Expert Interview: Oxford Performance Materials’ Scott DeFelice on the Evolution of High-Performance Polymers for 3D Printing 

While general-use polymers, like ABS and nylon, currently dominate the 3D printing materials market, there is a growing demand for strong, functional materials that can withstand harsh environments and high temperatures. 
 
These materials, known as high-performance polymers, are increasingly sought after by 3D printing users in industries such as aerospace and medical. 
 
The key high-performance polymers currently available for 3D printing belong to the Polyaryletherketone (PAEK) family of thermoplastics, offering high-temperature stability and great mechanical strength. 
 
Only a few companies on the market are currently developing such materials, one being Oxford Performance Materials (OPM). 
 
Based in Connecticut, OPM is particularly focused on the PEKK material of the PAEK family and has developed proprietary technology and devices around that thermoplastic. 
 
To learn more about OPM and its offerings, we’ve caught up with the company’s CEO, Scott DeFelice. With Scott, we’ve discussed key applications for 3D printed PEKK, as well as trends and challenges shaping the 3D printing materials market. 
 

Can you tell me a bit about Oxford Performance Materials and your mission as a company?

 
Oxford Performance Materials was founded in 2000. We’re a high-performance thermoplastic materials company. We’ve spend all of our time on one particular polymer called Poly Ether Ketone Ketone or PEKK. And since 2000, we’ve been developing technologies around this material.

 
PEKK is the top of the food chain thermoplastic in the thermoplastic world. It’s a super high-performance polymer because of its excellent thermal, chemical and mechanical properties and biocompatibility.
 
Today, we have a broad portfolio of intellectual property and patents that go from how one makes PEKK at a synthetic level to how one processes it, prepares powders for 3D printing, to how one prints with the material.
 
In terms of 3D printing, our activities started around 10 years ago with the development of a selective laser melting process to 3D print with PEKK. We launched our first commercial 3D-printed devices around 2006 for the medical field. And that was the beginning of 3D printing development. 
 
In 2008, FDA cleared our first device, a cranial implant, which are patient-specific and distributed worldwide by Zimmer Biomet. We have ongoing production making cranial and facial implants every day. 
 
We moved from there to spinal implants over three years ago, and those products are sold in partnership with a company called RTI Surgical. We’ve shipped over 70,000 spinal implants to date. 
 
Most recently, we’ve received another FDA clearance in a sports med application for suture anchors, used to surgically reattach soft tissue to bone. 
 
In parallel to this, we developed and validated our technology for use in space and defense applications and received certification by Boeing and Northrop Grumman, among others. Since then, we sold that business to one of our strategic partners, Hexcel, which has a substantial scale to support it. 
 
OPM is coming at the 3D printing business, not from the point of view of people who were, say, in prototyping and then moved into production parts. We’re coming at it from the point of view of an advanced materials company who found that their material would be very good for additive manufacturing, due to interesting technical reasons. We’re now vertically integrated into those businesses and continue to exploit our materials and technology platform.
 

How do you see the 3D printing material space has developed over the years, and where you see that trajectory going in terms of material costs and materials development? 

 
3D printing is a process, and what makes that process unique and enabling is the material that’s used with it. I always tell people that you can print an apple, but then you have to eat it. So you have to print with materials that have the functionality for the end markets and end uses of interest. 
 
We’ve seen how over the years, for example, metal AM has become very popular for the reason that it has functional properties that are useful in specific end markets. 
 
I think this trend is going to continue. Materials – polymeric, metallic and others – will continue to evolve to allow for greater functionality in the end-use markets, regardless of what those markets are. 
 
The interesting thing about cost is there’s always been this ‘Oh, the materials are too expensive’ discussion. I argue that as you move into higher performance end markets and materials become more capable, the materials costs themselves actually become less significant. 
 
For example, we’re selling orthopaedic implants and when we sell a cranial implant at the hospital that implant may sell for $10,000. But when we look at the cost of what we do, the material cost is actually a fairly small component of cost. The rest of it is all the quality and the regulatory, the manufacturing systems that one has to have in place to sell into a highly regulated marketplace, whether it’s a biomedical or space and defense or semiconductor. 
 
So, as the industry continues to evolve away from the production of prototypes toward end-use products, the performance of the material is what’s critical and the component of material cost becomes less of a driver.
 

Could you expand on other industries, in addition to medical, that are able to benefit from the materials that you develop for 3D printing?

 
We started in the obvious places, biomedical and aerospace, because we have a long legacy in our business of servicing those markets. But now we’re getting our head up and looking around at other areas. 
 
