Fused Deposition Modeling 3D Printing Research Articles

Multi-material additive manufacturing: investigation of the combined use of ABS and PLA in the same structure

Abstract 3D printing using multi-materials has been one of the most popular topics recently. Fused deposition modeling (FDM) is one of the most widely used techniques for the three-dimensional printing of plastics and composites by all industries. In this study, acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA) were printed in the same structure with an independent double extruder FDM 3D printer. In the study, three different layer thicknesses (0.1 mm, 0.2 mm, and 0.3 mm), three different infill ratios (30%, 60%, and 90%) and three different infill types (hexagon, triangle, and 3D infill) were used. Tensile specimens were produced according to the ASTM D638 type-IV standard. Tensile specimens of 4 mm in thickness were produced in 1 mm ABS and PLA layers. As a result of the tensile tests, it has been seen that when PLA and ABS are used together in the same structure, the tensile strength increases significantly.

Constitutive Relation Development for Fused Deposition Modeling Three-Dimensional Printing Materials and Simulation of Printing Direction Combination

Abstract Due to the forming or curing process, the materials of three-dimensional (3D) printing have periodic meso-defects, which result in complex constitutive relations and anisotropy. Fused deposition modeling (FDM), which is a typical 3D printing process, inevitably introduces stacking pore defects due to the three-dimensional stacking of materials along the printing direction. At present, research focuses on the mechanical properties of materials printed along only one single direction. To consider the possibility of changing the mechanical properties of materials by adjusting the printing direction, the change in the properties of printing materials along the multiple printing direction combinations was analyzed in this paper. First, based on a continuous medium model, the constitutive model proposed by Garzon-Hernandez et al. was considered, and then to improve the prediction accuracy of the model in the plastic stage, a model describing the porosity change rate of porous materials was introduced to obtain better prediction results. Then, the finite element method (FEM) was developed using the new constitutive relation model implemented by the user defined material subroutine (USERMAT) into ansys software. Second, through the finite element subroutine, the mechanical response of the FDM 3D printing plate with two different printing direction combinations was simulated. The results show that by adjusting the print direction combination of the double-layer FDM 3D printing materials, the materials show a different anisotropy, maximum bearing capacity of tension and shear and buckling resistance.

Effect of ultrasonic vibration on the mechanical properties of 3D printed acrylonitrile butadiene styrene and polylactic acid samples

Fused deposition modeling (FDM) is an extrusion-based AM process that is widely used due to its cost-effectiveness and user friendly. However, FDM also has some limitations such as the appearance of seam lines between layers and the production of excess material residue leading to poor surface finish, poor bonding between layers and porosity. This paper presents the findings on the application of ultrasonic vibration in an open-source FDM 3D printer to investigate its effect on the mechanical properties and microstructure of acrylonitrile butadiene styrene (ABS) and Polylactic Acid (PLA) samples. Two units of ultrasonic piezoelectric transducer were clamped horizontally on the surface of the 3D printer platform. The ultrasonic vibration was transmitted directly to the platform while the sample received vibration with a specific frequency while the printing process commences. Two process parameters, namely build orientation and ultrasonic vibration were selected to analyze their significance and optimization on the mechanical properties and the microstructure of the printed samples. High compressive and low surface roughness are required to have the best properties for the printed sample. Therefore, the optimization parameters are performed with these settings where the compressive strength is maximized and the surface roughness is minimized. The result shows that the overall compressive strength in ABS and PLA samples created in the Z-axis orientation is higher than in the X-axis orientation. However, the compressive strength of ABS and PLA samples is not much different after the ultrasonic vibration was applied during the printing process. The microstructure analysis shows that bonding between the layers is similar when applying ultrasonic vibration for both ABS and PLA samples. Furthermore, the result indicates that the surface roughness increased at 10 kHz and then decreased or became smoother at 20 kHz for both ABS and PLA material samples. The analysis shows that the build orientation significantly affects the compressive strength in ABS and PLA samples. However, the ultrasonic vibration has no considerable impact. In surface roughness, the build orientation and ultrasonic vibration significantly affect ABS samples. However, the PLA samples are only slightly affected. The optimum parameters for both materials are found where Z-axis orientation and 0 kHz of the ultrasonic vibration samples gave the best compressive strength and surface roughness value.

