Development of a Pellet Extruder for Blending Different Materials and Study on the Properties of Eco-friendly Flame Retardant Materials Printed Using a Large-scale 3D Printer

Development of a Pellet Extruder for Blending Different Materials and Study on the Properties of Eco-friendly Flame Retardant Materials Printed Using a Large-scale 3D Printer | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Development of a Pellet Extruder for Blending Different Materials and Study on the Properties of Eco-friendly Flame Retardant Materials Printed Using a Large-scale 3D Printer minsu Jung, Jeong-Ung Ha, Jong-kyu Park This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4652395/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 20 Dec, 2024 Read the published version in The International Journal of Advanced Manufacturing Technology → Version 1 posted 4 You are reading this latest preprint version Abstract This study aims to design and fabricate a pellet extruder capable of blending different materials for the application of flame-retardant building materials in 3D printing and to evaluate the properties of eco-friendly flame-retardant materials printed using a large-scale 3D printer. The main content of the research is as follows: To ensure the printing stability of the large 3D printer, the deflection amount of the axis due to the weight of the pellet extruder was verified through structural analysis. This made it possible to achieve stable printing even on a large bed (1000mm x 1000mm). Next, a pellet extruder capable of blending different materials was developed to quickly collect initial mixing ratios and temperature data, and specimen printing was conducted using this extruder. The flame-retardant performance and mechanical properties of the printed flame-retardant material were evaluated, and PLA specimens mixed with calcium carbonate at various ratios from 5% to 20% were produced to conduct flame-retardant performance tests and tensile tests according to UL-94 standards. As a result, it was found that the flame-retardant performance improved as the calcium carbonate content increased, and the optimal mixing ratio was derived. Finally, to verify the printing stability of the extruder and large 3D printer, a honeycomb composite structure was printed continuously for 1 hour and 30 minutes, and it was confirmed that continuous printing was possible with a maximum error of 1mm. The proposed development systems satisfy both stable printing of large composite structures and excellent flame-retardant performance, confirming the potential for use as eco-friendly building material prints. 3D Printer Flame Retardant Meterial Pellet Extruder UL-94 HB Mixed Material Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 Figure 15 Figure 16 Figure 17 Figure 18 Figure 19 Figure 20 Figure 21 Figure 22 Figure 23 Figure 24 1. Introduction As the need for eco-friendly building materials continues to rise in modern society, there is an increasing demand for construction materials to transition to environmentally friendly and recyclable materials in line with the growing interest in sustainable development and environmental protection. Particularly, the development of fire-retardant materials with enhanced fire safety is a critical factor in ensuring the safety of buildings. These fire-retardant materials help minimize damage in the event of a fire, protecting both lives and property. However, existing 3D printing technology primarily uses single materials for printing, making it challenging to print materials with complex functionalities. This results in difficulties in ensuring stability when printing large structures, as the output stability of large 3D printers is low, and sagging of the axis can reduce the quality of the prints. In the development of fire-retardant materials, there has been insufficient research on achieving adequate fire-retardant performance and on deriving optimal performance through the use of various mixed ratios.[ 1 ] In this study, we aim to develop a pellet extruder capable of blending different materials and use it to print eco-friendly fire-retardant materials with a large 3D printer, evaluating their characteristics. Unlike traditional 3D printing technology, which primarily uses single materials, this study aims to mix materials with different properties to impart new functionalities. This approach aims to meet the diverse requirements for building materials and achieve safer and more efficient buildings. Using large 3D printers to print building materials offers significant advantages in terms of time and cost. In particular, it simplifies the process and reduces production time by allowing complex-shaped structures to be manufactured in a single, integrated process. To maximize these technical advantages, it is essential to ensure the output stability of large 3D printers and the physical properties of the materials.[ 2 , 3 ] In this study, we verified the deflection of the axis due to the weight of the pellet extruder through structural analysis to ensure the output stability of large 3D printers. This enabled stable printing even on large beds. Additionally, to quickly collect initial mixing ratio settings and temperature data, we developed a pellet extruder capable of blending different materials and used it to print test specimens.[ 4 ] To evaluate the fire-retardant performance and mechanical properties of the printed fire-retardant materials, we produced PLA specimens mixed with calcium carbonate in various ratios from 5–20%. We conducted fire-retardant performance tests according to the UL-94 standard and tensile tests. The results showed that the fire-retardant performance improved with the increase in calcium carbonate content, allowing us to derive the optimal mixing ratio. Finally, to confirm the output stability of the extruder and the large 3D printer, we printed a honeycomb composite structure for 1 hour and 30 minutes. The continuous printing was successful, with a maximum deviation of 1mm. The study results confirm that the proposed development systems satisfy both the stable output of large composite structures and excellent fire-retardant performance. This demonstrates the potential for their use in printing eco-friendly building materials and suggests a broad range of applications in the construction field in the future.[ 5 ] The pellet extruder and large 3D printer developed in this study significantly enhance the functionality of building materials by enabling the mixed printing of various materials. The development of eco-friendly fire-retardant materials, in particular, is an innovative approach that simultaneously achieves the crucial goals of environmental protection and improved safety. We aim to continue enhancing the technology through ongoing research and development, thereby increasing its practicality and potential for commercialization. This paper details the development process and results of the heterogeneous material blending extrusion technology based on the background and necessity of the research. Through this, we aim to convey the importance and potential of this technology to the readers. 2. Research Objectives The research objectives of the pellet extruder 3D printer capable of blending different materials are as follows: First, Ensuring the printing stability of a large 3D printer equipped with a pellet extruder. The main design factor for ensuring the printing stability of the 3D printer is verifying the deflection amount of the axis due to the weight of the pellet extruder.[ 6 ] Second, Conducting flame-retardant performance and mechanical property tests on the printed flame-retardant material. PLA specimens mixed with calcium carbonate at various ratios from 5–20% will be produced, and flame-retardant performance tests and tensile tests according to UL-94 standards will be conducted to verify the performance of the printed flame-retardant material. Last, Establishing a system for printing large composite structures with flame-retardant materials. The use of desktop-sized 3D printers for printing flame-retardant interior/exterior materials requires splitting the object into parts, which increases time and cost, making it difficult to use. A 5mm nozzle will be applied to reduce the printing time of honeycomb composite structures, and the printing efficiency and error will be evaluated. 3. Design and Fabrication of a Large 3D Printer 3.1 Design Considerations In this paper, the proposed 3D printer employs a blending extrusion method, which differs from traditional filament-based 3D printers. Therefore, it is necessary to consider not only the structural sagging due to weight but also the extrusion characteristics of the extruder. Additionally, the design of the extruder must take into account factors such as the screw shape of the extruder, temperature control for material melting, control of bottlenecks occurring during material extrusion, and cooling devices to ensure material supply stability, all of which are crucial for output stability.[ 7 ] The sagging of the extrusion unit is a primary consideration in the gantry structure, which is applied to most 3D printing methods. This sagging refers to the deformation amount of the frame to which the extrusion unit is attached. When both ends of the frame are fixed, the maximum deformation occurs at the middle of the frame, interacting with factors such as the nozzle size of the extrusion unit and the bed's levelness, leading to extrusion errors. Theoretically, the thickness of the extruded plastic resin should be uniform and adhere to the bed regardless of the direction in which the bed moves. However, if extrusion errors occur, variations in thickness and adhesion degree affect the overall quality. Therefore, it is necessary to verify the maximum sagging amount at each position of the extrusion unit through structural analysis in the design of 3D printers.[ 8 ] 3.2 System Appearance and Extruder Design As shown in Fig. 1 , the design was advanced to enable output with a maximum size of 1000mm x 1000mm x 700mm, and the frame was made of aluminum square tubes with a size of 50mm x 50mm. The movement of each axis was controlled by a step motor, and for the Z axis, four motors were installed at each corner to distribute the load. The bed was designed to be 1200mm x 1200mm, 200mm larger than the maximum size that can be output, to prevent deviation in output. For the outer frame, it was designed to be 1600mm x 1600mm with 200mm intervals on the left and right.[ 9 ] For the extrusion frame, a 40mm x 80mm aluminum profile was used to ensure torsion and part installation space, and two LM guides were installed to ensure drive straightness. The extrusion section can be roughly divided into a rotating section, extrusion screw, nozzle, etc., and a 35W DC motor with a 150:1 gearbox was used for extrusion to ensure a maximum torque of 450Nm, and the maximum rotation speed was 20rpm. The screw and motor are connected using a coupler, and a nozzle with a diameter of 5 mm is attached to enable the extrusion of a large amount of resin. The weight of the extrusion section is about 4.4 kgf, and a hopper is installed in the material input section so that the raw material can be supplied regularly.