For the first time, graphene nanoplatelets (xGnP) were incorporated at 4wt% in acrylonitrile–butadiene–styrene (ABS) filaments obtained by a solvent-free process consisting of melt compounding and ...extrusion. Nanocomposite filaments were then used to feed a fused deposition modelling (FDM) machine to obtain specimens with various build orientations. The elastic modulus and dynamic storage moduli of 3D printed parts along three different build orientations were increased by the presence of xGnP in the ABS matrix. At the same time, a decrease in both stress and strain at break was observed when xGnP is added to ABS. Moreover, a higher thermal stability was induced on 3D printed parts by xGnP, as indicated by a reduction in both coefficient of linear thermal expansion and creep compliance. A comparison between 3D printed and compression moulded parts highlighted the importance of the orientation effects induced by the fused deposition modelling process.
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•Extrusion optimization of PP and GRPP filaments for 3D printing.•3D printing vs. compression molding benchmark with the same raw material.•Optimal 3D printing conditions for PP and ...GRPP.•3D printing deposition orientation with minimum mechanical performance impact.•Reinforcing role of glass fibers is maintained with 3D printing.
This paper addresses the potential of polypropylene (PP) as a candidate for fused deposition modeling (FDM)-based 3D printing technique. The entire filament production chain is evaluated, starting with the PP pellets, filament production by extrusion and test samples printing. This strategy enables a true comparison between parts printed with parts manufactured by compression molding, using the same grade of raw material. Printed samples were mechanically characterized and the influence of filament orientation, layer thickness, infill degree and material was assessed. Regarding the latter, two grades of PP were evaluated: a glass-fiber reinforced and a neat, non-reinforced, one. The results showed the potential of the FDM to compete with conventional techniques, especially for the production of small series of parts/components; also, it was showed that this technique allows the production of parts with adequate mechanical performance and, therefore, does not need to be restricted to the production of mockups and prototypes.
The Fused Deposition Modelling (FDM) has become one of the most used techniques to 3D object rapid prototyping. In this process, the model is built as a layer-by-layer deposition of a feedstock wire. ...In recent years, the FDM evolved from rapid prototyping technique towards a rapid manufacturing method, changing the main purpose in producing finished components ready for use. Thus, the prediction of the mechanical properties of this new technology has an increasingly important role. Previous papers have highlighted the orthotropic mechanical behaviour of FDM parts showing that the stacking sequence controls the mechanical properties of FDM parts. The aim of this work is to describe the mechanical behaviour of FDM parts by the classical laminate theory (CLT). In order to reach this objective, the values of the elastic modulus in the longitudinal and transverse directions to the fibre (E1, E2), the Poisson's modulus (ν12) and the shear modulus (G12) will be experimentally measured.
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•Fused deposition modelling parts show an orthotropic behaviour.•The mechanical properties of the layer decrease with the raster angle increasing.•Classical laminate theory well predicts the elastic behaviour for both PLA and ABS.
Polylactic acid (PLA) is one of the most popular thermoplastics for fused deposition modeling (FDM). Attributed to its semi-crystalline nature, the relation between printing parameters and properties ...are more complicated than amorphous thermoplastics like acrylonitrile-butadiene-styrene (ABS). This study was designed to investigate two printing parameters, layer height (0.2 and 0.4 mm) and plate temperature (30 and 160 °C) on the Izod impact strength of printed PLA. X-ray diffraction (XRD) analysis confirmed the existence of α crystals in parts printed from 160 °C-plate temperature and α′ crystals in those printed at 30 °C-plate temperature. Parts printed with a 160 °C (plate temperature) had higher crystallinity. Polarized optical microscope (POM) observations illustrated that the plate temperature of 160 °C and layer height of 0.2 mm induced higher crystallinity, smaller crystals and interfacial crystal bands. The Izod impact strength of printed PLA at higher plate temperature was up to 114% higher than injection molded PLA made using conventional molding parameters.
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•Printed PLA from FLM process can be 114% higher in Izod impact strength than injection molded PLA.•High crystallinity and small crystal size induced by a high plate temperature improves the toughness of printed PLA.•Crystal morphology at the interfaces among printed layers was visualized for the first time by a light microscope and SEM.