Conductive Filament Composites from Waste Battery Rod-Derived Exfoliated Graphite for Fused Deposition Modeling 3D Printing: A Two-Level Factorial Design Optimization Study

This study used carbon rods from spent zinc-carbon batteries as a source of exfoliated graphite (EG) to produce conductive filament composites for fused deposition modeling 3D printing. The EG filler was prepared through microwave irradiation, while the resulting 3D printable electroconductive EG composites were prepared using polylactic acid (PLA) and polyethylene glycol (PEG) as the polymer matrix and compatibilizer, respectively, via a sonication-assisted solution blending and melt extrusion process. A two-level full factorial design was employed to fully investigate the influence of filament production parameters such as EG loading, PEG:PLA ratio, and sonication time on the resistivity (i.e., conductivity-1) of the prepared composites. Analysis of variance showed that both EG loading and sonication time had significant effects on the resistivity of the composites. The optimum electrical resistivity of the new EG filament composites was found to be 916.418 Ω-cm (maximum conductivity = 1.091 x10-3 S/cm) at EG loading = 45 % w/w, PEG:PLA ratio = 1:10, and sonication time = 2 hours. The conductivity of the 3D printed composites was also correlated with EG amount by the power law model of percolation theory, resulting in an electrical percolation threshold at around 35 % w/w of EG. Our filament composites enable the fabrication of high-value conductive materials from waste resources for sustainable additive manufacturing in the electronics industry.

A Review of Natural Fiber-Based Filaments for 3D Printing: Filament Fabrication and Characterization.

Today, additive manufacturing (AM) is the most recent technology used to produce detailed and complexly built parts for a variety of applications. The most emphasis has been given to fused deposition modeling (FDM) in the development and manufacturing fields. Natural fibers have received attention in the area of 3D printing to be employed as bio-filters with thermoplastics, which have prompted an effort for more ecologically acceptable methods of manufacturing. The development of natural fiber composite filaments for FDM requires meticulous methods and in-depth knowledge of the properties of natural fibers and their matrices. Thus, this paper reviews natural fiber-based 3D printing filaments. It covers the fabrication method and characterization of thermoplastic materials blended with natural fiber-produced wire filament. The characterization of wire filament includes the mechanical properties, dimension stability, morphological study, and surface quality. There is also a discussion of the difficulties in developing a natural fiber composite filament. Last but not least, the prospects of natural fiber-based filaments for FDM 3D printing are also discussed. It is hoped that, after reading this article, readers will have enough knowledge regarding how natural fiber composite filament for FDM is created.

Towards point-of-care manufacturing and analysis of immediate-release 3D printed hydrocortisone tablets for the treatment of congenital adrenal hyperplasia

Hydrocortisone (HC) is the preferred drug in children with congenital adrenal hyperplasia due to its lower potency as well as fewer reports of side effects. Fused deposition modelling (FDM) 3D printing holds the potential to produce low-cost personalised doses for children at the point of care. However, the compatibility of the thermal process to produce immediate-release bespoke tablets for this thermally labile active is yet to be established. This work aims to develop immediate-release HC tablets using FDM 3D printing and assess drug contents as a critical quality attribute (CQA) using a compact, low-cost near-infrared (NIR) spectroscopy as a process analytical technology (PAT). The FDM 3D printing temperature (140 °C) and drug concentration in the filament (10%-15% w/w) were critical parameters to meet the compendial criteria for drug contents and impurities. Using a compact low-cost NIR spectral device over a wavelength of 900–1700 nm, the drug contents of 3D printed tablets were assessed. Partial least squares (PLS) regression was used to develop individual calibration models to detect HC content in 3D printed tablets of lower drug contents, small caplet design, and relatively complex formula. The models demonstrated the ability to predict HC concentrations over a wide concentration range (0–15% w/w), which was confirmed by HPLC as a reference method. Ultimately, the capability of the NIR model had preceding dose verification performance on HC tablets, with linearity (R2 = 0.981) and accuracy (RMSECV = 0.46%). In the future, the integration of 3DP technology with non-destructive PAT techniques will accelerate the adoption of on-demand, individualised dosing in a clinical setting.

