There is no doubt that filament selection is one of the most significant factors in 3D printing, with filament types offering unique qualities that perform better for different areas of usage.
Strength, flexibility, durability, print temperature, glass transition temperature, and many more other factors go into deciding the correct filament type for a print, as each of these factors plays a vital role in how successful the model you print will be.
Today, we will take a look at the glass transition temperature of PETG in particular, as we believe that it’s an attribute most 3D printing enthusiasts don’t consider while choosing the filament they will be using.
So, what is the glass transition temperature of PETG?
The glass transition temperature of PETG filament falls between 80 and 85 degrees Celsius.
While the temperature can show differences between different brands of filaments, the glass transition temperature of all PETG filaments we have tried so far has been in the 80-85C range.
In the upcoming sections, we will be analyzing the glass transition temperature of PETG in greater detail, take a look at how this temperature affects the printing process, and compare PETG with other filament types on this front.
Table of Contents
What Is the Glass Transition Temperature of PETG?
While the glass transition temperature of a filament should always be on the packaging or the manufacturer’s webpage, this is not always the case, whether you’re using PETG, PLA, ABS, or something else.
For PETG filaments, the glass transition temperature is between the 80 degrees Celsius to 85 degrees Celsius range.
As the exact temperature can show differences due to the manufacturing process of the filament, two different brands of PETG can have slightly different (1-5 degrees Celsius difference) glass transition temperatures.
With a small amount of experimentation, you can easily find out the exact glass transition temperature of your PETG filament and use this value to optimize your printer’s settings accordingly.
Now that we know the glass transition temperature of PETG, it’s time to find out how it affects the 3D printing process.
How Does Glass Transition Temperature of PETG Affect Prints?
The glass transition temperature of PETG, or any other filament, is something you shouldn’t ignore as it affects both the printing process and the product you have created in significant ways.
First off, let’s find out the effects of glass transition temperature on the printing process.
Effects of PETG Glass Transition Temperature on the Printing Process
In a nutshell, the glass transition temperature of a filament determines the optimal heated bed temperature.
If the bed temperature is way too low compared to the glass transition temperature, you will have adhesion issues between the bed and the object due to the filament staying in its rigid state.
On the other hand, a bed temperature that is too high will cause warping and a phenomenon known as Elephant’s Foot, where the layers that touch the heated bed can’t go back to their rigid state, which causes the weight of the object to crush these layers.
If you are struggling to find the optimal heated bed temperature, you can use the glass transition temperature range as a base value and experiment with values that are close to this range.
Effects of PETG Glass Transition Temperature on the Final Product
The glass transition temperature is also vital to consider after the printing process due to its effects on the object itself.
Essentially, the glass transition temperature determines the heat resistance of the object, as the object starts losing its integrity and deforms at this temperature.
Because of this, it’s vital to ensure that you don’t expose the object to temperatures above this level.
While it’s unlikely for PETG or any other filament to hit its glass transition temperature in a regular spot, it’s definitely something to keep in mind if you are planning on printing functional parts that you will expose to high temperatures.
PETG Glass Transition Temperature Compared to Other Filaments
Now that we have been over the glass transition temperature of PETG and how it affects the printing process – let’s look at how PETG compares to other filament types in this department.
- PETG Glass Transition Temperature – 80 to 85 degrees Celsius
- PLA Glass Transition Temperature – 60 to 65 degrees Celsius
- ABS Glass Transition Temperature – 105 degrees Celsius
- TPU Glass Transition Temperature – 60 degrees Celsius
- Nylon Glass Transition Temperature – 70 to 75 degrees Celsius
- Polycarbonate Glass Transition Temperature – 145 to 150 degrees Celsius
From the values above, we can tell that the glass transition temperature of PETG falls into the middle, with PLA, TPU, and nylon sitting below and ABS and polycarbonate sitting above.
PETG Glass Transition Temperature vs. Melting Point
Glass transition temperature and melting point are two terms that are often confused as they sound like they refer to the same thing. In reality, these two terms are entirely different.
The glass transition temperature of PETG is between 80 and 85 degrees Celsius, whereas its melting point sits between 240 and 260 degrees Celsius.
As you can see, the melting point of PETG is much higher than its glass transition temperature.
So, what’s the difference between the two?
Glass transition temperature refers to the point where the material starts losing its rigidity and transforms into a more rubbery, flexible state. At this point, the material begins deforming and becomes viscous; but doesn’t completely liquefy.
On the other hand, the melting point is the temperature where the material turns from solid to liquid. At this point, the material flows freely with no characteristics of a solid material.
You can think of the melting point as the temperature the extruder extrudes the filament at – and the glass transition temperature as the temperature the object stays at on the heated bed.
The glass transition temperature of PETG is neither too low nor too high, placing it around the middle compared to most other popular filaments used in 3D printing.
As the glass transition temperature of a filament is a vital consideration for many reasons ranging from setting the correct bed temperature during print to deciding the right area of usage for the model you print, we highly recommend keeping it in mind before deciding on a filament.
Despite being a factor that is often overlooked, remember that not paying attention to the glass transition temperature can quickly ruin a print by causing it to warp during the printing process or disintegrate during usage.
Mike started his 3D printing journey with the Anet A8 when it first came out back in 2017, and has been obsessed with 3D printers ever since. Nowadays, he primarily uses his Ender 3 to print functional parts that make his life more convenient whenever possible.