University of Auckland: Growth-Induced Bending of 3D Printed Samples Based on PET-RAFT Polymerization

4D printed objects are 3D printed objects made with smart materials that respond to environmental stimuli, like liquid and heat, or return to an original form after deformation. Researchers from the University of Auckland published a paper regarding 3D printing and growth-induced bending based on photo electron/energy transfer reversible addition-fragmentation chain-transfer (PET-RAFT) polymerization.

By adding reversible deactivation radical polymerization (RDRP) constituents to a 3D printed structure to create “living” materials, which keep polymerizing on-demand, allows structures to be built with post-production functionality and modularity. But, as the Auckland team states, “this forms only half of the solution.”

RAFT processes have been used as a controlled polymerization technique to help with self-assembling macromolecules and block copolymerization. They previously demonstrated photo-RAFT polymerization 3D printing under several visible wavelengths, showing that a facile surface modification “could be performed on the samples after printing with a range of different monomers.”

Graphical abstract

“For this work, we further optimized the PET-RAFT 3D printing formulation and demonstrated the 3D printability using a commercial DLP 3D printer with standard 405nm light sources,” they wrote. “We also explore the 4D post-production modification capabilities of the 3D printed object using green light (λmax = 532 nm).”

The PET-RAFT recipe they used, below, adds a tertiary amine and the photo redox catalyst EY, the latter of which “is raised to an excited state (EY*) under irradiation where it then has several pathways to release its energy.” This is useful for 3D printing, since it’s a desirable “oxygen tolerant pathway.”

(A) Chemical structures of Eosin Y (EY), 2-(butylthiocarbonothioylthio) propanoic acid (BTPA), poly (ethylene glycol) diacrylate (PEGDA, average Mn = 250 g/mol), N, N-dimethylacrylamide (DMAm), and triethanolamine (TEtOHA). (B) Proposed combined PET-RAFT mechanism showing tertiary amine pathway by Qiao, Boyer, and Nomeir15, 23-25 (C) Reaction scheme for PET-RAFT polymerization of our 3D printing resin. (D) Schematic of a standard DLP 3D printer.

In their previous research, they used a 3D printing resin that was much slower to polymerize, and produced brittle objects. This time, they made several changes to the resin, such as replacing the RAFT agent CDTPA with BTPA and adjusting monomer composition.

“The development of an optimized 3D printing resin formula for use in a commercial DLP printer (λmax = 405nm, 101.86µW/cm2) was the first step in this research. Thus, several criteria were used to determine the quality of the optimized resin; the optimized resin must be able to hold its form in 60 seconds or less exposure time, the printed objects must have a good layer to layer resolution and binding, must be an accurate representation of the CAD model, and the resin must be stable enough to be reusable for consecutive runs,” the team explained.

They kept these criteria in mind while creating and testing new resin recipes with Photo Differential Scanning Calorimetry (Photo-DSC) and a 400-500 nm light source range.

“A monomer to RAFT agent ratio of 500:1 was chosen as a balance between a faster build speed, and a high enough RAFT concentration to perform post-production modifications,” they said. “For the first step in optimization we decided to compare two asymmetric RAFT agents, CDTPA and BTPA.”

Photo-DSC plot showing resin composition of [BTPA]: [PEGDA]: [EY]: [TEtOHA] = 1:500:0.01:20 (blue), [BTPA]: [PEGDA]: [DMAm]: [EY]: [TEtOHA] = 1:350:150:0.01:20 (green), [BTPA]: [PEGDA]: [DMAm]: [EY]: [TEtOHA] = 1:150:350:0.01:20 (red), [CDTPA]: [PEGDA]: [EY]: [TEOHA] = 1:500:0.01:20 (black), and [CDTPA]:[PEGDA]:[EY]:[TEA] = 1:200:0.01:2 (orange) form our previous PET-RAFT work, were compared to find an optimum new resin formula. The effects of different RAFT agent and comonomer ratio are noticeable on the maximum heat flow and the peak position of tmax.

The first formula, [BTPA]: [PEGDA]: [EY]: [TEtOHA] = 1:500:0.01:20, had a limited inhibition period, while [CDTPA]: [PEGDA]: [EY]: [TEtOHA] = 1:500:0.01:20 had a longer one.

“These results help to demonstrate the increase in polymerization rate that can be achieved by using BTPA in place of CDTPA,” they noted.

