The 3D printing industry is full of everything from delusional hype to realized productivity gains, and everything in between. BUT the recent advancements in both materials and hardware has made 3D printing less hype and more productive for industrial applications.

Today I’d like to discuss high performance polymers and how their exceptional material properties are helping to advance industrial 3D printing. In this exploration, we'll compare five different materials, each representing distinct categories of polymers. We will compare each material based on stiffness, strength, chemical resistance, and high temperature behavior in order to illustrate the advantage of using these polymers.

Materials Overview

1. ABS Plastic - The Standard

ABS plastic is an amorphous polymer that is the benchmark standard for standard plastic components. Its versatility and familiarity make it a common choice for various applications.

2. Neat PA (Nylon) - Engineering Excellence

Nylon, an engineering grade plastic material, brings a unique set of properties to the table. Its semi crystalline structure gives it strength and durability which sets it apart in the realm of 3D printing.

3. Onyx (PA with Chopped Carbon Fiber) - Reinforced Engineering

The chopped carbon fiber in the Markforged Onyx material enhances its material properties, providing a significant boost to stiffness and provides an exception surface finish.

4. VEGA (PEKK + Chopped Carbon Fiber) - Semicrystalline Excellence

VEGA combines PEKK, a semicrystalline high-performance thermoplastic,  with chopped carbon fiber, showcasing exceptional stiffness and strength at high temperatures.

5. PEI (Ultem) - Amorphous High Performance

Ultem, an amorphous high-performance thermoplastic material, balances strength and versatility. Its amorphous structure sets it apart in the world of high-performance polymers.

Comparing Material Performance

Amorphous vs. Semicrystalline Polymers

Understanding the differences between amorphous and semicrystalline polymers helps to know when and how to use different materials. Amorphous polymers, resembling a soup of random polymer chains, are generally more flexible but lower chemical resistance. Semicrystalline polymers, with neatly arranged crystal structures, provide higher tensile modulus and enhanced chemical resistance.

Key Performance Metrics

When selecting a plastic material for an engineering application there are hundreds of potential factors to influence the designer's choice, but for general comparison purposes we will use the four most common material properties.

• Stiffness: pull a sample and measure how much it moves as the stress changes. Tensile modulus, measured in MPa, used as a metric.
• Strength: the maximum stress that a material can withstand when subjected to a force. Ultimate tensile strength, measured in MPa, used as a metric.
• High Temperature Behavior: how a given material’s physical properties change when exposed to elevated temperatures. Heat deflection temperature (D648 B), measured in ℃ used as a metric.
• Chemical Resistance- a relative rating of how the different polymers withstand exposure to common chemicals. A weight average score for a polymer's resilience to 10 classes of chemicals and environmental exposures used as a metric. Source.

Stiffness

Based on the chart above we can notice a few things.

• Amorphous polymers, ABS and Ultem, are less stiff than their semi crystalline counterparts nylon and VEGA(PEKK).
• Adding chopped fiber fill to Nylon yields a significant increase in tensile modulus
• VEGA (PEKK+chopped carbon fiber) shows clear stiffness advantage with more than 2X Onyx.
• Ultem can provide high stiffness performance, comparable to Onyx, but with pure polymer composition.

Strength

Based on the chart above, we notice a few things about how different polymers perform when tested for their strength.

• Adding a chopped fiber fill  to nylon makes no significant impact on UTS.
  • The same is true for PEKK and VEGA, although PEKK is not shown here.
• Ultem and VEGA, both being high performance thermoplastics, show clear strength advantages.
• VEGA again dominates the material property comparison with nearly 1.4X the UTS value compared to its nearest competitor.

High Temperature Performance

Based on the chart above, we notice a few things about how different polymers perform when exposed to elevated environmental conditions.

• Amorphous polymers perform better than the neat composition of their semi crystalline counterparts.
• Adding a chopped fiber fill to nylon provides Onyx with a 3.5X increase in HDT.
• High performance polymers like Ultem and VEGA, are the only option for applications where parts will be exposed to 150+℃ conditions.

Chemical Resistance

A chemical resistance study of 48 common polymers was conducted with 10 classes of chemical and environmental exposures. Thermoplastic polyimide, the stuff Kapton tape is made from, is the king polymer of chemical resistance with a score of 100% resistance.

The chart above shows how the 5 polymers we are discussing compare in chemical resistance to polyimide as a percentage. There are two main takeaways here.

• Semi-crystalline polymers perform better than amorphous
• PEKK (VEGA) again dominated the comparison with a score of 90%

Cost Considerations

There is no such thing as a free lunch! The extreme performance of the VEGA material comes at a literal price. For applications that require a combination of incredible material properties and great chemical resistance it really is the only choice. Although, that does mean you probably won’t be printing that 300% Benchy you have always wanted out of VEGA.

While ABS remains the most economical choice, Onyx strikes a balance between cost and stiffness. Ultem stands out for high-temperature and high-strength applications at a reasonable cost.

Conclusion

As we navigate the landscape of high-performance polymers in 3D printing, the possibilities are vast. Choosing the right material depends on a careful consideration of specific application requirements. Whether it's the affordability of ABS, the engineering excellence of Nylon, or the high-performance capabilities of VEGA and Ultem, each material brings something unique to the table. As Markforged continues to expand the capabilities of the Digital Forge, the future of 3D is full of productivity and less hype .
If you have questions about what material is right for your application don’t hesitate to contact our team of additive engineers for help selecting the right material and process for you.