Additive manufacturing technologies provide new opportunities for the manufacturing of components with customisable geometries and mechanical properties. In particular, fused deposition modelling ...(FDM) allows for customisable mechanical properties by controlling the void density and filament orientation. In this work, a methodology is provided for the prediction of the mechanical properties and mesostructure of FDM polymers. To this end, we propose a computational framework for the simulation of the printing process taking as input data specific manufacturing parameters and filament properties. A new two-stage thermal and sintering model is developed to predict the bond formation process between filaments. The model predictions are validated against original experimental data for acrylonitrile butadiene styrene (ABS) components manufactured by FDM. A parametric study is finally presented to interpret the effects of different manufacturing parameters on the mechanical performance of ABS specimens. Overall, the proposed framework offers new avenues for the design of 3D printed polymeric components with custom properties, directly in terms of manufacturing settings.
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•FDM ABS specimens are tested for different combinations of printing parameters.•A two-stage model is proposed to simulate the FDM manufacturing process.•The model predicts thermal conditions and sintering within filaments.•Analytical expressions are established for FDM ABS.•Layer height and environment temperature main drivers for mechanical properties.
Nowadays, passive radiative cooling (PRC) has being attracted intensive attention because it can realize cooling effect without consuming any energy. Unfortunately, fabricating polymer film with ...radiative cooling effect by a facile, continuous and environmentally friendly method is still a large challenge. In this study, high density polyethylene (HDPE)/polyvinyl oxide (PEO) film were first fabricated by melt extrusion casting method, and polyethylene film composed of directional microfibrils (PFCDM) were finally obtained after selective dissolution of PEO phase in deionized water at 70 °C. The as-prepared PFCDM shows higher average solar reflectivity of 85.17% in the visible range and stronger average mid-infrared emissivity of 82.04% within the atmospheric window. It shows a sub-ambient cooling of 23.28 °C during the day and 3.1 °C at night, suggesting that it has a remarkable PRC performance. Moreover, the as-prepared PFCDM has outstanding wearability and self-cleaning property, showing promising potential of personal thermal management. This study proposes a facile but environmentally friendly method for fabricating PFCDM, paving a new way to develop wearable PRC film following the concept of thermoplastic polymers “functionalized” processing.
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•PFCDM was efficiently prepared via melt extrusion casting and water leaching.•PFCDM shows remarkable passive radiative cooling performance.•PFCDM has higher day and night cooling power.•PFCDM has outstanding wearability and self-cleaning property.
Purpose
This paper aims to investigate the deposited structure and mechanical performance of printed materials obtained during initial development of the Big Area Additive Manufacturing (BAAM) system ...at Oak Ridge National Laboratory. Issues unique to large-scale polymer deposition are identified and presented to reduce the learning curve for the development of similar systems.
Design/methodology/approach
Although the BAAM’s individual extruded bead is 10-20× larger (∼9 mm) than the typical small-scale systems, the overall characteristics of the deposited material are very similar. This study relates the structure of BAAM materials to the material composition, deposition parameters and resulting mechanical performance.
Findings
Materials investigated during initial trials are suitable for stiffness-limited applications. The strength of printed materials can be significantly reduced by voids and imperfect fusion between layers. Deposited material was found to have voids between adjacent beads and micro-porosity within a given bead. Failure generally occurs at interfaces between adjacent beads and successive layers, indicating imperfect contact area and polymer fusion.
Practical implications
The incorporation of second-phase reinforcement in printed materials can significantly improve stiffness but can result in notable anisotropy that needs to be accounted for in the design of BAAM-printed structures.
Originality/value
This initial evaluation of BAAM-deposited structures and mechanical performance will guide the current research effort for improving interlaminar strength and process control.