The use of near-infrared as process analytical technology (PAT) during 3D printing tablets at the point-of-care

Fused deposition modelling (FDM) is one of the most researched 3D printing technologies that holds great potential for low-cost manufacturing of personalised medicine. To achieve real-time release, timely quality control is a major challenge for applying 3D printing technologies as a point-of-care (PoC) manufacturing approach. This work proposes the use of a low-cost and compact near-infrared (NIR) spectroscopy modality as a process analytical technology (PAT) to monitor a critical quality attribute (drug content) during and after FDM 3D printing process. 3D printed caffeine tablets were used to manifest the feasibility of the NIR model as a quantitative analytical procedure and dose verification method. Caffeine tablets (0–40 % w/w) were fabricated using polyvinyl alcohol and FDM 3D printing. The predictive performance of the NIR model was demonstrated in linearity (correlation coefficient, R2) and accuracy (root mean square error of prediction, RMSEP). The actual drug content values were determined using the reference high-performance liquid chromatography (HPLC) method. The model of full-completion caffeine tablets demonstrated linearity (R2 = 0.985) and accuracy (RMSEP = 1.4 %), indicated to be an alternative dose quantitation method for 3D printed products. The ability of the models to assess caffeine contents during the 3D printing process could not be accurately achieved using the model built with complete tablets. Instead, by building a predictive model for each completion stage of 20 %, 40 %, 60 % and 80 %, the model of different completion caffeine tablets displayed linearity (R2 of 0.991, 0.99, 0.987, and 0.983) and accuracy (RMSEP of 2.22 %, 1.65 %, 1.41 %, 0.83 %), respectively. Overall, this study demonstrated the feasibility of a low-cost NIR model as a non-destructive, compact, and rapid analysis dose verification method enabling the real-time release to facilitate 3D printing medicine production in the clinic.

Shape memory performance assessment of FDM 3D printed PLA-TPU composites by Box-Behnken response surface methodology

In this paper, for the first time, the role of manufacturing parameters of fused deposition modeling (FDM) on the shape memory effect (SME) is investigated by design of experiments. PLA-TPU blend with a weight composition of 30:70% is processed by melt mixing and then extruded into 1.75 mm filaments for 3D printing via FDM. SEM images reveal that TPU droplets are distributed in the PLA matrix, and the immiscible matrix-droplet morphology is evident. Box-Behnken design (BBD), as an experimental design of the response surface method (RSM), is implemented to fit the model between variables and responses. The shell, infill density, and nozzle temperature are selected as variables, and their effects on loading stress, recovery stress, shape fixity, and shape recovery ratio are studied in detail. An analysis of variance (ANOVA) is applied to estimate the importance of each printing parameter on the output response and assess the fitness of the presented model. The ANOVA results reveal the high accuracy of the model and the importance of the parameters. Infill density and nozzle temperature had the greatest and least roles on shape memory properties, respectively. Also, the values of shape fixity and shape recovery were obtained in the ranges of 58–100% and 53–91%, respectively. Despite many researches on 4D printing of PLA, low ductility at room temperature and high stress relaxation rate are its weakness, which are covered by adding TPU in this research. Due to the lack of similar outcomes in the specialized literature, this paper is likely to fill the gap in the state-of-the-art problem and supply pertinent data that are instrumental for FDM 3D printing of functional shape memory polymers with less material consumption.

FDM 3D Printing and Soil-Burial-Degradation Behaviors of Residue of Astragalus Particles/Thermoplastic Starch/Poly(lactic acid) Biocomposites.

Astragalus residue powder (ARP)/thermoplastic starch (TPS)/poly(lactic acid) (PLA) biocomposites were prepared by fused-deposition modeling (FDM) 3D-printing technology for the first time in this paper, and certain physico-mechanical properties and soil-burial-biodegradation behaviors of the biocomposites were investigated. The results showed that after raising the dosage of ARP, the tensile and flexural strengths, the elongation at break and the thermal stability of the sample decreased, while the tensile and flexural moduli increased; after raising the dosage of TPS, the tensile and flexural strengths, the elongation at break and the thermal stability all decreased. Among all of the samples, sample C-which was composed of 11 wt.% ARP, 10 wt.% TPS and 79 wt.% PLA-was the cheapest and also the most easily degraded in water. The soil-degradation-behavior analysis of sample C showed that, after being buried in soil, the surfaces of the samples became grey at first, then darkened, after which the smooth surfaces became rough and certain components were found to detach from the samples. After soil burial for 180 days, there was weight loss of 21.40%, and the flexural strength and modulus, as well as the storage modulus, reduced from 82.1 MPa, 11,922.16 MPa and 2395.3 MPa to 47.6 MPa, 6653.92 MPa and 1476.5 MPa, respectively. Soil burial had little effect on the glass transition, cold crystallization or melting temperatures, while it reduced the crystallinity of the samples. It is concluded that the FDM 3D-printed ARP/TPS/PLA biocomposites are easy to degrade in soil conditions. This study developed a new kind of thoroughly degradable biocomposite for FDM 3D printing.

