Consonance of 3D Printed Fiber Network

Leather manufacturing process involves a lot of waste disposal which pollutes environment, some of the processes are inevitable. In the present investigation, 3D printing technology was used to reduce the wastage and to cover defective regions in leather. The present study focuses on synthesis of acrylic binder using emulsion polymerization technique. These binders were analysed for solid content for better optimisation of the amount of binder to be utilised for finishing operation. The experimental binder was prepared with 26% solids. Particle size and thermogravimetric analyses were carried out to understand the size and shape of the particles and their thermal resistance. These binders were used for leather finishing and the performance of leather was studied. Surface morphology changes of leathers were studied using Scanning Electron Microscopy (SEM). Wet and dry rub fastness, finish film adhesion, light fastness and organoleptic properties were studied and found to be superior compared with control leathers. The acrylic finished leather with minor defects was taken for 3D printing and designed using Thermoplastic Polyurethane (TPU) as filament. The acrylic finished leather shows good adhesion for TPU and it results in numerous designs in short duration. The new additive was added to leather using 3D printing technology to produce a tailor-made valuable design without any waste disposal and chemical discharge. This invention may convert the rejected waste leather into valuable material and lead to the new generation hybrid leather for use.

Chapter 2 - 3D printing and nanotechnology

This study aims to address a key challenge in geosynthetic engineering by ensuring that scaled geocells are produced and utilized in accordance with dimensional analysis principles and similarity laws, thereby accurately replicating the behavior of prototype geocells. Utilizing a commercially available 3D printer, model geocells were fabricated to closely represent the geometric and material properties of prototype high-density polyethylene geocells. A comprehensive examination was conducted on the tensile strength/modulus of 3D-printed geocells using different filaments and infill rates. The findings revealed that geocells printed with thermoplastic polyurethane filaments, particularly with a 5% infill rate, closely resembled the prototype geocells in terms of the tensile modulus at specific elongation levels, showcasing a promising avenue for 1:3 scaled model tests. The successful creation of geocell layers using the elastic filaments was achieved through careful calibration of printing settings, including first-layer precision, bed leveling, and controlled printing speed. The effects of scaling on strip footings reinforced by both HDPE-fabricated and 3D-printed geocells were also evaluated in small-scale laboratory tests, focusing on their pressure-settlement response and improvement factors. Utilizing 3D-printed geocell layers in model tests addresses the challenge of employing unscaled prototype geocells.

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.

Textiles are an essential part of human lives and are associated with them from cradle to grave. There is a limitless choice of materials, processes, designs, and applications of fibers and textiles. However, conventional textile processing uses considerable resources and is not always environment friendly. Three-dimensional (3D) printing offers new avenues and provides a considerable value in addition to textile materials. From simple printing of designs or patterns, complex structures such as wearable electronics and space textiles are made using 3D technology. Similarly, the creation of nanostructures, self-colored clothing, and imparting functional finishes are also done through 3D printing. Innovative smart textiles that contain bioactive agents, carbon nanotubes, etc. which can provide high-performance properties, improve appearance or durability, which can be done using 3D printing. One such example is of temperature-regulated clothing developed using 3D printing. In this chapter, we will provide an overview of the opportunities and the challenges of 3D printing in fashion and textiles. Examples include the application of 3D printing in medical textiles, industrial textiles, jewelry, and fashion. Most 3D-printing 190technologies are done using synthetic polymers such as nylon, polyester, poly(lactic acid), and thermoplastic polyurethane. Possibilities of developing 3D-printed objects using natural polymers or other additives have been discussed.

Individuals choose to undergo vasectomy reversal for a variety of reasons, including remarriage or due to the death of a child. To be proficient in this procedure, the surgeons need to be high volume and the trainees require a safe environment to develop their microsurgical skills. To overcome this challenge, we used three-dimensional (3D) printing to create a synthetic model of the vas deferens with properties similar to the human vas deferens. We distributed this model to experienced microsurgeons for evaluation. The vas deferens model was created using thermoplastic polyurethane filament. The filament was then infused with a foaming agent to allow for temperature-dependent tuning of the material's stiffness. The model's outer diameter was 1 mm and the inner lumen was 0.5 mm. Fellowship-trained male reproductive urologists were recruited from the Society for the Study of Male Reproduction website. They used our model and judged it on several factors by completing a 13-question survey. We received completed evaluations from five microsurgeons. Eighty percent of the surgeons were able to complete a full anastomosis on the model using 9-0 and 10-0 sutures. The majority of the completed anastomoses were performed using the one-layer technique. The average responses for the model's usefulness as a practice tool, a training tool, and overall assessment ranged from 72 to 79 out of 100. Comments for the improvement included the need for a more flexible and softer model. We created a 3D-printed synthetic vas deferens that serves as a valuable training and practice tool.

