 15 tonnes of material per year. Even though some things are recycled, these recycled goods do not often become high-value items. Repurposing existing waste streams and materials that are already near are to me key low marginal cost ways to better our world and lot. Yes, there may be more impactful things that we could do, but this is one with few, percieved unintended consequences. Also, whereas planting a billion trees would seem like a good idea, there would be a lot to control there operationally, and a lot of things could not pan out in the long run. Recycling existing waste into high-value consumer goods, however, has a much shorter and directer feedback loop. These products would need to survive based on their own merits in the marketplace alongside goods made of new materials. If they are to really work and expand, they would be cost-competitive or maybe even less expensive to make but higher performing than regular goods. If we want to take recycling from something we have to do to something that we like doing, we need to make it fun, enjoyable and pleasing. If we can then transform recycled goods into high-value ones, we can begin to make a dent in all of the senseless weight in materials that we use up.

The weight of the Eurocopter Tiger, the Sikorsky Blackhawk, and Boeing Apache helicopters together is less than the total weight of material that you use up per year. That’s kind of sad but also an opportunity. There are a few distinct advantages to recycling materials as opposed to using new ones.

Recycled materials are often found close to consumers. This is super obvious but also in terms of the low cost of transport and storage a huge advantage.
Recycled materials have fewer parties participating in the value chain, which can give you more control, direct interaction with every market participant and leverage. A virgin material may be made of a few different petrochemicals which are transported, processed and distributed by dozens or more companies until they reach a consumer. A recycled material is collected, sorted and processed; very often through one firm in one region. Less consecutive margin cuts make for a potentially attractive business overall as well.
Recycled materials are often very inexpensive. There are exceptions to this of course but generally recycled materials are available at a discount to virgin materials, giving you pricing advantages.
Consumers like recycled materials because it makes them feel less bad about their consumption.

There are also some disadvantages to recycled materials:

Tracability in recycled materials is often difficult. We don’t always know which polymer has which additives and how it has been processed if we find it in a trash bin. The same material with a pedigree will be worth much more than one without.

Due to this certification of recycled goods is difficult unless processes are designed such as the rPet process that Krones has whereby used water bottles can be turned into flakes, then preforms and finally food-safe certified waterbottles. The image above shows you the layout of a Krones rPet plant.
There is still something icky about recycled materials as in, you wouldn’t mind a recycled book bag but would mind a recycled baby bottle. But, then again you wouldn’t mind a paper recycled napkin touching your mouth but you would probably have misgivings about a recycled plastic mouthguard.

Recycled materials have a particular rough/mixed esthetic that is not always appealing. Particularly this is by design to make things look recycled and partially this is to offset costs, but in some cases, it is also not always possible to recreate the look and feel of a virgin object.
You can’t recycle everything infinitely and most recycled objects lose strength for example when they’re recycled.
Sorting, separating and processing recycled items is time-consuming and expensive.
There are no real standards for recycled or green or environmentally friendly which puts the bar very low for a lot of recycling projects.
There is a lot of greenwash, that undercuts the value of real recycling projects.

So generally as a product family, all recycled materials everywhere are not ideal. Recycling will also not work for many products. But if we pick the right categories of recycled goods and make them the right way we could very well find success for ourselves and the planet.

Photos by: ClevrCat, Timothy Swinson, Karliss Dambrans, Anna Zevereva, Krones, Scoobyfoo.

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Argonne National Laboratory Using 3D Printed PEEK Connectors to Recycle Molybdenum More Efficiently

Just a few years ago, the FDA approved the first Molybdenum-99 (Mo-99) to be produced domestically without the use of highly enriched uranium (HEU). This medical isotope helps radiologists detect bone decay, heart disease, and some types of cancers that are difficult to find, and in 2018, the US Department of Energy’s National Nuclear Security Administration (NNSA) reported that Mo-99 was used in over 40,000 medical procedures daily in the US – a number that has likely increased. So a team of scientists from the DOE’s Argonne National Laboratory turned to 3D printing to try and get more out of this important isotope.