Magnetically activated 3D printable polylactic acid/polycaprolactone/magnetite composites for magnetic induction heating generation

Additive manufacturing technology has attracted the attention of industrial and technological sectors due to the versatility of the design and the easy manufacture of structural and functional elements based on composite materials. The embedding of magnetic nanoparticles in the polymeric matrix enables the development of an easy manufacturing process of low-cost magnetically active novel polymeric composites. In this work, we report a series of magnetic composites prepared by solution casting method combining 5 to 60 wt.% of 140 pm 50 nm commercial Fe3O4 nanoparticles, with a semi-crystalline, biocompatible, and biodegradable polymeric blend made of polylactic acid (PLA) and polycaprolactone (PCL). The composites were extruded, obtaining 1.5 pm 0.2 mm diameter continuous and flexible filaments for fused deposition modelling 3D printing. The chemical, magnetic, and calorimetric properties of the obtained filaments were investigated by differential scanning calorimetry, thermogravimetric analysis, magnetometry, and scanning electron microscopy. Furthermore, taking advantage of the magnetic character of the filaments, their capability to generate heat under the application of low-frequency alternating magnetic fields (magnetic induction heating) was analyzed. The obtained results expose the versatility of these easy manufacturing and low-cost filaments, where selecting a desired composition, the heating capacity can be properly adjusted for those applications where magnetic induction plays a key role (i.e., magnetic hyperthermia, drug release, heterogeneous catalysis, water electrolysis, gas capture, or materials synthesis).Graphical This paper presents the manufacture of novel magnetically activated 3D printable filaments, low cost and easy to manufacture, whereby selecting the desired composition, the heating capacity (ρ) generated under the application of an alternating magnetic field (Happ) can be adjusted to the needs of the user.

Spectroelectrochemical sensing of reaction intermediates and products in an affordable fully 3D printed device

Recent advances in fused deposition modelling 3D printing (FDM 3DP) and synthesis of printable electrically conductive materials enabled the manufacture of customized electrodes and electrochemical devices by this technique. The past couple of years have seen a boom in applying approaches of FDM 3DP in the realm of spectroelectrochemistry (SEC). Despite significant progress, reported designs of SEC devices still rely on conventionally manufactured optical components such as quartz windows and cuvettes. To bridge this technological gap, in this work we apply bi-material FDM 3DP combining electrically conductive and optically translucent filaments to manufacture working electrodes and cells, constituting a fully integrated microfluidic platform for transmission absorption UV–Vis SEC measurements. The cell design enables de-aeration of samples and their convenient handling and analysis. Employing cyclic voltammetric measurements with ruthenium(III) acetylacetonate, ethylviologen dibromide and ferrocenemethanol redox-active probes as model analytes, we demonstrate that the presented platform allows SEC sensing of reactants, intermediates and products of charge transfer reactions, including the inspection of their long-term stability. Approaches developed and presented in this work pave the way for manufacturing customized SEC devices with dramatically reduced costs compared to currently available commercial platforms.

Optimization of 3D Printing Parameters of Polylactic-Co-Glycolic Acid-Based Biodegradable Antibacterial Materials Using Fused Deposition Modeling.

