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Mrs. Athina Maniadi
University Of Crete

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0 Nanocomposites
0 Polymers
0 Rapid Prototyping
0 Recycling
0 3D printing

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Journal article
Published: 02 March 2021 in Materials
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The continuous demand for thermoplastic polymers in a great variety of applications, combined with an urgent need to minimize the quantity of waste for a balanced energy-from-waste strategy, has led to increasing scientific interest in developing new recycling processes for plastic products. Glycol-modified polyethylene terephthalate (PETG) is known to have some enhanced properties as compared to polyethylene terephthalate (PET) homopolymer; this has recently attracted the interest from the fused filament fabrication (FFF) three-dimensional (3D) printing community. PET has shown a reduced ability for repeated recycling through traditional processes. Herein, we demonstrate the potential for using recycled PETG in consecutive 3D printing manufacturing processes. Distributed recycling additive manufacturing (DRAM)-oriented equipment was chosen in order to test the mechanical and thermal response of PETG material in continuous recycling processes. Tensile, flexure, impact strength, and Vickers micro-hardness tests were carried out for six (6) cycles of recycling. Finally, Raman spectroscopy as well as thermal and morphological analyses via scanning electron microscopy (SEM) fractography were carried out. In general, the results revealed a minor knockdown effect on the mechanical properties as well as the thermal properties of PETG following the process proposed herein, even after six rounds of recycling.

ACS Style

Nectarios Vidakis; Markos Petousis; Lazaros Tzounis; Sotirios Grammatikos; Emmanouil Porfyrakis; Athena Maniadi; Nikolaos Mountakis. Sustainable Additive Manufacturing: Mechanical Response of Polyethylene Terephthalate Glycol over Multiple Recycling Processes. Materials 2021, 14, 1162 .

AMA Style

Nectarios Vidakis, Markos Petousis, Lazaros Tzounis, Sotirios Grammatikos, Emmanouil Porfyrakis, Athena Maniadi, Nikolaos Mountakis. Sustainable Additive Manufacturing: Mechanical Response of Polyethylene Terephthalate Glycol over Multiple Recycling Processes. Materials. 2021; 14 (5):1162.

Chicago/Turabian Style

Nectarios Vidakis; Markos Petousis; Lazaros Tzounis; Sotirios Grammatikos; Emmanouil Porfyrakis; Athena Maniadi; Nikolaos Mountakis. 2021. "Sustainable Additive Manufacturing: Mechanical Response of Polyethylene Terephthalate Glycol over Multiple Recycling Processes." Materials 14, no. 5: 1162.

Journal article
Published: 19 January 2021 in Materials
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Plastic waste reduction and recycling through circular use has been critical nowadays, since there is an increasing demand for the production of plastic components based on different polymeric matrices in various applications. The most commonly used recycling procedure, especially for thermoplastic materials, is based on thermomechanical process protocols that could significantly alter the polymers’ macromolecular structure and physicochemical properties. The study at hand focuses on recycling of polyamide 12 (PA12) filament, through extrusion melting over multiple recycling courses, giving insight for its effect on the mechanical and thermal properties of Fused Filament Fabrication (FFF) manufactured specimens throughout the recycling courses. Three-dimensional (3D) FFF printed specimens were produced from virgin as well as recycled PA12 filament, while they have been experimentally tested further for their tensile, flexural, impact and micro-hardness mechanical properties. A thorough thermal and morphological analysis was also performed on all the 3D printed samples. The results of this study demonstrate that PA12 can be successfully recycled for a certain number of courses and could be utilized in 3D printing, while exhibiting improved mechanical properties when compared to virgin material for a certain number of recycling repetitions. From this work, it can be deduced that PA12 can be a viable option for circular use and 3D printing, offering an overall positive impact on recycling, while realizing 3D printed components using recycled filaments with enhanced mechanical and thermal stability.

ACS Style

Nectarios Vidakis; Markos Petousis; Lazaros Tzounis; Athena Maniadi; Emmanouil Velidakis; Nikolaos Mountakis; John D. Kechagias. Sustainable Additive Manufacturing: Mechanical Response of Polyamide 12 over Multiple Recycling Processes. Materials 2021, 14, 466 .

AMA Style

Nectarios Vidakis, Markos Petousis, Lazaros Tzounis, Athena Maniadi, Emmanouil Velidakis, Nikolaos Mountakis, John D. Kechagias. Sustainable Additive Manufacturing: Mechanical Response of Polyamide 12 over Multiple Recycling Processes. Materials. 2021; 14 (2):466.

Chicago/Turabian Style

Nectarios Vidakis; Markos Petousis; Lazaros Tzounis; Athena Maniadi; Emmanouil Velidakis; Nikolaos Mountakis; John D. Kechagias. 2021. "Sustainable Additive Manufacturing: Mechanical Response of Polyamide 12 over Multiple Recycling Processes." Materials 14, no. 2: 466.

