Properties Enhancement of Carbon PA 3D-Printed Parts by Post-processing Coating-Based Treatments

In recent years, Fused Deposition Modelling (FDM) has become one of the most attractive Additive Manufacturing (AM) techniques, due to the advantages in the production of complex shapes with a wide range of materials and low investment costs. The thermoplastic polymers used for FDM technology are characterized by low mechanical properties if compared to those of composites and metals. This issue is usually overcome by reinforcing the thermoplastic polymer with chopped fibres or particles. Moreover, a second issue arises, which is represented by the water absorption with a relevant impact on mechanical properties and dimensional stability of printed models. In this paper, an experimental study is presented with the aim at evaluating the water absorption influence on mechanical properties of Carbon PA (Polyamide matrix reinforced with Carbon Fiber at 20%) specimens fabricated with the FDM technique. Two post-processing treatments, based on the use of acrylic spray and photosensitive resin, have been also proposed to improve the behaviour of Carbon PA printed parts. Results of water absorption tests and tensile tests demonstrated a significant improvement in terms of weight stability and mechanical properties by adopting the proposed post-processing treatments.