[ 10 ] In the case of an extruder extrusion screw, shape design is important to ensure the material extrusion force. A single-axis screw extruder has low energy consumption, good quality, and stable operation. It also has low noise and a long life, making it suitable as an output screw for 3D printing work and small-lot production of a wide variety of products. In addition, as shown in Fig. 2 , the distance between the blades (lead) is constant, which is a characteristic of the plastic injection screw, so the volume decreases as you go to the metering section, pressure is generated in the material, the depth becomes narrower, and a gradient is formed, which is advantageous for material extrusion. The melting temperatures of different materials vary. If the temperature is set too high, the material may burn or undergo thermal decomposition, resulting in deformation and making it difficult to achieve the desired properties. If the temperature is too low, the material will not melt properly, leading to incomplete mixing, material clumping, or nozzle blockages, which can cause printer malfunction. To control this, individual temperature control devices were installed at both the barrel and nozzle sections. If heating devices are only installed at the nozzle tip, the material will be extruded without proper mixing. Conversely, if the system is only installed at the barrel section, the material will cool and block the nozzle during extrusion, so both sections were equipped with heating systems. This ensures that the material melts first in the barrel section and, through the rotation of the extruder, is mixed and then transported to the nozzle section for extrusion.[ 11 ] In 3D printing, a bottleneck refers to the condition where the excessive supply of molten material prevents proper extrusion, causing the material to cool down due to the cooling fan and block the extruder, hindering proper extrusion. To prevent the molten material at the upper part of the nozzle from cooling and solidifying, a screw was additionally installed to rotate the molten material. This prevents the material from solidifying due to the cooling fan before extrusion, thus avoiding nozzle blockage and maintaining an appropriate temperature for stable extrusion onto the bed. The cooling fan at the front of the extruder is used to prevent layers from becoming messy when printing models with sharp ends, small products, or when the next layer is built while the previous layer hasn't properly solidified. Typically, the cooling fan of an FDM filament printer prevents heat from being transferred to the nozzle neck, but the cooling fan of the developed extruder lowers the temperature of the molten material at the top of the nozzle to a similar level as the nozzle temperature control, aiding in stable extrusion. 3.3 Structural Analysis Table 3 Properties of Structural steel and Aluminum Elastic Modulus (GPa) Density (kg/㎥) Poisson’s Ratio Structural Steel 210 7850 0.29 Aluminum 70 2700 0.3 Structural analysis was conducted based on the designed extrusion frame and extruder shape. The structural analysis conditions, as shown in Fig. 4 , involved fixing both ends of the assembled extrusion frame and extruder. The deflection amount due to self-weight was checked with the extruder positioned on the left, center, and right. The materials were specified as structural steel and aluminum according to the design conditions, and their properties are shown in Table 3 . The analysis focused on the maximum deflection amount, considering the extruder positioned in the center of the frame. The analysis results, as shown in Fig. 5 , indicated that the maximum stress and deflection amounts when the extruder was positioned on the left, center, and right were (101 MPa, 0.3 mm), (116 MPa, 0.489 mm), and (102 MPa, 0.299 mm), respectively. The maximum stress occurred at the extrusion frame joint and LM guide, but since the yield stress of structural steel and aluminum are 275 MPa and 170 MPa, respectively, it was deemed safe. Additionally, the deflection difference between the center and the left and right was found to be 0.18 mm, and since the height of one layer when using a 5 mm nozzle is 0.8 mm, it was considered safe as it does not exceed the layer height. The pellet extruder system consists of a stepper motor, hopper, screw and barrel, and nozzle. To verify the design feasibility of the injection screw, FSI (Fluid-Structure Interaction) analysis was conducted. This analysis involves using a finite element approach to model the stress and deformation responses of the components to the pressure, temperature gradients, and specified boundary conditions of the surrounding fluid, indicating a fully coupled interaction between the fluid and the solid. The analysis conditions are shown in Fig. 6 , and the comparison was made between using the existing auger bit and the developed injection screw. The analysis results, as shown in Fig. 7 , indicate that in the case of the auger bit, pressure does not occur in the transport section, resulting in only about 1.1 MPa of pressure at the outlet due to the nozzle shape. In contrast, with the injection screw, the pressure increases linearly towards the nozzle due to the gradient effect, and the pressure formed in the transport section is maintained to the nozzle chamber, resulting in a stable pressure of about 1.7 MPa at the nozzle tip. 3.4 System Fabrication The fabrication process is divided into the following stages: manufacturing the external frame and printing bed, attaching motors and components for operation, installing limit switches, and configuring the circuitry. For the external frame, aluminum square frames and joints were cut and machined to the required specifications and assembled to complete the external frame. Subsequently, power supplies connected to the MCU, stepper motors, motor drivers, and limit switches were installed. The proposed 3D printer system configuration, as shown in Fig. 8 , utilizes a total of three axes: X, Y, and Z. Therefore, motor drivers and motors are needed to control each axis. The motor drivers controlling the motors are independently controlled for each axis. The external power supply uses a 24V power supply unit, but to supply power to seven motors simultaneously, individual power supplies were applied for each axis. For the Z-axis, the movement of four motors is synchronized, so two motors were connected to one motor driver. For the pellet extruder, as shown in Fig. 9 , the initial 24V power supply is used to set the temperatures of Control 1 and Control 2 (barrel and nozzle sections) to the melting temperature of the mixed material. Then, to prevent the stepper motor of the extruder from stalling, the stepper motor of the mixing screw is activated, causing the entire system to operate. Each operating system can be turned on or off offline, and the system is configured to immediately stop in case of an error. Each temperature control unit can be set individually, and the extruder and the left screw also have separate speed controls, allowing for suitable screw speed adjustment depending on the situation, making it an ideal system for controlling various products. The fabricated extruder consists of a controller and an extruder. The controller can control the motor power, temperature, and rotation speed. When power is supplied to the controller and the target temperature is set, the extruder starts heating. After adding pellets to the hopper and setting the rotation speed, the extrusion drill rotates and extrudes the pellets. As shown in Fig. 10 , a driving test confirmed that the pellets were extruded as the extrusion drill rotated. Through final assembly, as shown in Fig. 11 , a large 3D printer with dimensions of 1.6 × 1.6 × 1 m was produced. The assembly precision of each axis was checked using electronic measuring instruments, and it was confirmed that the maximum error was 0.3° for the X and Y axes, and ± 1 mm for the Z axis. This ensures a manufacturing precision with a maximum error of 5 mm for a print size of 1 m. 4. Printing and Flame Retardant Experiments 4.1 Production of Experimental Raw Materials To achieve consistent flame retardancy performance, it is necessary to secure uniformly mixed raw materials. In this study, the aim is to produce and print flame retardant materials through mechanical mixing. To optimize the material ratios, the flame retardant was mixed with PLA by mass ratio to verify the characteristics of the specimens. As shown in Fig. 12 , PLA and calcium carbonate were mixed in initial ratios of 5%, 10%, 15%, and 20% based on a total mass of 100%.[ 12 ] Since the first mixture of PLA and calcium carbonate is in a mixed state, it was fed into a pellet production machine consisting of an extruder and a pelletizer to produce pellets. The produced pellets were re-fed into the pellet production machine to produce second mixed pellets. This process was repeated to produce pellets with calcium carbonate mixed at 5–20% ratios, and the extrusion characteristics of the pellets mixed once and twice were verified. In the case of the 20% calcium carbonate in the twice-mixed specimen, the ductility of the plastic decreased, and brittleness increased, making specimen production impossible. Therefore, raw materials were produced at 5–20% for single mixing and 5–15% for double mixing. 4.2 LV-SEM Experiment Results The LV-SEM experiment was conducted to verify whether calcium carbonate and PLA were uniformly mixed during the production of raw materials for testing. The experiment environment is shown in Fig. 13 , and cubic specimens with an edge length of 1 cm were used. Since the specimens were composed of insulating PLA and calcium carbonate, making it difficult to observe the surface, the surface of the specimens was coated with a conductive paint. Each coated specimen was photographed at magnifications of 500x, 1000x, 2000x, and 3000x to verify the surface characteristics for each ratio. As shown in Fig. 14 , the surface of the specimens was observed to become brighter and the surface protrusions decreased as the ratio of calcium carbonate increased from 5–20%. Due to the characteristics of LV-SEM, it was not possible to distinguish between PLA and calcium carbonate since the images were only in black and white. EDS (Energy Dispersive X-ray Spectroscopy) analysis was used to verify the distribution of calcium on the surface. However, due to the high voltage, the surface of the specimen showed bubbling phenomena, as seen in Fig. 15 , making it impossible to confirm the internal mixing uniformity of the specimen. 