Abstract
Multi-component structured filaments offer the potential for enhanced mechanical performance in 3D printed plastics. Here, the interactions between filament components in the core (polycarbonate, PC)-shell (polypropylene, PP) geometry are manipulated by light maleation (1%) of PP to understand how the inclusion of favorable polar interactions and potential grafting reactions at the core-shell interface impact the mechanical performance of the 3D printed parts. The elastic modulus of the 3D printed tensile bars is essentially independent of the shell selection for the fully isotactic PP (iPP) or maleated PP (miPP), but the strain at break is generally significantly improved with the miPP shell to increase the toughness of the printed parts for both flat and stand-on build orientations. This is counter to compression molded specimens where iPP is more ductile than miPP. The mechanical behavior in the flat orientation is consistent with long fiber composites, where the PC core essentially acts as fiber-reinforcement. Tribo-testing results indicate increased friction between miPP and PC through the interaction of the maleate anhydride group with the carbonate relative to the iPP with PC. This small increase in the interfacial interaction between the core and shell polymers with miPP increases the work required to pull out fibers of the stiffer PC from the PP matrix for the flat build orientation and more energy is required to delaminate the core from the shell, which is the loci of failure, when the stand-on build orientation is stretched. The subtle change in chemistry with a maleation of 1% of PP leads to a larger strain at failure and tougher parts due to the interaction with PC. These results illustrate that the selection of the polymers in structured filaments needs to also consider their potential intermolecular interactions including the potential for grafting reactions to best enhance the mechanical response of 3D printed parts.
| Original language | English |
|---|---|
| Pages (from-to) | 105-116 |
| Number of pages | 12 |
| Journal | RSC Applied Polymers |
| Volume | 2 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jan 16 2024 |
| Externally published | Yes |
Funding
This work was financially partially supported by the National Science Foundation (grant CMMI-2011289). Polycarbonate materials were supplied by Covestro LLC (Pittsburgh PA). The authors acknowledge the use of the Penn State Materials Characterization Lab for tensile measurements. The tribo-testing was done with the support from the NSF (Grant No: CMMI-1912199). WF acknowledges the support from an undergraduate research internship through the National Aeronautics and Space Administration under Grant No. 80NSSC20M0097 issued through the Pennsylvania Space Grant Consortium. The authors thank Yun Zhu for his assistance with obtaining optical micrographs of the fractured samples, Po-Hao Lai for his assistance with FTIR and Sierra Yost for her help with rheology.