(Image: SHINE Medical Technologies)

“Every year, doctors rely on Molybdenum-99 to conduct millions of medical procedures to diagnose illnesses like heart disease or cancer. But producers of this medical isotope lacked an easy, cost-effective way to recycle it – until now,” Dave Bukey, the Integrated Communications Lead at Argonne, told 3DPrint.com.

Argonne, the nation’s first national laboratory, employs people from over 60 nations, and works to come up with solutions to important national problems in science and technology, often turning to 3D printing to solve them. The laboratory often works with researchers from other companies, universities, and agencies to help solve these problems, as well as advance the nation’s scientific leadership.

Mo-99 decays into technetium-99m, which is then used by radiologists to develop pharmaceuticals for medical procedures. It can be made from enriched molybdenum, but it’s definitely not cheap, costing roughly $1,000 per gram. But now, it’s possible to scale up recycling of isotopically enriched molybdenum, Mo-98 or 100, for the first time in the US, thanks to Argonne’s recycling method and some 3D printed parts.

This method was first pioneered back in 2015 by the laboratory’s Mo-99 program manager, Peter Tkac, and his team, and is faster, more reliable, and cost-effective.

Tkac said, “Our original method would have been very difficult to automate.”

The team’s original recycling process for enriched molybdenum was, as Bukey aptly described in an Argonne post, “tedious.” Along with other corrosive chemicals, used enriched molybdenum was converted into an acidic solution, then purified with test tubes and funnels in a lengthy, multi-step process.

Argonne scientists 3D printed parts like these to accomplish the recycling milestone.

In 2016, Tkac and other researchers turned their attention to automating the process, together with aerospace engineer, 3D printing expert, and fellow Argonne employee Peter Kozak. Instead of relying on the funnels and test tubes, they instead used 3D printed acrylic contactors, which use centrifugal force (acts outward on a body moving around a center) to spin and separate the chemicals.

“We printed each contactor as one piece with streamlined features and fewer external connections. This allows us to push the liquid through the system as quickly and reliably as possible,” Kozak explained.

These 3D printed contactors made the recycling of enriched molybdenum more efficient and less expensive, according to the research team, which includes Alex Brown and Brian Saboriendo. An article published in the Journal of Solvent Extraction and Ion Exchange in December explained that this updated recycling process was better able to separate enriched molybdenum from potassium and other contaminants.

The laboratory’s new 3D printing approach makes its recycling method — pioneered in 2015 by Mo-99 program manager Peter Tkac (left) and others — faster, more reliable, and more cost effective. Also shown: Peter Kozak (center) and Brian Saboriendo (right). Not shown: Alex Brown.

However, the team did run into a problem – after about 15 hours of operation, the 3D printed plastic contactors were corroded by hydrochloric acid used in the recycling process.

Kozak said, “Our experiment was successful. But if you want to move into full production, you need material that will survive a lot longer than that.”

Tkac and Kozak soon discovered polyetheretherketone, or PEEK, which is more durable than the original acrylic plastic they were using, and also resists the Argonne recycling method’s organic solvents and mineral acids. However, PEEK does shrink during 3D printing, which causes the material to warp, so Kozak changed the temperature and speed of the 3D printer’s fan to compensate for this difficulty. This allowed the team to 3D print their contactors out of PEEK, which made them stronger and more flexible. Now, they can quickly, efficiently, and cost-effectively recycle enriched molybdenum, thanks to 3D printed PEEK parts that can stand up to the chemicals that separate the Mo-99 from other materials during the recycling process.

The DOE National Nuclear Security Administration’s Office of Defense Nuclear Nonproliferation and Office of Material Management and Minimization supported this important research.

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(Images by Argonne National Laboratory)

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Climate Disrupted: The Problem(s) with PLA

While our ecosystem is collapsing, we are at the very least fortunate to witness the rise of a potentially more sustainable form of manufacturing coinciding with the rise of potentially more sustainable materials. In the next few articles, we will cover both the new materials that are emerging for use with 3D printing, as well as the ways that 3D printing might contribute to a climate disrupted world.

As discussed in a previous story, oil majors are hoping to shift to petrochemicals as the world attempts to replace fossil fuels with renewable energy. Due to the historic role these conglomerates have played in our ongoing ecological collapse as well as the basic need to move away from fossil fuels altogether, industrial society might instead aim to supplant petro-based polymers with polymers derived from other natural sources.

