APPLICATION OF 3D PRINTING IN THE PRODUCTION OF MULTIMATERIAL HOLLOW POLYMERIC PARTS

The combined application of polymeric 3D printing technologies along with post-processing methods also based on the application of polymeric resins enables the rapid production of multi-material parts with complex geometries. In these parts, materials that provide various functionalities and performance can be combined. It is possible to combine rigid and flexible, solid and foamed materials, or materials that combine mechanical, thermal, acoustic, gas barrier, or thermal and electrical conductivity properties. In this work, using extrusion, laser sintering of thermoplastic resins, and digital light processing of photopolymerizable resins as 3D printing technologies, the production of a hollow multi-material part has been explored through its combination with reactive resin casting post-processing. The selected hollow part represents a demonstrator liner for the subsequent manufacturing, by filament winding, of a tank for the storage of pressurized gases. In hydrogen tanks, the liner provides impermeability to the tank, minimizing hydrogen leakage. In the field of mobility and transport, type IV hydrogen tanks are commonly used. These are lightweight and resistant tanks formed by an inner plastic lining, usually produced by injection molding, extrusion-blow molding, or rotational molding, surrounded by an external composite wrapper that provides mechanical properties. The study has successfully applied 3D printing to obtain a multi-material liner capable of providing additional functionalities to the entire tank, in which materials from the same family as those used in the composite envelope can be used. It has been verified that the hollow multi-material structure can withstand the stresses generated in the application by filament winding of the external carbon composite layers. This opens the possibility of using 3D printing technologies as an additional tool in the manufacturing of tanks for the storage of pressurized gases. Key Words: 3d printing, multimaterial, multifunction, liner, filament winding, hydrogen tank.