scholarly journals Numerical Simulation of a Core–Shell Polymer Strand in Material Extrusion Additive Manufacturing

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 476
Author(s):  
Hamid Narei ◽  
Maryam Fatehifar ◽  
Ashley Howard Malt ◽  
John Bissell ◽  
Mohammad Souri ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Velocity Ratio ◽  
Diameter Ratio ◽  
Core Material ◽  
Operating Parameters ◽  
Core Shell ◽  
Material Extrusion ◽  
The Core ◽  
3D Printed ◽  
Core Polymer

Material extrusion additive manufacturing (ME-AM) techniques have been recently introduced for core–shell polymer manufacturing. Using ME-AM for core–shell manufacturing offers improved mechanical properties and dimensional accuracy over conventional 3D-printed polymer. Operating parameters play an important role in forming the overall quality of the 3D-printed manufactured products. Here we use numerical simulations within the framework of computation fluid dynamics (CFD) to identify the best combination of operating parameters for the 3D printing of a core–shell polymer strand. The objectives of these CFD simulations are to find strands with an ultimate volume fraction of core polymer. At the same time, complete encapsulations are obtained for the core polymer inside the shell one. In this model, the deposition flow is controlled by three dimensionless parameters: (i) the diameter ratio of core material to the nozzle, d/D; (ii) the normalised gap between the extruder and the build plate, t/D; (iii) the velocity ratio of the moving build plate to the average velocity inside the nozzle, V/U. Numerical results of the deposited strands’ cross-sections demonstrate the effects of controlling parameters on the encapsulation of the core material inside the shell and the shape and size of the strand. Overall we find that the best operating parameters are a diameter ratio of d/D=0.7, a normalised gap of t/D=1, and a velocity ratio of V/U=1.

scholarly journals Iron Based Core-Shell Structures as Versatile Materials: Magnetic Support and Solid Catalyst

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 72
Author(s):  
Christian Zambrzycki ◽  
Runbang Shao ◽  
Archismita Misra ◽  
Carsten Streb ◽  
Ulrich Herr ◽  
...  
Keyword(s):  
Water Purification ◽  
Functional Materials ◽  
Core Material ◽  
Solid Catalyst ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
The Core ◽  
Shell Nanostructures ◽  
Sio2 Shell ◽  
Iron Based

Core-shell materials are promising functional materials for fundamental research and industrial application, as their properties can be adapted for specific applications. In particular, particles featuring iron or iron oxide as core material are relevant since they combine magnetic and catalytic properties. The addition of an SiO2 shell around the core particles introduces additional design aspects, such as a pore structure and surface functionalization. Herein, we describe the synthesis and application of iron-based core-shell nanoparticles for two different fields of research that is heterogeneous catalysis and water purification. The iron-based core shell materials were characterized by transmission electron microscopy, as well as N2-physisorption, X-ray diffraction, and vibrating-sample magnetometer measurements in order to correlate their properties with the performance in the target applications. Investigations of these materials in CO2 hydrogenation and water purification show their versatility and applicability in different fields of research and application, after suitable individual functionalization of the core-shell precursor. For design and application of magnetically separable particles, the SiO2 shell is surface-functionalized with an ionic liquid in order to bind water pollutants selectively. The core requires no functionalization, as it provides suitable magnetic properties in the as-made state. For catalytic application in synthesis gas reactions, the SiO2-stabilized core nanoparticles are reductively functionalized to provide the catalytically active metallic iron sites. Therefore, Fe@SiO2 core-shell nanostructures are shown to provide platform materials for various fields of application, after a specific functionalization.

scholarly journals Carbon Fiber and Syntactic Foam Hybrid Materials via Core–Shell Material Extrusion Additive Manufacturing

2020 ◽  
Vol 5 (12) ◽  
pp. 2000731
Author(s):  
Robert C. Pack ◽  
Stian K. Romberg ◽  
Aly A. Badran ◽  
Nadim S. Hmeidat ◽  
Trenton Yount ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Carbon Fiber ◽  
Hybrid Materials ◽  
Syntactic Foam ◽  
Core Shell ◽  
Shell Material ◽  
Material Extrusion

Nanoparticle@MoS2 Core–Shell Architecture: Role of the Core Material

2018 ◽  
Vol 30 (14) ◽  
pp. 4675-4682 ◽  
Author(s):  
Jennifer G. DiStefano ◽  
Yuan Li ◽  
Hee Joon Jung ◽  
Shiqiang Hao ◽  
Akshay A. Murthy ◽  
...  
Keyword(s):  
Core Material ◽  
Core Shell ◽  
The Core

scholarly journals Mechanical Recyclability of Polypropylene Composites Produced by Material Extrusion-Based Additive Manufacturing

Polymers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1318 ◽  
Author(s):  
Martin Spoerk ◽  
Florian Arbeiter ◽  
Ivan Raguž ◽  
Clemens Holzer ◽  
Joamin Gonzalez-Gutierrez
Keyword(s):  
Additive Manufacturing ◽  
Chain Scission ◽  
Fused Filament Fabrication ◽  
Polypropylene Composites ◽  
Material Extrusion ◽  
Wide Range ◽  
Tremendous Amount ◽  
3D Printed ◽  
The Impact