In this series, we’ll discuss biopolymers that could become prominent feedstock in additive manufacturing (AM), as well as some that are already being used in 3D printing. One of them is so important, however, that it’s worth spending an entire article on the topic. Naturally, we have start to with polylactic acid (PLA).

Where Does PLA Come from?

PLA is the most popular material for desktop 3D printers, largely due to the fact that it is easy to process and has decent durability. Many 3D printer operators also believe PLA to be safe since it is derived from natural materials. PLA is made from natural sugars, which can be derived from corn starch, sugarcane, as well as cassava roots, chips or starch. In part due to the massive corn subsidies in the U.S., the most widely available brand of PLA is the corn-based Ingeo from NatureWorks, jointly owned by Cargill, the largest privately owned company in the U.S., and the Thai state-owned oil and gas business PTT Public Company Limited. The second-largest PLA manufacturer is Corbion, which manufactures Luminy brand PLA from sugarcane.

Ingeo comes from a specific breed of corn known as grade #2 yellow dent corn (or “field corn”), grown for industrial purposes such as livestock feed, sweetener, ethanol, starch for adhesives and other materials, and Ingeo. PLA is made only from the kernels of the corn, which are milled before the starch is extracted and converted from glucose to dextrose. Microorganisms ferment the dextrose into lactic acid, which is then converted into lactide and formed into long polymer chains using ring-opening polymerization to create PLA.

How Sustainable is PLA?

Instinct might tell us that PLA is more sustainable than petro-based plastics because they are not derived from petroleum or natural gas, but from biomass. Therefore, supplanting petroplastics with PLA could reduce the 1 percent of U.S. greenhouse gas (GHG) emissions associated with plastic production. In fact, a 2017 study determined that doing so would reduce GHG emissions by 25 percent and that, by powering plastic production facilities (PLA or not) with renewable energy, emissions could be cut by 50 to 75 percent.

However, there are other factors to consider related to PLA that should be taken into account, many of which are associated with the crops used to make PLA. PLA releases fewer GHGs from outgassing as it degrades in the environment when compared to petro-plastics; however, the fertilizers and pesticides used to grow the plants that make up PLA in the first place could release more pollutants. This could be reduced by switching to organic, non-genetically modified crops. In the meantime, NatureWorks gives its customers the option of purchasing non-GMO Ingeo, but the default product uses GMO plants, which are correlated with higher pesticide usage.

Moreover, fertilizers used to grow PLA feedstock are responsible for a large amount of GHG emissions. Nitrous oxide, a byproduct of low-cost, nitrogen-based fertilizers, is 310-times more potent than carbon dioxide. A competing bioplastic manufacturer calculated that, “if Natureworks was at full capacity in production it would create 56 [terra grams] of carbon dioxide equivalent more than all of the landfills combined in the United States…”

Image courtesy of Filabot.

PLA is also considered compostable and recyclable, but it such a categorization is misleading due to the fact that it can only be composted in an industrial compositing facility. Only one-quarter of the 113 total such facilities in the U.S. accept residential waste. In other words, not only is PLA not compostable in one’s backyard, but it is even difficult to compost via municipal waste collection in the U.S.

An industrial composting facility. Image courtesy of BioCycle.

As a result, PLA in the U.S. tends to end up in landfills, with researchers unable to determine the exact natural decomposition rate but estimating between 100 and 1,000 years. As it decomposes, it releases methane, a gas 23 times more potent than carbon dioxide.

We should also note the amount of water required to make PLA, which is about 2.5-times less than is needed to produce Styrofoam but 38 percent more than polypropylene and 10 percent more than PET. If we look at total water usage throughout production, some estimates state that around 50 Kg of water is needed for one kilogram of PLA. This is probably higher than you imagined but is still significantly lower than the 700 Kg needed for one kilogram of Polyamide 66. If we look at the water footprint of bioplastics one researcher found that PLA compares well to almost all bioplastics in that regard.

