Emission of particulate matter from a desktop three-dimensional (3D) printer

Scaffold is one of the key components for tissue engineering application. Three-dimensional (3D) printing has given a new avenue to the scaffolds design to closely mimic the real tissue. However, material selection has always been a challenge in adopting 3D printing for scaffolds fabrication, especially for hard tissue. The fused filament fabrication technique is one of the economical 3D printing technology available today, which can efficiently fabricate scaffolds with its key features. In the present study, a hybrid polymer-ceramic scaffold has been prepared by combining the benefit of synthetic biodegradable poly (lactic acid) (PLA) and osteoconductive calcium sulphate (CaS), to harness the advantage of both materials. Composite PLA filament with maximum ceramic loading of 40 wt% was investigated for its printability and subsequently scaffolds were 3D printed. The composite filament was extruded at a temperature of 160 °C at a constant speed with an average diameter of 1.66 ± 0.34 mm. PLA-CaS scaffold with ceramic content of 10%, 20%, and 40% was 3D printed with square pore geometry. The developed scaffolds were characterized for their thermal stability, mechanical, morphological, and geometrical accuracy. The mechanical strength was improved by 29% at 20 wt% of CaS. The porosity was found to be 50–60% with an average pore size of 550 µm with well-interconnected pores. The effect of CaS particles on the degradation behaviour of scaffolds was also assessed over an incubation period of 28 days. The CaS particles acted as porogen and improved the surface chemistry for future cellular activity, while accelerating the degradation rate.

This study evaluates the three-dimensional (3D) printing materials used in Fused Deposition Modeling (FDM) printing technology. 3D printing technology has been developing strongly, becoming an effective support tool in production and research. The 3D printing process involves many stages, with many parameters affecting the quality and properties of the product, in which 3D printing material is one of many essential factors affecting that process. The study conducts a comprehensive assessment of the most common materials in 3D printing technology to determine the advantages and limitations of precisely five types of materials: Polylactic acid, acrylonitrile butadiene styrene, polyethylene terephthalate glycol-modified, thermoplastic polyurethane, and acrylonitrile styrene acrylate. With 3D printing, parameters such as sintering temperature, printing speed, and layer thickness are kept constant. These parameters are applied equally to all five material samples. The experiment evaluates the tensile strength of materials. The study results provide an overview of the properties and applicability of 3D printing materials, helping to select materials suitable for specific FDM 3D printing technology applications.

Advances in Computer aided design (CAD), modeling and Three-dimensional (3D) printing has led to paradigm shift in development of innovative and miniaturized explosive devices for armament applications. In conventional techniques, explosives are either pressed or casted and machined to required geometry. These conventional processes are mostly manual and monotonous; require high-cost tooling and the lead-time from concept to product is high. 3D printing is an automated additive manufacturing process in which the material is deposited layer-by-layer to build physical part with any intricate geometry and profile, from the CAD model of the part. 3D printing of explosive devices offers advantages of computer aided design techniques, automation, direct physical part fabrication, low lead-time, low cost and any geometrical shape can be printed. It also offers advantage of printing explosive parts in the battlefields. In this paper, along with the detailed review of future trends in 3D printing of armament and explosive devices, a case study of 3D printing of plastic bullets in Acrylonitrile Butadiene Styrene (ABS) material is presented. The plastic bullets are used in low intensity conflicts and riot control. The experimental firing trials were conducted using standard AK- 47 gun firing on Gelatin target blocks placed at 30 m distance from the muzzle of the gun. The trials showed performance of ABS bullets in terms of lethality and velocity drop comparable to existing plastic bullets made of Nylon-66 manufactured by injection molding process. 3D printed ABS bullets have advantage of batch-to-batch repeatability, high accuracy. 3D printing is revolutionizing the way armament and explosive devices are manufactured, performance improvement and miniaturization.

The widespread application of additive manufacturing (AM) technologies, commonly known as three-dimensional (3D) printing, in industrial and home-business sectors, and the expected increase in the number of workers and consumers that use these devices, have raised concerns regarding the possible health implications of 3D printing emissions. To inform the risk assessment and management processes, this review evaluates available data concerning exposure assessment in AM workplaces and possible effects of 3D printing emissions on humans identified through in vivo and in vitro models in order to inform risk assessment and management processes. Peer-reviewed literature was identified in Pubmed, Scopus, and ISI Web of Science databases. The literature demonstrated that a significant fraction of the particles released during 3D printing could be in the ultrafine size range. Depending upon the additive material composition, increased levels of metals and volatile organic compounds could be detected during AM operations, compared with background levels. AM phases, specific job tasks performed, and preventive measures adopted may all affect exposure levels. Regarding possible health effects, printer emissions were preliminary reported to affect the respiratory system of involved workers. The limited number of workplace studies, together with the great variety of AM techniques and additive materials employed, limit generalizability of exposure features. Therefore, greater scientific efforts should be focused at understanding sources, magnitudes, and possible health effects of exposures to develop suitable processes for occupational risk assessment and management of AM technologies.

