![]() Incorporation of fillers into high-performance polymers for improving their performance may further increase melt viscosity thus creating potential problems in achieving sufficient power to process the material and risking thermal/shear degradation of the polymer. The processing of high-performance polymers is generally more difficult and expensive compared with commodity thermoplastics due to their high melt viscosity and higher melting temperatures ( Golbang et al., 2020). ![]() Incorporation of expanded graphite (EG) into PEEK via twin-screw compounding and injection moulding, results in significant enhancement of PEEK electrical conductivity ( Mokhtari et al., 2021b). For example, addition of hydroxyapatite particles increases the bioactivity of PEEK for development of cranial implants with improved biocompatibility ( Manzoor et al., 2021). Nanofillers are added to polymers to further improve their thermal, mechanical and optical properties, depending on the type of filler ( Aradhana et al., 2018 Golbang et al., 2020 Mokhtari et al., 2021a). Apart from the intrinsic properties of the polymer, the applied manufacturing method, processing conditions, and the material composition play a major role on the final quality and properties of high-performance thermoplastic parts ( Golbang et al., 2017 Golbang et al., 2020 Liu and Kunc, 2020). Owing to their high thermal and chemical stability, exceptional strength-to-weight ratio, and recyclability, high performance thermoplastic polymers, such as Polysulfone (PSU), polyetherimide (PEI), and polyether ether ketone (PEEK) are becoming increasingly attractive in competition with metals and ceramics for load bearing applications under harsh operating conditions ( Wiesli and Özcan, 2015 Al Christopher et al., 2021). Therefore, incorporation of IF-WS2 nanoparticles into PEEK is a useful strategy to improve the mechanical performance of FDM PEEK. However, addition of just 1 wt% of IF-WS2 nanoparticles into PEEK increased the tensile strength and Young’s modulus of the FDM PEEK materials to similar levels to those achieved for unfilled injection moulded PEEK. ![]() ![]() In general, the lower mechanical properties of the 3D printed samples compared with the injection moulded ones are ascribed to poor interlayer bonding between the deposited layers and the presence of voids. This effect is ascribed to the increased inter-layer bonding of PEEK in the presence of IF-WS 2 nanoparticles in FDM. However, this increment was more noticeable in the 3D-printed nanocomposite samples, resulting in smaller gap between the mechanical properties of the 3D-printed samples and the injection moulded counterparts, in respect to pure PEEK, particularly at 1 wt% IF-WS 2. In general, incorporation of IF-WS 2 nanoparticles increased the mechanical properties of pure PEEK in both 3D printed and injection moulded samples. The 3D printed samples showed slightly higher crystallinity at each IF-WS 2 loading in relation to the injection moulded samples and extruded filaments, because of multiple reheating effect from subsequent layer deposition during FDM, causing recrystallization. The crystallization degree of PEEK increased with increasing loading of IF-WS 2 nanoparticles up to 1wt% and then declined at 2 wt%, due to lower level of particle dispersion in this sample. In general, a good distribution of nanoparticles was observed in PEEK, although larger agglomerates were visible at 2 wt% IF-WS 2. To compare the impact of the two processing methods and the incorporated nanoparticles on the morphology, crystallization and final mechanical properties of the nanocomposites, SEM, DSC and tensile testing were performed. In this study, PEEK nanocomposites with 0, 0.5, 1, and 2wt% IF-WS 2 were manufactured by injection moulding and Fused Deposition Modelling (FDM). Ulster University, Jordanstown, United Kingdom.Atefeh Golbang, Mozaffar Mokhtari, Eileen Harkin-Jones*, Edward Archer and Alistair Mcilhagger
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