Since 1937, this robust polymer has been making waves among the polymer communities. With its incredible durability, toughness and ease of processing, TPU has the advantages of rubber and plastic. This article will explain why this best-of-both worlds polymer is so useful.
What is TPU?
TPU, also known as Thermoplastic polyurethane, has been around even before World War II. However, its uses range from sporting goods to medical devices, from phone covers to Aerospace Surface Protection. To create this polymer in a lab, simply create a polyaddition reaction between a diisocyanate and one or more diols, well maybe not too simple, but after that a unique category of plastic emerges.
Uses of TPU
Below are some popular uses of TPU:
- Sportswear (shoes)
- Wire and cable coating
- Hydraulic seals and hoses
- Inflatable rafts
- Phone cases
- Medical tubing
As you can see, TPU is mainly used where flexibility plays a key role. However, it is not just flexible. Below are some other advantages of this filament.
Advantages of the Flexible Filament
You can think of TPU as a hybrid material, with a mix between hard plastic and soft silicon. When it comes to 3D-printing, usually ABS and PLA are used as the industry standard. However, if you are looking to create bending prototypes, these two fall short. TPU on the other hand is very flexible in nature. It can bend easily without affecting its design, durability and strength, with it even coming with a mild “self-healing” ability.
TPU vs Popular 3D-printing Polymers
TPU works well if you are looking for flexibility, very similar to PETG, a polymer we featured in a previous article. Lets see how it compares with PETG as well as the other popular 3D-printing materials, ABS and PLA.
|ABS||Durable, Impact Resistant||Functional Parts||2/3||2/3||3/3||2/3||210 – 250||50 – 100|
|PLA||Easy to Print, Biodegradable||Consumer Products||2/3||1/3||2/3||1/3||180 – 230||No|
|PETG||Flexible, Durable||All-Rounder||2/3||3/3||3/3||2/3||220 – 235||No|
|TPU||Extremely Flexible, Rubber-Like||Elastic Parts,|
|1/3||3/3||2/3||3/3||225 – 235||No|
Values courtesy of all3dp.
How Hard is TPU?
The flexible polymer also comes in different forms, most notable by the letter at the end, A or D, which refers to its hardness. This hardness is measured by different types of Shore hardness scales (for example Shore A00, Shore A and Shore D). The different Shore Hardness scales measures the resistance of a material to indentation.
- Shore A00 Scale – measures rubbers and gels that are very soft.
- Shore A Hardness Scale – measures the hardness rubbers that range in hardness from very soft to almost no flexibility at all, essentially the middle-ground scale.
- Last is the Shore D Hardness Scale – measures the hardness of hard rubbers, semi-rigid plastics and hard plastics.
As you can see from the chart, these scales can overlap. For example, shoe heels with a Shore Hardness of 70A can also be converted into a Shore hardness of 22D.
Our results with TPU
This polymer is great, and we really enjoy its creative uses. We were able to obtain some TPU Shore 75A, so a bit harder than the heel of a formal shoe.
Doing some tests on the filament, we wanted to see how well it would extrude in our NEXT Advanced Level Filament Extruder. The results were better than we expected. As you can see in the images above, the filament extruded quite easily, resulting in a clean egg-shell white roll of filament.
Once the roll was complete, we decided to see how it would handle 3D printing. Going for a simple 3devo logo, we also wanted to test its flexibility. True to its hardness rating, it was still able to deform a bit, pretty neat!
In the end, this polymer serves a great purpose at providing a filament that is very easy to print with, but also durable and very flexible. If you are looking for a filament that is a combines the benefits of rubber and plastic, then TPU is for you.