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With the advances in additive manufacturing, polyetheretherketone (PEEK), a biocompatible polymer, can be used in biomedical applications such as spinal implants. This paper aims to investigate the evolution of the microstructure of PEEK parts manufactured by material extrusion (MEX)‐based additive manufacturing with different printing parameters. The effect of layer thickness (LT) and nozzle diameter on mechanical properties was investigated using tensile, Charpy impact, and short beam strength (SBS) tests. Two different LTs, 0.1 and 0.2 mm, and two different nozzle diameters, 0.6 and 0.8 mm, were used as printing parameters. By increasing the LT, tensile strength dropped by around 24%, and impact strength by almost 55%. Moreover, altering the LT resulted in a 15% decrease in interlaminar shear strength (ILSS) from the SBS test. In addition, increasing the nozzle diameter also led to a significant reduction in all of the results as tensile strength, Charpy impact strength, and ILSS. The results were also consolidated by scanning electron microscopy. The main findings were that increasing LT leads to an increase in microstructural defects that act as stress concentrators. Following the tests, response surface methodology (RSM) was used to determine optimal printing parameters. In the end, using the optimum printing parameters from the RSM study, a structural analysis of a MEX‐printed spinal implant was conducted through finite element method, considering the loading cases mimicking daily human body motions. Highlights: As layer thickness increased, tensile and impact strength dropped.Tensile and impact strength dropped truly with increasing nozzle diameter.SEM revealed that increasing layer thickness causes more microstructural flaws.FEM analysis showed that PEEK‐based implant provides structural integrity. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the effect of different printing orientations and post‐polymerization time with thermal cycling on the translucency of 3D‐printed denture base resins. Methods: Heat‐polymerized (HP) acrylic resin specimens were fabricated and 3D‐printed denture base materials (NextDent, ASIGA, FormLabs) were printed with different printing orientations (0, 45, 90 degrees) and subjected to different post‐polymerization times (15‐, 30‐, 60‐, and 90‐min). All specimens were polished and immersed in distilled water for 1 day at 37°C. CIEDE2000 was used to measure the translucency parameters (TP00) before and after thermal cycling (5000 cycles) recording the color parameters (L*, a*, b*) against a black and white background using a spectrophotometer. k‐factors ANOVA followed by post hoc Tukey's test (α =.05) was performed for statistical analysis. Results: The k‐factors ANOVA test showed a significant effect of resin material, post‐polymerization time, and printing orientation on translucency (p < 0.001). In comparison to HP, all 3D‐printed resins showed lower translucency with all post‐polymerization times and printing orientation (p < 0.001) except FormLabs resin (p > 0.05). For all 3D‐printed resins, the translucency increased, with increasing the post‐polymerization time (p < 0.001) and 60‐ and 90‐min showed the highest translucency. For printing orientation, 90 and 45 degrees significantly showed high translucency in comparison to 0 degrees (p < 0.001). FormLabs showed significantly higher translucency when compared with NextDent and ASIGA per respective printing orientation and post‐polymerization time. The translucency significantly decreased after thermal cycling for all tested resins (p < 0.001). Conclusion: The findings of this study demonstrated that the translucency of 3D‐printed resins is influenced by the printing orientation, post‐polymerization time, and resin type. As a result, choosing a resin type, and printing orientation, with a longer post‐polymerization time should be considered since it may improve the esthetic appearance of the 3D‐printed resins. [ABSTRACT FROM AUTHOR]

The challenge of three‐dimensional (3D) printing by polymeric extrusion in tissue bioengineering is to control with precision the microarchitecture and porous interconnectivity of scaffolds, as well as search for models that allow and facilitate the development of personalized constructs that meet optimal characteristics for the regeneration of significant bone defects. In this study, anatomically accurate scaffolds were designed and printed to a critical size defect from a microtomography image of the rat calvaria. Different software is used to design a scaffold with exact anatomy. With Ultimaker Cura software, distinct printing parameters were standardized, permitting the printing of different types of pores and graded porosity scaffolds, with exact adaptation to the bone defect, utilizing a commercial 3D printer with a fused deposition modeling technique and compensating for the limitations of the method. The scaffolds were characterized by evaluating their mechanical properties and surface characteristics (pore size and porosity), employing scanning electron microscopy images, verifying that the size and shape of the pores were controlled, and evaluating cell viability and cell distribution on the 3D printed scaffold. Therefore, this work proves that by standardizing the printing parameters, it was possible to print a unique customized scaffold, controlling the shape and size of pores. [ABSTRACT FROM AUTHOR]

