3D Printing Filament Research Articles

In Situ Functionalisation and Upcycling of Post‐Consumer Textile Blends into 3D Printable Nanocomposite Filaments

AbstractThe linear lifecycle of the textile industry contributes to the enormous waste generation of post‐consumer garments. Recycling or repurposing of post‐consumer garments typically requires separation of the individual components. This study describes a novel and facile chemo‐thermo‐mechanical method for producing extrudable pellets, involving one‐pot, 2,2,6,6‐Tetramethylpiperidine‐1‐oxyl (TEMPO)‐mediated oxidation of post‐consumer polycotton textiles, followed by mild mechanical treatment, all without isolating the constituents of the polycotton blend. The oxidized blend with high cellulose and carboxylate content of 1221 ± 82 mmol COO− per kg of cotton, is pelletised into a masterbatch and further in situ extruded into nanocomposite filaments for 3D printing. The carboxyl groups introduced on the polycotton‐based filters enable cotton fibrillation into nanoscaled fibers during mechanical treatment and extrusion resulting to a variety of functional and high surface‐finish quality models, including filters and fashion accessories. The electrostatic interactions with positively charged species, such as methylene blue (MB), facilitate their adsorption from water while exhibiting promising adsorption capacities. The adsorption of MB follows the Freundlich model and depends on the printed porosity of the filter. A “trash to treasure” concept for textile waste is further corroborated through the use of the developed 3D printing filament into commodity products.

Dielectric And Mechanical Properties Of PLA-Carbon Composites

This study focuses on the development and characterization of Carbon-based Polylactide (PLA) composites for 3D printer filaments. The aim is to enhance the electrical and mechanical properties of PLA by incorporating recovered carbon black (RCB) in different mesh sizes (500, 1000, 1500, and 2000 mesh). Electrical impedance spectroscopy and dielectric constant measurements were performed to investigate the electrical properties of the composites. Results showed that the addition of RCB increased the dielectric constant, with values ranging from 2.5 to 7.1, indicating improved electrical performance. Scanning electron microscopy (SEM) analysis revealed the dispersion of carbon particles within the composites, enhancing their electrical conductivity. The effect of RCB particle size on electrical properties was also explored, with smaller particle sizes (2000 mesh) resulting in the highest conductivity of 6.2 S/m. Tensile testing demonstrated that the addition of RCB increases the tensile strength of PLA, with values ranging from 28.6 MPa to 47.2 MPa, and the elastic modulus, ranging from 832 MPa to 1.56 GPa, depending on the mesh size. The optimal combination of RCB content and mesh size resulted in a composite with a tensile strength of 43.8 MPa. Overall, this research provides insights into the development of Carbon-based PLA composites with improved electrical and mechanical properties.

A miniaturized additive-manufactured carbon black/PLA electrochemical sensor for pharmaceuticals detection

Additive manufacturing is a technique that allows the construction of prototypes and has evolved a lot in the last 20 years, innovating industrial fabrication processes in several areas. In chemistry, additive manufacturing has been used in several functionalities, such as microfluidic analytical devices, energy storage devices, and electrochemical sensors. Theophylline and paracetamol are important pharmaceutical drugs where overdosing can cause adverse effects, such as tachycardia, seizures, and even renal failure. Therefore, this paper aims at the development of miniaturized electrochemical sensors using 3D printing and polylactic acid-based conductive carbon black commercial filament for theophylline and paracetamol detection. Electrochemical characterizations of the proposed sensor were performed to prove the functionality of the device. Morphological characterizations were carried out, in which chemical treatment could change the surface structure, causing the improvement of the analytical signal. Thus, the detection of theophylline at a linear range of 5.00–150 μmol L−1 with a limit of detection of 1.2 μmol L−1 was attained, and the detection of paracetamol at a linear range of 1.00–200 μmol L−1 with a limit of detection of 0.370 μmol L−1 was obtained, demonstrating the proposed sensor effectively detected pharmaceutical drugs.

