Acrylonitrile Styrene Acrylate (ASA) and Polyethylene Terephthalate Glycol (PETG) are two popular thermoplastic materials used in 3D printing. Both are available from a variety of manufacturers at a low cost, and both can be used on low-end hardware. ASA vs PETG therefore comes down to other factors.

ASA is a variant of Acrylonitrile Butadiene Styrene (ABS), another common 3D printing material. It offers improved weather resistance over ABS, making it suitable for outdoor applications. On the other hand, PETG is a modified version of PET, one of the most commonly used plastics in the world. It combines the durability of PET with the ease of use of other materials like PLA, making it a versatile choice for 3D printing.

This article aims to provide a side-by-side comparison of ASA vs PETG, exploring their properties, respective advantages, and applications in 3D printing. This information will provide a comprehensive understanding of these materials, enabling you to make an informed decision when choosing between ASA and PETG for your 3D printing projects.

Introduction to ASA

ASA is used for outdoor parts like roof vents

Acrylonitrile Styrene Acrylate, commonly known as ASA, is a variant of Acrylonitrile Butadiene Styrene (ABS), a widely used plastic in manufacturing. ASA was developed as an alternative to ABS to overcome some of its limitations, particularly its poor UV resistance.

ASA is produced through a process called graft polymerization. This process involves three monomers: acrylonitrile, styrene, and acrylic ester. The acrylic ester is grafted onto a styrene-acrylonitrile copolymer backbone, resulting in a material that combines the beneficial properties of its constituents.

The use of ASA extends beyond 3D printing. It is commonly used in the automotive industry for exterior parts due to its excellent weather resistance. It is also used in the construction industry for items like roof vents and door and window profiles. Its UV resistance, high impact strength, and excellent finish make it a preferred choice for outdoor applications.

What is ASA?

ASA, or Acrylonitrile Styrene Acrylate, is a type of plastic that is known for its strong resistance to weathering and its high impact strength. It is a copolymer of SAN (Styrene Acrylonitrile) and acrylic rubber. The acrylate rubber phase is grafted with a SAN matrix, which gives ASA its unique properties.

ASA was first developed by the chemical company BASF in the 1970s under the trade name Luran S.[1] It was designed to be a material that could withstand outdoor use better than ABS, which tends to yellow and become brittle when exposed to UV light over time.

In terms of its physical properties, ASA has a density of around 1.07 g/cm³, a tensile strength of around 44 MPa, and a flexural modulus of around 2200 MPa. It has a melting temperature of around 250 °C, making it suitable for high-temperature applications. It also has good dimensional stability.

ASA in 3D Printing

ASA's unique properties make it a popular choice for 3D printing. Its excellent UV resistance, high impact resistance, and good chemical resistance make it suitable for creating parts that need to withstand outdoor conditions. This includes items like drone parts, outdoor signage, and automotive components.

ASA is available in filament form for FFF/FDM 3D printing, typically in diameters of 1.75 mm or 2.85 mm. ASA requires a higher printing temperature compared to some other materials, typically around 260 °C. This high temperature can lead to issues like warping if the print is not properly managed. To mitigate this, a heated print bed is often used to keep the lower layers of the print warm and prevent them from cooling too quickly. An enclosed heated chamber can also help maintain a consistent temperature throughout the print.

Despite these challenges, ASA offers several benefits that make it a worthwhile 3D printer filament. It provides excellent layer adhesion, resulting in strong, durable prints. It also has a smooth surface finish. ASA's UV resistance is a significant advantage for 3D printed parts that will be exposed to sunlight.[2] Unlike materials like ABS, ASA parts will not yellow or become brittle over time, ensuring they maintain their functionality and appearance.

In terms of post-processing, ASA is quite versatile. It can be sanded to smooth out layer lines and improve the surface finish. It can also be painted, allowing for a wide range of colors and finishes. Additionally, ASA can be glued using common adhesives, making it easy to assemble multi-part prints.