Three-dimensional (3D) printing offers the promise of fabricating optical phantoms with arbitrary geometry, but commercially available thermoplastics provide only a small range of physiologically relevant absorption (µa) and reduced scattering (µs`) values. Here we demonstrate customizable acrylonitrile butadiene styrene (ABS) filaments for dual extrusion 3D printing of tissue mimicking optical phantoms. µa and µs` values were adjusted by incorporating nigrosin and titanium dioxide (TiO2) in the filament extrusion process. A wide range of physiologically relevant optical properties was demonstrated with an average repeatability within 11.5% for µa and 7.71% for µs`. Additionally, a mouse-simulating phantom, which mimicked both the geometry and optical properties of a hairless mouse with an implanted xenograft tumor, was printed using dual extrusion methods. 3D printed tumor optical properties matched the live tumor with less than 3% error at a wavelength of 659 nm. 3D printing with user defined optical properties may provide a viable method for durable optically diffusive phantoms for instrument characterization and calibration.

Electromagnetic biaxial scanning mirror based on 3D printing and laser patterning

Four-dimensional printing is a process in which a 3D-printed object is intentionally transformed in response to an external stimulus such as temperature, which is useful when the final geometry of a 3D-printed part is not easily manufacturable. One method to demonstrate this is to print a part made of thin strips of material on a sheet of paper, heat the part, and allow it to cool. This causes the part to curl due to the difference in the thermal expansion coefficients of the paper and plastic. In an attempt to quantify the effect of different temperatures on various materials, samples of three common 3D printing filaments, acrylonitrile butadiene styrene (ABS), polyethylene terephthalate glycol (PETG), and polylactic acid (PLA), were heated at different temperatures (85 °C, 105 °C, and 125 °C) for intervals of 15 min and then allowed to cool until curling stopped. This heating and cooling cycle was repeated three times for each sample to determine if repeated heating and cooling influenced the curling. Each sample was filmed as it was cooling, which allowed the radius of curvature to be measured by tracking the uppermost point of the part, knowing the arc length, and calibrating the video based on a known linear length. After three cycles, all three materials showed a decrease in the radius of curvature (tighter curl) as heating temperature increased, with PLA showing the trend much more predominantly than ABS and PETG. Furthermore, for PETG and PLA, the radius of curvature decreased with each cycle at all temperatures, with the decrease being more significant from cycle 1 to 2 than cycle 2 to 3. Conversely, ABS only shared this trend at 125 °C. The findings of this work can provide guidelines to users on the temperature dosage for the mass manufacturing of complex geometries such as packaging, self-assembly robots, and drug delivery applications.

Additive manufacturing (AM), also known as 3D printing, has significantly advanced in recent years, especially with the introduction of multifunctional 3D-printed parts. AM fabricated monolith has multiple material capabilities, thus various functionalities are well-perceived by the manufacturing communities. As an example, a traditional fused filament fabrication (FFF) 3D printer fabricates multi-material thermoplastic parts using a dual extrusion system to increase the functionality of the part including variable stiffening and gradient structures. In addition to the multiple thermoplastic feedstocks in a dual extrusion system, multifunctional AM can be achieved by embedding electronics or reinforcing fibers within the fabricated thermoplastic parts, which significantly impacts the rapid prototyping of hybrid components in manufacturing industries. State-of-the-art techniques such as coextrusion systems, ultrasonic welding tools, and thermal embedding tools have been implemented to automate the process of embedding conductive material within the 3D-printed thermoplastic substrate. The goal of this tool development effort is to embed wires within 3D 3D-printed plastic substrate. This research consisted of developing a wire embedding tool that can be integrated into an FFF desktop 3D printer to deposit conductive as well as resistive wires within the 3D-printed thermoplastic substrate. By realizing the challenges for discrete materials interaction at the interface such as nichrome wires and Acrylonitrile Butadiene Styrene (ABS) plastics and polylactic acid (PLA), the goal of this tool was to immerse wire within ABS and PLA substrate using transient swelling mechanisms under non-polar solvent. A proof-of-concept test stands with a wire feed system and the embedding wheel was first designed and manufactured using 3D printing to examine if a traditional roller-guided system, primarily used for plastic extrusion, would be sufficient for wire extrusion. The development of the integrated wire embedding tool was initiated based on the success of the proof-of-concept wire extrusion system. The design of the integrated wire embedding tool consisted of three sub-assemblies: wire delivery assembly, wire shearing assembly, and swivel assembly. The wire delivery assembly is responsible for feeding the wire towards the thermoplastic using the filament delivery system seen within FFF printers. For the wire shearing mechanism, a cutting Tungsten carbide blade in conjunction with a Nema-17 external stepper motor was used to shear the wire. For the wire embedding assembly, a custom swivel mount was fabricated with a bearing housing for a ball bearing that allowed for a 360-degree motion around the horizontal plane. A wire guide nozzle was placed through the mount to allow for the wire to be fed down into a brass embedding wheel in a tangential manner. Additionally, the solvent reservoir was mounted such that an even layer of solution was dispensed onto the thermoplastic substrate. Through this tool development effort, the aim was to develop technologies that will enable 3D printing of wire-embedded monolith for various applications including a self-heating mold of thermoset-based composite manufacturing as well as smart composites with embedded sensors.