Developing Eco-Friendly 3D-Printing Composite Filament: Utilizing Palm Midrib to Reinforce High-Density Polyethylene Matrix in Design Applications.

Designers actively pursue the use of novel materials and concepts in furniture and interior design. By providing insights into their processing behavior and suitability for 3D-printing processes, this research helps to highlight the potential of using waste materials to create more environmentally friendly and sustainable 3D-printing filaments that can be used in furniture and interior design. Furthermore, the study evaluates the effect of incorporating palm midrib nanoparticles (DPFNPs) to reinforce a high-density polyethylene (HDPE) matrix with different loadings such as 10, 20, 30, 40, and 50 wt.%. The composites were extruded into filaments using a manual extruder, which was then utilized to fabricate 3D-printed specimens using a 3D-printing pen. The effect of adding DPFNPs on the composite's chemical, thermal, and mechanical properties was evaluated, with a particular focus on how these modifications influence the melt flow rate (MFR) and, subsequently, the material's printability. The results revealed that HDPE and filament composites presented similar FTIR spectra. On the other hand, the filament composites presented an increase in the thermal stability and a decrease in the mechanical strength with increasing DPFNP content in the HDPE matrix. The filaments were successfully printed using a 3D-printing pen. Thus, using DPFNPs in the HDPE matrix presents a low-cost alternative for filament production and may expand 3D-printing applications in interior and furniture design with more sustainable materials. Future work will delve into optimizing these composites for improved printability and assessing their recyclability, aiming to broaden their applications in 3D printing and beyond.

Quantitative Insight into the Compressive Strain Rate Sensitivity of Polylactic Acid, Acrylonitrile Butadiene Styrene, Polyamide 12, and Polypropylene in Material Extrusion Additive Manufacturing

Herein, a research and engineering gap, i.e., the quantitative determination of the effects of the compressive loading rate on the engineering response of the most popular polymers in Material Extrusion (MEX) Additive Manufacturing (AM) is successfully filled out. PLA (Polylactic Acid), ABS (Acrylonitrile Butadiene Styrene), PP (Polypropylene), and PA12 (Polyamide 12) raw powders were evaluated and melt-extruded to produce fully documented filaments for 3D printing. Compressive specimens after the ASTM-D695 standard were then fabricated with MEX AM. The compressive tests were carried out in pure quasi-static conditions of the test standard (1.3 mm/min) and in accelerated loading rates of 50, 100, 150, and 200 mm/min respectively per polymer. The experimental and evaluation course proved differences in engineering responses among different polymers, in terms of compressive strength, elasticity modulus, toughness, and strain rate sensitivity index. A common finding was that the increase in the strain rate increased the mechanical response of the polymeric parts. The increase in the compressive strength reached 25% between the lowest and the highest strain rates the parts were tested for most polymers. Remarkable variations of deformation and fracture modes were also observed and documented. The current research yielded results with valuable predictive capacity for modeling and engineering modeling, which hold engineering and industrial merit.

Asahi Kasei to highlight sustainability, 3D printing filaments, purging compounds, and more at NPE 2024

On April 11, 2024, Asahi Kasei announced it would be coming to NPE 2024, reportedly the largest plastics industry trade show in the Americas, from May 6 through 10 in Orlando, Florida.

Filamen printer 3D berbasis limbah PET (polyethylene terephthalate) dan kitosan cangkang udang

One alternative for processing PET (polyethylene terephthalate) plastic waste is to convert it into a basic material for making 3D printer filaments with the addition of shrimp shell chitosan. The addition of shrimp shell chitosan to the filament can increase its mechanical strength. The aim of this research is to determine the best formulation and effectiveness of the combination of PET plastic with chitosan as 3D printer filament on the mechanical properties and microstructure of the surface. Making 3D printer filament from a combination of PET and shrimp shell chitosan using a double screw extruder with varying ratios between PET and shrimp shell chitosan (99 : 1, 97.5 : 2.5 and 95 : 5) with temperature variations at 175° C (Hopper Zone ), 195°C, 225°C, 245°C (Die zone) using a screw rotation speed of 50 rpm, with the testing process including a tensile test, to determine the mechanical properties of the material by analysis using the SEM (Scanning Electron Microscope) test ) to identify the surface morphology and size of the filament material. The test results for composition 99:1 (sample 1) had the lowest tensile strength value of 35.79 MPa, breaking 0.10 mm with an elongation value of 0.32%. Composition 97.5:2.5 (sample 2) with a tensile strength value of 96.20 Mpa, longest breaking length of 0.13 mm and highest elongation value of 0.42%. Composition 95:5 (sample 3) only has the highest tensile value of 98.95 MPa, with a breaking length of 0.06 mm and the lowest elongation of 0.18%.

