PET-CF vs PETG-CF: Differences in Performance and Applications

In the world of 3D printing filaments, PET-CF (Polyethylene Terephthalate Carbon Fiber) and PETG-CF (Polyethylene Terephthalate Glycol Carbon Fiber) are often compared due to their similar names.

However, these materials differ significantly in their chemical properties, performance characteristics, and ideal applications. Let’s dive into the key differences and explore why PET-CF stands out as a premium material for demanding use cases.

PET-CF is a blend of polyethylene terephthalate (PET) and carbon fiber, while PETG-CF is a blend of glycol-modified polyethylene terephthalate (PETG) and carbon fiber.

The key difference is the addition of a glycol modifier to the base polymer, making PETG-CF less stiff but easier to print and more transparent. PET-CF, on the other hand, is stronger, more temperature resistant, and dimensionally stable than PETG-CF, though it is more expensive.

The Chemistry Behind the Performance

At the heart of their differences is the molecular structure of PET and PETG:

（Image from Xueqiu.com）

These structural differences affect their performance, especially when combined with carbon fiber reinforcement.

PET’s crystalline structure enhances its fiber bonding, offering better load transfer and mechanical reliability, while PETG struggles under high temperatures due to its amorphous nature.

 Mechanical Properties: Why PET-CF Excels

Siraya Tech Fibreheart PET-CF Filament

Carbon fiber enhances the strength and stiffness of both PET and PETG, but PET-CF’s molecular structure amplifies these benefits.

Key Advantages of PET-CF:

• Superior Strength and Stability: PET-CF maintains mechanical integrity under prolonged loads and high temperatures, unlike PETG-CF, which softens beyond 70-80°C.

• Exceptional Dimensional Stability: PET-CF exhibits minimal warping and shrinkage, making it ideal for precise parts.

• Enhanced Layer Bonding: PET-CF's molecular design ensures better interlayer adhesion, resulting in stronger, more reliable prints.

• Heat Resistance: Higher heat deflection temperatures (HDT) make PET-CF suitable for high-temperature applications.

Comparison of Mechanical Properties:

Applications: Where PET-CF Shines

Thanks to its outstanding performance characteristics, PET-CF is the material of choice for industries requiring reliability and precision.

Ideal Applications for PET-CF:

• Aerospace: Lightweight, high-strength components for drones and UAVs.
• Automotive: Heat-resistant under-hood parts and structural components.
• Industrial: Durable tools, jigs, and functional prototypes.
• Consumer Goods: High-performance sports equipment and protective gear.
• Robotics: Strong, precise parts for automation projects.

To explore this subject in more depth, read our article, PET-CF vs PETG-CF: Understanding the Key Differences in Performance and Applications, and compare their strengths side by side.

While PETG-CF is sufficient for less demanding tasks, PET-CF is indispensable for applications where mechanical reliability, heat resistance, and dimensional accuracy are critical.

Cost vs. Value

PET-CF is usually 20-30% more expensive than PETG-CF (price depends on supplier and carbon fiber content). Although PET-CF is more expensive than PETG-CF, the performance benefits justify the investment:

• Performance Advantages: PET-CF delivers higher strength, better stability, and superior heat resistance.

• Manufacturing Benefits: PET-CF minimizes warping, offers better layer adhesion, and produces more consistent results.

• Long-Term Savings: With improved durability and reliability, PET-CF reduces the need for replacements, saving time and costs in the long run.

Printing Recommendations

To achieve the best results with these materials, follow these printing guidelines:

PET-CF Printing Tips:

• Drying: PET-CF has low moisture absorption but should still be kept dry to maintain optimal performance.

• Environment: A controlled printing environment is recommended for dimensional accuracy.
• Layer Bonding: PET-CF offers excellent layer adhesion, reducing the chance of delamination.

• Warping: Minimal warping makes PET-CF ideal for precise and complex designs.

PETG-CF Printing Tips:

• Simplicity: PETG-CF is easier to print but less consistent in mechanical performance.

• Warping: More prone to warping compared to PET-CF.

• Moisture Sensitivity: PETG-CF absorbs more moisture, requiring careful drying before use.

Final Thoughts

While PETG-CF remains a valuable material for general applications, PET-CF stands out as the superior choice for demanding projects requiring high strength, stability, and heat resistance. Its higher cost is offset by enhanced performance, durability, and reliability, making it an essential investment for engineers, manufacturers, and 3D printing professionals working on critical applications.

For those seeking the best performance from their 3D printed parts, PET-CF’s combination of strength, precision, and heat resistance makes it the clear winner.

If you want to unlock even more potential from your prints, check out our guide, Guide to Annealing Siraya Tech PET-CF: Enhancing Performance Through Heat Treatment, for practical tips.

Frequently Asked Questions

Is PET-CF the same as PETG-CF?

No, PET-CF and PETG-CF are not the same. PET-CF is carbon-fiber-reinforced polyethylene terephthalate, while PETG-CF is carbon-fiber-reinforced glycol-modified PET.

The glycol modification in PETG makes it easier to print but slightly less heat-resistant and mechanically strong compared to PET. PET-CF, on the other hand, offers higher stiffness, durability, and heat resistance, making it better suited for demanding applications.

Is PET better than PETG?

Whether PET is better than PETG depends on the application. PET generally provides higher heat resistance, strength, and dimensional stability, making it ideal for functional or load-bearing parts.

ETG, however, is easier to print, less prone to warping, and more forgiving for hobbyist use. In short, PET is preferred for performance, while PETG is often chosen for ease of use.

What is stronger, PLA CF or PETG?

PLA CF (carbon-fiber-reinforced PLA) is stiffer and can feel stronger in terms of rigidity, but it is more brittle and less impact-resistant. PETG, while not as rigid, provides better toughness, impact resistance, and temperature tolerance.

For structural parts that need durability and resilience, PETG typically outperforms PLA CF, especially in real-world applications.

Is PET-CF good for outdoor use?

Yes, PET-CF is generally well-suited for outdoor use. The base PET material has good resistance to moisture, UV exposure, and higher temperatures compared to PETG.

When reinforced with carbon fiber, PET-CF gains improved stiffness and dimensional stability, making it reliable for outdoor parts such as brackets, enclosures, or mechanical components exposed to the elements.

What is the difference between PET and PETG thermoforming?

The main difference lies in processing behavior and end-use properties. PET thermoforms into strong, clear, and highly stable parts but requires more precise temperature control during forming.

PETG, due to its glycol modification, is easier to thermoform, less prone to crystallization, and allows for more complex shapes without cracking. However, PET typically results in stronger and more heat-resistant finished parts.