BackgroundMaterial extrusion is used to 3D print anatomic models and guides. Sterilization is required if a 3D printed part touches the patient during an intervention. Vaporized Hydrogen Peroxide (VHP) is one method of sterilization. There are four factors to consider when sterilizing an anatomic model or guide: sterility, biocompatibility, mechanical properties, and geometric fidelity. This project focuses on geometric fidelity for material extrusion of one polymer acrylonitrile butadiene styrene (ABS) using VHP.MethodsDe-identified computed tomography (CT) image data from 16 patients was segmented using Mimics Innovation Suite (Materialise NV, Leuven, Belgium). Eight patients had maxillary and mandibular defects depicted with the anatomic models, and eight had mandibular defects for the anatomic guides. Anatomic models and guides designed from the surfaces of CT scan reconstruction and segementation were 3D printed in medical-grade acrylonitrile butadiene styrene (ABS) material extrusion. The 16 parts underwent low-temperature sterilization with VHP. The dimensional error was estimated after sterilization by comparing scanned images of the 3D printed parts.ResultsThe average of the estimated mean differences between the printed pieces before and after sterilization were − 0,011 ± 0,252 mm (95%CI − 0,011; − 0,010) for the models and 0,003 ± 0,057 mm (95%CI 0,002; 0,003) for the guides. Regarding the dimensional error of the sterilized parts compared to the original design, the estimated mean differences were − 0,082 ± 0,626 mm (95%CI − 0,083; − 0,081) for the models and 0,126 ± 0,205 mm (95%CI 0,126, 0,127) for the guides.ConclusionThis project tested and verified dimensional stability, one of the four prerequisites for introducing vaporized hydrogen peroxide into 3D printing of anatomic models and guides; the 3D printed parts maintained dimensional stability after sterilization.

Monitoring the liberation of volatile organic compounds during fused deposition modeling three dimensional printing using solid-phase microextraction coupled to gas chromatography/mass spectrometry

Additive manufacturing or 3D printing technologies might advance the fabrication sector of personalised biomaterials with high-tech precision. The selection of optimal precursor materials is considered the first key-step for the development of new printable filaments destined for the fabrication of products with diverse orthopaedic/dental applications. The selection route of precursor materials proposed in this study targeted two categories of materials: prime materials, for the polymeric matrix (acrylonitrile butadiene styrene (ABS), polylactic acid (PLA)); and reinforcement materials (natural hydroxyapatite (HA) and graphene nanoplatelets (GNP) of different dimensions). HA was isolated from bovine bones (HA particles size < 40 μm, <100 μm, and >125 μm) through a reproducible synthesis technology. The structural (FTIR-ATR, Raman spectroscopy), morphological (SEM), and, most importantly, in vitro (indirect and direct contact studies) features of all precursor materials were comparatively evaluated. The polymeric materials were also prepared in the form of thin plates, for an advanced cell viability assessment (direct contact studies). The overall results confirmed once again the reproducibility of the HA synthesis method. Moreover, the biological cytotoxicity assays established the safe selection of PLA as a future polymeric matrix, with GNP of grade M as a reinforcement and HA as a bioceramic. Therefore, the obtained results pinpointed these materials as optimal for future composite filament synthesis and the 3D printing of implantable structures.