Recommended reading: ASA vs ABS: Finding the right 3D printing filament

Introduction to PETG

PETG is a modified form of PET

Polyethylene Terephthalate Glycol, or PETG, is another thermoplastic that is widely used in 3D printing. It is a variant of Polyethylene Terephthalate (PET), a common plastic used in items like water bottles and food packaging. The addition of glycol to the PET polymer chain reduces the material's brittleness and increases its durability, making it more suitable for 3D printing.

PETG is known for its excellent combination of strength, flexibility, and dimensional stability. It also has good chemical resistance and is food safe, making it suitable for a wide range of applications. PETG is used in various industries, including food and beverage, medical, and automotive.

What is PETG?

PETG stands for Polyethylene Terephthalate Glycol-modified. It is a transparent thermoplastic that offers a unique combination of properties. It has the strength and durability of PET, along with the ease of use of PLA, another popular 3D printing material.

PETG was developed to overcome some of the limitations of PET. While PET is a strong and durable material, it can be brittle and difficult to work with. The addition of glycol to the polymer chain reduces the crystallinity of the material, making it more flexible and easier to print with.

PETG has a density of around 1.27 g/cm³, a tensile strength of around 50 MPa, and a flexural modulus of around 2000 MPa. It has a melting temperature of around 220–250 °C.

PETG in 3D Printing

PETG has become a popular choice in the 3D printing community due to its unique combination of properties. It offers the strength and durability of materials like ABS and ASA, but with better printability. This makes it a versatile material that can be used for a wide range of applications, from functional parts to decorative items.

PETG prints best in the temperature range of 220–260 °C, slightly lower than ASA. 3D printer company Prusa suggests a printing temperature of 230 °C for the first layer and a slightly higher temperature of 240 °C for the rest of the build, while MatterHackers recommends 245 °C for the whole build. The material is fairly resistant to common 3D printing issues like warping and layer separation. PETG also has a low shrinkage rate, which further helps to maintain the dimensional accuracy of the print.

One of the key advantages of PETG is its transparency. PETG prints are naturally clear, although the level of transparency can be affected by the printing settings. For instance, higher layer heights and slower print speeds can result in clearer prints. This property makes PETG a popular choice for applications that require see-through parts, such as light diffusers or containers. Researchers have found that chemical surface treatments using dichloromethane can improve the optical properties of PETG.[3]

In terms of post-processing, PETG is quite versatile. It can be sanded to smooth out layer lines, although it's worth noting that sanding can reduce the material's transparency. PETG can also be painted, allowing for a wide range of colors and finishes. Additionally, PETG can be glued using common adhesives, making it easy to assemble multi-part prints.

Despite its many advantages, PETG is not without its challenges. It is a hygroscopic material, meaning it absorbs moisture from the air. This can affect the quality of the print, leading to issues like stringing or poor layer adhesion. To prevent this, it is recommended to store PETG filament in a dry environment and to dry it before printing if necessary.

Comparing ASA and PETG

ASA and PETG differ in important regards

ASA and PETG, while both popular choices, offer different sets of properties that make them suitable for different applications.

ASA is known for its excellent UV resistance, making it a preferred choice for outdoor applications. It also has high impact strength and a good surface finish. However, ASA requires a higher printing temperature and a heated bed, which can make it more challenging to print with, especially for hobbyists or those with less advanced 3D printers.

On the other hand, PETG offers a balance of strength, flexibility, and ease of use. It prints at a lower temperature than ASA and does not require a heated bed, making it more accessible for a wider range of 3D printers. PETG also has good chemical resistance and is food safe, which expands its range of potential applications.

Physical Properties

In terms of physical properties, ASA and PETG have some similarities but also key differences. ASA has a slightly higher flexural modulus and melting temperature than PETG but a lower density and tensile strength. ASA also has better weather resistance than PETG but worse layer adhesion.

For printing applications that require transparency — in packaging, optics, or fluidics, for example — PETG has a clear advantage. PETG prints are naturally clear, although the level of transparency can be affected by the printing settings. ASA, on the other hand, is not transparent, although it can be produced in a variety of colors.

PETG is hygroscopic and absorbs moisture from the air, which can affect the quality of the print. ASA does not have this issue, but it still requires careful storage and handling.

