Investigation of process-structure-property relationships in polymer extrusion based additive manufacturing through in situ high speed imaging and thermal conductivity measurements

Ravoori, Darshan; Alba, Lorenzo; Prajapati, Hardikkumar; Jain, Ankur

doi:10.1016/j.addma.2018.07.011

Cited by 25 publications

(17 citation statements)

References 24 publications

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“…Despite it being difficult to make a real comparison with κ data reported for distinct 3D printed materials, namely metals and polymers, due to the multitude of printing variables affecting their structuring features as well as the different thermal conductivity measurement methods, data approximate the exponential Equation (1) when identifying the π macro (present work) to the void fraction, which is the parameter commonly used in fused deposition modeling (FDM). Most of the data included in Figure 7d correspond to materials fabricated by FDM using metal and polymer filaments (empty symbols in Figure 7d), and methods used for measuring the thermal conductivity varied between the TPS [44] for which the average κ (calculated as √κ x κ z from the reported data) was represented, and the heat flow meter [45,46] and the guarded hot-plate, [47] both providing values of κ z . On the other hand, data for 3D ceramic scaffolds manufactured by robocasting (full symbols in Figure 7d) were estimated from high resolution infrared thermography.…”

Section: Resultsmentioning

confidence: 99%

Enhanced Thermal and Mechanical Properties of 3D Printed Highly Porous Structures Based on γ‐Al₂O₃ by Adding Graphene Nanoplatelets

Moreno‐Sanabria

Ramírez

Osendi

et al. 2022

Adv Materials Technologies

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logically active materials and, recently, in other emerging applications like flame retardants for polymers, quasi-solid electrolytes, or antimicrobial agents. [3] In particular, macroporous alumina with hierarchical pore structure, high surface area, and narrow pore size distribution are highly desirable for heterogeneous catalysts, as for example, hydrotreating catalysts used for heavy oils. [6][7][8] In this way, the catalytic performance can be enhanced through the development of suitable macrostructures of the catalysts, which depends on the support, reducing the mass transfer resistance, improving the reaction efficiency and increasing the lifetime of the catalysts. In this context, the additive manufacturing (AM) techniques allow developing highly hierarchical 3D structures that include channels of controlled size and shape in the millimeter scale, while porosity at meso-and micro-scales within the struts can be tailored using different strategies. Direct ink writing (DIW), an AM technology, allows building customized porous scaffolds with precise intricate geometries of a wide range of materials by computer controlling the scaffold parameters and adjusting the ink properties. DIW presents some drawbacks as compared to other AM technologies employed for porous ceramic scaffolds, such as stereolithography, in particular, poor surface quality of the 3D printed structures, which can be greatly improved by using smaller nozzle diameters, and, especially, the limitation to directly produce scaffolds with spanning, overhanging, and floating features that would require employing sacrificial supporting materials. [9][10][11] Main concerns for the application of the 3D printed macroporous γ-Al 2 O 3 structures are its reduced mechanical resistance that may restrain their possible applications, and its limited heat transfer capability associated to the high porosity, which is particularly important in the case of 3D printed porous materials with applications in fields like catalysis, energy production and storage, and for thermal management as heat exchangers and heat sinks. [12][13][14][15][16][17][18][19][20] The incorporation of welldispersed graphene nanostructures, 2D carbon allotropes with outstanding electronic and physiochemical properties, [21] into the γ-Al 2 O 3 matrix can increase both the mechanical and the thermal performance of 3D printed γ-Al 2 O 3 structures [22] and One of the main challenges to widen the potential applications of 3D printed highly porous ceramic structures in catalysis, energy storage or thermal management resides in the improvement of both their mechanical resistance and thermal conductivity. To achieve these goals, highly hierarchical γ-alumina (γ-Al 2 O 3 ) scaffolds containing up to 18 vol% of graphene nanoplatelets (GNP), including channels of controlled size and shape in the millimeter scale and meso-porosity within the rods, are developed by robocasting from boehmite-based aqueous inks without other printing additives. These 3D structures exhibit high porosity (85%) and spe...

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Section: Resultsmentioning

confidence: 99%

Enhanced Thermal and Mechanical Properties of 3D Printed Highly Porous Structures Based on γ‐Al₂O₃ by Adding Graphene Nanoplatelets

Moreno‐Sanabria

Ramírez

Osendi

et al. 2022

Adv Materials Technologies

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“…This phenomenon reduces crystallization time and has a significant impact on the inter-strand bonding, thus affecting the mechanical strength of the print. Ravoori et al [2] performed thermal conductivity measurements of the extruded strand and used high-speed imaging techniques to observe microstructure of the build path. They observed that thermal conductivity increases with increasing infill percentage, layer height and decreasing extruder speed.…”