Modeling of 3D-printed composite filaments using X-ray computer tomography images segmented by neural networks

This study introduces a novel semi-analytical two-scale approach to model 3D-printed composite filament where both fibers and voids are present. The proposed approach utilizes micro computer tomography (micro-CT) images to visualize fibers and voids. Then, a novel segmentation process based on neural network algorithms (specifically the YOLO v7 algorithm) is employed to segment the distinct fiber and void phases. The volume fractions and the geometries of the phases are then used in the first scale (the micro-scale) of the approach and the effective elastic properties of internal regions of the filament are obtained using the Mori–Tanaka effective field method. These regions are then joined together to form the second scale (the macro-scale), for which the elastic properties are evaluated using the finite element method. The two-scale approach is applied for 3D-printed nylon reinforced with continuous carbon fibers and the predictions of the elastic properties are compared to tensile tests conducted on the single filament. A great agreement is observed for Young’s modulus along the fiber direction of the single printed filament.

SMART DEVICE FOR PET RECYCLING

PET (polyethylene terephthalate) is a common plastic substance used to make water bottles, carbonated drinks, juices and others. PET is durable and easy to transport, but can be difficult to degrade in nature. If not recycled, PET can remain in the environment for hundreds of years, polluting the sea and other environmental areas. The work presents the creation of an smart device, which can easily, with low costs, be transformed in laboratory conditions, respecting the steps of the industrial technological process, of polyethylene terephthalate (PET) into recycled PET. The final goal is to research the mechanical characteristics of recycled PET. The method used is Computer Assisted Thermoplastic Extrusion, the main parameters of the entire technological process being permanently monitored. The results of mechanical and thermal tests were demonstrated that recycled PET can be transformed into filament for 3D printing of finished products that have properties similar to those obtained industrially.

Recycling of Polycarbonate/Acrylonitrile Butadiene Styrene Blends with Flame Retardant Additives for 3D Printing Filament

Recycling waste from electrical and electronic equipment (WEEE) for valuable materials is a critical aspect of the circular economy and sustainable waste management. Recycling these solid wastes into value-added products is one method for reducing landfill waste and pollution. The purpose of this research was to investigate the recyclability of plastic wastes of Polycarbonate Acrylonitrile Butadiene Styrene blends with Brominated Flame-Retardant additives (PC-ABS-FR). Two types of plastic wastes, PC-ABS-FR (GL) and PC-ABS-FR (DB), were collected and converted into polymer chips using a mechanical process. To study the effectiveness of waste recyclability, 3D printing filaments were produced through the extrusion process. Chemical elements, functional groups, and thermal and mechanical properties of recycled products were evaluated using EDX, FTIR, DSC, and universal tensile testing equipment, respectively. TGA, cone calorimetry, and melt flow index analyses were also carried out. The results showed that recycled PC- ABS–FR (GL) waste-based filament samples had better thermal and mechanical properties. On the contrary, PC- ABS–FR (DB) waste recyclability was not effective in filament extrusion. The mechanical properties of the 3D printing filaments produced from PC-ABS-FR electronic waste were found to be similar to those observed in commercially available and previously reported filaments. The strength, thermal property, cross-sectional homogeneity, and filament diameter of 1.8 ± 0.03 mm of the 3D printer filament made from PC- ABS–FR (GL) were suitable for 3D printing applications such as children’s toys, dust bins, and flower vases.