Research in the field of 3D printing and water industry, in particular, on the fabrication and evaluation of feed spacers produced via 3D printing, rapid prototyping or additive manufacturing (AM) techniques is presented in this thesis. Feed spacer is a mesh-like structure placed between membrane sheets to create channels for fluid flow in a spiral wound membrane module (SWM). It has an important role in the hydrodynamic conditions of a SWM, which serves to facilitate mass transfer in the feed channel by generating vortex and promoting mixing. The mass transfer is critical in reducing the concentration polarisation phenomenon in membrane processes, which is often associated with membrane fouling. However, the challenges of commercial feed spacers include the trade-off between mass transfer and pressure drop along the channel that leads to the rise in energy demand as well as their impact on membrane fouling. Many studies via computational fluid dynamics (CFD) simulations have shown that spacers with complex structures have great potential in enhancing the mass transfer. However, conventional method of spacer manufacturing by extrusion could not realise the complicated designs of spacers. In this work, the 3D printing technology is employed as a tool to fabricate novel feed spacers with structures that maximise the mass transfer while minimise the channel pressure drop. It is nevertheless important to note that there are limitations in current AM technology. A link between the design and fabrication i.e. printability and surface finish properties of spacers was established. The printability of polypropylene (PP) which is the representative material of spacers was also investigated. The fabricated spacers were evaluated in terms of flux and pressure drop. Direct observation through the membrane (DOTM) technique was also used to study the impact of different 3D printed spacers on the critical flux of particles. Among the 3 broad classes of solid, liquid, powder based 3D printing techniques, the liquid based Polyjet technique was found to give the most accurate representation of the intended design while the solid based FDM (Fused Deposition Modeling) technique produced spacers that showed the greatest deviation from the specifications. On the other hand, the improvement in mass transfer by the FDM printed spacer was unexpectedly the greatest among the three 3D printed spacers, due to the ‘randomness’ in the strand of spacer. In addition, the surface finish of the spacers was found to have an effect on the critical flux, specifically, the anisotropic surface finish of FDM and semi-anisotropic surface finish of Polyjet. Biofouling potential was discovered to be correlated to the surface roughness of samples. Among which, Polyjet and SLS printed samples have greater bacteria attachment due to their higher microscale roughness. Eventually, three design considerations for developing 3D printed novel spacers were recommended. A series of existing (i.e., taken from the literatures), modified and innovative spacer structures, compared with commercial feed spacer, were examined to identify the basis form of spacer structure with the greatest potential. Further optimization of the selected structure was conducted to improve the spacer performance. With the primary structure made up of sinusoidal curves and secondary structures consisting cylindrical protrusions along the curve, the novel spacer S12 showed an improvement of 18% at power number, Pn=106, and 25% at Pn= 105 in mass transfer compared to commercial spacer. With this optimal design, a smart multi-material spacer was developed by designing the primary structure with a rigid material and the secondary structures with flexible materials. The multi-material responsive spacer with Tangoblackplus as the flexible material was able to lower the flux decline due to bentonite fouling by 7.6% as compared to the commercial spacer and 5.2% when compared to the single rigid material spacer. This indicates that a spacer with flexible filaments has a beneficial effect on fouling reduction. The flexible properties of the selected section on the spacer allow dynamic movement under varying flow rate, which creates a “sweeping” effect that disrupts the boundary layers and prevents foulants from accumulating near spacer filaments and on the membrane surface, thereby mitigating fouling. These favourable findings have contributed as one of the pioneering work in this interdisciplinary field.

Thermoplastic polyurethane (TPU) is a highly elastic linear polymer composed of soft segments, usually flexible polyester, or polyether. It is widely used in 3D printing technologies, being FFF the most common technique. However, stiffness and hardness values of 3D printed TPU in filament form are higher than would be desirable for some applications, which require softer parts. Therefore, it was seen necessary to find a new methodology for 3D printing soft TPU. In this way, the present study seeks to be the first research study that focuses on the possibility of 3D printing TPU using DIW (Direct Ink Writing) technology with UV light. Firstly, the optimal 3D printing and curing parameters to print soft TPU are determined and then two different TPU formulations are 3D printed. Then, both bulk and 3D printed TPU samples were characterized in terms of shear strength using the Warner-Bratzler shear test and hardness using the Shore hardness test. It was seen that the 3D printed samples showed higher softness than bulk samples compared to TPU filament. Finally, it was concluded that the 3D printing of TPU is challenging due to several points: (1) the viscosity of the TPU; (2) their main issue is their sticky behavior; and (3) the shrinkage which takes place after the thermal treatment and for some applications, it might be a problem. Despite that, TPU appears to be a promising material to be used in different industrial applications.

