Additive manufacturing of PA12 carbon nanotube composites with a novel laser polymer deposition process

• Published in: Journal of applied polymer science 2021-05, Vol.138 (19), p.n/a
• Main Authors: Wencke, Yannick L., Kutlu, Yunus, Seefeldt, Malte, Esen, Cemal, Ostendorf, Andreas, Luinstra, Gerrit A.
• Format: Article
• Language: English
• Subjects: Additives; Bulk modulus; composites; Deposition; Failure mechanisms; Lasers; manufacturing; Material properties; Materials science; Mechanical properties; Melting; Modulus of elasticity; morphology; Multi wall carbon nanotubes; Nanocomposites; nanotubes; Network formation; Polymer matrix composites; Polymers; porous materials; Silicon dioxide
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/app.50395

The facile manufacture of PA12 MWCNT/silica (50/50 by weight) nanocomposite powders through a high energy mixing process is presented, which are useful to generate 3D objects by a novel Laser Polymer Deposition (LPD) process. The mixing as well as the LPD process led to no discernible changes in the material properties (DSC, SEM, LD) of the core‐shell nanocomposites, enabling the recycling of unconverted powder. The built parts yield ultimate tensile stresses and Young's modulus at 10%–20% of the bulk material. Partially unmolten particles and voids were identified as the main mechanical failure mechanism in the built parts. The mechanical properties are better with low additive content (Young's modulus: 89.8 ± 5.4 MPa; UTS: 12.9 ± 5.3 MPa with 0.25 wt% additives). Electronic conductivity up to the region of moderate conductivity could be achieved by multiwalled carbon nanotube (MWCNT) network formation (8 × 10−4 S cm−1 at 1.25 wt% of additives). A variant of the processing strategy revealed that a higher mechanical strength can be achieved by a laser induced remelting of the traces following their initial construction. Commercial polyamide‐12 powder was modified to give a carbon nanotube silica composite powder useful for a novel directed energy material deposition process. Three dimensional objects were obtained without support structures, showing a moderate mechanical strength and electric conductivity. These are, together with a substantial recycling stream of unconverted powder, valuable arguments for this new (adapted) technology.