With so many different filament types available, it can be difficult to know which is most suitable for your 3D printing project. PETG and PLA are two of the most commonly used variety, but which is stronger?
When comparing the strength of PLA and PETG— PETG is the clear winner. It is a durable and impact-resistant plastic that is known for its strong molecular structure.
In this article, we will compare the strength of the two filament types and consider a few other key factors. Read on to find out what makes PETG the strongest choice.
How strong is PETG?
Polyethylene terephthalate, more commonly known as PETG, is often praised for its strength. The ‘G’ in this acronym stands for glycol.
The presence of glycol is a good sign, as it’s necessary for effective 3D printing. It’s so renowned for its ability to withstand impact, that it’s commonly used to make sailcloths- which of course need to be exceptionally strong.
It’s also sometimes used to make reusable plastic food containers, which proves just how durable and long-lasting must be. The addition of glycol is what differentiates PETG from PET- it is added at a molecular level which gives it the ability to offer different, more advanced, chemical properties.
One of the best things about PETG is that it has all the ease of use of PLA combined with the physical properties of ABS, making it the ideal filament type for 3D printing.
The strength and impact-resistant properties of PETG make it perfect for glazing, creating durable display units and 3D printed products, displays, and commercial signage.
However, PETG does have its downsides. It is notorious for taking on water as it is extremely absorbent, so if you don’t store it correctly in a cool and dry environment, it is more likely to become brittle as a result of the moisture.
How strong is PLA?
PLA, also known as polylactic acid or polylactide, is a thermoplastic that’s constructed using renewable resources such as corn starch, tapioca roots, and sugar cane.
It’s the most popular filament type in the world of 3D printing, making it even more popular than PETG. It is often the preferred choice for beginners in 3D printing as it is a very simple material to work with.
This material is considered a non-Newtonian pseudoplastic fluid. This means that its viscosity (flow resistance) will change depending on the stress to which it is subjected. Specifically, PLA is a fine-cut material, which means that the viscosity decreases as you apply stress.
As well as being environmentally friendly and compostable, PLA filament is also pretty strong. It has a tensile strength of 7,250 psi- which isn’t too shabby.
Many researchers have carried out various different experiments on this filament type, and it’s believed that PLA is strong enough to support the weight of a single bookshelf with books, or a large television on a wall bracket.
However, PLA also comes with its disadvantages. One of these is that it is biodegradable. While this has positive environmental impacts, it negatively affects the strength and longevity of your 3D printed creations. As PLA is biodegradable, it is not uncommon for it to break down over time during use.
It is also extremely sensitive to UV light, so it is considered an unpredictable material that can warp and change form within just a couple of hours. Because of this, you shouldn’t use PLA to support a large load.
For example, if you try to use a PLA filament when printing a tow hook, it is not going to be strong enough.
We recommend sticking to what PLA is best for, toys, miniatures, and figurines. Due to the low heat resistance of PLA, it is not advisable to use it in warmer climates- if you want it to be last a long time, that is.
Which is stronger?
As stated above, PETG is in fact stronger than PLA. We know this because each filament type has been thoroughly researched and tested. While this may be surprising, as PLA is the most popular type when it comes to 3D printing, PETG has far more advantages than its competition.
PETG is strong enough to withstand high temperatures better than PLA. At a temperature where PLA begins to warp, a PETG filament will still maintain its shape and form. This is because PETG is a hard filament. However, harder filaments require much more time to melt compared to PLA filaments.
Despite the sheer strength of PETG, more people still choose to opt for PLA because it is extremely easy to use, so it appeals to both beginners and experts alike.
PETG can also cause problems of stringing and oozing, which will require you to re-calibrate your printer through the settings to combat this. PLA doesn’t come with this issue, and you’re more than likely to get a smooth finished result.
However, don’t let this put you off trying out PETG. Although it is definitely more difficult to print with, its stickiness prevents it from detaching from the print bed during use, which is a common occurrence with other filament types.
Because of this, PETG requires much less pressure when you’re extruding the initial layer.
What about PLA+?
While PETG and PLA are both thermoplastics, which become malleable when exposed to high temperatures— but PLA has an enhanced version. PLA+ is considered superior to regular PLA, this is because of the updated features.
PLA+ is often defined as just PLA with additives, which is somewhat true, there’s not a huge specific difference between the two filament types.
PLA+ has all of the same characteristics such as print speed and temperature that regular PLA possesses, but the former tends to have a slightly better surface quality, color, and mechanical properties.
Depending on the vendor, PLA+ is usually a mixture of other plastics, additives, or pigments that help in improving on the weaknesses of standard PLA, such as moisture absorption and brittleness.
The PLA vs PLA+ mystery is made more complicated by the fact that there is no standard formulation for distinguishing between PLA and PLA+.
Manufacturers will typically add their modifiers and additives and remain tight-lipped about their formulas. They then simply market their product as having more benefits over standard PLA.
In terms of strength, PLA+ is often considered superior to regular PLA. Here are a few of the advantages of opting for PLA+.
- Surface texture: Standard PLA has a rough surface both on the surface of the layers and on the outer part of the layers.
- Overhang: PLA+ has better overhang properties that leave less stringing on the final print.
- Print temperature: PLA+ typically has a higher print temperature than PLA.
- Reflection: PLA+ has a glossy reflection that helps to showcase it better.
- Strength: Based on a number of videos on YouTube, PLA+ seems harder to break. Users exposed it to various tests, including smashing, weight holding, and bending. When over-stretched, PLA+ bends while regular PLA snaps.
What are the other differences between PETG and PLA?
Safety
Probably the main reason why PLA is more popular than PETG is that the former is considered a ‘safer’ filament.
This is due to the fact that PLA is made using organic and natural materials and only produces lactic acid, which poses no harm to the user.
The lack of man-made materials used in PLA means that you won’t get that melted-plastic-like aroma that you’ll often notice when using other filaments such as PETG. While PETG is safer than other filaments such as Nylon or ABS, it still comes with more risks than PLA does.
Ease of Use
PLA is far easier to use than PETG. This is why it is often the filament of choice for beginners to 3D printing.
If you’re new to the world of 3D printing, it is likely that you’re going to experience issues with print quality and color at the beginning. However, opting for PLA instead of PETG could lessen your chances of this happening.
While PETG isn’t as easy to use as PLA, it’s still pretty straightforward. PETG is still a great filament to work with, but the settings will need to be dialed-in correctly especially retraction settings, so you’ll need to keep this in mind when printing with PETG.
Chance of Shrinkage
Most 3D printing filament types will show some signs of shrinkage after cooling, but the amount of shrinkage does differ from filament to filament.
You should expect at least a little shrinkage when working with both PETG and PLA. The shrinkage rate of these filaments when cooled can range between 0.20 - 0.25%.
To put this in perspective, ABS filaments shrink anywhere from 0.7% to 0.8% and Nylon may even shrink up to 1.5%.
Food Safety
Fortunately, both PETG and PLA filament types are considered food safe, which is why they’re often used in plastic food containers.
PLA can be considered food safe as it is made using sugarcane and corn starch, making it natural and organic.
PETG can be considered food safe thanks to its great resistance to heat, UV light, and many types of solvents. While both are food safe, if we really had to choose between the two, PLA would just about take the crown.
It is also important to remember that if you plan on using filaments that are food-safe, avoid using any that contain color additives. This is easy to do with PETG, but it can be a little more difficult to find pure PLA.