We might consider the amount of land that PLA feedstock requires. The Plastic Pollution Coalition projected that, to meet global demand for bioplastics by 2019, 3.4 million acres of land (bigger than Belgium, the Netherlands and Denmark combined), would be required. In a climate-disrupted world with a rising population, where agricultural yields are shrinking as a result of volatile weather, increased drought, and more pests, land for bioplastics will be competing with land used for food production.

This is then linked to how land by PLA manufacturing agro-businesses is used. Putting aside its issues that aren’t directly tied to the climate crisis—such as its human rights abuses, child trafficking and land grabs—Cargill has been heavily involved in deforestation to make room for the production of its crops, such as soy, palm oil and cocoa.

For all of these reasons, we will have to thoughtfully consider the role that we want plastics, petro-based or otherwise, to play in a society constrained by climate disruption. In the next section of this series, we will consider more of these bioplastics with the hope of overcoming some of the issues associated with desktop 3D printing’s favorite plastic, PLA.

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New Method for Circular Chemical Recycling of PLA

In existing mechanical recycling processes, plastic items are chopped into fine pieces, melted and extruded into new plastic feedstock, which causes them to degrade in quality. Recycled virgin plastic is often used for lower grade applications, including park benches, water pipes, and traffic cones. For that reason, scientists from the Universities of Bath and Birmingham are researching a method of chemical recycling that breaks polymers like PLA and PETG into their base molecules.

The paper, published in ChemSusChem, describes how McKeown et al., sought about developing a viable method of chemically recycling PLA plastic into its constituent chemical components. Using a complex made up of zinc as a catalyst, the team successfully performed the break up of PLA and the formation of lactic acid, the basis for PLA plastic. The researchers employed several zinc complexes for dissolving PLA samples, with the most active complex consuming the PLA completely within 30 minutes.

Though PLA is often described as biodegradable and compostable, it is only biodegradable in industrial composting facilities and not in backyard composters. Moreover, it is not easily recycled in traditional recycling facilities and usually ends up in landfills.

The research team was able to derive different constituent materials depending on the exact nature of the zinc complex. When combined with ethanol as a solvent, for instance, the zinc complex was able to form alkyl lactates, which are considered “green” solvents and, therefore, a useful and potentially sustainable result of PLA recycling. In addition to PLA, the researchers were able to run small tests on the recycling of PET, the plastic used to make water bottles, using the same process.

While chemical recycling has been demonstrated in the past, the researchers consider the zinc complexes used in this study to be more environmentally friendly than catalysts used in previous methods of chemical recycling. The team was also able to perform the recycling at lower temperatures, which means less energy was used. The scale at which the recycling was carried out was very small, but the University of Birmingham team is exploring ways to scale the system up to produce larger quantities of starting chemicals.

Compared to fossil fuel used for transportation, electricity and industrial applications, plastics represent a small, but still significant portion of industrialized society’s carbon footprint. Finding the global numbers is a bit more difficult, but the production of plastics makes up 1 percent of U.S. greenhouse gas (GHG) emissions and 3 percent of the country’s primary energy use. Moreover, the Center for International Environmental Law points out that, as polymers are often made using the byproducts of fossil fuel extraction, “the two product chains [plastics and fossil fuels] are intimately linked.”

If society wants to maintain any semblance of its current industrial and consumer form, it will be necessary to ditch the petro-plastics, leaving industrialized society in need of alternatives. This means recycling the plastics we do have and finding other sources for our polymers. For the moment, the dominant form of polymer not derived from fossil fuels is polylactic acid (PLA), primarily derived from the sugar in corn starch and sugarcane, as well as cassava roots, chips or starch.

A 2017 study suggested that by using PLA as a replacement for plastics derived from fossil fuels, GHG emissions could be cut by 25 percent. Using renewable energy sources to power PLA production could reduce emissions even further. However, switching to PLA alone is not enough to completely drop its ecological impact. The material must be disposed of and recycled properly.

PLA releases GHGs as it degrades, though fewer than its petro-based counterparts, and, according to a 2010 study, it may release more pollutants due to the fertilizers and pesticides used to grow the crops that serve as the basis for PLA. NatureWorks, the largest supplier of PLA, allows partners to purchase Ingeo made without genetically modified (GM) crops. However, the use of GM plants is the default practice and, because GM plants have high pesticide resistance, they are typically linked to increased pesticide usage.