Durability and Strength

When it comes to durability and strength, both ASA and PETG perform well, but they excel in different areas. ASA is known for its high impact strength, which makes it a good choice for parts that need to withstand physical stress. It also has excellent UV resistance, which means that parts printed with ASA will not degrade or discolor when exposed to sunlight. 

PETG, on the other hand, has a tensile strength of around 50 MPa, which is higher than that of ASA. This means that PETG parts can withstand a high degree of tension without breaking. This makes PETG a versatile material that can be used for a wide range of applications.

In terms of layer adhesion, PETG outperforms ASA. PETG has excellent layer adhesion, which results in strong, durable prints that are resistant to layer separation. This is a significant advantage, especially for complex prints or those that require a high level of detail.

However, it's important to note that while both materials are durable and strong, they have different levels of hardness. ASA is a harder material, which makes it more resistant to scratches and wear. PETG, while still durable, is a softer material, which means it may be more prone to scratching or wear over time.

Temperature Resistance

Both ASA and PETG have good temperature resistance, but there are some important differences between the two materials.

ASA has a higher glass transition temperature, which is the temperature at which the material transitions from a hard, glassy state to a rubbery state. The glass transition temperature of ASA is around 105 °C. This means that ASA can withstand higher temperatures without deforming, making it suitable for applications such as automotive parts or outdoor fixtures that are exposed to sunlight and heat.

PETG, on the other hand, has a lower glass transition temperature of around 80 °C. While this is lower than ASA, it is still higher than many other common 3D printing materials, such as PLA. This means that PETG parts can withstand moderate temperatures without deforming. However, for applications that require high temperature resistance, ASA may be a better choice.

Ease of Printing

Printability is a significant factor when choosing a 3D printing material, particularly for hobbyists or those new to 3D printing. This encompasses several aspects, including the printing temperature, the need for a heated bed, the risk of warping or other printing issues, and the ease of post-processing.

ASA can be more challenging to print with due to its slightly higher printing temperature. This higher temperature can make it more difficult to achieve a successful print, particularly for those with less advanced 3D printers. ASA also requires a heated bed and, ideally, an enclosed chamber, which can add another layer of complexity to the printing process. Furthermore, ASA is prone to warping if the print is not properly cooled, which can lead to distorted or failed prints.

PETG, on the other hand, prints at a lower temperature of around 220–260 °C, which can make it easier to achieve a successful print. It does not strictly require a heated bed, which makes it more accessible for a wider range of (older) 3D printers. PETG also has excellent layer adhesion, which reduces the risk of warping or layer separation. It is, however, prone to oozing and stringing, which often requires tweaking of retraction settings.

Recommended reading: PETG Stringing: What It Is & How To Prevent It During 3D Printing

Post-Processing

ASA is a hard material that can be sanded to a smooth finish. This can be beneficial for parts that require a high-quality surface finish or for removing layer lines from the print. PETG, on the other hand, is a softer material. It can also be sanded, although it may not achieve as smooth a finish as ASA. In most other respects, PETG and ASA can be post-processed in a similar way. Both materials can be painted and glued, which is helpful for adding color and texture or for making assemblies.

One unique aspect of PETG is that it can be flame polished. This involves carefully applying a flame to the surface of the print, which melts the outer layer of the material and results in a glossy, smooth finish. This can be a useful technique for improving the appearance of PETG prints, although it requires careful handling to avoid damaging the print.

Choosing Between ASA and PETG

The choice between ASA and PETG will depend on the specific requirements of the project. Both materials offer a range of properties that make them suitable for different applications, and the best choice will depend on factors such as the expected physical stresses, the need for UV resistance, the desired balance of strength and flexibility, the printing capabilities, and the post-processing requirements.

When to Choose ASA

ASA, or Acrylonitrile Styrene Acrylate, is a thermoplastic that is known for its robustness and resistance to environmental factors. It's an ideal choice for applications that require a high degree of durability and resilience to external conditions.