A high incidence of ureteral diseases was needed to find better treatments such as implanting ureteral stents. The existing ureteral stents produced a series of complications such as bacterial infection and biofilm after implantation. The fused deposition modeling (FDM) of 3D printing biodegradable antibacterial ureteral stents had gradually become the trend of clinical treatment. But it was necessary to optimize the FDM 3D printing parameters of biodegradable bacteriostatic materials to improve the precision and performance of manufacturing. In this study, polylactic-co-glycolic acid (PLGA), polycaprolactone (PCL), and nanosilver (AgNP) were mixed by the physical blending method, and the 3D printing parameters and properties were studied. The relationship between printing parameters and printing errors was obtained by single-factor variable method and linear fitting. The performance of 3D printing samples was obtained through infrared spectrum detection, molecular weight detection, and mechanical testing. The printing temperature and the printing pressure were proportional to the printing error, and the printing speed was inversely proportional to the printing error. The 3D printing has little effect on the functional groups and molecular weights of biodegradable antibacterial materials. The addition of AgNP increases the compressive strength and breaking strength by 8.332% and 37.726%, which provided ideas for regulating the mechanical properties. The parameter range of biodegradable bacteriostatic materials for thermal melting 3D printing was precisely established by optimizing the parameters of printing temperature, printing pressure, and printing speed, which would be further applied to the advanced manufacturing of biodegradable implant interventional medical devices.

Systematic evaluation of antibiotic activity of a cefazolin-loaded scaffold with varying 3D printing temperatures and its application in treating osteomyelitis

Osteomyelitis is one of the most common inflammatory bone diseases caused by gram-positive bacteria. Although cefazolin is widely used as an osteomyelitis antibiotic against Staphylococcus aureus, its thermolabile properties may decrease its antibiotic activity when incorporated into bone cement, such as polymethyl methacrylate. Thus, to fully characterize the loss of antibiotic activity during the fused deposition modeling 3D-printing processes, we systematically evaluated the antibacterial activity of a cefazolin-loaded polycaprolactone (PCL)-based scaffold at varying 3D printing temperatures against S. aureus. In vitro antibacterial activity analysis revealed that cefazolin-loaded PCL scaffolds printed between 60 °C and 120 °C could maintain the antibacterial activity, whereas the antibacterial activity of scaffolds printed between 140 °C and 160 °C was significantly decreased. In addition, the therapeutic potential of the 3D-printed, scaffolds was assessed based on serum interleukin-6 (IL-6) levels, micro-computed tomography (micro-CT), and histological evaluation using a rabbit model of S. aureus-induced chronic osteomyelitis. Our in vivo results demonstrated that the serum level of IL-6 decreased in the cefazolin-loaded PCL scaffold-transplanted group. Furthermore, micro-CT and histological analyses confirmed the decreased deformation and overgrowth of the bone. The utilization of a 3D-printable, cefazolin-loaded PCL scaffold offers a promising and distinct approach for the treatment of osteomyelitis.

Preparation of Polylactic Acid/Calcium Peroxide Composite Filaments for Fused Deposition Modelling.

Fused Deposition Modelling (FDM) 3D printers have gained significant popularity in the pharmaceutical and biomedical industries. In this study, a new biomaterial filament was developed by preparing a polylactic acid (PLA)/calcium peroxide (CPO) composite using wet solution mixing and extrusion. The content of CPO varied from 3% to 24% wt., and hot-melt extruder parameters were optimised to fabricate 3D printable composite filaments. The filaments were characterised using an X-ray diffraction analysis, surface morphology assessment, evaluation of filament extrudability, microstructural analysis, and examination of their rheological and mechanical properties. Our findings indicate that increasing the CPO content resulted in increased viscosity at 200 °C, while the PLA/CPO samples showed microstructural changes from crystalline to amorphous. The mechanical strength and ductility of the composite filaments decreased except for in the 6% CPO filament. Due to its acceptable surface morphology and strength, the PLA/CPO filament with 6% CPO was selected for printability testing. The 3D-printed sample of a bone scaffold exhibited good printing quality, demonstrating the potential of the PLA/CPO filament as an improved biocompatible filament for FDM 3D printing.