The actual growing of the feedstock for PLA also results in its own significant GHG emissions with the nitrous oxide used in low-cost fertilizers 310 times as powerful in terms of its effect on the atmosphere than CO2 and 15 times more powerful than methane. According to one calculation the use of these fertilizers in NatureWorks products results in the emission of “56 Tg of carbon dioxide equivalent, more than all of the landfills combined in the United States according to the US Gas and Sinks.”

In other words, the sort of circular economy envisioned by the Bath and Birmingham scientists is needed more than one might even imagine. Of course, it’s important to remember that, even in such a scenario, this process is not a zero-sum game. It still requires extra material and energy inputs to recycle the plastic, which have to come from somewhere.

In this case, zinc is the major material input, though at very small quantities. Though the U.S. has its own share of zinc reserves, it imported nearly as much refined zinc as the amount of raw zinc that it produced in 2018. Other industrialized countries, like every country in Europe except for Sweden, have no zinc reserves of their own and must rely on imports entirely, which means shipping, which means more emissions.

This may sound like needless nitpicking but given the fact that our ecosystem is collapsing due in no small part to global society’s near-total reliance on fossil fuels, it is completely necessary to consider every material input and output when embarking on new technological endeavors. Such an accounting probably should have been employed form the beginning, but you live and you learn, right?

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Plumen & Batch.Works: 3D Printed Lampshade Collection Made from Recycled Plastic

3D printing has obviously done a lot of good in many of the major sectors of the world, like aerospace and medical. But, every once in a while, Plumen sneaks in to remind me that the technology is just as useful in the consumer goods market…and can also be just as sustainable.

The designer low energy lighting company, founded nearly a decade ago by Nicolas Roope and Michael-George Hemus, believes that the way to get people on board with energy efficient lighting is by providing them with attractive low energy light bulbs, and all the sustainable accessories that go with them, like lampshades.

Now, Plumen is collaborating with London-based design company Batch.works on a new range of lampshades, 3D printed out of recycled plastic from waste items like water bottles.

“When we first met Batch.works, it seemed like the perfect match. We’re both small businesses with a similar ethos and approach to things. The fact that you can use recycled plastics and they can then be industrially biodegraded or reused again is really fascinating to me, and plays into the circular economy – which we are trying to put into practice everywhere we can,” said Plumen co-founder Hemus.

“To Plumen, 3D-printing is a very exciting opportunity for lighting. 3D-printing allows shapes and forms that are not possible otherwise. More importantly, there is very little waste compared to traditional methods – products are made to order, from recycled plastic bottles and at the end of their lives they can be recycled once again. It’s a sustainable vision for the future.”

The collection’s first two 3D printed shades, Neo by Matthias Lauche and Ribbon by BOLD, were recently released, and are available to purchase from the online stores of both Plumen and Batch.works; more lampshades will be released in 2020.

Neo, based on geometric Art Deco forms, is for Plumen’s Milky Willow bulb, and features two shades stacked one on top of the other in order to frame the Plumen E27 pendant light. Because there are two parts to the Neo shade, it can be created in multiple color combinations.

The Ribbon shade has a more fluid surface, thanks to the capabilities of 3D printing, and bends over itself to, as Plumen explained in a press release, “surround and protect” its Milky Wilma bulb.

“The space created by the shade is filled with light, revealing and emphasising the different volumes created by the enveloping surface,” the release continues. “The vertical lines that run through the shade, combined with the horizontal layers that are characteristic of this manufacturing technique, amplify the appearance of a piece of textile that’s solidified around the light – directing it and enhancing it. Light peeks through the shade’s open space, allowing the iconic bulb to be seen from another angle.”

As part of the companies’ continuing commitment to reduce and reuse plastic, each of the 3D printed lampshades is fully recyclable. The shades are all made at Batch.works’ east London headquarters, as the company is also committed to local manufacturing, and are printed on-demand using filament from Amsterdam-based social enterprise Reflow, which also re-purposes plastics that would otherwise be wasted. Additionally, the shades can also be returned to Batch.works for recycling once they’ve reached the end of their lifespan.

