3D printing of Continuous Fiber Reinforced composites (3CFRc) is a new additive process allowing unprecedented structural optimization and considerable potential in several sectors. However, the accreditation of this technology requires the overcoming of some scientific and technological limits. Among these, the poor mechanical properties, the strong anisotropy, and the low reproducibility in the results undoubtedly represent the most critical obstacles to overcome.

INFINITE project aims to design and develop a new generation of high-performance fiber-reinforced polymer composites, with integrated Self-Healing (SH) properties, suitable to be used in 3CFRc processes. The use of SH composites in 3D printing will offer the potential to increase the quality of produced parts, extend their operational lifetimes increasing the damage tolerance and improve their recyclability.

INFINITE aims to develop the whole process from the synthesis of the hybrid filler and the polymer matrix to their blend and manufacturing into continuous filament up to the 3D printing process with the relative functional characterizations. New hybrid fillers will be synthesized to include SH properties within an engineering thermoplastic material such as polyamides. These fillers will be obtained by combining carbonaceous fillers (graphene, carbon nanotubes, nanofibers) with organic molecules. The resulting nanocomposites will be used for the coating and sizing of high-performance continuous fibers such as glass and carbon fibers.

3D printing tests will be carried out with different configurations and processing conditions. Specific mechanical tests will be carried out to assess the properties of both bulk and printed samples along with their self-healing behavior. This will indicate if the self-healing property of the polymer retained even after multiple processing steps and printing. Compared to a conventional thermoplastic polyamide, the SH properties are expected to reduce the mechanical dependency on the printing conditions.

An extensive experimental campaign will also characterize the static and fatigue behavior of both the new material and a similar commercially available version: this will allow an assessment of the mechanical performance improvement, as well as a deeper understanding of the failure mechanisms of these materials, which are currently still unknown.

The key contributions brought from INFINITE will be the development of a new multifunctional composite material, suitable for a wide spectrum of applications, the identification of a 3CFRc process, and significant advancement of the knowledge on the mechanical behavior of 3D printed materials.