The advent of additive manufacturing also referred to as 3D printing, has brought about substantial changes in the industrial domain, as it possesses the capability to fabricate intricate items with enhanced cost‐efficiency and productivity. Fused Filament Fabrication (FFF) is a 3D printing process that has gained significant popularity due to its versatile capabilities and cost‐effectiveness. This paper investigates the impact of the printing parameters on the tensile characteristics of Triply Periodic Minimal Surface (TPMS) manufactured using FFF 3D printing. TPMS patterns have unique geometric properties and potential applications, making them an intriguing subject of study. The behavior of three different TPMS lattices with three printing parameters is investigated. Finding the best testing settings is done with the Taguchi method, and the data is analyzed with the Analysis of Variance (ANOVA) test. TPMS pattern was found to be the most effective parameter with 83.78%. While the highest strength was obtained in Schwarz diamond, the highest energy absorption was observed in the Gyroid structure. The contributions of printing parameters to tensile strength are line thickness, printing speed, and layer height, respectively. As line width and printing speed increase, both energy absorption and strength increase. Therefore, 0.40 mm line width and 60 mm/s printing speed give optimum values. When considered for energy absorption, the optimum value is 0.20 mm layer height, while when considered for strength, 0.10 mm layer height is the optimum value. The findings emphasize the importance of optimizing printing parameters for desired mechanical characteristics in 3D printed components and highlight the potential of TPMS structures in various applications. This research contributes to the growing knowledge in additive manufacturing and provides insights into optimizing FFF 3D printing for improved mechanical performance. [ABSTRACT FROM AUTHOR]

In this work we report the dramatic effects that changing the infill pattern has on the electrochemical performance of an additively manufactured electrode made from commercial filament. Electrodes were produced using six different slicing patterns and imaged to confirm how the infill pattern altered the working electrode surface. These electrodes were then electrochemically characterised against the near‐ideal outer sphere redox probe [Ru(NH3)6]3+, the common inner sphere probe [Fe(CN)6]3−, and then used for the electroanalytical determination of acetaminophen. It was found that changing the infill pattern had a dramatic effect on the electrochemical performance of the electrodes. Over the course of the manuscript, it can be seen that Aligned Rectilinear and Rectilinear infill patterns perform consistently well and offer good reproducibility. On the other hand, Concentric infill pattern had noticeably poor inter‐electrode reproducibility and the Hilbert Curve infill was one of the worst performing electrodes in many categories. For future work in this field, we recommend the infill pattern is always reported within the experimental section to allow other researchers to repeat work properly. Additionally, when optimising an electroanalytical sensing platform, we encourage researchers to optimise the infill pattern as it has direct influence on the analytical parameters. [ABSTRACT FROM AUTHOR]

The combination of continuous natural fiber and fused filament fabrication (FFF) 3D printing enables the manufacturing of low carbon emitting, environment friendly, lightweight, and high strength biomass composites with designated geometry characteristics. In current literature, reviews associated with continuous fiber 3D printing primarily cover synthetic fibers, such as carbon fiber, Kevlar, and glass fiber. Very few pieces of literature on the FFF printing of continuous natural fibers are available. Techniques/methodologies for incorporating continuous natural fiber reinforcements in FFF is an emerging field of research. A comprehensive review and discussion on current progress and the future prospects of continuous natural fiber 3D printing would be beneficial to its development. This article summarizes the current research status of continuous natural fiber 3D printing, including information on printing techniques, materials, and the influence of printing parameters on composite properties, so as to provide reference for the future development of FFF technology using continuous natural fiber and thermoplastic composites. [ABSTRACT FROM AUTHOR]

This paper deals with the analysis and comparative studies of the two of the most used types of polymer filaments dedicated to the 3D printing industry. The study is focused on the mechanical, elastic, and thermal properties of two different types of plastic materials filaments – acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA) as well as on future development in various categories like industrial, medical, home decoration, and education. For carrying out this study, different specimens are printed using fused filament fabrication (FFF) technique, taking into account an infill percentage of 30% with a triangular shape as pattern type (internal structure). [ABSTRACT FROM AUTHOR]