Manufacturing and experimental analysis of a dew-point indirect evaporative cooler using fused deposition modelling 3D printing and polymeric materials

Evaporative cooling (EC) is an interesting alternative for reducing energy consumption and CO2 emission associated with the cooling of building. In the present work, a prototype of an innovative dew-point indirect evaporative cooler (DIEC) was manufactured by additive manufacturing technology. This prototype was made up of two types of materials: (a) one porous, with high water absorption capacity, polyvinyl alcohol (PVA) with felt, and therefore, high capacity of generate EC; and (b) another with high hydrophobic properties, polylactic acid (PLA) with bronze. The materials were characterised in terms of thermal, water absorption properties and morphological properties. Prior to manufacturing, a design of experiments was conducted in order to find the optimal manufacturing parameters. The prototype was produced through an innovative process, based on the simultaneous use of two extruders, and the manufacture of a porous layer of felt by dissolving the PVA matrix where the felt was initially embedded. Finally, the energy performance of the prototype was experimentally analysed, reaching values of dew-point effectiveness up to 0.9 and energy efficiency ratio up to 22.74 at 45 °C outside dry bulb temperature. These results show that additive manufacturing is promising for developing competitive compact and highly energy efficient DIEC systems.

Flexural, impact, and dynamic mechanical analysis of glass fiber/ABS and glass fiber/carbon fiber/ABS composites

AbstractIn this study, a hybrid manufacturing technique was proposed to fabricate composites of acrylonitrile butadiene styrene (ABS) with Bidirectional woven glass fiber mat (GF)/ABS and GF/Bidirectional woven carbon fiber mat (CF)/ABS. The composites were fabricated using fused deposition modeling 3D printing, followed by hot compression molding, and their flexural, impact, and dynamic mechanical behaviors were examined. Results indicated that composites with GF and ABS combinations had shown the highest maximum flexural strength (64.46 MPa) and impact strength (0.089 J/mm2). The hybrid composites showed intermediate performance between ABS and GF/ABS composites, with higher flexural strain before failure than ABS and GF/ABS. A comprehensive analysis utilizing scanning electron microscopy was carried out to evaluate the adhesion characteristics of the fiber‐matrix interface in impact‐tested samples. Dynamic mechanical analysis showed that GF/ABS composites had offered superior E′, E″, and tanδ than the hybrid configuration. The peak tan delta values obtained from ABS, GF/ABS, and GF/CF/ABS composites were utilized to determine their respective glass transition temperatures. The observed values for ABS, GF/ABS, and GF/CF/ABS composites were 109.65, 69.95, and 71.5°C, respectively. Some potential applications for the composites fabricated in this study could include the development of lightweight and strong components for aerospace or automotive industries.

Composite magnetic 3D-printing filament fabrication protocol opens new perspectives in magnetic hyperthermia

Three-dimensional (3D) printing technology has emerged as a promising tool for meticulously fabricated scaffolds with high precision and accuracy, resulting in intricately detailed biomimetic 3D structures. Producing magnetic scaffolds with the aid of additive processes, known as 3D printing, reveals multitude and state-of-the-art areas of application such as tissue engineering, bone repair and regeneration, drug delivery and magnetic hyperthermia. A crucial first step is the development of innovative polymeric composite magnetic materials. The current work presents a fabrication protocol of 3D printed polymer-bonded magnets using the Fused Deposition Modeling 3D printing method. Polymer-bonded magnets are defined as composites with permanent-magnet powder embedded in a polymer binder matrix. By using a low-cost mixing extruder, four (4) different filament types of 1.75 mm were fabricated using commercial magnetite magnetic nanoparticles mixed with a pure polylactic acid powder (PLA) and a ferromagnetic PLA (Iron particles included) filaments. The powder mixture of the basic filaments was compounded mixed with the nanoparticles (NPs), and extruded to fabricate the 3D printing filament, which is subsequently characterized structurally and magnetically before the printing process. Magnetic polymer scaffolds are finally printed using composite filaments of different concentration in magnetite. Our results demonstrate that the heating efficiency (expressed in W g−1) of the 3D printed magnetic polymer scaffolds (ranging from 2 to 5.5 W g−1 at magnetic field intensity of 30 mT and field frequency of 365 kHz) can be tuned by choosing either a magnetic or a non-magnetic filament mixed with an amount of magnetite NPs in different concentrations of 10 or 20 wt%. Our work opens up new perspectives for future research, such as the fabrication of complex structures with suitable ferromagnetic custom-made filaments adjusting the mixing of different filaments for the construction of scaffolds aimed at improving the accuracy of magnetic hyperthermia treatment.