Journal article
Published: 04 January 2021 in Recycling
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Polymer recycling is nowadays in high-demand due to an increase in polymers demand and production. Recycling of such materials is mostly a thermomechanical process that modifies their overall mechanical behavior. The present research work focuses on the recyclability of high-density polyethylene (HDPE), one of the most recycled materials globally, for use in additive manufacturing (AM). A thorough investigation was carried out to determine the effect of the continuous recycling on mechanical, structural, and thermal responses of HDPE polymer via a process that isolates the thermomechanical treatment from other parameters such as aging, contamination, etc. Fused filament fabrication (FFF) specimens were produced from virgin and recycled materials and were experimentally tested and evaluated in tension, flexion, impact, and micro-hardness. A thorough thermal and morphological analysis was also performed. The overall results of this study show that the mechanical properties of the recycled HDPE polymer were generally improved over the recycling repetitions for a certain number of recycling steps, making the HDPE recycling a viable option for circular use. Repetitions two to five had the optimum overall mechanical behavior, indicating a significant positive impact of the HDPE polymer recycling aside from the environmental one.

ACS Style

Nectarios Vidakis; Markos Petousis; Athena Maniadi. Sustainable Additive Manufacturing: Mechanical Response of High-Density Polyethylene over Multiple Recycling Processes. Recycling 2021, 6, 4 .

AMA Style

Nectarios Vidakis, Markos Petousis, Athena Maniadi. Sustainable Additive Manufacturing: Mechanical Response of High-Density Polyethylene over Multiple Recycling Processes. Recycling. 2021; 6 (1):4.

Chicago/Turabian Style

Nectarios Vidakis; Markos Petousis; Athena Maniadi. 2021. "Sustainable Additive Manufacturing: Mechanical Response of High-Density Polyethylene over Multiple Recycling Processes." Recycling 6, no. 1: 4.

Journal article
Published: 25 December 2020 in Sustainability
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The recycling of polymeric materials has received a steadily growing scientific and industrial interest due to the increase in demand and production of durable and lightweight plastic parts. Recycling of such materials is mostly based on thermomechanical processes that significantly affect the mechanical, as well as the overall physicochemical properties of polymers. The study at hand focuses on the recyclability of Fused Filament Fabrication (FFF) 3D printed Polypropylene (PP) for a certain number of recycling courses (six in total), and its effect on the mechanical properties of 3D printed parts. Namely, 3D printed specimens were fabricated from non-recycled and recycled PP material, and further experimentally tested regarding their mechanical properties in tension, flexion, impact, and microhardness. Comprehensive dynamic scanning calorimetry (DSC), thermogravimetric analysis (TGA), Raman spectroscopy, and morphological investigations by scanning electron microscopy (SEM) were performed for the different 3D printed PP samples. The overall results showed that there is an overall slight increase in the material’s mechanical properties, both in tension and in flexion mode, while the DSC characterization indicates an increase in the polymer crystallinity over the recycling course.

ACS Style

Nectarios Vidakis; Markos Petousis; Lazaros Tzounis; Athena Maniadi; Emmanouil Velidakis; Nicolaos Mountakis; Dimitrios Papageorgiou; Marco Liebscher; Viktor Mechtcherine. Sustainable Additive Manufacturing: Mechanical Response of Polypropylene over Multiple Recycling Processes. Sustainability 2020, 13, 159 .

AMA Style

Nectarios Vidakis, Markos Petousis, Lazaros Tzounis, Athena Maniadi, Emmanouil Velidakis, Nicolaos Mountakis, Dimitrios Papageorgiou, Marco Liebscher, Viktor Mechtcherine. Sustainable Additive Manufacturing: Mechanical Response of Polypropylene over Multiple Recycling Processes. Sustainability. 2020; 13 (1):159.

Chicago/Turabian Style

Nectarios Vidakis; Markos Petousis; Lazaros Tzounis; Athena Maniadi; Emmanouil Velidakis; Nicolaos Mountakis; Dimitrios Papageorgiou; Marco Liebscher; Viktor Mechtcherine. 2020. "Sustainable Additive Manufacturing: Mechanical Response of Polypropylene over Multiple Recycling Processes." Sustainability 13, no. 1: 159.

Journal article
Published: 26 October 2020 in Materials
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The incorporation of graphene nanoplatelets (GnPs) within a polymer matrix can play an important role in the physical properties and the functionality of the composite material. Composites consisting of low-density polyethylene (LDPE) and GnPs of different concentrations were developed by mixing GnPs with a molten form of the polymeric matrix. The effect of the GnPs content on the morphological, structural, and electrical properties of the composites were investigated. As shown, graphene presence and its concentration significantly modified the polymer matrix properties, a behavior that can be employed for tailoring its applicability in electrical applications. It was found that the increase of the graphene platelets concentration seems to promote the formation of graphene agglomerates, air gaps, and inhomogeneities, while higher dielectric constant/lower dielectric losses can be achieved.