This study intended for the assessment of the stiffness, tensile and bursting properties of 3D printed auxetic sinusoidal patterns of different density and thickness deposited on the nylon fabric by means of fused deposition modeling (FDM) with the use of thermoplastic polyurethane (TPU) filament. Morphology, weight variation, flex stiffness, tensile property, Poisson’s ratio and bursting strength were analyzed for the characteristic evaluation of produced composite. The prototypes of two auxetic pattern repeat of 47 mm×43 mm and 20 mm×20 mm were developed named as low density (LD) and high density (HD) respectively. Both patterns were repeatedly combined to produce bigger size patterns and 3D printed with various thicknesses. Weight variation is found proportional to the density and thickness of 3D printed auxetic sinusoidal. Maximum up to 552 % weight increase was recorded for LD pattern and for HD 857 %. Flex stiffness increased with the rise of density and thickness of 3d printed auxetic sinusoidal pattern. Maximum flex stiffness for HD was 7.21 cm-g and for LD 4.73 cm-g. Warp direction is stiffest comparing with diagonal and weft in all cases. In case of tensile strength, a great extent of elongation was noticed due to the presence of auxetic sinusoidal 3D pattern and TPU filament. Maximum, more than 500 % elongation was showed by HD diagonal direction. HD patters exhibited more strength and toughness than LD patterns. In addition, warp direction is strongest and diagonal direction is weakest whereas the weft stays in between. Both LD-1.0 and HD-1.0 3D printed pattern showed negative Poisson’s ratio and the value was between -1.0 to 0. The enhanced bursting strength is found in HD patterns up to 1514 kPa comparing up to 1449 for LD. Thus, this study confirmed the excellent stiffness, tensile and bursting properties of HD 3D printed auxetic sinusoidal pattern/nylon composite over LD.

Preparation and characterization of hot-melt extruded polycaprolactone-based filaments intended for 3D-printing of tablets

Three-dimensional (3D) printing technology in medicine is one of the new and innovative technology for fabricating 3D models of complex anatomical structures that can be observed both visually and haptically. Patient-specific 3D models fabricated through this process are currently being used for various purposes, including surgical simulation, training, and medical education. Most of the personal use/low-end desktop 3D printers that are becoming widespread are fused deposition modeling (FDM) 3D printers. Compared to professional/high-end 3D printers, the price of the personal use/low-end desktop FDM 3D printer itself, filament, and running costs are lower; it can lower the economic bottleneck for introducing 3D printing technology into clinical practice, such as surgical simulation. With a desktop FDM 3D printer and a general-purpose PC, anyone can now rapidly fabricate 3D models on their own without having to rely on 3D printing labs and specialized technicians. However, it is also true that FDM 3D printers, due to their mechanical characteristics, encounter many difficulties and problems that emerge during the 3D printing process. Knowledge, know-how, and tips about FDM 3D printers have been introduced in various media, and it has become easy to know about them worldwide via the Internet. However, there has been no comprehensive technical review to date to produce osseous 3D models for use in oral and maxillofacial surgery. In this report, to create 3D models according to the characteristics of maxillofacial and oral surgery, we enable surgeons themselves to create 3D models smoothly by presenting ideas for CT scanning, points to note when exporting Digital Imaging and Communications in Medicine (DICOM) image data, how to create optimal stereolithography (STL) models, and problems and solutions for 3D printing.

Three-dimensional (3D) printing allows for the design and printing of more complex designs than traditional manufacturing processes. For the manufacture of personalised medicines, such an advantage could enable the production of personalised drug products on demand. In this study, two types of extrusion-based 3D printing techniques, semi-solid syringe extrusion 3D printing and fused deposition modelling, were used to fabricate a combi-layer construct (combi-pill). Two model drugs, tranexamic acid (water soluble, rapid release) and indomethacin (poorly water-soluble, extended release), were printed with different geometries and materials compositions. Fourier transform infrared spectroscopy results showed that there were no interactions detected between drug-drug and drug-polymers. The printed combi-pills demonstrated excellent abrasion resisting properties in friability tests. The use of different functional excipients demonstrated significant impact on in vitro drug release of the model drugs incorporated in two 3D printed layers. Tranexamic acid and indomethacin were successfully 3D printed as a combi-pill with immediate-release and sustained-release profiles, respectively, to target quick anti-bleeding and prolonged anti-inflammation functions. For the first time, this paper systematically demonstrates the feasibility of coupling syringe-based extrusion 3D printing and fused deposition modelling as an innovative platform for various drug therapy productions, facilitating a new era of personalised combi-pills development.