Background Three-dimensional (3D) printers are used in various industrial sectors, the potential exposure and health risks are still little understood. This study aimed to measure the emissions of nanoparticles during...

The present study investigates the feasibility of using 3D-printed Acrylonitrile Butadiene Styrene (ABS) and Polylactic Acid (PLA) as propellant grains for hybrid rocket engines. The primary objective is to assess their combustion performance, focusing on regression rate, chamber pressure, and pressure drop across the orifice. The propellant grain is designed using a CAD software and manufactured using 3D printing techniques while taking the standard considerations of a propellant grains in a Hybrid Rocket Propulsion System (HRPS). Materials used for manufacturing of the 3D-printed propellant grain are ABS and PLA. In addition to the advantages of the 3D printing manufacturing technology, both materials exhibit significant reactivity when burned in the presence of an oxidizer. The present study concludes with a demonstration of manufacturing and static testing of the propellant grains for the HRPS. ABS produced a higher regression rate that suggests it is a better fuel for the Hybrid rocket propulsion system. Future studies will explore alternative 3D-printed materials, thrust profile evaluations, and extended-duration burn tests to further optimize fuel grain performance.

3D printing has revolutionized the manufacturing industry, offering unique opportunities for rapid prototyping and customized production. Acrylonitrile Butadiene Styrene (ABS) and Polylactic Acid (PLA) are widely used thermoplastics in 3D printing due to their versatility and mechanical properties. Tensile strength is a critical mechanical property that determines the load-bearing capacity of printed parts. However, the orientation of the printed layers during the additive manufacturing process can significantly affect the printed parts’ tensile strength and overall mechanical behaviour. The effect of printing orientation on the tensile strength of 3D printed ABS and PLA materials was investigated. The printing orientation of printed tensile samples varies from 0°, 45°, and 90°, layer thickness of 0.1 mm, and refers to ASTM D638 standard. Tensile testing is carried out with the Tensilon machine. The results showed that the orientation influence the tensile strength of the ABS and PLA samples. The change of orientation from 0° to 90° causes a decrease in tensile strength of 44.3% of ABS and 52.8% of PLA materials. The findings of this study will provide valuable insights into the mechanical behaviour of 3D printed parts and inform design considerations for optimizing printing orientations to achieve enhanced tensile strength.