This paper reviews the potential application of graphene and its derivatives as nano filler in a variety of thermoplastic polymers. The graphene derivatives in the form of graphene oxide (GO) and ...reduced graphene oxide (rGO) have been explored. Processing routes like dip coating, casting, spray deposition, vacuum infiltration, solution mixing, melt mixing and In-situ polymerization to derive graphene-based thermoplastic polymer nano composites have been discussed. Various thermoplastic polymers like Acrylic, ABS, Nylon 6, PLA, PBI, PC, PES, POM, PEEK, PEI, PE, PPO, PPS, PP, PS, PVC, PVDF and PTFE have been taken into consideration. Characterization of these polymer composites was reviewed.
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The main objective of this work was to explore the potential of coupling hot-melt extrusion (HME) to Fused Filament Fabrication (FFF), also known as Extrusion-Based Additive ...Manufacturing (EBAM) or 3D Printing, in order to manufacture 3D printed tablets with different release behavior from plasticizer-free filament matrices. The suitability of different thermoplastic polymers towards FFF was investigated, and a link between the mechanical properties of filaments produced by HME and the feeding performance into the FFF printer was established. Model drugs with different aqueous solubility (metoprolol tartrate and theophylline anhydrous) were processed with hydrophilic and hydrophobic polymers, and the influence of the formulation, drug concentration and applied process settings on the release kinetics was investigated. Filaments with up to 40% drug load were successfully extruded with a smooth surface and a diameter of 1.75 ± 0.05 mm. However, filaments with high brittleness and low toughness were broken by the feeding gears. In contrast, none of the filaments were squeezed aside by the gears, which indicated that they were sufficiently stiff as indicated by the high Young’s moduli of all formulations. For all formulations, the release from the tablets with 50% infill degree was faster as compared to the tablets with 100% infill degree. Theophylline (20% w/w) release from Kollicoat® IR matrix was completed within 40 min from 50% infill tablets. In contrast, 80% metoprolol tartrate was released from the hydrophobic Capa® 6506 polymer within 24hrs from 50% infill 3D tablets containing 40% w/w MPT.
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Fused deposition modeling by 3D-printing is a rapid technique for the production of personalized drug dosage forms. One of the most delicate step of the whole process is the drug ...loading onto the thermoplastic polymer to obtain the drug-loaded filament used as feedstock for 3D FDM printers. With the aim of improving the drug loading, a systematic study on the influence of polymer size distribution on the quantity of drug able to adhere onto the polymer surface was conducted. Several solid mixtures were prepared, using five PVA batches (4000–5000 µm, 1000–2000 µm, 600–1000 µm, 250–600 µm, <250 µm) and Ciprofloxacin hydrochloride as active compound in different ratios.
Operative specifics and printer’s parameters were tuned for an optimal print of drug-loaded filaments into the desired dosage forms, i.e. cylindrical printlets, fully characterized in terms of homogeneity, process efficiency, physical properties, drug content and release kinetics. The PVA particle size affected the polymer ability to form homogeneous mixture with the drug and the efficiency of the extrusion process. In particular, finest PVA batches showed better processability and reduced the drug loss during the drug/polymer mixing and the extrusion process. Drug-loaded filaments with different drug concentrations were successfully printed and the obtained printlets dissolution profiles were almost superimposable, taking an important step for the future application of 3D-printing manufacturing process to obtain personalized galenic formulations.
As a result of their favorable physical and chemical characteristics, thermoplastics have garnered significant interest in the area of microfluidics. The moldable nature of these inexpensive polymers ...enables easy fabrication, while their durability and chemical stability allow for resistance to high shear stress conditions and functionalization, respectively. This review provides a comprehensive examination several commonly used thermoplastic polymers in the microfluidics space including poly(methyl methacrylate) (PMMA), cyclic olefin polymer (COP) and copolymer (COC), polycarbonates (PC), poly(ethylene terephthalate) (PET), polystyrene (PS), poly(ethylene glycol) (PEG), polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), and polyester. We describe various biofunctionalization strategies applied within thermoplastic microfluidic platforms and their resultant applications. Lastly, emerging technologies with a focus on applying recently developed microfluidic and biofunctionalization strategies into thermoplastic systems are discussed.