Additive manufacturing (AM) or 3D printing is a digital manufacturing process and offers virtually limitless opportunities to develop structures/objects by tailoring material composition, processing ...conditions, and geometry technically at every point in an object. In this review, we present three different early adopted, however, widely used, polymer-based 3D printing processes; fused deposition modelling (FDM), selective laser sintering (SLS), and stereolithography (SLA) to create polymeric parts. The main aim of this review is to offer a comparative overview by correlating polymer material-process-properties for three different 3D printing techniques. Moreover, the advanced material-process requirements towards 4D printing via these print methods taking an example of magneto-active polymers is covered. Overall, this review highlights different aspects of these printing methods and serves as a guide to select a suitable print material and 3D print technique for the targeted polymeric material-based applications and also discusses the implementation practices towards 4D printing of polymer-based systems with a current state-of-the-art approach.
Additive manufacturing or three-dimensional (3D)-printing is an emerging technology that has been applied in the development of novel materials and devices for a wide range of applications, including ...Electrochemistry and Analytical Chemistry areas. This review article focuses on the contributions of 3D-printing technology to the development of electrochemical sensors and complete electrochemical sensing devices. Due to the recent contributions of 3D-printing within this scenario, the aim of this review is to present a guide for new users of 3D-printing technology considering the required features for improved electrochemical sensing using 3D-printed sensors. At the same time, this is a comprehensive review that includes most 3D-printed electrochemical sensors and devices already reported using selective laser melting (SLM) and fused deposition modeling (FDM) 3D-printers. The latter is the most affordable 3D-printing technique and for this reason has been more often applied for the fabrication of electrochemical sensors, also due to commercially-available conductive and non-conductive filaments. Special attention is given to critically discuss the need for the surface treatment of FDM 3D-printed platforms to improve their electrochemical performance. The insertion of biochemical and chemical catalysts on the 3D-printed surfaces are highlighted as well as novel strategies to fabricate filaments containing chemical modifiers within the polymeric matrix. Some examples of complete electrochemical sensing systems obtained by 3D-printing have successfully demonstrated the enormous potential to develop portable devices for on-site applications. The freedom of design enabled by 3D-printing opens many possibilities of forthcoming investigations in the area of analytical electrochemistry.
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•We review the contributions of 3D-printing to fabricate electrochemical sensors.•Different 3D-printing methods are compared highlighting fused deposition modeling (FDM).•Surface treatment and modification with (bio)chemical mediators for improved performance.•Strategies for fabrication of conductive filaments are presented for future applications.•3D-printing of all-in-one electrochemical devices in different designs are assessed.
The advent of additive manufacturing has brought a paradigm shift in many engineering applications involving polymer composites. The current study aims at integrating artificial neural network (ANN) ...with experimentation to assess the wear properties of glycol‐modified polyethylene terephthalate (PETG) composites reinforced with organically modified montmorillonite (OMMT) nanoclay (1%, 3%, and 5% weight percentages). The specimens are fabricated using fused deposition modeling technology. The proposed composites are compounded and developed using a single screw extruder with a diameter of 1.75 mm. As per ASTM G99 standard, the tribological characteristics were investigated using sliding wear with the dry pin on disc arrangement. The data points owing to the wear properties of PETG/OMMT nanocomposites are collected with the aid of the experimentation, which is then used to train the ANN model using Levenberg– Marquardt backward propagation algorithm. The experimental results show that adding OMMT nanoclay at a 3% weight percentage improves the wear properties of the composites compared to virgin PETG. A scanning electron microscope study of the wear mechanism reveals that adding OMMT nanoclay to the proposed composites results in mild wear as opposed to heavy wear in the case of virgin PETG. The ANN model developed to predict the tribological performance of PETG/OMMT facilitates better predictability with 99.6% accuracy, thereby reducing the requirement of expensive experimentation and analysis. The proposed composites may be applicable in the prosthetic, aerospace and automobile industries.
Experiment‐ANN methodology for wear analysis of PETG/OMMT nanoclay composites.
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•Thirty PC specimen made with FDM were tested contributing to data availability.•Correlation of physical test and Finite Element Analysis has been performed.•FEA isotropic model may ...be better than orthotropic model for elastic region.•Manufacturing parameters affect mechanical response besides building orientation.