Because of its high glass transition temperature, DMAm was added as a comonomer in [PEGDA]: [DMAm] = 70:30 and 30:70 ratios. This slowed the polymerization rate for the resin formulas [BTPA]: [PEGDA]: [DMAm]: [EY]: [TEtOHA] = 1:350:150:0.01:20 and [BTPA]: [PEGDA]: [DMAm]: [EY]: [TEtOHA] = 1:150:350:0.01:20, but it was still faster than the CDTPA formulation. The researchers used this formulation to 3D print samples for dynamic mechanical analysis (DMA) and 4D post-production modification.

UV-Vis absorption spectra; (A) EB under 405nm (397.45µW/cm2) exposure for; initial (black), 10 (red), 20 (blue), 30 (magenta) and 40 minutes (olive). (B) EY under 405nm exposure for; initial, 10, 20, 30 and 40 minutes.

It’s important that photocatalysts don’t have issues like photobleaching or photodegradation during a photocatalytic process. Above, you can see a comparison in absorbance loss between organic photocatalysts EY and Erythrosin B (EB), “using their absorbance curves after different periods of 405 nm light irradiation.”

“Both showed a noticeable gradual decrease in UV absorbance which could likely be due to irreversible photodegradation, given that the effect remains after the sample has been stored overnight in a dark environment and measured again,” the team explained.

After longer periods of time, the EB solution started changing color, but this didn’t happen with the EY formulation, which is why the team kept it in their 3D-RAFT resin composition. A photostable catalyst, like EY, makes it possible for the 3D printing process to continue undisturbed.

The 3D printed samples that underwent DMA analysis were:

  • optimized RAFT resin before and after post-production modification
  • non-3D printed DMA sample by PET-RAFT polymerization in bulk
  • 3D printed free radical polymerization (FRP) control sample

The first type were 3D printed with a 30 µm thickness, a 60 second attachment time, and 30 seconds of exposure per each of the 53 layers. The second was fabricated with the same optimized formula “but polymerized in bulk using an external mold and a conventional 405nm lamp external,” while the FRP samples were printed with the same monomer composition and parameters but used a “conventional photoinitiator, phenylbis (2, 4, 6-trimethylbenzoyl) phosphine oxide (TPO).”

DMA plot showing (black) storage modulus (E’) and (black dashed) Tan δ from 3D printed DMA sample by normal FRP of resin formula [PEGDA]: [DMAm]: [TPO] = 350:150 and 2wt% TPO; (blue) the E’ and (blue dashed) Tan δ from 3D-RAFT printed DMA sample using resin formula [BTPA] :[PEGDA]: [DMAm]: [EY]: [TEtOHA] = 1:350:150:0.01:20; (green) the E’ and (green dashed) Tan δ from the post-print modified DMA sample; lastly (red) the E’ and (red dashed) Tan δ from the non-3D printed DMA sample prepared by normal PET-RAFT polymerization in bulk.

A temperature ramp (2˚C/min) was performed in order to find the storage modulus (E’) and glass transition temperature (Tg) of the samples, and there was a major change “in the E’ to 80 MPa and Tg to 15˚C” when the samples were compared to ones that weren’t 3D printed but instead polymerized in a mold.

“This layer-by-layer construction appeared to play a major role in the E’ at room temperature of the overall sample,” the team noted. “Each layer in the 3D printed sample received equal light irradiation (apart from attachment layer where specified), whereas in the bulk samples light had to penetrate through the entire thickness of the resin.”

Samples printed with RAFT resin had methyl methacrylate (MMA) monomer inserted post-production “in a growth medium devoid of solvent,” and DMA was used to analyze the effect of this modification on the prints’ mechanical properties, as well as “the relative effect on E’ and Tg of the sample.”

“The E’ at room temperature of the sample had decreased to 100 MPa but the Tg remained constant at about 19˚C,” they explained. “These limited changes can largely be attributed to the fact that BTPA is an asymmetric RAFT agent, all the growth being surface focused thus limiting the mechanical effects on the 3D printed RAFT sample.”

A1) CAD model for shapes upon 3 × 3 cm base. A2) Corresponding 3D-RAFT objects printed using DLP 3D printer. B1) Kiwi bird CAD model upon tiered base. B2) Corresponding 3D-RAFT printed object.

Once they determined the optimal RAFT 3D printing resin, the researchers designed CAD models for the objects they would print. They arranged different shapes, like triangles and Kiwi birds, on top of square and hexagonal base plates and circular coins, in order to see how the PET-RAFT resin formulation could handle features like corners and curves.