One of the key strengths of ASA is its excellent UV resistance. Unlike many other 3D printing materials, ASA does not degrade or discolor when exposed to sunlight. This makes it an excellent choice for outdoor applications, such as garden fixtures, outdoor signage, or any other project that will be exposed to the elements.

ASA also has a high glass transition temperature of around 105 °C. This means that it can withstand higher temperatures without deforming, which is a crucial property for parts that will be exposed to heat. This makes ASA a suitable choice for applications such as automotive parts, which need to withstand the high temperatures generated by the engine and other components.

In terms of mechanical properties, ASA has a high impact strength, which makes it a good choice for parts that need to withstand physical stress. This could include protective casings and housings, mechanical parts, or any other application where the part needs to resist impact or stress.

In summary:

• Outdoor applications

• High-temp applications

• Rugged parts like protective casings

When to Choose PETG

PETG, or Polyethylene Terephthalate Glycol, is a thermoplastic that is known for its balance of strength and flexibility. It's a versatile material that can be used in a wide range of applications.

One of the key strengths of PETG is its excellent layer adhesion and tensile strength. This results in strong, durable prints that are resistant to warping or layer separation and makes PETG a good choice for parts that need to be strong and stable.

PETG prints at a lower temperature of around 220–260°C, which can make it easier to achieve a successful print. It does not require a heated bed, which makes it more accessible for a wider range of 3D printers. This, combined with its excellent layer adhesion, makes PETG a more forgiving material to print with, particularly for those new to 3D printing or those with less advanced printers. Users therefore often choose it for simple, quick prototypes.

One unique aspect of PETG is that it can be flame polished, which can improve the appearance of the print. The material is also naturally transparent, which opens up a range of potential applications.

In summary:

• Quick prototypes

• Load-bearing parts

• Clear parts like packaging and tubing

Conclusion

The decision between ASA and PETG does not have a one-size-fits-all answer, but rather depends on the specific requirements of the project. Both materials have their strengths and weaknesses, and understanding these can help you make an informed decision.

ASA filament stands out for its UV resistance and heat resistance, making it a suitable choice for outdoor applications or parts that will be exposed to heat. Its high impact strength also makes it a good choice for parts that need to withstand bumps and knocks. However, its higher printing temperature and the need for a heated bed can make it more challenging to print with, particularly for those with less advanced 3D printers.

PETG, on the other hand, offers a balance of strength and printability, making it a versatile material for a wide range of applications. Its excellent layer adhesion results in strong, durable prints, and it prints at a lower temperature without the need for a heated bed, making it more accessible for a wider range of printers. It also allows for the printing of clear printed parts.

Frequently Asked Questions

What is the main difference between ASA and PETG?

The main difference between ASA and PETG lies in their physical properties and printing requirements. ASA is known for its UV resistance and high temperature tolerance, while PETG offers a balance of strength and flexibility. ASA requires a higher printing temperature and a heated bed, while PETG prints at a slightly lower temperature without the strict need for a heated bed.

Can ASA and PETG be used interchangeably?

While ASA and PETG both have their strengths, they are not always interchangeable due to their different physical properties and printing requirements. The choice between the two will depend on the specific requirements of the project, including the expected physical stresses, the need for UV resistance, the desired balance of strength and flexibility, the printing capabilities, and the post-processing requirements.

What are the post-processing options for ASA and PETG?

Both ASA and PETG can be sanded and painted, but there are some differences in how they respond to these processes. ASA is a harder material that can be sanded to a smooth finish, while PETG is a softer material that can also be flame polished.

References

[1] Qua EH, Major IF, Lew CY, McNally GM, Clarke AH. Structure and Performance of Novel Acrylonitrile-Styrene-Acrylate Nanocomposite.

[2] El Magri A, Ouassil SE, Vaudreuil S. Effects of printing parameters on the tensile behavior of 3D‐printed acrylonitrile styrene acrylate (ASA) material in Z direction. Polymer Engineering & Science. 2022 Mar;62(3):848-60.

[3] Petrov P, Agzamova D, Pustovalov V, Zhikhareva E, Saprykin B, Chmutin I, Shmakova N. Research into the effect of the 3D-printing mode on changing the properties of PETG transparent plastic.