Due to a lack of long-term experience with burgeoning material extrusion-based additive manufacturing technology, also known as fused filament fabrication (FFF), considerable amounts of expensive material will continue to be wasted until a defect-free 3D-printed component can be finalized. In order to lead this advanced manufacturing technique toward cleaner production and to save costs, this study addresses the ability to remanufacture a wide range of commercially available filaments. Most of them either tend to degrade by chain scission or crosslinking. Only polypropylene (PP)-based filaments appear to be particularly thermally stable and therefore suitable for multiple remanufacturing sequences. As the extrusion step exerts the largest influence on the material in terms of temperature and shear load, this study focused on the morphological, rheological, thermal, processing, tensile, and impact properties of a promising PP composite in the course of multiple consecutive extrusions as well as the impact of additional heat stabilizers. Even after 15 consecutive filament extrusions, the stabilized additively manufactured PP composite revealed an unaltered morphology and therefore the same tensile and impact strength as the initial material. As the viscosity of the material of the 15th extrusion was nearly identical to that of the 1st extrusion sequence, the processability both in terms of extrusion and FFF was outstanding, despite the tremendous amount of shear and thermal stress that was undergone. The present work provides key insights into one possible step toward more sustainable production through FFF.

scholarly journals Core–Shell Structured Phenolic Polymer@TiO2 Nanosphere with Enhanced Visible-Light Photocatalytic Efficiency

Nanomaterials ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 467
Author(s):  
Xiankui Xu ◽  
Lei Zhang ◽  
Shihua Zhang ◽  
Yanpeng Wang ◽  
Baoying Liu ◽  
...  
Keyword(s):  
Visible Light ◽  
Hydrothermal Reaction ◽  
Sol Gel ◽  
Core Material ◽  
Core Shell ◽  
Photocatalytic Efficiency ◽  
The Core ◽  
Phenolic Polymer ◽  
Colloid Nanoparticles ◽  
Tio2 Shell

Core–shell structured TiO2 is a promising solution to promote the photocatalytic effectiveness in visible light. Compared to metal or semiconductor materials, polymers are rarely used as the core materials for fabricating core–shell TiO2 materials. A novel core–shell structured polymer@TiO2 was developed by using phenolic polymer (PP) colloid nanoparticles as the core material. The PP nanoparticles were synthesized by an enzyme-catalyzed polymerization in water. A subsequent sol–gel and hydrothermal reaction was utilized to cover the TiO2 shell on the surfaces of PP particles. The thickness of the TiO2 shell was controlled by the amount of TiO2 precursor. The covalent connection between PP and TiO2 was established after the hydrothermal reaction. The core–shell structure allowed the absorption spectra of PP@TiO2 to extend to the visible-light region. Under visible-light irradiation, the core–shell nanosphere displayed enhanced photocatalytic efficiency for rhodamine B degradation and good recycle stability. The interfacial C–O–Ti bonds and the π-conjugated structures in the PP@TiO2 nanosphere played a key role in the quick transfer of the excited electrons between PP and TiO2, which greatly improved the photocatalytic efficiency in visible light.

scholarly journals Mixed polymer and bioconjugate core/shell electrospun fibres for biphasic protein release

2021 ◽  
Author(s):  
Inchirah Adala ◽  
Jopeth Ramis ◽  
Cynthia Ntone Moussinga ◽  
Isabella Janowski ◽  
Mahetab H. Amer ◽  
...  
Keyword(s):  
Polyethylene Oxide ◽  
Protein Release ◽  
Core Material ◽  
Core Shell ◽  
Electrospun Scaffold ◽  
The Core ◽  
Bioactive Molecule

We report the fabrication of a coaxial electrospun scaffold with a bioactive molecule in the core and a protein conjugated at the surface. To construct the scaffold, we chose polyethylene oxide for the core material and a polycaprolactone/Jeffamine blend for the shell.

scholarly journals Effect of Microcapsules of a Waterborne Core Material on the Properties of a Waterborne Primer Coating on a Wooden Surface

Coatings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 657 ◽  
Author(s):  
Xiaoxing Yan ◽  
Wenwen Peng
Keyword(s):  
Mass Fraction ◽  
Impact Resistance ◽  
Chromatic Aberration ◽  
Core Material ◽  
Core Shell ◽  
The Core ◽  
Mass Fractions ◽  
Wooden Surface ◽  
The Impact ◽  
Wooden Products

Microcapsules of a waterborne core material were prepared using a waterborne primer. The microcapsules of the waterborne core material were added to the waterborne primer to explore the effects of different core–shell ratios and mass fractions of the microcapsules on the property of the waterborne primer coating on the wooden surface. The results show that as the mass fraction of the microcapsules increased, the chromatic aberration increased by degrees, the glossiness decreased gradually, and the hardness increased by degrees, whilst—except for the coating with 0.50:1 microcapsules—the adhesion decreased gradually. When the mass fraction of the microcapsules increased, the impact resistance increased first and decreased later, or remained unchanged after reaching a certain value. When the mass fraction of the microcapsules increased, the elongation at the break increased first and decreased later. When the core–shell ratio was small and the mass fraction was between 5.0% and 15.0%, the coating had better liquid resistance. When the core–shell ratio was 0.67:1 and the mass fraction was 10.0%, the overall property of the coating on the Basswood was the best. The technology of microencapsulation provides a technical reference for the waterborne primer with self-repair qualities on the surface of wooden products.

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