Building end-use functional parts with additive manufacturing (AM) technologies is a challenging task. Several factors influence their surface finish, dimensional accuracy, mechanical properties and cost. Their orientation inside the building chamber is one of the most significant factors in AM processes. When using Fused Deposition Modeling (FDM) to build such parts, additional factors must be considered.
This paper aims to accomplish two purposes: finding a good model to simulate FDM parts and correlating a finite element analysis (FEA) simulation with physical testing.
The first objective was achieved by experimental tensile test of specimens to determine the nine mechanical constants that defines the stiffness matrix of an orthotropic material. Three Young’s modulus, three Poisson’s ratio and three shear modulus were experimentally obtained as well as yield tensile and ultimate strength of each specimen.
A simple part was designed and manufactured in different orientations to be physically tested and simulated to achieve the second objective. Polycarbonate (PC) was used as part material. Combined loading including bending and torsion was used. Differences on mechanical response were observed during the physical test of the parts depending on the building direction. Conclusions comment results and the convenience of using a different constitutive model depending on the design and use specifications.
Different from other 3D printing techniques such as selective laser sintering (SLS), stereolithography (SLA), three-dimensional printing (3DP), and laminated object manufacturing (LOM), the fused ...deposition modeling (FDM) technology is widely used in aerospace, automobile making, bio-medicals, smart home, stationery and training aids, and creative gifts for its easy use, simple operation, and low cost. The polylactic acid (PLA) is a material most extensively applied in FDM technology for its low melting point, non-poison, non-irritation, and sound biocompatibility. The FDM 3D-printed PLA parts are a research hotspot in the 3D printing field. This paper is intended to sum up the latest research results and achievements made in recent years in the interface bonding property, mechanical properties, and shape precision promotion of FDM 3D-printed PLA parts as well as the functional expansion of the PLA parts based on vast domestic and overseas literature. The literature research collection focuses on the following two aspects: one is the macroscopic technical research on the optimal settings of key technological parameters; the other one is the PLA modification research on improvement of cross-linking state and crystallinity of PLA molecular chains, carbon reinforced phase modification of PLA, and PLA functional compound modification. The researches in the two aspects are of importance in improving whole properties, enhancing functional applications, and expanding and enriching the applications of FDM 3D-printed PLA parts. This paper is expected to give some helps and references to the researchers who are specializing in the 3D printing field.
Additive Manufacturing (AM), and more specifically Fused Filament Fabrication (FFF), allow the production of highly customized parts, provide enormous freedom-of-design and can lead to material ...savings due to the layer-by-layer material deposition that is inherent to this family of production processes. FFF utilizes both amorphous and semi-crystalline thermoplastic filaments as feedstock materials, offering a wider range of materials compared to some other polymer-based additive manufacturing techniques. However, the current trend where FFF, and AM in general, are changing from a technique for rapid prototyping to the production of fully functional parts designed for high-end applications creates the inevitable need to incorporate more engineering and high-performance thermoplastics, which are most often semi-crystalline polymers, into the material palette. Crystallization provides semi-crystalline polymers with some distinct features that set them apart from their amorphous counterparts, yet it also can present difficulties regarding their processing. Understanding of the behavior of semicrystalline polymers during FFF processing is thus a prerequisite to exploit their full potential. This review provides a broad overview of FFF processing of semicrystalline polymers. Particular focus lies on the impact of processing conditions and feedstock modifications, such as the incorporation of fillers or the formation of blends, on crystallinity as well as the microstructure of printed parts, the impact of microstructure on the mechanical performance, and general part quality. Furthermore, attention is given to some specific phenomena that can occur during printing of semi-crystalline feedstock filaments which have shown to strongly impact the printing process. Examples are self-nucleation in the case of insufficient heat transfer and melting, flow-induced crystallization due to high shear deformations upon extrusion, and the negative impact of crystallization on chain mobility which is relevant for the development of interlayer strength and on dimensional accuracy due to excessive shrinkage. Finally, this review is concluded with a critical outlook on perspectives for future research to address the current challenges that are still faced when employing semi-crystalline polymers as FFF feedstock.
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