4.3 Tensile Test Results The mechanical strength of the flame retardant materials was verified using the produced specimens. The tensile test specimens were prepared according to ASTM D-638 standards, as shown in Fig. 16 , and the tests were conducted using the MINOS-100 tensile tester shown in Fig. 17 . The specimens were made from raw materials mixed once at ratios of 5–20%, and the tensile behavior during the test was observed using a DIC camera. Each specimen was subjected to tensile testing at a speed of 0.342 mm/min, and the load and tensile stress were measured at 0.1-second intervals. The test results, shown in Fig. 18 , indicated that as the calcium carbonate ratio increased, the maximum tensile strength decreased, the modulus of elasticity increased, the yield strength decreased, the fracture strength decreased, and the elongation decreased. This demonstrates that the brittleness of the material increased due to the addition of calcium carbonate. 4.4 Flame Retardant Test Results Since the goal of this study is to apply flame retardant materials to buildings, flame retardant testing of the produced materials is necessary. The flame retardant tests were conducted according to the UL-94 HB test environment standards, as shown in Fig. 19 . Specimens made from materials mixed once and twice were printed and finished through post-processing. Specimens mixed twice at 20% were excluded due to increased brittleness, making specimen processing impossible. Therefore, the experiment was conducted with three specimens each for single mixing at 5%, 10%, 15%, and 20% and for double mixing at 5%, 10%, and 15%, making a total of 21 specimens. For the combustion test of the single-mixed raw materials, specimens made only from pure PLA were also produced and tested, as shown in Fig. 20 . It was observed that the flames were larger and there was more dripping in the 100% PLA specimens compared to the specimens mixed with calcium carbonate. The specimens mixed with calcium carbonate showed a reduction in flame size and dripping, with some specimens self-extinguishing. In the flame retardant test for the twice-mixed specimens, as shown in Fig. 21 , the self-extinguishing rate increased after combustion compared to the once-mixed specimens. Except for one specimen with a 15% ratio, all specimens self-extinguished within 30 seconds. This is summarized in Tables 4 and 5 . The analysis of these results indicates that at least two mixing processes are necessary to achieve sufficient flame retardant performance in specimens produced through physical mixing. Table 4 UL-94 HB test result of once mixed 1 2 3 5% 35.85 mm/min 100 mm point Digestion 25 mm point Digestion 10% 29.15 mm/min 33.57 mm/min 25 mm point Digestion 15% 35.32 mm/min 37.76 mm/min 27.6 mm/min 20% 50 mm point Digestion 38.77 mm/min 39.62 mm/min Table 5 UL-94 HB test result of twice mixed 1 2 3 5% In 30sec Digestion In 30sec Digestion In 30sec Digestion 10% In 30sec Digestion 25 mm point Digestion 25 mm point Digestion 15% 28.02 mm/min In 30sec Digestion In 30sec Digestion 4.5 Determination of Mixing Ratio By analyzing the results of the mechanical and flame retardant tests conducted in this study, the appropriate mixing ratio of PLA and calcium carbonate that can be applied to building materials was derived, as shown in Fig. 22 . The tensile test indicated that as the calcium carbonate ratio increased to 20%, brittleness increased, making the material more prone to breaking rather than deforming like regular plastic. These characteristics are unsuitable not only for construction but also for environments where vibrations may occur. The analysis of the flame retardant test results showed that, unlike the once-mixed test, the flame retardant performance improved in all specimens with double mixing. When examining the ratios of calcium carbonate, it was found that increasing the calcium carbonate content did not significantly change the flame retardant performance. Considering raw material costs, elasticity changes, and ensuring flame retardancy, a ratio of approximately 5% calcium carbonate mixed with PLA is deemed appropriate.[ 13 ] 4.6 Printing of Composite Structures The printing of composite structures was carried out to verify the possibility of printing complex-shaped structures using mixed materials. This process was not only to confirm the stability of the printed material but also to check the printing error of complex building structures. To generate the prints, G-code was created as shown in Fig. 23 , and the printing conditions were set the same as those for the tensile test specimens. It was confirmed that the printing was stable for both small specimens and large, complex structures. The results of the printing, shown in Fig. 24 , indicate that continuous printing was conducted for about 1 hour and 30 minutes without any stoppages or nozzle blockages. The maximum error was within approximately 1 mm. 5. Conclusion In this study, a pellet extruder capable of blending different materials was developed, and a system was designed and fabricated to print eco-friendly flame retardant materials using a large 3D printer. Various experiments were conducted to collect and analyze data to examine the applicability of this system in the construction field. The main conclusions are as follows: 1. To solve the problem of structural deflection caused by the weight of the pellet extruder, it was verified through multiphysics analysis. By using aluminum profiles (40 mm × 80 mm), the deflection was reduced compared to conventional square pipes, and it was confirmed that the maximum deflection did not exceed the layer height. The developed 3D printer adopted a gantry system to enhance the stability of the extruder's transport and used linear motion guides to ensure precision. 2. Pellets were produced by mixing PLA and calcium carbonate in various ratios. To improve the uniformity of the physical mixture, the initially mixed materials were re-extruded to produce secondary mixed pellets. LV-SEM experiment results showed that as the calcium carbonate content increased, the surface of the specimens became smoother and brighter, but the mixing uniformity was not confirmed. The tensile test results indicated that as the calcium carbonate content increased, the maximum tensile strength of the specimens decreased, the modulus of elasticity increased, the yield strength decreased, the fracture strength decreased, and the elongation decreased. This indicates that calcium carbonate increases the brittleness of the material. 3. In the flame retardant test according to UL-94 HB standards, the twice-mixed specimens showed superior flame retardant performance compared to the once-mixed specimens. Specifically, all specimens, except those with 15% calcium carbonate content in the twice-mixed test, self-extinguished within 30 seconds. The twice-mixed specimens burned more slowly than the specified combustion rate at all mixing ratios, confirming their flame retardancy. This demonstrates that sufficient flame retardant performance can be achieved through physical mixing. 4. The development of large composite structures and printing them with a large 3D printer confirmed precision within a maximum error of ± 1 mm. This indicates that stable quality can be maintained even when printing large structures. 5. The system developed in this study successfully printed eco-friendly flame retardant building materials using a mixture of PLA and calcium carbonate. Additionally, it was confirmed that various inorganic materials, such as oyster shells, peanut shells, and coffee grounds, can be mixed to be used as flame retardant materials. The potential for application to not only pellets but also liquid materials such as epoxy was confirmed, indicating that flame retardant properties can be imparted to a variety of materials. This study significantly increases the applicability of large-scale 3D printing of eco-friendly flame retardant materials in the construction field. Future research will focus on developing improved flame retardant materials by comparing and analyzing the performance differences between chemically mixed pellets and the existing physically mixed ones. Declarations ACKNOWLEDGEMENTS This research was supported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Education(2018R1A6A1A0302450922) Funding This research was supported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Education(2018R1A6A1A0302450922) Competing Interests The authors have no relevant financial or non-financial interests to disclose. Author Contributions All authors contributed to the conceptualization and design of the study. Minsu Jeong was in charge of design, production, and creation of the experimental environment. Guidance on the experiment progress and data analysis was provided by Jeong-woong Ha. Supervision, funding, manuscript writing, and editing were performed by corresponding author Jong-Gyu Park. All authors read and approved the final manuscript. References B. Setiawan, D. C. Permatasari, A. D. Sumari, T. Winarno, V. U. Audiana, A. M. Damayanti, HDPE plastic extruder design and control for 3D printing with plastic pellet feeding method. IOP Conference Series: Materials Science and Engineering 2021;1073 K. Schwarzinger, K. Schlacher, Temperature Management for a Model Predictive Controlled Extruder. Temperature Management for a Model Predictive Controlled Extruder 2022;55(20):115`120 Deodhar S, Shanmuganathan K, Fan Q, Wilkie CA, Costache MC, Dembsey NA, Patra PK. Calcium carbonate and ammonium polyphosphate‐based flame-retardant composition for polypropylene. J Appl Polym Sci 2011;120(3):1866-1873. Shah AUR, Prabhakar MN, Lee DW, Kim BS, Song JI. Development and characterization of oyster shell powder filled polypropylene composite. KSME Composites Research 2014;27(5):201-206. Chong MH, Chun BC, Chung Y-C, Cho BG. Fire-retardant plastic material from oyster-shell powder and recycled polyethylene. J Appl Polym Sci 2006;99(4):1583-1589. Prabhakar MN, Shah AUR, Rao KC, Song JI. Mechanical and thermal properties of epoxy composites reinforced with waste peanut shell powder as a bio-filler. Fibers Polym 2015;16:1119-1124. Vahabi H, Jouyandeh M, Parpaite T, Saeb MR, Ramakrishna S. Coffee wastes as sustainable flame-retardants for polymer materials. Coatings 2021;11(9):1021. Xiong Z, Zhang Y, Du X, Song P, Fang Z. Green and scalable fabrication of core–shell biobased flame-retardants for reducing flammability of polylactic acid. ACS Sustain Chem Eng 2019;7(9):8954-8963. Choi J, Jang I, Kwak P, John Y, Kwon HS, Lee KH. 3D printer combined tower-crane for making huge structures. In: Proceedings of the Society of CAD/CAM Conference. Pyeongchang-gun in Republic of korea. 2015, Feb . pp.923-925. Lee JW, Kim J-H. Extrusion nozzle design capable of infinite rotation for construction 3D printing systems. KSCE 2019 CONVENTION. Pyeongchang-gun in Republic of korea. 