On-chip fabrication and in-flow 3D-printing of microgel constructs: from chip to scaffold materials in one integral process

Bioprinting has evolved into a thriving technology for the fabrication of cell-laden scaffolds. Bioinks are the most critical component for bioprinting. Recently, microgels have been introduced as a very promising bioink, enabling cell protection and the control of the cellular microenvironment. However, the fabrication of the bioinks involves the microfluidic production of the microgels, with a subsequent multistep process to obtain the bioink, which so far has limited its application potential. Here we introduce a direct coupling of microfluidics and 3D-printing for the continuous microfluidic production of microgels with direct in-flow printing into stable scaffolds. The 3D-channel design of the microfluidic chip provides access to different hydrodynamic microdroplet formation regimes to cover a broad range of droplet and microgel diameters. After exiting a microtubing the produced microgels are hydrodynamically jammed into thin microgel filaments for direct 3D-printing into two- and three-dimensional scaffolds. The methodology enables the continuous on-chip encapsulation of cells into monodisperse microdroplets with subsequent in-flow cross-linking to produce cell-laden microgels. The method is demonstrated for different cross-linking methods and cell lines. This advancement will enable a direct coupling of microfluidics and 3D-bioprinting for scaffold fabrication.

An evaluation of the usability and durability of 3D printed versus standard suture materials.

The capability to produce suture material using three-dimensional (3D) printing technology may have applications in remote health facilities where rapid restocking of supplies is not an option. This is a feasibility study evaluating the usability of 3D-printed sutures in the repair of a laceration wound when compared with standard suture material. The 3D-printed suture material was manufactured using a fused deposition modelling 3D printer and nylon 3D printing filament. Study participants were tasked with performing laceration repairs on the pigs' feet, first with 3-0 WeGo nylon suture material, followed by the 3D-printed nylon suture material. Twenty-six participants were enrolled in the study. Survey data demonstrated statistical significance with how well the 3D suture material performed with knot tying, 8.9 versus 7.5 (p = 0.0018). Statistical significance was observed in the 3D-printed suture's ultimate tensile strength when compared to the 3-0 Novafil suture (274.8 vs. 199.8 MPa, p = 0.0096). The 3D-printed suture also demonstrated statistical significance in ultimate extension when compared to commercial 3-0 WeGo nylon suture (49% vs. 37%, p = 0.0215). This study was successful in using 3D printing technology to manufacture suture material and provided insight into its usability when compared to standard suture material.

Dispersion state analysis in hot melt extruded, highly drug-loaded 3D printing filaments applying Raman microscopy

Abstract Objectives Highly drug-loaded polymer formulations are favorable intermediates in pharmaceutical applications, for example, for the individualized production of medicines via 3D printing with the maximum flexibility regarding dose strength and drug combination in a single dosage form. However, high-disperse drug loads are challenging for the process itself and the (intermediate) product properties, making the knowledge about the dispersion state of the drug particles achieved by the production process helpful to overcome such challenges. Methods Therefore, a novel dispersion state analysis technique based on scanning Raman microscopy is proposed in the present study and applied to HPMC filaments loaded with 20 wt%, 40 wt%, and 60 wt% theophylline. The qualitative and quantitative evaluations of the scans were correlated to melt viscosities, process data, and mechanical properties of the filaments. Key findings The analyses revealed not only an increasing particle size reduction with increasing drug load and thus increasing viscosity and mechanical energy input. The particle size reduction also caused a change in the filaments’ mechanical properties from elastic ductile to rigid brittle. Furthermore, an alignment of the elongated drug particles with the frozen three-dimensional flow pattern of the extruder and not only with the extrusion direction was elucidated. Conclusions Therefore, the necessity to investigate the dispersion state further is highlighted for future studies on highly drug-loaded polymer formulations, providing a novel measuring technique applicable to challenging pharmaceutical formulations.