Fused filament fabrication is a 3D printing technique that has gained widespread use from homes to schools to workplaces. Thermoplastic filaments, such as acrylonitrile–butadiene–styrene (ABS) and polylactic acid (PLA), are extruded at temperatures near their respective glass transition temperature or melting point, respectively. Little has been reported on the inorganic elemental composition and concentrations present in these materials or the methods available for extracting that information. Because inorganic constituents may be included in the aerosolized particulates emitted during the printing process, identifying elements that could be present and at what specific concentrations is critical. The objective of the current research is to determine the range of metals present in thermoplastic filaments along with their relative abundance and chemical speciation as a function of polymer type, manufacturer, and color. A variety of filaments from select manufacturers were digested using a range of techniques to determine the optimal conditions for metal extraction from ABS and PLA polymers. The extraction potential for each method was quantified using by ICP-MS analysis. When possible, further characterization of the chemical composition of the filaments was investigated using X-ray Absorption spectroscopy to determine chemical speciation of the metal. Optimal digestion conditions were established using a high temperature, high pressure microwave-assisted acid digestion method to produce the most complete and repeatable extraction results. The composition and abundance of metals in the filaments varied greatly as a function of polymer, manufacturer, and color. Potential elements of concern present in the filaments at elevated concentration included that could pose a respiratory risk included Si, Al, Ti, Cu, Zn, and Sn. XAS analysis revealed a mixture of metal oxides, mineral, and organometallic compounds were present in the filaments that were being used to increase opaqueness impart color (dyes), polymeric catalysts, and flame retardants. This work shows that a variety of metals are present in the starting materials used for 3D printing and depending on their partitioning into 3D printed products and byproducts as well as the exposure route, may pose a health risk which merits further investigation.

3-Dimensional (3D) printing has become a common tool to aid implant molding for cranioplastic surgery of large skull defects. Until now, 3D printing of cranial implants itself has not been used, mainly because of medicolegal concerns. With a 3D printer developed for printing medical applications and with implant-grade polyetheretherketone (PEEK) filament available, we established a workflow (in compliance with medical device regulations) to 3D print cranial implants for cranioplastic surgery directly at the point of care (POC). Here, we describe the implementation of 3D printing these PEEK implants for cranioplastic surgery at our academic hospital. A thorough design and 3D printing process, in accordance with local medical device regulations, was developed. Implants are digitally designed based upon pre- and post-craniectomy cranial computed tomography scans by trained 3D printing experts from the department of medical engineering at our institution. Implants are then produced on a medical 3D printer with implant-grade PEEK filament using the fused filament fabrication process. After postprocessing and steam sterilization, implantation for reconstruction of the skull can be performed. Cranioplastic surgery with a 3D-printed PEEK implant was performed at our institution in a patient with a large frontotemporoparietal skull defect after traumatic brain injury with consecutive decompressive craniectomy. No intra- or post-operative complications occurred. Postoperative cranial computed tomography scans showed perfect reconstruction of precraniectomy skull shape. The aesthetic result was promising and satisfactory to the patient. This novel 3D printing workflow enables the production of patient-specific cranial implants from PEEK, to reconstruct large skull defects directly at the POC in accordance with the European Medical Device Regulation. This marks an unprecedented technological and legal advancement, enabling the hospital infrastructure not only to deliver the cranioplastic surgery itself, but also additive manufacturing of the implant directly at the POC.

Indonesia, as the world's largest archipelagic country, plays a strategic role in international trade, maritime transportation, and maritime defense, making efficient and reliable ship propulsion technology a key priority. Waterjet thrusters offer advantages in maneuverability, energy efficiency, and resistance to cavitation compared to conventional propellers, with the geometric design of components such as impellers, inlets, and outlets, as well as Thermoplastic Polyurethane (TPU) materials produced via 3D printing, significantly influencing thrust performance. The twin waterjet thruster system provides fault-tolerant benefits, while TPU has adjustable mechanical properties and potential biocompatibility. This experimental research designed a twin waterjet thruster prototype using SolidWorks, produced components (4-blade impeller, 12-blade inlet, 12-blade outlet) via FDM 3D printing with an Anet A8 Plus PRO machine and TPU filament, and tested it in a water tank using a 22 HP engine at 1000-4100 rpm with thrust measurement via a scale. Results showed thrust increased linearly with engine speed: 2.6 kg (25.5 N) at 1000 rpm, 5.2 kg (51.01 N) at 2000 rpm, 7.4 kg (72.59 N) at 3000 rpm, and 11.3 kg (111.24 N) at 4100 rpm, with small variations between experiments indicating stable performance. Overall, the TPU-based twin waterjet thruster demonstrated consistent and efficient performance, potential for small-to-medium-sized vessels, with further development including hydrodynamic design optimization, stronger materials, and electric motors for energy sustainability.