TPU SMP - 4D Filament

Convena is Europe's largest independent trader of fluoropolymers, offering materials in different formats such as powder, pellets or filaments. Fluoropolymers are high performance polymers which have a particularly good chemical resistance to almost all acids, bases and solvents due to their high fluorine content.

The filaments distributed by Convena are manufactured using raw materials of the highest quality, and all its products are subject to strict controls in order to offer high performance solutions.

Its portfolio of FDM 3D printing filaments includes the most innovative materials on the market, including TPU SMP, also known as 4D filament.

The TPU SMP filament owes its name to the Shape Memory Polymer technology. It is a special filament with a TPU-based composition that allows post-processing to modify the shape of 3D printed parts.

Image 1: TPU SMP filament. Source: Convena.

TPU (thermoplastic polyurethane) is a widely used material in filament form for FDM 3D printing. This elastomeric polymer is characterised by its high resistance to abrasion, certain chemical elements, UV rays and low temperatures, making it a material widely used in a wide variety of sectors for the manufacturing of parts that require good impact absorption in addition to the characteristics described above.

In the case of the TPU SMP filament, it has been possible to develop a new material that remains rigid at room temperature and offers special properties when it reaches its glass transition temperature.

4D Filament

Thanks to its special composition and the Shape Memory Polymer technology, 3D printed parts with SMP TPU filament can be modified manually, allowing them to acquire another shape and maintain it over time. To do this, the 3D printed part needs to reach the material's glass transition temperature. At this point, the elastic properties of the material change drastically.

Thanks to this characteristic, the TPU SMP filament is considered the first 3D printing filament called 4D by experts, referring to a fourth dimension achieved in the post-processing of 3D printed parts with this material.

Video 1: Demonstration of the SMP TPU shape modification process. Source: Convena.

The process of modifying the shape of a 3D printed part with SMP TPU filament involves placing the 3D printed part in a container of hot water until it reaches its glass transition temperature. At this point, the part softens and the user can easily modify its shape. Once cooled, the part maintains the acquired shape and remains stable. For more information on the post-processing of 3D printed parts with SMP TPU filament, we recommend accessing the "Usage tips" section of the product.

Image 2: 3D printed part before and after post-processing. Source: Convena.

In addition to being able to modify the shape of 3D printed parts with SMP TPU filament, another of its differentiating features is that it is possible to restore the original shape by reversing the process carried out. To do this, the modified 3D printed part must be brought back to the material's glass transition temperature.

By doing this in hot water, the part can be seen to return to its original shape within seconds. This process eliminates the stress added by customising the shape of the part resulting in the recovery of its original shape. The SMP filament allows a maximum deformation of 400% with respect to the original shape of the 3D printed part.

Innovative applications

This novel filament opens the door to a myriad of applications in various sectors, including potential R&D uses in the aerospace industry and the medical environment. In the latter, it is possible to manufacture parts with flat geometries that can later be adapted to different parts of the body, such as arms or legs, making it possible to manufacture customised orthoses from a common model.