2019 Oct. pp.917-918. Choi JR, Choi SH, Shin JY, Hur NK. Numerical simulations for predicting the temperature profiles of a barrel and resin for an injection molding machine. KSME 2019. Vol.2019(11). pp.506-507. Bos F, Wolfs R, Ahmed Z, Salet T. Additive manufacturing of concrete in construction: potentials and challenges of 3D concrete printing. Virtual Phys Prototyp 2016;11(3):209-225. Choi DY, Ko YB, Kim CK, Cho SH, Ju SK. A study on contact dynamic characteristics of screw and barrels in injection molding machine. J Korean Soc Tribol Lubr Eng. 2000 Nov. pp.212-220. Cite Share Download PDF Status: Published Journal Publication published 20 Dec, 2024 Read the published version in The International Journal of Advanced Manufacturing Technology → Version 1 posted Reviewers agreed at journal 05 Jul, 2024 Reviewers invited by journal 05 Jul, 2024 Editor assigned by journal 05 Jul, 2024 First submitted to journal 03 Jul, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4652395","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":323015371,"identity":"76af527e-ca8a-404e-9fe9-f7dfc361302d","order_by":0,"name":"minsu Jung","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA/klEQVRIiWNgGAWjYFCCAwYMD4AUP39jw4EPQAYbOzFaEhgMGCRnHG48OAOkhZmwNRAtBg3pzYd5QHxCWgwOHt74IeHPnzwDhoMNh21+bZPnY2Zg/PAxB4+WA8eKJRLbDIrNmRsbDuf23TZsY2Zglpy5DbcWswNnDCQSGwwSdzYAbcntuc0I1MLGzItfi/GPhD8GiRsOJDYctuy5bU+MFjOJBDaoFoYftxMJarE/cKzMIrHNOHHmjIMNB3sbbie3MTM24/ULMDo23/jwRy6xn7/98Ycff27bzm9vPvjhIx4tDBIHkDiMbWCyAY96IOBHkf+DX/EoGAWjYBSMTAAAosthkQk4hGEAAAAASUVORK5CYII=","orcid":"https://orcid.org/0009-0007-2435-2464","institution":"Changwon National University","correspondingAuthor":true,"prefix":"","firstName":"minsu","middleName":"","lastName":"Jung","suffix":""},{"id":323015372,"identity":"1e7d7187-ae1b-4725-b458-7d565d18eb7a","order_by":1,"name":"Jeong-Ung Ha","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Jeong-Ung","middleName":"","lastName":"Ha","suffix":""},{"id":323015373,"identity":"9d042cfa-fb97-4475-a4dd-3689b9f2c0d0","order_by":2,"name":"Jong-kyu Park","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Jong-kyu","middleName":"","lastName":"Park","suffix":""}],"badges":[],"createdAt":"2024-06-28 06:09:42","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4652395/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4652395/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s00170-024-14931-8","type":"published","date":"2024-12-20T15:57:23+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":61303757,"identity":"6c8a8966-178e-4c9e-9f7f-17bed8f70618","added_by":"auto","created_at":"2024-07-29 09:32:30","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":91644,"visible":true,"origin":"","legend":"\u003cp\u003eTotal assembly shape\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-4652395/v1/daef8259928c590a0d03dc6c.png"},{"id":61303737,"identity":"b720c249-5f5d-45ea-80a6-bb93cd969651","added_by":"auto","created_at":"2024-07-29 09:32:28","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":110767,"visible":true,"origin":"","legend":"\u003cp\u003eFeatures of plastic injection screw\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-4652395/v1/489cf1562ca3b7f5383bdbca.png"},{"id":61304846,"identity":"fd8e1b61-4e08-484d-b0b9-8ef7dc43f986","added_by":"auto","created_at":"2024-07-29 09:48:29","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":383795,"visible":true,"origin":"","legend":"\u003cp\u003eEquipped with mixing screw motor and cooling fan to secure material supply stability\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-4652395/v1/3cbb4d8d14bef7a8a0b13a95.png"},{"id":61303735,"identity":"484b4001-64c9-4c7f-85a6-ac1a5cddbe10","added_by":"auto","created_at":"2024-07-29 09:32:28","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":101496,"visible":true,"origin":"","legend":"\u003cp\u003eBoundary conditions of structural analysis\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-4652395/v1/5c81654bc7f8f35ba546a358.png"},{"id":61303736,"identity":"480ed264-8369-4150-818e-46d11767f60b","added_by":"auto","created_at":"2024-07-29 09:32:28","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":166956,"visible":true,"origin":"","legend":"\u003cp\u003eStructural analysis result (Maximum stress, Displacement)\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-4652395/v1/5c8b471d8d438d395dc99b8e.png"},{"id":61303741,"identity":"ae61ca83-fc13-4ecc-9afa-17f86f6b4b8f","added_by":"auto","created_at":"2024-07-29 09:32:29","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":121371,"visible":true,"origin":"","legend":"\u003cp\u003eAuger Bit and Injection Screw FSI Analysis Conditions\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-4652395/v1/e909b4fed1857d745caafce7.png"},{"id":61304845,"identity":"032fa33f-4372-4f7c-9f17-a31ef7a9c1b3","added_by":"auto","created_at":"2024-07-29 09:48:28","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":80144,"visible":true,"origin":"","legend":"\u003cp\u003eAuger bit and injection screw FSI analysis results\u003c/p\u003e","description":"","filename":"floatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-4652395/v1/c132c121f74ac1933d1daaec.png"},{"id":61303756,"identity":"d95e252b-0ecc-46b9-80c6-aa18db546cf0","added_by":"auto","created_at":"2024-07-29 09:32:29","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":513917,"visible":true,"origin":"","legend":"\u003cp\u003eControl part and circuit configuration\u003c/p\u003e","description":"","filename":"floatimage8.png","url":"https://assets-eu.researchsquare.com/files/rs-4652395/v1/f68b50ca26e8a860f2f251f4.png"},{"id":61304849,"identity":"cff4ba86-59b0-48ff-a123-35c3cca1227e","added_by":"auto","created_at":"2024-07-29 09:48:29","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":387862,"visible":true,"origin":"","legend":"\u003cp\u003eIntegrated control system design\u003c/p\u003e","description":"","filename":"floatimage9.png","url":"https://assets-eu.researchsquare.com/files/rs-4652395/v1/02c8672d7eb8387c79222d3a.png"},{"id":61304180,"identity":"9b9a4eef-8c9f-4618-a2d5-e6ab01414e3c","added_by":"auto","created_at":"2024-07-29 09:40:29","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":391852,"visible":true,"origin":"","legend":"\u003cp\u003ePellet extrusion test\u003c/p\u003e","description":"","filename":"floatimage10.png","url":"https://assets-eu.researchsquare.com/files/rs-4652395/v1/ab34c2c42bc21b90a8db5f17.png"},{"id":61303738,"identity":"d85279c3-9c1a-41ae-b5f8-377a7c074928","added_by":"auto","created_at":"2024-07-29 09:32:28","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":303623,"visible":true,"origin":"","legend":"\u003cp\u003eAssembly of system\u003c/p\u003e","description":"","filename":"floatimage11.png","url":"https://assets-eu.researchsquare.com/files/rs-4652395/v1/7a65899954b30e34605a2777.png"},{"id":61303745,"identity":"57dcf604-2943-4434-85c7-8cac1b993617","added_by":"auto","created_at":"2024-07-29 09:32:29","extension":"png","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":210468,"visible":true,"origin":"","legend":"\u003cp\u003ePellet production\u003c/p\u003e","description":"","filename":"floatimage12.png","url":"https://assets-eu.researchsquare.com/files/rs-4652395/v1/7bbda6a0b5d267301b3b22ea.png"},{"id":61304179,"identity":"2710de48-cb53-4aab-9b1b-9627c151b6c7","added_by":"auto","created_at":"2024-07-29 09:40:29","extension":"png","order_by":13,"title":"Figure 13","display":"","copyAsset":false,"role":"figure","size":252262,"visible":true,"origin":"","legend":"\u003cp\u003eLV-SEM machine and specimens\u003c/p\u003e","description":"","filename":"floatimage13.png","url":"https://assets-eu.researchsquare.com/files/rs-4652395/v1/8a6d09095a8512292cd47cef.png"},{"id":61304848,"identity":"10a8e63a-17a4-4609-bcd9-bfa515e00158","added_by":"auto","created_at":"2024-07-29 09:48:29","extension":"png","order_by":14,"title":"Figure 14","display":"","copyAsset":false,"role":"figure","size":208011,"visible":true,"origin":"","legend":"\u003cp\u003ePhotograph taken by magnification of specimens\u003c/p\u003e","description":"","filename":"floatimage14.png","url":"https://assets-eu.researchsquare.com/files/rs-4652395/v1/466698280d08156b772d479a.png"},{"id":61305395,"identity":"9abb5083-dcb5-4840-9a3d-d7aae0230c2e","added_by":"auto","created_at":"2024-07-29 09:56:29","extension":"png","order_by":15,"title":"Figure 15","display":"","copyAsset":false,"role":"figure","size":187518,"visible":true,"origin":"","legend":"\u003cp\u003eSwollen surface of 10% specimen and EDS analysis result\u003c/p\u003e","description":"","filename":"floatimage15.png","url":"https://assets-eu.researchsquare.com/files/rs-4652395/v1/d241cb08ff3bc00b83c2bdc5.png"},{"id":61304183,"identity":"feaa400d-931d-4560-9cca-032c5dc5d93b","added_by":"auto","created_at":"2024-07-29 09:40:29","extension":"png","order_by":16,"title":"Figure 16","display":"","copyAsset":false,"role":"figure","size":186185,"visible":true,"origin":"","legend":"\u003cp\u003eInital printing condition and result of ASTM D638 specimen\u003c/p\u003e","description":"","filename":"floatimage16.png","url":"https://assets-eu.researchsquare.com/files/rs-4652395/v1/4cc797125e9034e10a1054da.png"},{"id":61303750,"identity":"dc20e0f6-3a70-466e-a8a3-f4634c585b60","added_by":"auto","created_at":"2024-07-29 09:32:29","extension":"png","order_by":17,"title":"Figure 17","display":"","copyAsset":false,"role":"figure","size":384660,"visible":true,"origin":"","legend":"\u003cp\u003eConfiguration of universal testing machine\u003c/p\u003e","description":"","filename":"floatimage17.png","url":"https://assets-eu.researchsquare.com/files/rs-4652395/v1/6461728f8c5ee4cadd8240dd.png"},{"id":61304174,"identity":"8f9c0185-0615-4784-99f5-e6344741ee0a","added_by":"auto","created_at":"2024-07-29 09:40:28","extension":"png","order_by":18,"title":"Figure 18","display":"","copyAsset":false,"role":"figure","size":37434,"visible":true,"origin":"","legend":"\u003cp\u003eResult of Tensile test\u003c/p\u003e","description":"","filename":"floatimage18.png","url":"https://assets-eu.researchsquare.com/files/rs-4652395/v1/4596e108041f61766c1bbb87.png"},{"id":61303753,"identity":"7865348c-af19-44e2-a3d9-0b38405c2ccd","added_by":"auto","created_at":"2024-07-29 09:32:29","extension":"png","order_by":19,"title":"Figure 19","display":"","copyAsset":false,"role":"figure","size":319140,"visible":true,"origin":"","legend":"\u003cp\u003eConfiguration of UL-94 horizontal burning test\u003c/p\u003e","description":"","filename":"floatimage19.png","url":"https://assets-eu.researchsquare.com/files/rs-4652395/v1/8c3d719646b78dde32f288d4.png"},{"id":61303754,"identity":"4cbe4968-c740-460c-a569-6d2092700370","added_by":"auto","created_at":"2024-07-29 09:32:29","extension":"png","order_by":20,"title":"Figure 20","display":"","copyAsset":false,"role":"figure","size":253269,"visible":true,"origin":"","legend":"\u003cp\u003eBurning test of pure PLA and once mixed specimens\u003c/p\u003e","description":"","filename":"floatimage20.png","url":"https://assets-eu.researchsquare.com/files/rs-4652395/v1/c6ba031446c31ea3b51e7d96.png"},{"id":61303758,"identity":"e2dd0074-fe8f-4ad1-84ac-528e55365a15","added_by":"auto","created_at":"2024-07-29 09:32:30","extension":"png","order_by":21,"title":"Figure 21","display":"","copyAsset":false,"role":"figure","size":210667,"visible":true,"origin":"","legend":"\u003cp\u003eBurning test of twice mixed specimens\u003c/p\u003e","description":"","filename":"floatimage21.png","url":"https://assets-eu.researchsquare.com/files/rs-4652395/v1/8cb1406a14ef0ee30301464b.png"},{"id":61304175,"identity":"c0b19051-e659-445b-959b-a3e74bd96914","added_by":"auto","created_at":"2024-07-29 