&lt;p&gt;&lt;b&gt;The wettability of a surface is determined by two factors; the chemistry of the surface, which determines the inherent chemical hydrophilicity or hydrophobicity, and the physicality of the surface, whereby the surface roughness enhances and exaggerates the inherent hydrophilicity or hydrophobicity of the surface. Hence, controlling the wettability of a surface requires manipulation of both the chemical nature of the surface and the surface roughness. This research predominantly investigated controlling the wettability of surfaces through creation and manipulation of surface roughness, but also studied alterations of the chemical hydrophilicity and hydrophobicity of surfaces. These studies were performed using two different substrates, for different potential commercial applications. Wool fabrics were studied, in order to increase their hydrophobicity and produce a stain and water repellent wool fabric. 3D printed polymers were also investigated in order to create surfaces with useful wetting behaviours, including superhydrophobicity and anisotropic wetting.&lt;/b&gt;&lt;/p&gt; &lt;p&gt;First, wool fabrics were manipulated through physical processing alone, in order to increase the surface roughness. This relied on altering the arrangement of the micrometre–sized wool fibres in the fabrics and creating a more disordered array. This was achieved through hand–felting of the wool fabrics and was found to successfully increase the surface roughness of the fabrics, and hence increase the hydrophobicity. However, it was found that the increased felting led to detectable increases in the macro–scale roughness of the surface, reducing the soft hand feel of the wool fabrics. This effect is an undesirable property in the textiles industry and another physical process of shearing protruding wool fibres was investigated in order to reduce this macro–scale roughness and increase the softness of the fabric. However, this processes was found to also reduce the micro-scale roughness of the surface and hence, the hydrophobicity of the fabrics was also decreased. This decrease in hydrophobicity was exacerbated due to the increased chemical hydrophilicity of the surface due to the exposure of more fibre ends, which are hydrophilic. Hence, the hydrophobicity of the sheared fabrics was reduced to a level lower than the untreated fabrics. Therefore, the use of physical processes to increase the roughness of wool fabrics was found to be successful in increasing the hydrophobicity of the surfaces. However, as the soft texture of the wool fabrics was compromised, the fields of application of these fabrics was determined to be somewhat limited.&lt;/p&gt; &lt;p&gt;Subsequently, the hydrophobicity of wool fabrics was increased using chemical modifications to increase the surface roughness, while not compromising the soft texture of the fabrics themselves. In these investigations, the surface roughness was again increased, but on a smaller scale, through the functionalisation of wool fibres with inorganic particles on the micro- or nano-scale. Three types of particles were investigated, gold nanoparticles, Ag/AgCl particles and CaCO3 particles. The gold nanoparticle functionalisation successfully increased the surface roughness on a very small scale, but the concurrent increase in chemical hydrophilicity was found to outweigh this increased surface roughness and result in a net decrease in hydrophobicity of the functionalised fabrics. The Ag/AgCl and CaCO3 functionalisations both successfully increased the hydrophobicity of the wool fabrics. Of these treatments, the Ag/AgCl functionalisation was found to have the greatest impact on increasing the hydrophobicity and Ag/AgCl functionalised fabrics showed increased water repellency in practical tests. The Ag/AgCl functionalisation also renders the fabrics antimicrobial, due to the known antimicrobial activity of silver nanoparticles (present as silver nanodomains on AgCl microparticles in Ag/AgCl composites). Hence, these investigations led to the development of water and stain repellent, and antimicrobial wool fabrics with great potential for commercial applications.&lt;/p&gt; &lt;p&gt;Polymer substrates and 3D printing were used in order to create surfaces with specific surface roughness patterns and changeable surface chemistry for the purpose of creating surfaces with controlled wetting behaviours. For these investigations, a fused deposition modelling (FDM) 3D printing process was used to facilitate rapid prototyping of surface roughness pattern designs and allow for optimisation of these designs. These surfaces were printed using acrylonitrile butadiene styrene (ABS). Firstly, a highly hydrophobic surface was designed. An array of droplet-shaped structures was printed onto a flat substrate. These droplet structures were on the size scale of a few hundred micrometres, but the process of melting and extruding the polymer in the printing process also gave the surface some degree of smaller scale roughness. This roughness was then increased further, by functionalising the surface with silver nanoparticles. This functionalisation was achieved in-situ and also rendered the surface antimicrobial. Due to the inherent chemical hydrophilicity of silver, the surfaces also required a subsequent treatment with a fluoroalkyl silane (FAS) to render them chemically hydrophobic. While these surfaces did not achieve the typically defined conditions of superhydrophobicity, they were found to be highly hydrophobic and were also antimicrobial. Hence, these surfaces were deemed to be potentially useful for commercial applications in healthcare industries.&lt;/p&gt; &lt;p&gt;FDM 3D printing was also used to create a surface with anisotropic wetting behaviour. This was achieved through printing a surface with 1-dimensional roughness in the form of protruding lines extending in one direction across the surface plane. These surfaces were printed using ABS or polylactic acid (PLA). Different shapes, sizes and spacings of these lines were investigated and these parameters were optimised. The resulting surface displayed significant anisotropy in its wetting behaviour with highly hydrophobic behaviour observed in the direction parallel to the protruding lines, but significantly more hydrophilic behaviour in the perpendicular direction. Hence, this surface allowed the movement of water in one direction across the surface but hindered movement in the perpendicular direction. This surface was then treated with a FAS, and subsequently treated with ion implantation in selected areas, using varied fluence of Ar+ or C+ ions. The FAS treatment served to change the surface chemistry from that of the printed polymer to a generic hydrophobic chemistry, using a surface treatment that is applicable to many different substrate materials. The ion implantation treatment significantly decreased the hydrophobicity of the treated areas of the FAS functionalised surface; in fact the ion implantation treatment was found to render the selected areas formally hydrophilic. This allowed for the design of a surface with both hydrophilic and hydrophobic areas, that allowed for movement of water in only one direction across the surface. Such a surface has potential applications in water harvesting, utilising the hydrophilic areas for condensation of water from the air, and the hydrophobic areas for movement of this water across the surface toward a collection tank.&lt;/p&gt; &lt;p&gt;The research carried out herein led to the successful increase in hydrophobicity of wool fabrics using both physical and chemical processes. 3D printing was also successfully utilised to create two different surfaces with controlled wetting behaviours. Firstly, a surface with high hydrophobicity and antimicrobial activity was produced. And secondly, a surface with anisotropic wetting behaviour and areas of hydrophilicity and areas of hydrophobicity was achieved. Possible applications of these surfaces were considered.&lt;/p&gt;