Section: Influence Of Inter-strand Bonding On Strengthmentioning

confidence: 99%

Implementation of viscosity and density models for improved numerical analysis of melt flow dynamics in the nozzle during extrusion-based additive manufacturing

et al. 2021

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Fused Filament Fabrication (FFF) is an Additive Manufacturing (AM) process that builds up a part via layer by layer deposition of polymeric material. The purpose of this study is to implement viscosity and density models for improving the assessment of melt flow behavior inside the nozzle during deposition. Numerical simulations are carried out for different combinations of important process parameters like extrusion velocity Ve, extrusion temperature Te, and filament material (Acrylonitrile Butadiene Styrene (ABS) and Polylactic Acid (PLA)). Cross-Williams–Landel–Ferry (Cross-WLF) viscosity and Pressure–Volume–Temperature (PVT) density models are incorporated to get realistic results. Distribution of printing parameters like pressure, temperature, velocity and viscosity inside the nozzle are observed at steady state and their relationship with the print quality is discussed. Effect of the PVT model on polymer deposition is illustrated by comparing it with deposition considering a constant density. Velocity profiles are obtained for the different cases considered and locations where the flow is fully developed, along the axial distance of the nozzle, are determined and termed as stable zones. A direct correlation between the position of the developed melt flow profile and printing quality is established and the best combination of printing parameters is proposed for ABS and PLA. Extended stable zones are obtained for the polymer melt in the nozzle at Ve = 60 mm/s, Te = 220 °C for ABS and Ve = 30 mm/s and Te = 195 °C for PLA and hence, these can be considered as the optimum values of the printing parameters.

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“…Quantitative predictions also rely on thorough materials characterization, including linear viscoelasticity, nucleation and crystal growth rates, as well as thermal properties, which remains non-trivial since the thermoplastic polymer properties for elevated temperature processing in MatEx are usually highly temperature dependent [107]. The Additive Manufacturing Benchmark (AM-Bench), focused primarily on MatEx and selective laser sintering, has been created as a platform for performing extensive in-situ and ex-situ to generate a huge repository of experimental data.…”

Section: Discussion and Future Directionsmentioning

confidence: 99%

Advances in modeling transport phenomena in material-extrusion additive manufacturing: Coupling momentum, heat, and mass transfer

2020

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Material-extrusion (MatEx) additive manufacturing involves layer-by-layer assembly of extruded material onto a printer bed and has found applications in rapid prototyping. Both material and machining limitations lead to poor mechanical properties of printed parts. Such problems may be addressed via an improved understanding of the complex transport processes and multiphysics associated with the MatEx process. Thereby, this review paper describes the current (last 5 years) state of the art modeling approaches based on momentum, heat and mass transfer that are employed in an effort to achieve this understanding. We describe how specific details regarding polymer chain orientation, viscoelastic behavior and crystallization are often neglected and demonstrate that there is a key need to couple the transport phenomena. Such a combined modeling approach can expand MatEx applicability to broader application space, thus we present prospective avenues to provide more comprehensive modeling and therefore new insights into enhancing MatEx performance.

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Investigation of process-structure-property relationships in polymer extrusion based additive manufacturing through in situ high speed imaging and thermal conductivity measurements

Cited by 25 publications

References 24 publications

Enhanced Thermal and Mechanical Properties of 3D Printed Highly Porous Structures Based on γ‐Al₂O₃ by Adding Graphene Nanoplatelets

Enhanced Thermal and Mechanical Properties of 3D Printed Highly Porous Structures Based on γ‐Al₂O₃ by Adding Graphene Nanoplatelets

Implementation of viscosity and density models for improved numerical analysis of melt flow dynamics in the nozzle during extrusion-based additive manufacturing

Advances in modeling transport phenomena in material-extrusion additive manufacturing: Coupling momentum, heat, and mass transfer

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Investigation of process-structure-property relationships in polymer extrusion based additive manufacturing through in situ high speed imaging and thermal conductivity measurements

Cited by 25 publications

References 24 publications

Enhanced Thermal and Mechanical Properties of 3D Printed Highly Porous Structures Based on γ‐Al2O3 by Adding Graphene Nanoplatelets

Enhanced Thermal and Mechanical Properties of 3D Printed Highly Porous Structures Based on γ‐Al2O3 by Adding Graphene Nanoplatelets

Implementation of viscosity and density models for improved numerical analysis of melt flow dynamics in the nozzle during extrusion-based additive manufacturing

Advances in modeling transport phenomena in material-extrusion additive manufacturing: Coupling momentum, heat, and mass transfer

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Product

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About

Enhanced Thermal and Mechanical Properties of 3D Printed Highly Porous Structures Based on γ‐Al₂O₃ by Adding Graphene Nanoplatelets

Enhanced Thermal and Mechanical Properties of 3D Printed Highly Porous Structures Based on γ‐Al₂O₃ by Adding Graphene Nanoplatelets