09:40:29","extension":"png","order_by":22,"title":"Figure 22","display":"","copyAsset":false,"role":"figure","size":76238,"visible":true,"origin":"","legend":"\u003cp\u003eDetermination of proper mixing ratio according by test results\u003c/p\u003e","description":"","filename":"floatimage22.png","url":"https://assets-eu.researchsquare.com/files/rs-4652395/v1/49c7656f680367acdc0e2e2e.png"},{"id":61304850,"identity":"593dd0ea-58d0-4f87-ba4c-622ccf44e868","added_by":"auto","created_at":"2024-07-29 09:48:29","extension":"png","order_by":23,"title":"Figure 23","display":"","copyAsset":false,"role":"figure","size":96972,"visible":true,"origin":"","legend":"\u003cp\u003eDetermination of proper mixing ratio according by test results\u003c/p\u003e","description":"","filename":"floatimage23.png","url":"https://assets-eu.researchsquare.com/files/rs-4652395/v1/cbdb2541d6d303da47a71197.png"},{"id":61303748,"identity":"52e4fe09-c765-4cc5-ab37-c7e27e840304","added_by":"auto","created_at":"2024-07-29 09:32:29","extension":"png","order_by":24,"title":"Figure 24","display":"","copyAsset":false,"role":"figure","size":531021,"visible":true,"origin":"","legend":"\u003cp\u003eDetermination of proper mixing ratio according by test results\u003c/p\u003e","description":"","filename":"floatimage24.png","url":"https://assets-eu.researchsquare.com/files/rs-4652395/v1/4dba12013a6944486bfbb519.png"},{"id":72201743,"identity":"e68663b0-e4d4-4bc5-ad5d-d2f3159d650f","added_by":"auto","created_at":"2024-12-23 16:10:27","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":6343978,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4652395/v1/4511dd8a-cb02-45ca-ab0d-94b6f9ae4e92.pdf"}],"financialInterests":"","formattedTitle":"Development of a Pellet Extruder for Blending Different Materials and Study on the Properties of Eco-friendly Flame Retardant Materials Printed Using a Large-scale 3D Printer","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eAs the need for eco-friendly building materials continues to rise in modern society, there is an increasing demand for construction materials to transition to environmentally friendly and recyclable materials in line with the growing interest in sustainable development and environmental protection. Particularly, the development of fire-retardant materials with enhanced fire safety is a critical factor in ensuring the safety of buildings. These fire-retardant materials help minimize damage in the event of a fire, protecting both lives and property.\u003c/p\u003e \u003cp\u003eHowever, existing 3D printing technology primarily uses single materials for printing, making it challenging to print materials with complex functionalities. This results in difficulties in ensuring stability when printing large structures, as the output stability of large 3D printers is low, and sagging of the axis can reduce the quality of the prints. In the development of fire-retardant materials, there has been insufficient research on achieving adequate fire-retardant performance and on deriving optimal performance through the use of various mixed ratios.[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eIn this study, we aim to develop a pellet extruder capable of blending different materials and use it to print eco-friendly fire-retardant materials with a large 3D printer, evaluating their characteristics. Unlike traditional 3D printing technology, which primarily uses single materials, this study aims to mix materials with different properties to impart new functionalities. This approach aims to meet the diverse requirements for building materials and achieve safer and more efficient buildings.\u003c/p\u003e \u003cp\u003eUsing large 3D printers to print building materials offers significant advantages in terms of time and cost. In particular, it simplifies the process and reduces production time by allowing complex-shaped structures to be manufactured in a single, integrated process. To maximize these technical advantages, it is essential to ensure the output stability of large 3D printers and the physical properties of the materials.[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eIn this study, we verified the deflection of the axis due to the weight of the pellet extruder through structural analysis to ensure the output stability of large 3D printers. This enabled stable printing even on large beds. Additionally, to quickly collect initial mixing ratio settings and temperature data, we developed a pellet extruder capable of blending different materials and used it to print test specimens.[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eTo evaluate the fire-retardant performance and mechanical properties of the printed fire-retardant materials, we produced PLA specimens mixed with calcium carbonate in various ratios from 5\u0026ndash;20%. We conducted fire-retardant performance tests according to the UL-94 standard and tensile tests. The results showed that the fire-retardant performance improved with the increase in calcium carbonate content, allowing us to derive the optimal mixing ratio. Finally, to confirm the output stability of the extruder and the large 3D printer, we printed a honeycomb composite structure for 1 hour and 30 minutes. The continuous printing was successful, with a maximum deviation of 1mm.\u003c/p\u003e \u003cp\u003eThe study results confirm that the proposed development systems satisfy both the stable output of large composite structures and excellent fire-retardant performance. This demonstrates the potential for their use in printing eco-friendly building materials and suggests a broad range of applications in the construction field in the future.[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eThe pellet extruder and large 3D printer developed in this study significantly enhance the functionality of building materials by enabling the mixed printing of various materials. The development of eco-friendly fire-retardant materials, in particular, is an innovative approach that simultaneously achieves the crucial goals of environmental protection and improved safety. We aim to continue enhancing the technology through ongoing research and development, thereby increasing its practicality and potential for commercialization.\u003c/p\u003e \u003cp\u003eThis paper details the development process and results of the heterogeneous material blending extrusion technology based on the background and necessity of the research. Through this, we aim to convey the importance and potential of this technology to the readers.\u003c/p\u003e"},{"header":"2. Research Objectives","content":"\u003cp\u003eThe research objectives of the pellet extruder 3D printer capable of blending different materials are as follows:\u003c/p\u003e \u003cp\u003eFirst, Ensuring the printing stability of a large 3D printer equipped with a pellet extruder. The main design factor for ensuring the printing stability of the 3D printer is verifying the deflection amount of the axis due to the weight of the pellet extruder.[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eSecond, Conducting flame-retardant performance and mechanical property tests on the printed flame-retardant material. PLA specimens mixed with calcium carbonate at various ratios from 5\u0026ndash;20% will be produced, and flame-retardant performance tests and tensile tests according to UL-94 standards will be conducted to verify the performance of the printed flame-retardant material.\u003c/p\u003e \u003cp\u003eLast, Establishing a system for printing large composite structures with flame-retardant materials. The use of desktop-sized 3D printers for printing flame-retardant interior/exterior materials requires splitting the object into parts, which increases time and cost, making it difficult to use. A 5mm nozzle will be applied to reduce the printing time of honeycomb composite structures, and the printing efficiency and error will be evaluated.\u003c/p\u003e"},{"header":"3. Design and Fabrication of a Large 3D Printer","content":"\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Design Considerations\u003c/h2\u003e \u003cp\u003eIn this paper, the proposed 3D printer employs a blending extrusion method, which differs from traditional filament-based 3D printers. Therefore, it is necessary to consider not only the structural sagging due to weight but also the extrusion characteristics of the extruder. Additionally, the design of the extruder must take into account factors such as the screw shape of the extruder, temperature control for material melting, control of bottlenecks occurring during material extrusion, and cooling devices to ensure material supply stability, all of which are crucial for output stability.[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eThe sagging of the extrusion unit is a primary consideration in the gantry structure, which is applied to most 3D printing methods. This sagging refers to the deformation amount of the frame to which the extrusion unit is attached. When both ends of the frame are fixed, the maximum deformation occurs at the middle of the frame, interacting with factors such as the nozzle size of the extrusion unit and the bed's levelness, leading to extrusion errors. Theoretically, the thickness of the extruded plastic resin should be uniform and adhere to the bed regardless of the direction in which the bed moves. However, if extrusion errors occur, variations in thickness and adhesion degree affect the overall quality. Therefore, it is necessary to verify the maximum sagging amount at each position of the extrusion unit through structural analysis in the design of 3D printers.[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e3.2 System Appearance and Extruder Design\u003c/h2\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAs shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, the design was advanced to enable output with a maximum size of 1000mm x 1000mm x 700mm, and the frame was made of aluminum square tubes with a size of 50mm x 50mm. The movement of each axis was controlled by a step motor, and for the Z axis, four motors were installed at each corner to distribute the load. The bed was designed to be 1200mm x 1200mm, 200mm larger than the maximum size that can be output, to prevent deviation in output. For the outer frame, it was designed to be 1600mm x 1600mm with 200mm intervals on the left and right.[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eFor the extrusion frame, a 40mm x 80mm aluminum profile was used to ensure torsion and part installation space, and two LM guides were installed to ensure drive straightness.\u003c/p\u003e \u003cp\u003eThe extrusion section can be roughly divided into a rotating section, extrusion screw, nozzle, etc., and a 35W DC motor with a 150:1 gearbox was used for extrusion to ensure a maximum torque of 450Nm, and the maximum rotation speed was 20rpm. The screw and motor are connected using a coupler, and a nozzle with a diameter of 5 mm is attached to enable the extrusion of a large amount of resin. The weight of the extrusion section is about 4.4 kgf, and a hopper is installed in the material input section so that the raw material can be supplied regularly.