Prediction of Mechanical Properties and Failure Behavior of Nano-Alumina Reinforced Poly(Lactic) Acid Composite for Fused Deposition Modeling 3D Printing via Finite Element Analysis

Mechanical properties and failure behavior of 3D printed poly (lactic) acid (PLA) reinforced with varying loadings of nano-alumina (Al2O3) (0, 2.5, 5.0, and 10.0 wt.%) were investigated through simulation using a finite element analysis (FEA)-based software. Tensile test specimens were 3D printed via fused deposition modeling (FDM) technique and underwent actual testing. The mechanical properties determined were then used as parameters for the FEA simulation to achieve prediction accuracy. Specifically, this study utilized MSC Patran and Nastran software to simulate the tensile test on the modeled test specimen with tetrahedron mesh. The finite element model was verified by comparing the simulated values with the results of actual experimental testing. Upon calculation, the average percentage differences for the tensile strength, elastic modulus, and displacement were 5.86%, 12.07%, and 10.57%, respectively. Although percentage differences were obtained, using FEA as an initial analysis for the prediction of mechanical properties and failure behavior could serve as a solution for better design and materials optimization.

3D printed TPMS structural PLA/GO scaffold: Process parameter optimization, porous structure, mechanical and biological properties

Bone scaffolds should have good biocompatibility and mechanical and biological properties, which are primarily by the material design, porous structure, and preparation process. In this study, we proposed polylactic acid (PLA) as the base material, graphene oxide (GO) as an enhancing filler, triply periodic minimal surface (TPMS) as a porous structure, and fused deposition modeling (FDM) 3D printing as a preparation technology to develop a TPMS structural PLA/GO scaffold and evaluate their porous structures, mechanical properties, and biological properties towards bone tissue engineering. Firstly, the influence of the FDM 3D printing process parameters on the forming quality and mechanical properties of PLA was studied by orthogonal experimental design, based on which the process parameters were optimized. Then, GO was composited with PLA, and PLA/GO nanocomposites were prepared by FDM. The mechanical tests showed that GO can effectively improve the tensile and compression strength of PLA; only by adding 0.1% GO the tensile and compression modulus was increased by 35.6% and 35.8%, respectively. Then, TPMS structural (Schwarz-P, Gyroid) scaffold models were designed and TPMS structural PLA/0.1%GO nanocomposite scaffolds were prepared by FDM. The compression test showed that the TPMS structural scaffolds had higher compression strength than the Grid structure; This was owing to the fact that the continuous curved structure of TMPS alleviated stress concentration and had a more uniform stress bearing. Moreover, cell culture indicated bone marrow stromal cells (BMSCs) showed better adhesion, proliferation, and osteogenic differentiation behaviors on the TPMS structural scaffolds as the continuous surface structure of TPMS had better connectivity and larger specific surface area. These results suggest that the TPMS structural PLA/GO scaffold has potential application in bone repair. This article suggests the feasibility of co-designing the material, structure, and technology for achieving the good comprehensive performance of polymer bone scaffolds.

Fabrication of superhydrophobic PLA surfaces by tailoring FDM 3D printing and chemical etching process

The present study describes a simple and robust method for fabricating superhydrophobic surfaces of Polylactic Acid (PLA) using the Fused Deposition Modelling (FDM) process without the need for nanoparticles. FDM 3D printing technology allows for replicating the surface topology of superhydrophobic surfaces. The resulting PLA samples show excellent non-wetting properties after chemical etching and coating with a low surface energy material. The water contact angles (WCA’s) of the FDM printed PLA samples were found to be up to 142° at an optimized average roughness value of 148.6 nm on a 3D printed square pyramid structure with equal height and edges of base of 1.5 mm. Microstructural analyses suggest that the observed high WCA results from the hierarchical structures created by FDM 3D printing and chemical etching. The study found that increasing the distance between the peaks of two pyramids changes the wetting mechanism from the Cassie-Baxter state to the Wenzel wetting state, leading to a decrease in the WCA. This paper presents a detailed study of the impact of roughness created by 3D printing, surface topology, and chemical etching on the wetting properties of PLA. The vital outcome of this study is the fabrication of superhydrophobic surfaces using FDM 3D printing and low surface energy material without the use of nanoparticles.