Initial Study on Rheological Behaviour of Hydroxyapatites / Polylactic Acid Composite for 3D Printing Filament

The present fused deposition modeling (FDM) printing process has concentrated on combining metal or ceramic filled with polymer because it could provide a strong composite in layered manufacturing technology in comparison to a single polymer material. However, the ability of the composite material to flow into the extruder becomes an obstacle because of the changes in the polymer concentration and dispersion of filler particles in producing the printed part. Hence, the rheological behavior of Hydroxyapatites (HAp) / Polylactic Acid (PLA) composite with different contents of HAp was studied to assess its ability to flow through the extruder during the 3D printing process. Measurements such as pycnometer density, thermal analysis (DSC) and FT-IR were performed on the composite feedstock containing a variation of 10% to 30% HAp powder. The feedstocks behavior then were characterized by rheological tests at three different temperatures (140 oC, 150 oC, and 160 oC). The composition of PLA/20HAp has produced optimum rheological behavior with effective flow behavior index (n) and activation energy (E) of 0.396 and 89.03 kJ/mol, respectively which is suitable for extruding out the HAp/PLA composite to become a 3D printing filament material.

Plastic waste recycling in additive manufacturing: Recovery of polypropylene from WEEE for the production of 3D printing filaments

The inefficient management of wastes recovered from electric and electronic apparatuses (the so-called WEEE or e-waste) has become a severe global concern in the last years, since the indiscriminate accumulation of wastes containing hazardous material poses serious risks for the environmental, as well as for the human health. Despite the continuous development of innovative and efficient technologies for the mechanical recycling of WEEE plastics, the effective re-utilization of these fractions is often limited by their poor value-added. In this work, we propose a strategy for the valorization of a typical WEEE plastic stream recovered from small appliances (mainly composed on polypropylene filled with talc particles) through the formulation of filaments suitable for Fused Filament Fabrication (FFF) 3D printing processes. Preliminary spectroscopic analyses on the WEEE plastics allowed separating the sample in two streams, according to the different content of talc. Both streams were first characterized from a rheological point of view, aiming at assessing their 3D printability. Then, the mechanical properties and the morphology of the filaments (obtained after a close optimization of the extrusion conditions) were evaluated; the obtained results indicated the achievement of a regular geometry and mechanical properties comparable to those of commercial filaments. Finally, 3D printed specimens showed a satisfactory quality in terms of resolution and definition, demonstrating the possibility of profitably enhancing the value-added of WEEE plastics, using them as feedstock to produce sustainable 3D printing filaments.

The Effects of Microcrystalline Cellulose Addition on the Properties of Wood-PLA Filaments for 3D Printing.

This paper describes the use of microcrystalline cellulose (MCC) as an additive in wood-polylactic acid (PLA) filaments suitable for 3D printing. Filaments prepared with PLA, thermally modified (TM) wood, and three different MCC loadings (1, 3, and 5 wt%) by two-step melt blending in the extruder were characterized with respect to their rheological, thermal, and mechanical response. The analyses demonstrate that a low MCC content (1%) improves the mobility of the polymer chains and contributes to a higher elasticity of the matrix chain, a higher crystallinity, a lower glass transition temperature (by 1.66 °C), and a lower melting temperature (by 1.31 °C) and leads to a higher tensile strength (1.2%) and a higher modulus of elasticity (12.1%). Higher MCC loading hinders the mobility of the polymer matrix and leads to a rearrangement of the crystal lattice structure, resulting in a decrease in crystallinity. Scanning electron micrographs show that the cellulose is well distributed and dispersed in the PLA matrix, with some agglomeration occurring at higher MCC levels. The main objective of this study was to develop and evaluate a filament containing an optimal amount of MCC to improve compatibility between wood and PLA, optimize melt processability, and improve mechanical properties. It can be concluded that a 1% addition of MCC favorably changes the properties of the wood-PLA filaments, while a higher MCC content does not have this effect.