“These objects generally represented an accurate 3D print of the corresponding CAD model, confirming that the current 3D-RAFT resin was capable of printing 3D objects using a 405nm DLP 3D printer (λmax = 405 nm, 101.86µW/cm2),” they noted.

“Objects printed with 3D-RAFT also displayed an actual build speed of 2286 µm/hr (calculated from the actual height of printed objects over the full print time) consistent with that of the theoretical build speed, which is significantly faster than our previous PET-RAFT resin formula…”

Only limited shrinkage occurred on these prints, and after being washed for two days each in ethanol, THF, and DMSO, the team did not note a visible loss in yellow “arising from the trithiocarbonate group of the RAFT agent.” The 3D-RAFT resin was also reusable over more than ten prints.

“Having demonstrated that we could reliably print objects using our new RAFT resin, we endeavoured to demonstrate that these objects had retained their desired “living” behavior and could undergo post-production modification,” the team wrote.

They immersed half of a 3D-RAFT printed strip in a growth medium containing [BA]: [EY]: [TEtOHA] = 500:0.01:20 in DMSO. Then, a green 532 nm LED light was directed onto one of its faces, and after 15 minutes, “the strip showed moderate curvature.” They could see the strip was bending considerably after 15 more minutes, and it was also much softer, with the irradiated face paler than the other, and the growth medium was cloudier.

Optical images and graphical representations of growth-induced bending process. (A) The initial 3D-RAFT printed strip. (B) 3D-RAFT strip after 15 minutes monodirectional green light irradiation (532nm, 58.72µW/cm2) in a growth medium of DMSO and BA. (C) The same strip after 30 minutes monodirectional green light irradiation in the same growth medium. (D) Reaction scheme for the photo-catalyzed insertion of BA monomer under green light irradiation.

They next performed some control experiments. First, they tried the same thing with an FRP printed strip and a [PEGDA]: [DMAm] = 350:150 and 2wt% TPO growth medium, but this did not bend. A 3D-RAFT printed strip was left to soak in the original growth medium, without any light irradiation, for 24 hours, “to ensure that the bending was coming from growth rather than an alternate stimulus such as solvent swelling,” and saw no changes. Finally, they tried the same original process to return the bent 3D-RAFT strip back to its original form by shining the green light at it from the opposite direction. While it ultimately worked, it took three hours of irradiation to bend the strip back, which “indicates the unfavorability of introducing stress on the opposing side of the strip by our current methods.”

“To the best of our knowledge, this is the first demonstration of the growth of new material into the surface of an existing 3D printed object using RAFT polymerization to induce a bending response,” they concluded.

“In summary, we have further developed a 3D printable RAFT resin formula with an improved build speed up to 2286 µm/hr and demonstrated its ability to undergo 4D post-production transformation. We first demonstrated a facile method for growth induced bending of 3D-RAFT printed strips which opens an alternative pathway for movement and modification of these printed objects.”

Discuss this and other 3D printing topics at 3DPrintBoard.com or share your thoughts below.

The post University of Auckland: Growth-Induced Bending of 3D Printed Samples Based on PET-RAFT Polymerization appeared first on 3DPrint.com | The Voice of 3D Printing / Additive Manufacturing.

Formlabs’ Tough 1500 Resin: Stiff, Yet Pliable

Formlabs is expanding its portfolio of 3D printing resins. The latest is Tough 1500, a stiff and pliable polymer that can bend and return to its former shape. Formlabs is targeting the material at engineers, product designers and manufacturers who need pliable parts.

In response to customer feedback, Formlabs developed Tough 1500 Resin as a middle ground between the two ends of the elasticity-toughness spectrum in Formlabs’ existing product range, which already includes durable materials on one end and elastic and flexible photopolymers on the other. Marketed applications include springs, snap fits, press fits and hinges that need to bend and rapidly bend back to shape. It can also be used for jigs and fixtures that must absorb impact and undergo continuous deflection. Formlabs also suggests that it can be used to prototype polypropylene parts.

The “1500” in Tough 1500 represents the 1500 MPa tensile modulus of the material.

One customer using the material is Unplugged Performance, which offers upgrades to Tesla cars. Unplugged Performance is currently deploying Tough 1500 parts to install carbon fiber car bumpers onto vehicles. Without 3D printing, it would take about 45 minutes to remove each sensor mount from a bumper and then another 10 minutes to attach it onto the new one. With six such sensors on a car, this process, along with the other upgrades, would take about a day-and-a-half.