The end markets are very particular to the performance of our materials. Our PEKK material, for example, loves acidic and base environments, so that’s where we go in terms of the environment. So one area that we’re tracking pretty closely is, for example, carbon capture. 
 
Carbon capture is a technology that works today, but the capital cost of those plants are too expensive. 
 
So we looked at that area and there’s lots of opportunity for our materials and 3D printing in that space. Shortly we’ll be announcing a collaboration with one of the US’s leading government labs in that area. 
 
We also like the pharmaceutical process and bioprocess areas where you want a material with the right attributes of our polymer to improve process efficiencies and reduce capital costs. 
 
Obviously with COVID-19 situation right now, there’s a need to scale some of these processes and you need to have a lot of complex structure and the right high-purity chemistry to practice in that space. We’re tracking that pretty closely as well. 
 
The Polyketones class of polymers does some very interesting jobs. 
 
We’ve spent many millions of dollars understanding the performance of our 3D-printed parts. That’s why our parts are flying manned spacecraft, that’s why we have thousands of parts in the human body. It’s because we did the exhaustive work of characterising what we print to the comfort of people who take very seriously what these structures are doing in practice.
 

What does that process of developing and testing material for 3D printing look like?

 
There are generally two parts. When we develop material and a process, we go through an internal assessment, which generally goes from analytical methods that we’ve developed over the years to fairly conventional mechanical, thermal, electrical screening tests that are done at a development level. 
 
Once you have the baseline and say ‘Yes, this is a reproducible product and we understand it’, it gets you to first base. 
 
Then to get home, you have to go in every industry, whether you’re printing or molding or machining or whatever your process technology is. Every industry has known ways for them to understand performance, whether that’s an ASTM standard, an ISO standard or a company-specific standard, or a government standard. 
 
We have a good example in the aerospace industry. After we did all that work and ensured that we had a stable and repeatable process, we then had to do something that was a MIL 17 standard that results in a statistical assessment of performance at very high predictability, and that’s called the B-Basis. 
 
But that program alone ran multiple years and required millions of dollars. We did that in collaboration with NASA and Northrop Grumman, and so it was a fairly exhaustive industry-specific assessment. 
 
In biomedical, if we take the case of our spinal implants, it first went through an exhaustive series of ISO 10993 tests which really assess biocompatibility and purity. Once you check that box in ‘Okay the material as printed is pure and biocompatible, not toxic’ then now we want to use it in a spinal implant. 
 
There’s a whole other series of mechanical tests as a part of ASTM F2077 standard that are specific to spinal implants. When you get through that, then you can make a submission to the FDA with that data. 
 
So, you have to first do your own internal testing to get comfortable, because these other test regimes are very expensive. And you don’t want to do that unless you have great confidence you’re going to pass those tests. 
 
That goes for every end market, especially in our class of materials. For technical materials, the standards are lower because the risk associated with the end-use adoption is lower.
 

It’s known that polymers are used to replace metals in certain applications. Can you share examples of how high-performance polymers have been able to replace metal materials? 

 
Going back 30 years ago, we’ve seen a steady advancement of polymeric materials replacing metal.  If you were buying a car in the 1970s, cars weighed twice what a car weighs today and most everything would be metal, or if you bought a vacuum cleaner, it would have been made of metal. 
 
Now if you get those things, they total a fraction of the weight and they’re mostly plastic. So this trend of polymers replacing metals for various functionality is very well established.
 
3D printing is just another process whereby you’re able to replace metals and the reasons for replacing metals are cost, weight and corrosion. 
 
We’re continually looking for metal replacement opportunities to reduce costs for people, reduce weight and improve the efficiency of devices. Good examples of that are spinal cages, fusion devices that fuse your spine together if you have chronic pain. 
 
These devices had historically been made out of machined titanium and now we’re printing them with PEKK.
 
Another example is cranial implants being made out of 3D-printed titanium. Today, we’re making them out of 3D-printed PEKK. 
 
As we look at some of the stuff in carbon capture, that’s exactly what we are looking at now: replacing very expensive machined stainless steel or titanium with 3D printed PEKK. 
 
So this idea of switching from metals to polymers has been a megatrend in the industry for quite some time. It’s been accelerating over the last years and 3D printing is now a part of that larger story, including area such as oil & gas and transportation, where we have early stage development projects underway with industry partners.
 

Speaking of trends, do you see any trends in the 3D printing materials space?

 
In the metallic side, we’re seeing people trying to drive metal AM to more known and predictable morphologies. 
 
I don’t want to get too technical, but 3D printing metal is not the moral equivalent to raw, or forged, or cast metal. It’s a different beast. 
 