Using dammar gum to reduce the warpage and shrinkage of high-density polyethylene (HDPE) 3D printing filament

Using dammar gum to reduce the warpage and shrinkage of high-density polyethylene (HDPE) 3D printing filament

Closing the loop in space 3D printing: Effect of vacuum, recycling, and UV aging on high performance thermoplastics produced via filament extrusion additive manufacturing

The outlook for space exploration, and the long-term sustainable presence of humans in space, rely upon the advancement of in-situ manufacturing capabilities. In-space additive manufacturing (AM) has gained significant attention due to its potential to produce spare parts in-situ and facilitate repairs for extending space missions. However, to date, there is no AM system capable of processing high-performance engineering thermoplastic polymers within uncontrolled space conditions (i.e., reduced gravity, vacuum, and radiation environment). Additionally, the effect of ultra-violet (UV) radiation on printed parts has remained unexplored. In this work, a custom-built filament extrusion AM breadboard has been developed and tested enabling the fabrication of engineering thermoplastic polymers, whereby the machine was placed inside a vacuum chamber to partly mimic the harsh space environment. Mechanical (tensile and flexural) and thermal (thermogravimetric analysis, differential scanning calorimetry and dynamic mechanical analysis) tests were conducted on the printed specimens before and after exposure to UV aging. Moreover, the printed geometries underwent a recycling process involved the shredding of the pristine 3D-printed polymeric samples, the drying of the obtained granulates and finally the extrusion of 3D-printable filaments. The polymeric recycled 3D-printed specimens were then subjected to further mechanical and thermal testing, offering valuable insights into the feasibility of in-space AM and the potential to augment the circularity of the printed parts. The results of the mechanical and thermal tests, together with the effect of vacuum printing, UV aging, and recycling, are provided within the manuscript. This work cements the basic building blocks to sustainably advance on-orbit and in-space infrastructure, and paves the way for long-term human space missions.

Production of nanocomposite based on PETG, manufactured by 3D printing, to combat the Sars-Cov-2 virus

With the collapse of the COVID-19 pandemic, it was necessary to explore new materials with resistance to SARS- CoV-2 of lower cost and effective and easy production methods, such as 3D printing. The objective was to produce and characterize filaments for 3D printing using PETG and copper nanoparticles (NCu) aiming at obtaining a virucidal surface. Nanocomposites were made with the addition of 0.75% and 1% of NCu and pure PETG. After printing, mechanical tests of nanoindentation, thermogravimetric analyses (TGA), digital optical microscopies and Fourier transform infrared spectroscopies (FTIR) were performed. The results showed a 48% increase in the elastic modulus for the 0.75% and 1% nanocomposites compared to pure PETG. In the TGA, the results were significant for the nanocomposites with the addition of 1% of NCu compared to pure PETG. In the chemical composition by FTIR spectrum, there were no significant changes.

Simulated gastric leachate of 3D printer metal-fill filaments induces cytotoxic effects in rat and human intestinal models

Metals are used in 3-dimensional (3D) printer filaments in the manufacture of 3D printed objects. Exposure to the filaments, printed objects and emissions from printing may pose health risks from release of toxic metals. This study investigated the cytotoxicity of extruded 3D printer filament leachates in rat and human intestinal cells. Copper-, bronze-, and steel-fill extruded filaments were incubated in acidic media for 2 h. Leachates were adjusted to pH 7 and cells exposed for 4 or 24 h. Concentration- and time-dependent decreases in rat and human cell viability were observed using a colorimetric assay and confirmed by microscopy. Copper- and bronze-fill leachates were more cytotoxic than steel. Copper-fill leachates had the highest copper concentrations by ICP-MS. Exposure to CuSO4 resulted in concentration-dependent cytotoxicity in rat cells. The copper chelator bathocuproine disulphonate alleviated cytotoxicity of CuSO4 and copper-fill leachate, suggesting that copper ions have a role in the cytotoxicity. Hydrogen peroxide increased and glutathione decreased in rat cells exposed to copper-fill leachate, suggesting the formation of reactive oxygen species. Overall, our data indicate that metals released from the acidic exposure of print objects using metal-fill filaments, especially copper, are toxic to rat and human intestinal cells and additional studies are needed.