Now, the firm 3D prints new sensor mounts from Tough 1500 in 30-unit batches, meaning that the old sensor mounts do not need to be removed from the old bumpers and reattached. Unplugged workers simply bond the new, 3D-printed mounts directly to the vehicles, aiding the company in improving throughput to three cars per day.

A 3D-printed prototype for a polypropylene cap.

Formlabs’ range of materials is growing slowly but steadily. By manufacturing its own photopolymers, the company is able to ensure the quality of the resins and that it works with its hardware. For hardware companies that sell their feedstock directly to their users, a continuous stream of revenue is generated. However, it also constrains the material range that users can rely on.

While companies such as Formlabs retain this razor-and-blade model, others like HP and Origin have adopted “open materials” platforms in which chemical companies work more or less directly with the hardware manufacturers to qualify their materials for use in their 3D printers. This frees up the material partners to develop their own feedstocks. The concept of open materials is being increasingly championed in a space that has previously been dominated by closed systems. Consider Jabil’s moves last year into material development, for instance.

As Formlabs continues to develop new materials, it will also have to do so for its new 3D printing technology line: low-cost selective laser sintering (SLS). The Fuse 1 3D printer should begin shipping mid-2020, at which point we will get a chance to see the material development strategy the company has for SLS powders, as well.

The post Formlabs’ Tough 1500 Resin: Stiff, Yet Pliable appeared first on 3DPrint.com | The Voice of 3D Printing / Additive Manufacturing.

Interview with Haleyanne Freedman of M. Holland Company

Haleyanne Freedman

Haleyanne Freedman is a Business Development and Engineering Professional with a demonstrated history of working in a variety of industries; she specializes in Additive Manufacturing. She has accumulated skills in application development, material specification and design for additive manufacturing. She currently is the Global 3D Printing Specialist at M. Holland Company.

Give us some background on your experience and how you got to this point?

I used to be in subtractive manufacturing. I wanted to work on machining, but I was with a company that was buying 3D Printers and then I learned more additive manufacturing. Then I got 7 3D printers on my own in my house.

M Holland

Explain what you do at M. Holland Company?

Traditionally, M. Holland Company works within the traditional manufacturing realm. They create resins. They wanted to get into the industry of 3D Printers. They then brought me in to reformulate the strategy for this particular field. We help teach engineering and design. We help molders with so much of their applications.

What are the biggest roadblocks?

Some people and organizations  in the field are focused solely on the sales and marketing. It is difficult in my position to have people marketing things in a non practical way. It forces people to give up and their expectations are now demolished. It is important to focus on things that are actually realistic.  

In terms of business development, how should classical manufacturing companies leverage 3D printing and additive manufacturing?

In our experience people have success when they educate themselves before they buy a printer. A lot of people will buy before they research. When you purchase your printer, you should allow everyone to use it. This causes all of your engineering team to not have knowledge on this. It is important for all the engineers to have skills in the actual machines. No one does this in classical manufacturing, so we should not do so in additive manufacturing. Adoption time increase when you have other people all working on printers in house. This still benefits companies in terms of future costs saved. It is important to have multiple people skilled on a technology. It must be a team effort and cross training is extremely vital. People and other organizations are also underestimating the value of 3D Printing. The companies that are saving millions are the people who have a printer on every engineer’s desk.

Women in Manufacturing

Which industries are the most open for disruption in terms of additive manufacturing?

I think custom molding is incredibly open to it. There are still companies paying 40,000 dollars per mold. Most of these molds could be created with 3D printing. It is still materials dependent. The people who buy parts must realize the benefit. Most parts need to be isotropic. There is an entire world that has yet to be put into use.

Talk about your involvement as the Vice Chair at Women in Manufacturing as well as women in 3D Printing.

I’m chairperson for Women in 3D Printing in Chicago. For Women in Manufacturing, I was concerned about why Madison, Wisconsin did not have a branch here with so many manufacturers as this is a nationwide organization. We had a huge conversation and panel discussion with various people here. We have 75 members consistently. Women in 3D Printing is new to everyone. It is a nonprofit that started a year ago. There are less people in this organization. It is more about are you in 3D printing and do you want to be in the sector.

Women in 3D Printing

How does one tackle the skills gap that is prevalent and lacking from people within diverse backgrounds?