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•Physical attachment of biomolecules in thermoplastic microfluidic channels.•Robust immobilization of biomolecules via covalent bonds in thermoplastic polymers.•3D scaffolds on thermoplastic microfluidics.•Innovative ideas for bio-functionalization of thermoplastic microfluidics.
Polydimethylsiloxane (PDMS) is the predominant material used for organ-on-a-chip devices and microphysiological systems (MPSs) due to its ease-of-use, elasticity, optical transparency, and ...inexpensive microfabrication. However, the absorption of small hydrophobic molecules by PDMS and the limited capacity for high-throughput manufacturing of PDMS-laden devices severely limit the application of these systems in personalized medicine, drug discovery, in vitro pharmacokinetic/pharmacodynamic (PK/PD) modeling, and the investigation of cellular responses to drugs. Consequently, the relatively young field of organ-on-a-chip devices and MPSs is gradually beginning to make the transition to alternative, nonabsorptive materials for these crucial applications. This review examines some of the first steps that have been made in the development of organ-on-a-chip devices and MPSs composed of such alternative materials, including elastomers, hydrogels, thermoplastic polymers, and inorganic materials. It also provides an outlook on where PDMS-alternative devices are trending and the obstacles that must be overcome in the development of versatile devices based on alternative materials to PDMS.
Unlike existing literature that primarily concentrates on either the plasma treatment of adherends alone or solely on adhesive surfaces, this work leverages plasma modification of both adhesive in ...tape form and adherend surfaces to largely enhance the interfacial bonding between a thermoset-based adhesive tape and carbon-fiber-reinforced thermoplastic polymer (CFRTP) for structural bonding applications. Here, by conducting single lap shear tests on adhesively-bonded AA6061-CFRPPA (carbon-fiber-reinforced polyphthalamide) dissimilar joints, it is shown that the plasma treatment of adherends alone can increase the lap shear strength (LSS) of the joints by approximately 200% compared to non-treated counterparts. An additional plasma treatment of adhesive tape surfaces leads to even higher LSS improvement, reaching up to 315%, due to the formation of a denser crosslinked network of covalent bonds and a reduced area fraction of interfacial voids at the CFRPPA/adhesive interface. The highest plasma-enhanced LSS of the metal-CFRTP dissimilar joints rivals that of metal-metal joints, which is typically stronger than the joints associated with fiber-reinforced polymers. This study is important for achieving strong CFRTP-related structural components bonded using adhesive tape, providing better compatibility with plasma treatment and other joining methods like riveting compared to adhesive paste or liquid.
The spread of integrated structural elements and parts made from low‐density materials (for example aluminum and polymers) created a need for joining technologies with which these can be joined. ...Herein, the most important surface preparation methods and joining processes, with which the surface structure of aluminum can be modified and aluminum and polymer structures can be joined, are reviewed. For both topics, a new classification method is introduced: surface preparation methods are grouped based on the method of creating surface structures, whereas joining technologies are grouped according to heat input and structural changes in the polymer material. Herein, “hot” joining technologies (in which so much heat is formed that the polymer material is melted) are reviewed. This grouping category includes techniques based on friction and induction, ultrasonic and laser welding, and some in situ joining technologies. With these, materials with highly different chemical structures and melting temperatures are joined in fast cycles, in a reliable manner. In the coming years, more integrated structures containing aluminum–polymer joints manufactured with fast, automatable joining techniques (such as ultrasonic and laser welding, in compliance with the requirements of Industry 4.0) will be used throughout the industry.
The state of the art in joining and surface preparation technologies available for aluminum–polymer hybrid structures is reviewed. A new categorization approach is used for both the joining and the surface preparation techniques and a brief outlook is also given concerning the scientific value and future of this topic.
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