Unmodified polyvinyl chloride (PVC) has low thermal stability and high hardness. Therefore, using plasticizers as well as thermal stabilizers is inevitable, while it causes serious environmental and health issues. In this work, for the first time, pure food‐grade PVC with potential biomedical applications is processed and 3D printed. Samples are successfully 3D printed using different printing parameters, including velocity, raster angle, nozzle diameter, and layer thickness, and their mechanical properties are investigated in compression, bending, and tension modes. Scanning electron microscopy is also used to evaluate the bonding and microstructure of the printed layers. Among the mentioned printing parameters, raster angle and printing velocity influence the mechanical properties significantly, whereas the layer thickness and nozzle diameter has a little effect. Images from scanning electron microscopy also reveal that printing velocity greatly affects the final part's quality regarding defective voids and rasters' bonding. The maximum tensile strength of 88.55 MPa is achieved, which implies the superiority of 3D‐printed PVC mechanical properties compared to other commercial filaments. This study opens an avenue to additively manufacture PVC that is the second most‐consumed polymer with cost‐effective and high‐strength features. [ABSTRACT FROM AUTHOR]

3D food printing has recently attracted significant attention, both from academic and industrial researchers, due to its ability to manufacture customized products in such terms as size, shape, texture, color, and nutrition to meet demands of individual consumers. 4D printing, which is a technique that allows evolution of various characteristics/properties of 3D printed objects over time through external stimulation, has also been gaining more attention. In order to produce defect‐free printed objects via both 3D and 4D printing, it is necessary to first identify the causes of defects and then their mitigation strategies. Comprehensive review on these important issues is nevertheless missing. The purpose of this review is to investigate causes and characteristics of defects occurring during and/or after 3D food printing, with a focus on how different factors affect the printing accuracy. Various techniques that can potentially minimize or eliminate printing defects and produce high‐quality 3D/4D printed food products without the need for time‐consuming trial and error printing experiments are critically discussed. Guidelines to avoid defects to improve the efficiency of future 3D/4D printed food production are given. [ABSTRACT FROM AUTHOR]

The shape of 3D printed products can be transformed over time, achieving 4D printing. In this work, poly(lactic acid) (PLA)/poly(ε‐caprolactone) (PCL) blends are fabricated via fused deposition modeling (FDM). The thermoresponsive shape memory effects (SMEs) of 3D printed blends are investigated by stress‐controlled dynamic mechanical analysis in tension mode. The SME mechanism is clarified in detail, along with the crystallization and melting behaviors, dynamic mechanical properties, and morphologies of PLA/PCL blends. It is confirmed that the crystallinity of reversible phase PCL, the glass transition behavior of fixed phase PLA and the two‐phase interfaces have important effects on the shape memory performance. Furthermore, the SME can be tuned by optimizing printing parameters. The 3D printed product fabricated with raster angle of 45°/−45°, infill density of 80%, and layer thickness of 0.05 mm exhibits a favorable SME at the deformation temperature of 65 °C. Shape memory products fabricated via FDM technology have great application potential for 4D printing. [ABSTRACT FROM AUTHOR]

By changing printing parameters, a serious of hydrogel actuators with high mechanical strength and multiple deformation were successfully prepared through three‐dimensional (3D) printing. Base on the enhancement role of cross‐linking density of hydrogel inks, nanofibrillated cellulose (NFC) was treated as reinforcement phase to realize controllable regulation of rheology characteristics. With the increase of NFC content, stress and strain values of hydrogels increased gradually. Attributed to swelling rate and gel‐sol transition point, hydrogel with 12 mg/mL NFC was treated as 3D printing ink. The 3D printing parameters significantly affected self‐driven deformations. The hydrogel actuators with 0°/90°, 45°/135° and Archimedes chord configurations owned bending, spiral and twist deformations, respectively. The hydrogel actuators with relative larger length‐width ratio exhibited higher spiral degree. The high precise anisotropic swelling property of printed bilayer structure was the self‐driven deformation mechanism of hydrogel actuators. The combination of hydrogels and 3D printing extended the application of intelligent hydrogels. [ABSTRACT FROM AUTHOR]