[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eIn the case of an extruder extrusion screw, shape design is important to ensure the material extrusion force. A single-axis screw extruder has low energy consumption, good quality, and stable operation. It also has low noise and a long life, making it suitable as an output screw for 3D printing work and small-lot production of a wide variety of products. In addition, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, the distance between the blades (lead) is constant, which is a characteristic of the plastic injection screw, so the volume decreases as you go to the metering section, pressure is generated in the material, the depth becomes narrower, and a gradient is formed, which is advantageous for material extrusion.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe melting temperatures of different materials vary. If the temperature is set too high, the material may burn or undergo thermal decomposition, resulting in deformation and making it difficult to achieve the desired properties. If the temperature is too low, the material will not melt properly, leading to incomplete mixing, material clumping, or nozzle blockages, which can cause printer malfunction. To control this, individual temperature control devices were installed at both the barrel and nozzle sections. If heating devices are only installed at the nozzle tip, the material will be extruded without proper mixing. Conversely, if the system is only installed at the barrel section, the material will cool and block the nozzle during extrusion, so both sections were equipped with heating systems. This ensures that the material melts first in the barrel section and, through the rotation of the extruder, is mixed and then transported to the nozzle section for extrusion.[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eIn 3D printing, a bottleneck refers to the condition where the excessive supply of molten material prevents proper extrusion, causing the material to cool down due to the cooling fan and block the extruder, hindering proper extrusion. To prevent the molten material at the upper part of the nozzle from cooling and solidifying, a screw was additionally installed to rotate the molten material. This prevents the material from solidifying due to the cooling fan before extrusion, thus avoiding nozzle blockage and maintaining an appropriate temperature for stable extrusion onto the bed. The cooling fan at the front of the extruder is used to prevent layers from becoming messy when printing models with sharp ends, small products, or when the next layer is built while the previous layer hasn't properly solidified. Typically, the cooling fan of an FDM filament printer prevents heat from being transferred to the nozzle neck, but the cooling fan of the developed extruder lowers the temperature of the molten material at the top of the nozzle to a similar level as the nozzle temperature control, aiding in stable extrusion.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Structural Analysis\u003c/h2\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eProperties of Structural steel and Aluminum\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eElastic Modulus\u003c/p\u003e \u003cp\u003e(GPa)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDensity\u003c/p\u003e \u003cp\u003e(kg/㎥)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePoisson\u0026rsquo;s Ratio\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStructural Steel\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e210\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e7850\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.29\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAluminum\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2700\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eStructural analysis was conducted based on the designed extrusion frame and extruder shape. The structural analysis conditions, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, involved fixing both ends of the assembled extrusion frame and extruder. The deflection amount due to self-weight was checked with the extruder positioned on the left, center, and right. The materials were specified as structural steel and aluminum according to the design conditions, and their properties are shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e3\u003c/span\u003e. The analysis focused on the maximum deflection amount, considering the extruder positioned in the center of the frame. The analysis results, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e, indicated that the maximum stress and deflection amounts when the extruder was positioned on the left, center, and right were (101 MPa, 0.3 mm), (116 MPa, 0.489 mm), and (102 MPa, 0.299 mm), respectively. The maximum stress occurred at the extrusion frame joint and LM guide, but since the yield stress of structural steel and aluminum are 275 MPa and 170 MPa, respectively, it was deemed safe. Additionally, the deflection difference between the center and the left and right was found to be 0.18 mm, and since the height of one layer when using a 5 mm nozzle is 0.8 mm, it was considered safe as it does not exceed the layer height.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe pellet extruder system consists of a stepper motor, hopper, screw and barrel, and nozzle. To verify the design feasibility of the injection screw, FSI (Fluid-Structure Interaction) analysis was conducted. This analysis involves using a finite element approach to model the stress and deformation responses of the components to the pressure, temperature gradients, and specified boundary conditions of the surrounding fluid, indicating a fully coupled interaction between the fluid and the solid.\u003c/p\u003e \u003cp\u003eThe analysis conditions are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e, and the comparison was made between using the existing auger bit and the developed injection screw. The analysis results, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e, indicate that in the case of the auger bit, pressure does not occur in the transport section, resulting in only about 1.1 MPa of pressure at the outlet due to the nozzle shape. In contrast, with the injection screw, the pressure increases linearly towards the nozzle due to the gradient effect, and the pressure formed in the transport section is maintained to the nozzle chamber, resulting in a stable pressure of about 1.7 MPa at the nozzle tip.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e3.4 System Fabrication\u003c/h2\u003e \u003cp\u003eThe fabrication process is divided into the following stages: manufacturing the external frame and printing bed, attaching motors and components for operation, installing limit switches, and configuring the circuitry. For the external frame, aluminum square frames and joints were cut and machined to the required specifications and assembled to complete the external frame. Subsequently, power supplies connected to the MCU, stepper motors, motor drivers, and limit switches were installed.\u003c/p\u003e \u003cp\u003eThe proposed 3D printer system configuration, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e, utilizes a total of three axes: X, Y, and Z. Therefore, motor drivers and motors are needed to control each axis. The motor drivers controlling the motors are independently controlled for each axis. The external power supply uses a 24V power supply unit, but to supply power to seven motors simultaneously, individual power supplies were applied for each axis. For the Z-axis, the movement of four motors is synchronized, so two motors were connected to one motor driver.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFor the pellet extruder, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e, the initial 24V power supply is used to set the temperatures of Control 1 and Control 2 (barrel and nozzle sections) to the melting temperature of the mixed material. Then, to prevent the stepper motor of the extruder from stalling, the stepper motor of the mixing screw is activated, causing the entire system to operate. Each operating system can be turned on or off offline, and the system is configured to immediately stop in case of an error. Each temperature control unit can be set individually, and the extruder and the left screw also have separate speed controls, allowing for suitable screw speed adjustment depending on the situation, making it an ideal system for controlling various products.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe fabricated extruder consists of a controller and an extruder. The controller can control the motor power, temperature, and rotation speed. When power is supplied to the controller and the target temperature is set, the extruder starts heating. After adding pellets to the hopper and setting the rotation speed, the extrusion drill rotates and extrudes the pellets. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e, a driving test confirmed that the pellets were extruded as the extrusion drill rotated.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThrough final assembly, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e, a large 3D printer with dimensions of 1.6 \u0026times; 1.6 \u0026times; 1 m was produced. The assembly precision of each axis was checked using electronic measuring instruments, and it was confirmed that the maximum error was 0.3\u0026deg; for the X and Y axes, and \u0026plusmn;\u0026thinsp;1 mm for the Z axis. This ensures a manufacturing precision with a maximum error of 5 mm for a print size of 1 m.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"4. Printing and Flame Retardant Experiments","content":"\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e4.1 Production of Experimental Raw Materials\u003c/h2\u003e \u003cp\u003eTo achieve consistent flame retardancy performance, it is necessary to secure uniformly mixed raw materials. In this study, the aim is to produce and print flame retardant materials through mechanical mixing. To optimize the material ratios, the flame retardant was mixed with PLA by mass ratio to verify the characteristics of the specimens. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e12\u003c/span\u003e, PLA and calcium carbonate were mixed in initial ratios of 5%, 10%, 15%, and 20% based on a total mass of 100%.[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eSince the first mixture of PLA and calcium carbonate is in a mixed state, it was fed into a pellet production machine consisting of an extruder and a pelletizer to produce pellets. The produced pellets were re-fed into the pellet production machine to produce second mixed pellets. This process was repeated to produce pellets with calcium carbonate mixed at 5\u0026ndash;20% ratios, and the extrusion characteristics of the pellets mixed once and twice were verified.