It is really dumb that people didn’t tell me I could be in manufacturing as a child. I think that is wrong. People brush manufacturing off as a dirty industry. It is a nice, lucrative, and non-dirty industry. It is useful for all people. The skills learned in this sector are great and they translate to different areas of career growth. We have to change our minds on what people can do. We should not be limited in our abilities.

What are those barriers to access?

In my mind a lot of them are starting to change. There are a lot of 3D Printers in highschools. You can buy a 3D Printer for a cheaper means. I can see things change due to the fact that this technology is tangible. Mindset is the biggest one. The physical nature of this is changing everyday.

The BIG IDEAS for UV + EB Technology Conference is the Place to Learn About Photopolymers and 3D Printing

The Radtech BIG IDEAS for UV+EB Technology conference takes place on Tuesday, March 19th and Wednesday, March 20th in Redondo Beach California. The BIG IDEAS for UV+EB Technology is the place to learn about advances in photopolymer material development for 3D printing and Additive Manufacturing.

By being specialized and focused on UV curable materials, this two-day conference is the one place in the world to find out what is happening in UV curable 3D printing technologies. This is the most efficient way for you to in one to be up to speed with the current state of UV curing in 3D Printing. All of the critical leaps in photopolymer technology from new materials to new industrializations of products and new applications will be discussed here. You can learn from companies such as Ford, Carbon, Formlabs, Fast Radius, Origin, Sartomer, Allnex, NIST, and more. At the conference, you can also learn directly from exhibitors, other attendees, and of course the speakers. The technologies Inkjet, stereolithography, DLP as well as emerging technologies will be covered.

Some speakers will include Darryl Boyd, of the US Naval Research Lab who will talk about “Photopolymerization of Thiolyne Polymers for Use in Additive Manufacturing.” While Ali Khademhosseini of UCLA will discuss “Light-Enabled Materials for Regenerative Engineering.” Ellen Lee, of Ford, will talk about, “Driving Additive Manufacturing Towards Production of End-Use Parts.” You can have a look at the complete program here.

Dr. Mike Idacavage is the Session Chair for Additive Manufacturing at the conference. We reached out to him to find out what is happening in the UV curables for 3D printing space.

Who are you looking to reach?

“We are looking to reach anyone within the entire photopolymer supply chain that is looking for a big idea in materials and processing to transition their SLA, DLP, and inkjet 3D printing from prototyping to production parts. We want the chemistry suppliers, material developers, equipment builders, and users of 3D printing and additive manufacturing to work together to build a stronger photopolymer supply chain and this is done through sharing big ideas.”

Is there anything unique or special about the conference?

“While many other 3D printing and additive manufacturing conferences focus on all the different printing processes, we focus only on photopolymer materials, and we bring together the experts and industry leaders to discuss big ideas. It is this deep dive into the science and applications of photopolymer 3D Printing/Additive Manufacturing that makes the BIG Ideas conference unique when compared to just about any (all?) other conferences in this field.”

What makes photopolymers exciting right now?

“Like most areas of chemistry, research on expanding the boundaries of what photopolymers can achieve has been steadily moving forward. However, what has accelerated the rate of development in photopolymers has been the demands of a wide range of industrial applications. Due to the tremendous pull of new applications, including Additive Manufacturing, Raw Material supply companies have focused on pushing the performance of photopolymers to meet the needs of the end user.”

What are the advantages of printing with photopolymers?

“Several advantages differentiate the use of photopolymers as a base material in 3D Printing from other methods. One f the most significant is that objects printed using photopolymers are typically stronger in the Z directions. During 3D printing using photopolymers, a chemical reaction takes place in the confined area where the UV energy interacts with the UV curable raw materials. The increased strength results from chemical bonding that takes place between the printed layers. As most objects printed by Additive Manufacturing require strength that is at least comparable to objects made by traditional methods such as injection molding, the increased strength in the Z direction is important. Another advantage in the use of photopolymers is the increase in resolution that results from focusing a very narrow region of UV energy in a liquid resin formulation to start the formation of a solid photopolymer. This gives a higher level of layer resolution than other more common forms of Additive Manufacturing such as FDM or SLS. There have been published reports of resolution in the nanometer scale using photopolymers in academic labs. While this is not yet practical in industry, it does indicate the potential for photopolymers. A third advantage is a result of the higher resolution. When properly tuned with the printer, an almost smooth surface can result which minimizes or eliminates any need for surface finishing of the printed object.”

