Hanemann Thomas, Klein Alexander, Baumgärtner Siegfried, Jung Judith, Wilhelm David, Antusch Steffen
Institute for Applied Materials, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany.
Department of Microsystems Engineering, University Freiburg, Georges-Koehler-Allee 102, D-79110 Freiburg, Germany.
Polymers (Basel). 2023 Aug 15;15(16):3412. doi: 10.3390/polym15163412.
High-performance thermoplastics like polyetheretherketone (PEEK), with their outstanding thermal stability, mechanical properties and chemical stability, have great potential for various structural applications. Combining with additive manufacturing methods extends further PEEK usage, e.g., as a mold insert material in polymer melt processing like injection molding. Mold inserts must possess a certain mechanical stability, a low surface roughness as well as a good thermal conductivity for the temperature control during the molding process. With this in mind, the commercially available high-performance thermoplastic PEEK was doped with small amounts of carbon nanotubes (CNT, 6 wt%) and copper particles (10 wt%) targeting enhanced thermomechanical properties and a higher thermal conductivity. The composites were realized by a commercial combined compounder and filament maker for the usage in a material extrusion (MEX)-based 3D-printer following the fused filament fabrication (FFF) principle. Commercial filaments made from PEEK and carbon fiber reinforced PEEK were used as reference systems. The impact of the filler and the MEX printing conditions like printing temperature, printing speed and infill orientation on the PEEK properties were characterized comprehensively by tensile testing, fracture imaging and surface roughness measurements. In addition, the thermal conductivity was determined by the laser-flash method in combination with differential scanning calorimetry and Archimedes density measurement. The addition of fillers did not alter the measured tensile strength in comparison to pure PEEK significantly. The fracture images showed a good printing quality without the MEX-typical voids between and within the deposited layers. Higher printing temperatures caused a reduction of the surface roughness and, in some cases, an enhanced ductile behavior. The thermal conductivity could be increased by the addition of the CNTs. Following the given results, the most critical process step is the compounding procedure, because for a reliable process-parameter-property relationship, a homogeneous particle distribution in the polymer matrix yielding a reliable filament quality is essential.
聚醚醚酮（PEEK）等高性能热塑性塑料具有出色的热稳定性、机械性能和化学稳定性，在各种结构应用中具有巨大潜力。与增材制造方法相结合进一步扩展了PEEK的用途，例如，作为聚合物熔体加工（如注塑成型）中的模具镶件材料。模具镶件必须具备一定的机械稳定性、低表面粗糙度以及良好的热导率，以便在成型过程中进行温度控制。考虑到这一点，市售的高性能热塑性塑料PEEK被掺杂了少量的碳纳米管（CNT，6重量%）和铜颗粒（10重量%），旨在提高热机械性能和热导率。这些复合材料是通过商用的组合混料机和长丝制造机实现的，用于基于材料挤出（MEX）的3D打印机，遵循熔丝制造（FFF）原理。由PEEK和碳纤维增强PEEK制成的商用长丝用作参考体系。通过拉伸测试、断口成像和表面粗糙度测量全面表征了填料以及MEX打印条件（如打印温度、打印速度和填充方向）对PEEK性能的影响。此外，通过激光闪光法结合差示扫描量热法和阿基米德密度测量来测定热导率。与纯PEEK相比，填料的添加并未显著改变测得的拉伸强度。断口图像显示打印质量良好，沉积层之间和内部没有MEX典型的空隙。较高的打印温度导致表面粗糙度降低，在某些情况下，还增强了韧性行为。添加碳纳米管可以提高热导率。根据给定的结果，最关键的工艺步骤是混合过程，因为对于可靠的工艺参数-性能关系而言，聚合物基体中均匀的颗粒分布以产生可靠的长丝质量至关重要。