\u003c/p\u003e \u003cp\u003eIn the case of the 20% calcium carbonate in the twice-mixed specimen, the ductility of the plastic decreased, and brittleness increased, making specimen production impossible. Therefore, raw materials were produced at 5\u0026ndash;20% for single mixing and 5\u0026ndash;15% for double mixing.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e4.2 LV-SEM Experiment Results\u003c/h2\u003e \u003cp\u003eThe LV-SEM experiment was conducted to verify whether calcium carbonate and PLA were uniformly mixed during the production of raw materials for testing. The experiment environment is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig13\" class=\"InternalRef\"\u003e13\u003c/span\u003e, and cubic specimens with an edge length of 1 cm were used. Since the specimens were composed of insulating PLA and calcium carbonate, making it difficult to observe the surface, the surface of the specimens was coated with a conductive paint. Each coated specimen was photographed at magnifications of 500x, 1000x, 2000x, and 3000x to verify the surface characteristics for each ratio.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAs shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig14\" class=\"InternalRef\"\u003e14\u003c/span\u003e, the surface of the specimens was observed to become brighter and the surface protrusions decreased as the ratio of calcium carbonate increased from 5\u0026ndash;20%. Due to the characteristics of LV-SEM, it was not possible to distinguish between PLA and calcium carbonate since the images were only in black and white.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eEDS (Energy Dispersive X-ray Spectroscopy) analysis was used to verify the distribution of calcium on the surface. However, due to the high voltage, the surface of the specimen showed bubbling phenomena, as seen in Fig.\u0026nbsp;\u003cspan refid=\"Fig15\" class=\"InternalRef\"\u003e15\u003c/span\u003e, making it impossible to confirm the internal mixing uniformity of the specimen.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e4.3 Tensile Test Results\u003c/h2\u003e \u003cp\u003eThe mechanical strength of the flame retardant materials was verified using the produced specimens. The tensile test specimens were prepared according to ASTM D-638 standards, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig16\" class=\"InternalRef\"\u003e16\u003c/span\u003e, and the tests were conducted using the MINOS-100 tensile tester shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig17\" class=\"InternalRef\"\u003e17\u003c/span\u003e. The specimens were made from raw materials mixed once at ratios of 5\u0026ndash;20%, and the tensile behavior during the test was observed using a DIC camera. Each specimen was subjected to tensile testing at a speed of 0.342 mm/min, and the load and tensile stress were measured at 0.1-second intervals.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe test results, shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig18\" class=\"InternalRef\"\u003e18\u003c/span\u003e, indicated that as the calcium carbonate ratio increased, the maximum tensile strength decreased, the modulus of elasticity increased, the yield strength decreased, the fracture strength decreased, and the elongation decreased. This demonstrates that the brittleness of the material increased due to the addition of calcium carbonate.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e4.4 Flame Retardant Test Results\u003c/h2\u003e \u003cp\u003eSince the goal of this study is to apply flame retardant materials to buildings, flame retardant testing of the produced materials is necessary. The flame retardant tests were conducted according to the UL-94 HB test environment standards, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig19\" class=\"InternalRef\"\u003e19\u003c/span\u003e. Specimens made from materials mixed once and twice were printed and finished through post-processing. Specimens mixed twice at 20% were excluded due to increased brittleness, making specimen processing impossible. Therefore, the experiment was conducted with three specimens each for single mixing at 5%, 10%, 15%, and 20% and for double mixing at 5%, 10%, and 15%, making a total of 21 specimens.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFor the combustion test of the single-mixed raw materials, specimens made only from pure PLA were also produced and tested, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig20\" class=\"InternalRef\"\u003e20\u003c/span\u003e. It was observed that the flames were larger and there was more dripping in the 100% PLA specimens compared to the specimens mixed with calcium carbonate. The specimens mixed with calcium carbonate showed a reduction in flame size and dripping, with some specimens self-extinguishing.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eIn the flame retardant test for the twice-mixed specimens, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig21\" class=\"InternalRef\"\u003e21\u003c/span\u003e, the self-extinguishing rate increased after combustion compared to the once-mixed specimens. Except for one specimen with a 15% ratio, all specimens self-extinguished within 30 seconds. This is summarized in Tables\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e4\u003c/span\u003e and \u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e5\u003c/span\u003e. The analysis of these results indicates that at least two mixing processes are necessary to achieve sufficient flame retardant performance in specimens produced through physical mixing.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eUL-94 HB test result of once mixed\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e35.85 mm/min\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e100 mm\u003c/p\u003e \u003cp\u003epoint Digestion\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e25 mm\u003c/p\u003e \u003cp\u003epoint Digestion\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e10%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e29.15 mm/min\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e33.57 mm/min\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e25 mm\u003c/p\u003e \u003cp\u003epoint Digestion\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e15%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e35.32 mm/min\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e37.76 mm/min\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e27.6 mm/min\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e20%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e50 mm\u003c/p\u003e \u003cp\u003epoint Digestion\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e38.77 mm/min\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e39.62 mm/min\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eUL-94 HB test result of twice mixed\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eIn 30sec\u003c/p\u003e \u003cp\u003eDigestion\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eIn 30sec\u003c/p\u003e \u003cp\u003eDigestion\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eIn 30sec\u003c/p\u003e \u003cp\u003eDigestion\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e10%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eIn 30sec\u003c/p\u003e \u003cp\u003eDigestion\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e25 mm\u003c/p\u003e \u003cp\u003epoint Digestion\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e25 mm\u003c/p\u003e \u003cp\u003epoint Digestion\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e15%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e28.02 mm/min\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eIn 30sec\u003c/p\u003e \u003cp\u003eDigestion\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eIn 30sec\u003c/p\u003e \u003cp\u003eDigestion\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e4.5 Determination of Mixing Ratio\u003c/h2\u003e \u003cp\u003eBy analyzing the results of the mechanical and flame retardant tests conducted in this study, the appropriate mixing ratio of PLA and calcium carbonate that can be applied to building materials was derived, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig22\" class=\"InternalRef\"\u003e22\u003c/span\u003e. The tensile test indicated that as the calcium carbonate ratio increased to 20%, brittleness increased, making the material more prone to breaking rather than deforming like regular plastic. These characteristics are unsuitable not only for construction but also for environments where vibrations may occur. The analysis of the flame retardant test results showed that, unlike the once-mixed test, the flame retardant performance improved in all specimens with double mixing. When examining the ratios of calcium carbonate, it was found that increasing the calcium carbonate content did not significantly change the flame retardant performance. Considering raw material costs, elasticity changes, and ensuring flame retardancy, a ratio of approximately 5% calcium carbonate mixed with PLA is deemed appropriate.[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003e4.6 Printing of Composite Structures\u003c/h2\u003e \u003cp\u003eThe printing of composite structures was carried out to verify the possibility of printing complex-shaped structures using mixed materials. This process was not only to confirm the stability of the printed material but also to check the printing error of complex building structures. To generate the prints, G-code was created as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig23\" class=\"InternalRef\"\u003e23\u003c/span\u003e, and the printing conditions were set the same as those for the tensile test specimens. It was confirmed that the printing was stable for both small specimens and large, complex structures. The results of the printing, shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig24\" class=\"InternalRef\"\u003e24\u003c/span\u003e, indicate that continuous printing was conducted for about 1 hour and 30 minutes without any stoppages or nozzle blockages. The maximum error was within approximately 1 mm.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"5. Conclusion","content":"\u003cp\u003eIn this study, a pellet extruder capable of blending different materials was developed, and a system was designed and fabricated to print eco-friendly flame retardant materials using a large 3D printer. Various experiments were conducted to collect and analyze data to examine the applicability of this system in the construction field. The main conclusions are as follows:\u003c/p\u003e\n\u003cp\u003e\u003cspan\u003e1. To solve the problem of structural deflection caused by the weight of the pellet extruder, it was verified through multiphysics analysis. By using aluminum profiles (40 mm \u0026times; 80 mm), the deflection was reduced compared to conventional square pipes, and it was confirmed that the maximum deflection did not exceed the layer height. The developed 3D printer adopted a gantry system to enhance the stability of the extruder\u0026apos;s transport and used linear motion guides to ensure precision.