What are some exciting developments in photopolymers?  

“In my opinion, the two most exciting areas of photopolymer development work are improvements to the raw materials used in the resin formulations and work being done in formulation labs to creatively combine different chemistries to achieve performance not yet obtainable from a single class of UV reactive materials.”

Are materials improving?

“Yes! Most raw material manufacturers are investing research time in the development of new materials that extend the performance of the fully cured photopolymer. An example of this is the current work being done by different companies to produce a liquid UV curable material that is both tough and flexible after cure. This target is extremely challenging, but results are being reported at conferences such as Big Ideas that clearly show that the cured performance properties are being expanded to the levels required by end-use.”

What kind of new manufacturing applications do you see emerging in 3D printing photopolymers?

“The majority of the current efforts in photopolymer Additive Manufacturing are focused on targeting industrial applications where individual/single or short manufacturing runs are needed. In addition, the performance of the object in the application requires properties currently obtained by bulk polymers using traditional manufacturing methods such as injection molding. Examples of the marriage between individual production of an object that must perform in the field and customization would be in the automotive industry in the custom replacement of hard to get parts, the shipping industry in preventing idle time of trains/ships by quickly making a replacement part and the electronics industry in the custom manufacture of earphones.”

Would you like to learn more? See all of the exhibitors, scheduled talks and pricing information on the Radtech BIG IDEAS for UV+EB Technology Conference here.

Plant-Derived Photoinitiator Free Resins as Alternatives to Petroleum-Based Photopolymers

In a paper entitled “Photoinitiator Free Resins Composed of Plant-Derived Monomers for the Optical µ-3D Printing of Thermosets,” a group of researchers discusses their investigation of acrylated epoxidized soybean oil (AESO) and mixtures of AESO and vanillin dimethacrylate (VDM) or vanillin diacrylate (VDA) as photosensitive resins for optical 3D printing without any photoinitiator and solvent. Natural oils like these, according to the researchers, are some of the best alternatives to petroleum-based resins.

UV/VIS curing tests were performed on pure AESO and two resin series: AESO/VDM and AESO/VDA. Chemical structure analysis was also performed, as well as Soxhlet extraction, differential scanning calorimetry, thermogravimetric analysis and mechanical testing. The researchers then experimented with the resins using direct laser writing 3D lithography.

“It is known that the acrylic group is more reactive than methacrylic,” the researchers state. “This explains the increase of the induction period and tgel value during the photocross-linking of the resin series AESO/VDM in comparison to AESO. Additionally, the slope of the G’ curve of AESO was steeper than that of the resin series AESO/VDM indicating the quicker formation of the polymer network [50]. High G’ values indicate better mechanical properties of polymers caused by the high density of cross-links. Thus, the higher G’ values of AESO indicate the higher density of cross-links in this polymer (pAESO).”

The researchers discovered through their experiments that AESO tends to form densely cross-linked polymers even without photoinitiators. AESO and AESO/VDM1, they add, can be “great candidates” as renewable materials for DLW 3D lithography.

“It is envisaged that the photostructuring without the photoinitiators is beneficial for the fields of biomedicine, micro-optics and nanophotonics,” they continue. “The avoidance of toxic photoinitiators increases the integrity of biodegradable cell-growth scaffolds and reduces the auto-fluorescence while performing microscopy in vitro or in vivo. The absorbing materials are detrimental for the use in micro-optics and nanophotonics due to their reduced optical resilience and induced signal losses. Moreover, the use of plant-derived materials in such technologies would benefit greatly due to their low toxicity, high biodegradability, and improved recycling options. Finally, it would reduce the dependency on limited and increasingly expensive fossil resources as well as greenhouse gas emission, which are the targets of the European Commission initiated ‘Europe 2020’ strategy.”

The researchers’ real-time photorheometry study “revealed the higher rate of photocross-linking of pure acrylated epoxidized soybean oil than that of its mixture with vanillin dimethacrylate or vanillin diacrylate without a photoinitiator and solvent.” The addition of vanillin dimethacrylate reduced the rate of photocross-linking the values of the glass transition temperature, thermal decomposition temperature and compressive modulus.

“The formation of more linear and/or branched macromolecules considered the vanillin dimethacrylate effect as a plasticizer for acrylated epoxidized soybean oil in photocross-linking without a photoinitiator,” the researchers conclude. “It was experimentally demonstrated that the homopolymer of acrylated epoxidized suitable materials for rapid 3D microstructuring by the direct laser writing lithography technique.”