“We believe that thinking more carefully about what materials are used, and how things are produced, is key to combating short-termism. That’s why this kind of collaboration is so promising. We believe 3D printing can be scaled to a wider variety of products, and become a practical manufacturing method for the future – and that’s what we want to achieve,” stated former architect Julien Vaissieres, who founded Batch.works in 2016 with a goal of making eco-friendly, affordable 3D printed products.

Batch.works created the Plumen lampshade collection with the help of five different design studios. Black and white are the currently the only available colors, though you can request custom ones, dependent on volume. The 3D printed Neo shade is £149, while the Ribbon is £199…a lot more than I’d typically spend on a lampshade, really, but I love that they are completely sustainable.

Discuss this story and other 3D printing topics at 3DPrintBoard.com or share your thoughts in the Facebook comments below.

[Images provided by Urban Alps]

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Industrie 4.0: Mein Har(t)z Brennt Part 3 Industrie 5.0

I hate the term 4D printing. Abhor it. I was horrified when I saw it quicker than anticipated gain currency in our market and in the lexicons of journalists. But, in order to print a future for ourselves and this planet, I’ll happily jump on the wordforge myself in order to help us all. Now, I’ll be the first to admit that Industrie 5.0 is a bit of a stretch. But, it seems logical and this is all you need really. So what is Industrie 5.0? Industrie 5.0 is the autonomous design, development, and manufacturing of goods in a sustainable way. Using learning algorithms, big data, 3D printing, robotics, and automation the future of manufacturing will be more precise, on-demand and respect our scarce energy resources. Manufacturing is no longer about making the most things but making the right things at the right place at the right time. Using recycling systems, renewable power and resources, and energy reclaiming systems goods will be designed for sustainability and for many efficient lives in many forms. Natural, recycled and recyclable sources will replace those that deplete the earth and software, automation and intelligent systems will monitor, optimize and reduce waste throughout the entire supply chain.

Happily I think I’ve managed to come up with something that almost everyone could get behind. If we look at supply chains holistically and in a cradle to cradle manner (and beyond into new goods for many decades!) we could come up with truly sustainable products. If at the design stage people started with which materials were available where and what they could be turned into later we could use the intelligence in the system to plan goods’ many lives throughout their many recycled iterations. We could design for optimizing low waste and low land usage while taking into account factors such as the availability of other products and the need for prioritization. More efficient industries help save the planet. More holistic looks at the entire supply chain and how things are made and distributed will bring savings for everyone in the value chain, especially the oft-forgotten planet.

The black bloc man kicking in a Mcdonald’s window may not like commerce, industry or 3D printing. But, if we could prove to him that there was a new future to believe in where a select group of companies were embarking on a journey towards lower waste and more environmentally friendly technologies and futures he may kick in their windows less. An environmentalist may not like a polymer chemist or industrial engineer until she sees that they to now with Industrie 5.0 are working actively towards a no-carbon future. A farmer may get the Heebie Jeebies from industry but would welcome a group of firms that are actively working for a greener world. A leftist politician will always distrust automation but if it is coupled with a greener planet and brighter future may find it in his heart to help out. Potentially with Industrie 5.0 we have a future that many people can believe in.

Industrie 5.0 gives us a technological business solution to the fact that our planet is dying. Industrie 5.0 could potentially unite many disparate people under one umbrella where building technology does not equate destroying the planet. If we as a 3D printing community want to engage with Industrie 5.0 we will have to be mindful of being as sustainable as possible while advancing the march towards better-suited end-use parts. Thermohardend or post-printing and curing heated stereolithography parts are a good example of this. On the one hand these parts are definitely much more world friendly than previous generations of resins. These materials are thermosets and can not be recycled, however. In some cases, these materials and their processing aids may be carcinogenic. Are these parts and processes that fit into an increasingly environmentally conscious world? If we’re a niche technology with mostly B2B applications, who cares but as we move into larger and more visible use cases we too need to make a choice. Environmentalism for us can not be an afterthought. So, on the one hand, the burning resins may be the future but on the other hand, we kind of already know that they’re in the past.

Part one of this story can be found here, part two is here.

Image credit: Stefan, Gerald.

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