Three‐dimensional (3D) printing becomes an attractive technique to fabricate tissue engineering scaffolds through its high control on fabrication and repeatability using the printing parameters. This technique can be combined by the finite element method (FEM), and tissue‐specific scaffolds with desirable morphological and mechanical properties can be designed and manufactured. In this study, the influential 3D printing parameters on the morphological and mechanical properties of polycaprolactone (PCL) filament and scaffold were studied experimentally and numerically. First, the effects of printing parameters and process on the properties of extruded PCL filament were investigated. Then, using FEM, the effects of filament specifications on the overall characteristics of the scaffold were evaluated. Results showed that both the printing process in terms of resting time and remaining time and the printing parameters like pressure, printing speed, and printing path length have influenced the filament properties. In addition, both the filament diameter and elastic modulus had significant effects on the properties of scaffold especially, a 20% increase in the filament diameter caused the scaffold compressive elastic modulus to rise by around 72%. It is concluded that the printing parameters and process must be tuned very well in fabricating scaffolds with the desired morphology and mechanical property. [ABSTRACT FROM AUTHOR]

This work aims to determine the influence of fused deposition modeling (FDM) printing parameters on the mechanical properties of parts fabricated on an Ultimaker2 printer with acrylonitrile butadiene styrene (ABS). The effect of several parameters such as interlayer cooling time (ILCT), nozzle diameter, infill density, raster angle and layer thickness on the ultimate tensile strength, yield strength, and elastic modulus of produced parts was evaluated. Two independent studies were conducted: a first study dedicated to the ILCT and a second study where the influence of other parameters was evaluated through a design of experiments (DoE) approach. Both studies were carried out through the execution of standard tensile tests. The statistical analysis of tensile tests results was processed with the ANOVA methodology. The obtained results indicate that a reduced ILCT improves the tensile strength of parts. It is shown that nozzle diameter and infill density are the parameters that most influence the mechanical properties of ABS, with the upper range selected values improving the studied mechanical properties. The raster angle configuration of (−45o/45o) benefits UTS and yield strength of ABS samples. Interactions of nozzle diameter on layer thickness were detected. It was observed that smaller layer thickness promotes a higher elastic modulus and UTS; however, for thinner layers (0.06‐0.10 mm), no significant differences were found on strength of samples due to potential high distortion levels. [ABSTRACT FROM AUTHOR]

Four‐dimensional (4D) printing of shape memory materials has attracted increasing interests for personalized structures. In this study, a biocompatible poly(d,l‐lactide‐co‐trimethylene carbonate) (PLMC) is utilized to fabricate 4D shape‐changing structures with customized geometries through direct ink writing. The printed objects show shape transformations at different dimensions under thermal programming. The influence of the printing parameters on the properties including rheological, solvent evaporation, and static mechanical behavior are systematically investigated. A printing map is further depicted to achieve high‐quality printing with high viscous ink flowed from micronozzle to construct various structures. The printed structures in one‐dimensional, two‐dimensional, and three‐dimensional (3D) exhibit shape‐changing behavior with fast response around body temperature. The fast responsive time shows potential in the field of surgical suture (4 s), nonwoven fabric (3 s), and self‐expandable stent (35 s). The feasibility of 3D printing of PLMC opens the way for applications in shape‐changing devices with small diameter. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48177. [ABSTRACT FROM AUTHOR]

The current study reports the mechanical properties of 3D printing using multiple composite filaments, infill percentages, and printed structures. Results show that graphene‐contained polylactic acid (G‐PLA) displays the highest bending strength, of 119.50 MPa, improving by 62.7%, compared with pure PLA. The scanning electron microscopy (SEM) microstructural observations indicate that the high bending strength is caused by the pull‐out of graphene. As for the double‐filament layer‐by‐layer alternatively printed specimens, the obtained bending strengths are between the single‐filament specimens printed by the two filaments, respectively. Changing infill percentages from 30%, 65%, and to 100% prove that the mechanical properties are greatly enhanced. In the bending tests, with an increase in the infill percentage from 30% to 100%, it is found that all the bending strengths of G‐PLA, copper powder‐containing polylactic acid (Cu‐PLA), and carbon fibers‐containing Cf‐PLA increase by 63.7%, 130.1%, and 106.6% on account of enlarged cross‐section areas sustaining stress. Furthermore, in the compressive tests, shear stress is only found in the hexangular structure, which has a positive effect on the 32.1% increase of the compressive strength compared with that in the rectangular structure. It implies that printed structures significantly influence the fractured modes due to the variation of stress distribution in the designed structures. [ABSTRACT FROM AUTHOR]