\u003cbr\u003e\u003c/span\u003e\u003cspan\u003e2. Pellets were produced by mixing PLA and calcium carbonate in various ratios. To improve the uniformity of the physical mixture, the initially mixed materials were re-extruded to produce secondary mixed pellets. LV-SEM experiment results showed that as the calcium carbonate content increased, the surface of the specimens became smoother and brighter, but the mixing uniformity was not confirmed. The tensile test results indicated that as the calcium carbonate content increased, the maximum tensile strength of the specimens decreased, the modulus of elasticity increased, the yield strength decreased, the fracture strength decreased, and the elongation decreased. This indicates that calcium carbonate increases the brittleness of the material.\u003cbr\u003e\u003c/span\u003e\u003cspan\u003e3. In the flame retardant test according to UL-94 HB standards, the twice-mixed specimens showed superior flame retardant performance compared to the once-mixed specimens. Specifically, all specimens, except those with 15% calcium carbonate content in the twice-mixed test, self-extinguished within 30 seconds. The twice-mixed specimens burned more slowly than the specified combustion rate at all mixing ratios, confirming their flame retardancy. This demonstrates that sufficient flame retardant performance can be achieved through physical mixing.\u003cbr\u003e\u003c/span\u003e\u003cspan\u003e4. The development of large composite structures and printing them with a large 3D printer confirmed precision within a maximum error of \u0026plusmn;\u0026thinsp;1 mm. This indicates that stable quality can be maintained even when printing large structures.\u003cbr\u003e\u003c/span\u003e\u003cspan\u003e5. The system developed in this study successfully printed eco-friendly flame retardant building materials using a mixture of PLA and calcium carbonate. Additionally, it was confirmed that various inorganic materials, such as oyster shells, peanut shells, and coffee grounds, can be mixed to be used as flame retardant materials. The potential for application to not only pellets but also liquid materials such as epoxy was confirmed, indicating that flame retardant properties can be imparted to a variety of materials.\u003cbr\u003e\u003c/span\u003e\u003c/p\u003e\n\u003cp\u003eThis study significantly increases the applicability of large-scale 3D printing of eco-friendly flame retardant materials in the construction field. Future research will focus on developing improved flame retardant materials by comparing and analyzing the performance differences between chemically mixed pellets and the existing physically mixed ones.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eACKNOWLEDGEMENTS\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;This research was supported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Education(2018R1A6A1A0302450922)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003eThis research was supported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Education(2018R1A6A1A0302450922)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eCompeting Interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003eThe authors have no relevant financial or non-financial interests to disclose.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003eAll authors contributed to the conceptualization and design of the study. Minsu Jeong was in charge of design, production, and creation of the experimental environment. Guidance on the experiment progress and data analysis was provided by Jeong-woong Ha. Supervision, funding, manuscript writing, and editing were performed by corresponding author Jong-Gyu Park. All authors read and approved the final manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eB. Setiawan, D. C. Permatasari, A. D. Sumari, T. Winarno, V. U. Audiana, A. M. Damayanti, HDPE plastic extruder design and control for 3D printing with plastic pellet feeding method. IOP Conference Series: Materials Science and Engineering 2021;1073\u003c/li\u003e\n\u003cli\u003eK. Schwarzinger, K. Schlacher, Temperature Management for a Model Predictive Controlled Extruder. Temperature Management for a Model Predictive Controlled Extruder 2022;55(20):115`120\u003c/li\u003e\n\u003cli\u003eDeodhar S, Shanmuganathan K, Fan Q, Wilkie CA, Costache MC, Dembsey NA, Patra PK. Calcium carbonate and ammonium polyphosphate‐based flame-retardant composition for polypropylene. J Appl Polym Sci 2011;120(3):1866-1873.\u003c/li\u003e\n\u003cli\u003eShah AUR, Prabhakar MN, Lee DW, Kim BS, Song JI. Development and characterization of oyster shell powder filled polypropylene composite. KSME Composites Research 2014;27(5):201-206.\u003c/li\u003e\n\u003cli\u003eChong MH, Chun BC, Chung Y-C, Cho BG. Fire-retardant plastic material from oyster-shell powder and recycled polyethylene. J Appl Polym Sci 2006;99(4):1583-1589.\u003c/li\u003e\n\u003cli\u003ePrabhakar MN, Shah AUR, Rao KC, Song JI. Mechanical and thermal properties of epoxy composites reinforced with waste peanut shell powder as a bio-filler. Fibers Polym 2015;16:1119-1124.\u003c/li\u003e\n\u003cli\u003eVahabi H, Jouyandeh M, Parpaite T, Saeb MR, Ramakrishna S. Coffee wastes as sustainable flame-retardants for polymer materials. Coatings 2021;11(9):1021.\u003c/li\u003e\n\u003cli\u003eXiong Z, Zhang Y, Du X, Song P, Fang Z. Green and scalable fabrication of core\u0026ndash;shell biobased flame-retardants for reducing flammability of polylactic acid. ACS Sustain Chem Eng 2019;7(9):8954-8963.\u003c/li\u003e\n\u003cli\u003eChoi J, Jang I, Kwak P, John Y, Kwon HS, Lee KH. 3D printer combined tower-crane for making huge structures. In: Proceedings of the Society of CAD/CAM Conference. Pyeongchang-gun in Republic of korea. 2015, Feb . pp.923-925.\u003c/li\u003e\n\u003cli\u003eLee JW, Kim J-H. Extrusion nozzle design capable of infinite rotation for construction 3D printing systems. KSCE 2019 CONVENTION. Pyeongchang-gun in Republic of korea. 2019 Oct. pp.917-918.\u003c/li\u003e\n\u003cli\u003eChoi JR, Choi SH, Shin JY, Hur NK. Numerical simulations for predicting the temperature profiles of a barrel and resin for an injection molding machine. KSME 2019. Vol.2019(11). pp.506-507.\u003c/li\u003e\n\u003cli\u003eBos F, Wolfs R, Ahmed Z, Salet T. Additive manufacturing of concrete in construction: potentials and challenges of 3D concrete printing. Virtual Phys Prototyp 2016;11(3):209-225.\u003c/li\u003e\n\u003cli\u003eChoi DY, Ko YB, Kim CK, Cho SH, Ju SK. A study on contact dynamic characteristics of screw and barrels in injection molding machine. J Korean Soc Tribol Lubr Eng. 2000 Nov. pp.212-220.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"the-international-journal-of-advanced-manufacturing-technology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jamt","sideBox":"Learn more about [The International Journal of Advanced Manufacturing Technology](https://www.springer.com/journal/170)","snPcode":"170","submissionUrl":"https://submission.nature.com/new-submission/170/3","title":"The International Journal of Advanced Manufacturing Technology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"3D Printer, Flame Retardant Meterial, Pellet Extruder, UL-94 HB, Mixed Material","lastPublishedDoi":"10.21203/rs.3.rs-4652395/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4652395/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"This study aims to design and fabricate a pellet extruder capable of blending different materials for the application of flame-retardant building materials in 3D printing and to evaluate the properties of eco-friendly flame-retardant materials printed using a large-scale 3D printer. The main content of the research is as follows: To ensure the printing stability of the large 3D printer, the deflection amount of the axis due to the weight of the pellet extruder was verified through structural analysis. This made it possible to achieve stable printing even on a large bed (1000mm x 1000mm). Next, a pellet extruder capable of blending different materials was developed to quickly collect initial mixing ratios and temperature data, and specimen printing was conducted using this extruder. The flame-retardant performance and mechanical properties of the printed flame-retardant material were evaluated, and PLA specimens mixed with calcium carbonate at various ratios from 5% to 20% were produced to conduct flame-retardant performance tests and tensile tests according to UL-94 standards. As a result, it was found that the flame-retardant performance improved as the calcium carbonate content increased, and the optimal mixing ratio was derived. Finally, to verify the printing stability of the extruder and large 3D printer, a honeycomb composite structure was printed continuously for 1 hour and 30 minutes, and it was confirmed that continuous printing was possible with a maximum error of 1mm. The proposed development systems satisfy both stable printing of large composite structures and excellent flame-retardant performance, confirming the potential for use as eco-friendly building material prints.","manuscriptTitle":"Development of a Pellet Extruder for Blending Different Materials and Study on the Properties of Eco-friendly Flame Retardant Materials Printed Using a Large-scale 3D Printer","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-07-29 09:32:24","doi":"10.21203/rs.3.rs-4652395/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2024-07-06T01:03:40+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-07-05T07:20:11+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-07-05T04:04:50+00:00","index":"","fulltext":""},{"type":"submitted","content":"The International Journal of Advanced Manufacturing Technology","date":"2024-07-04T01:23:57+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"the-international-journal-of-advanced-manufacturing-technology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jamt","sideBox":"Learn more about [The International Journal of Advanced Manufacturing Technology](https://www.springer.com/journal/170)","snPcode":"170","submissionUrl":"https://submission.nature.com/new-submission/170/3","title":"The International Journal of Advanced Manufacturing Technology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"2af22528-0701-4df0-b47b-49b1af6811ea","owner":[],"postedDate":"July 29th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-12-23T16:01:07+00:00","versionOfRecord":{"articleIdentity":"rs-4652395","link":"https://doi.org/10.1007/s00170-024-14931-8","journal":{"identity":"the-international-journal-of-advanced-manufacturing-technology","isVorOnly":false,"title":"The International Journal of Advanced Manufacturing Technology"},"publishedOn":"2024-12-20 15:57:23","publishedOnDateReadable":"December 20th, 2024"},"versionCreatedAt":"2024-07-29 09:32:24","video":"","vorDoi":"10.1007/s00170-024-14931-8","vorDoiUrl":"https://doi.org/10.1007/s00170-024-14931-8","workflowStages":[]},"version":"v1","identity":"rs-4652395","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4652395","identity":"rs-4652395","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}