Since photoinitiators can cause skin irritations and long term contact allergies in people working with them in liquid form, this may be a very good development for those who process DLP and stereolithography parts. Perhaps it would be safer in the final part as well. Any developments in 3D printing materials can now make all existing compatible materials safer and perhaps less expensive so these kinds of developments have to be applauded.

Authors of the paper include Migle Lebedevaite, Jolita Ostrauskaite, Edvinas Skliutas and Mangirdas Malinauskas.

Discuss this and other 3D printing topics at 3DPrintBoard.com or share your thoughts below. 

 

New UV-Curable Engineered Resins for 3D Printing

The rapid growth of 3D printing has challenged manufacturers to find materials that enable the advanced properties needed to support new performance demands. To help additive manufactures move beyond this challenge, Arkema offers market-leading solutions in photocurable resins and high-performance thermoplastic polymers for the 3D printing market.

Led by its flagship brands including N3xtDimension® liquid resins, Rilsan® biosourced polyamide 11, and ultra-high performance Kepstan® PEKK polymer, Arkema’s product offering spans all major 3D manufacturing technologies (UV curing, powder bed fusion, filament extrusion) in partnership with all of the market’s major equipment manufacturers. Seventy-five percent of Arkema’s active product development is with its partners.

      1. Liquid Resins for UV-Curing
      2. Sartomer, a business unit of Arkema, has developed the N3xtDimension® line of UV-curable 3D printing resins. These specialty liquid resins for 3D printing processes help additive manufacturers yield thermoplastic-like mechanical properties materials, ultra-high resolution, wavelength independency and enhanced processability. They also fulfil performance and regulatory requirements for a wide range of industrial uses in medical, dental, electronics and sporting goods applications. N3xtDimension® resins are ideal for multi-jet printing (MJP), stereolithography (SLA), digital light processing (DLP) and binder jetting (BJ) 3D printing technologies.

N3xtDimension® engineered liquid resins for UV curing enable a dedicated performance like impact resistance, flexibility, elastomeric recovery, water solubility, castability or prototyping; together with overall improved properties.

Sartomer Europe will introduce three new N3xtDimension® engineered liquid resins at the upcoming Formnext Show in Frankfurt, Germany:

  • N3D I-2105 Impact resin imparts excellent impact resistance to 3D-printed materials. It enables the manufacturing of functional parts such as snap-fit buckles.
  • N3D F-2115 Flexible resin achieves different flexibilities depending on the post treatment applied. Its elongation at break and modulus are fine-tunable to reach the desired set of properties such as elongation, tear resistance and Shore A hardness.
  • N3D P-2125 Prototyping resin exhibits a homogeneous network, enabling an excellent processability and limited evolution of mechanical properties after post-curing.

N3xtDimension® custom liquid resin systems

3D printing wax jewelry engagement ring 3d model on a white isolated background with shadow

The N3xtDimension® line also includes custom liquid resin systems developed from a novel selection of oligomer and monomer resins to address key market needs for end-use applications. These tailor-made solutions for UV-curable additive manufacturing enable freedom of design and customized properties such as impact resistance, resolution, flexibility, processability, toughness and clarity.

3D Printing Center of Excellence

As part of its commitment to 3D printing innovation, Arkema recently opened its 3D Printing Center of Excellence at the Sartomer Americas headquarters in Exton, Pennsylvania (USA). The center is an advanced R&D lab where Sartomer and its partners develop cutting-edge 3D printing resins through advanced materials research and collaboration. This center is part of Arkema’s worldwide R&D network dedicated to the development of advanced materials for additive manufacturing, including research centers in King of Prussia, Pennsylvania (USA) for filament extrusion technologies and Serquigny (France) for powder sintering technologies. In addition, Arkema has announced new production capacities for PEKK resins in the United States in 2018, photocure resins in China in 2019, and polyamide 11 biosourced resins in Asia in 2021.

Conclusion

Success in additive manufacturing applications requires new material development and close partnerships. Customized, engineered resins and chemist-to-chemist support give additive manufacturers the technological and market edge they need to be at the forefront of 3D printing innovation.  Arkema will showcase its material offerings at Formnext 2018 in hall 3.1, booth H58.  Arkema experts will be available to discuss how materials offerings can be customized to specific applications.

Sumeet Jain, Global Director for 3D Printing Business, Sartomer