When the industry first became very popular, there was a lot of confusion around that. Over time people have realised that it’s a different animal. And now, they’re working towards the material and process technologies that make metal AM more conventional in some way. I think it will significantly advance metal AM. 
 
On the polymer side, now there’s the general tendency to service end markets with polymer AM. The two dominant materials for this are Nylon 11 and Nylon 12. These are technical materials, and they are in the middle of the polymer pyramid. 
 
However, they have limited end-use. They’re not particularly thermally or mechanically robust. 
 
Now people are starting to figure out how to move up the pyramid. We’re starting to see companies like BASF introducing Nylon 6, which buys a bit more performance. 
 
I think we’ll continue to see that trend of more materials appearing to fill in between where OPM is with PEKK and other materials in the middle of the performance pyramid. 
 

As a flip side to that, what are some of the challenges you see still facing the 3D printing materials sector?

 
This is a fundamental question. 
 
When we started looking at 3D printing many years ago, one of the things we looked at was does our polymer have the basic attributes to be 3D printed? And that question comes down to the recognition that 3D printing is a zero pressure consolidation process. 
 
When you’re moulding a polymer, you mush it into a mould and you squish it all together and get this consolidation. This results in predictable performance and good mechanical properties. 
 
3D printing doesn’t have that virtue. With 3D printing, you have this low-pressure consolidation or zero pressure consolidation like an FDM process where you have a filament that gets melted and laid on top of each other. In that process, you end up with up to 10 per cent voids, and in my world voids are bad, because they mean a part isn’t robust. It’s great for a prototype but you’re not going to want to hang from it. 
 
Then you have these powder bed processes like OPM’s, where lasers are melting one layer of powder on top of another, but there’s no pressure. What you rely on to get repeatable performance in these types of environments is a polymer that likes to stick to itself. 
 
If a polymer doesn’t bond well, you end up with poor performance in the Z direction. 
 
PEKK is really unique in that because it has the affinity to stick to itself. That’s pretty unusual in the polymer world. 
 
To answer your question, what has held things back has been the development of fundamentally new chemistry. 
 
If you go to one of the big chemical companies today and say, ‘Could you develop a polymer specifically for this ability to stick to itself?’ They’re gonna look at you funny because you’re in the billion-dollar range and a number of years to develop new polymers. It’s a big deal. 
 
If you went and asked a polymer company consultant how many truly new chemistries have been developed in the last 20 years, you probably put it on one hand, because those investments are so substantial. And corporate America just doesn’t have the appetite for that stuff too often. So it is a big challenge and I don’t see a lot of that happening, frankly.
 

Do you think that will change or evolve in the months and years to come? 

 
New material platforms based upon novel new chemistry? I don’t think that’s going to happen. That’s very remote. 
 
Process technologies will advance and people will modify those existing material sets with other unique fillers and compatibilizers and sizing chemistries to improve things. So I think that’s probably where things will get more interesting.
 

What does the year ahead hold for OPM?

 
We’re pretty fortunate that we’re in a part of this industry, where we’re not relying on R&D contracts or venture capital at this point. 
 
We’re in the part of the “need economy”. 
 
Though we’ve seen as we’ve gone through this first phase of the COVID pandemic hospital availability dropped to service and away from elective surgery, we’re already starting to see that business start to come back. 
 
It’s been painful for every business, but the core technology we have will allow us to continue to grow. We’re just now introducing our suture anchor product, which is a new lower cost product line, and  even given COVID we’ll have opportunities to bring that to market.
 
We also have our heads up on new markets. We like the carbon capture market, other industrial areas, and the biopharma process market.
 
I think COVID-19 in some ways drives more capital and demands more efficiency towards the markets that we’re naturally suitable for, given the performance of our materials.
 

Any final thoughts?

 
The only thing I’d say is that this particular time does have substantial opportunities.
 
I think as a company in 3D printing, we’ve been trying to push technologies that truly add value. When times are challenging and tight, like they are now, people are starting to look for ways to reduce costs and penetrate new markets. CEOs are going to their CTO saying ‘Hey, what do you have for me? We need something new’.
 
So if you really have something substantive, not just another way to make a prototype, if you have something that bends the arc of technology in a substantive way, you’re going to get a good listen-to now. 
 
We’ve seen that in our business where some doors we’ve knocked on in the past, people weren’t ready to hear it. And we’re starting to get those callbacks now that say ‘Hey, tell us about that thing where we can save some money or do something more efficiently’. 
 
So I would encourage readers to not be despondent if they have real technology. It really changes the game. This is an interesting time.