ACS Style

Athena Maniadi; Maria Vamvakaki; Mirela Suchea; Ioan Valentin Tudose; Marian Popescu; Cosmin Romanitan; Cristina Pachiu; Octavian N. Ionescu; Zaharias Viskadourakis; George Kenanakis; Emmanouel Koudoumas. Effect of Graphene Nanoplatelets on the Structure, the Morphology, and the Dielectric Behavior of Low-Density Polyethylene Nanocomposites. Materials 2020, 13, 4776 .

AMA Style

Athena Maniadi, Maria Vamvakaki, Mirela Suchea, Ioan Valentin Tudose, Marian Popescu, Cosmin Romanitan, Cristina Pachiu, Octavian N. Ionescu, Zaharias Viskadourakis, George Kenanakis, Emmanouel Koudoumas. Effect of Graphene Nanoplatelets on the Structure, the Morphology, and the Dielectric Behavior of Low-Density Polyethylene Nanocomposites. Materials. 2020; 13 (21):4776.

Chicago/Turabian Style

Athena Maniadi; Maria Vamvakaki; Mirela Suchea; Ioan Valentin Tudose; Marian Popescu; Cosmin Romanitan; Cristina Pachiu; Octavian N. Ionescu; Zaharias Viskadourakis; George Kenanakis; Emmanouel Koudoumas. 2020. "Effect of Graphene Nanoplatelets on the Structure, the Morphology, and the Dielectric Behavior of Low-Density Polyethylene Nanocomposites." Materials 13, no. 21: 4776.

Journal article
Published: 22 October 2020 in Biomimetics
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Myopic macular foveoschisis maculopathy is an eye disease that is treated, in most cases, with surgical intervention, in which a macular buckle is applied to restore eye anatomy and functionality. A macular buckle is a type of exoplant that comes in various designs and sizes. Often, they are difficult to apply or they do not fit properly in the eye geometry since they have a generic form. In this work, the effort to develop the most suitable tailor-made macular buckle for each individual patient for treating myopic traction maculopathy is studied. Pattern recognition techniques are applied to the patient’s Computed Tomography (CT) data to develop the exact 3D geometry of the eye. Using this 3D geometry, the trajectory of the buckle is fitted and the buckle is formed, which is then 3D-printed with biocompatible polymer materials. It is expected that the power of technology will be used to activate the most precise approach for each individual patient. Considering the possible complications and technical difficulties of other surgical methods, the customized macular buckle is an appropriate, easy-to-use, and most precise piece of medical equipment for the treatment of myopic traction maculopathy.

ACS Style

George Pappas; Nectarios Vidakis; Markos Petousis; Athena Maniadi. Individualized Ophthalmic Exoplants by Means of Reverse Engineering and 3D Printing Technologies for Treating High Myopia Complications with Macular Buckles. Biomimetics 2020, 5, 54 .

AMA Style

George Pappas, Nectarios Vidakis, Markos Petousis, Athena Maniadi. Individualized Ophthalmic Exoplants by Means of Reverse Engineering and 3D Printing Technologies for Treating High Myopia Complications with Macular Buckles. Biomimetics. 2020; 5 (4):54.

Chicago/Turabian Style

George Pappas; Nectarios Vidakis; Markos Petousis; Athena Maniadi. 2020. "Individualized Ophthalmic Exoplants by Means of Reverse Engineering and 3D Printing Technologies for Treating High Myopia Complications with Macular Buckles." Biomimetics 5, no. 4: 54.

Journal article
Published: 17 July 2020 in Polymers
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In order to enhance the mechanical performance of three-dimensional (3D) printed structures fabricated via commercially available fused filament fabrication (FFF) 3D printers, novel nanocomposite filaments were produced herein following a melt mixing process, and further 3D printed and characterized. Titanium Dioxide (TiO2) and Antimony (Sb) doped Tin Oxide (SnO2) nanoparticles (NPs), hereafter denoted as ATO, were selected as fillers for a polymeric acrylonitrile butadiene styrene (ABS) thermoplastic matrix at various weight % (wt%) concentrations. Tensile and flexural test specimens were 3D printed, according to international standards. It was proven that TiO2 filler enhanced the overall tensile strength by 7%, the flexure strength by 12%, and the micro-hardness by 6%, while for the ATO filler, the corresponding values were 9%, 13%, and 6% respectively, compared to unfilled ABS. Atomic force microscopy (AFM) revealed the size of TiO2 (40 ± 10 nm) and ATO (52 ± 11 nm) NPs. Raman spectroscopy was performed for the TiO2 and ATO NPs as well as for the 3D printed nanocomposites to verify the polymer structure and the incorporated TiO2 and ATO nanocrystallites in the polymer matrix. The scope of this work was to fabricate novel nanocomposite filaments using commercially available materials with enhanced overall mechanical properties that industry can benefit from.

ACS Style

Nectarios Vidakis; Markos Petousis; Athena Maniadi; Emmanuel Koudoumas; Marco Liebscher; Lazaros Tzounis. Mechanical Properties of 3D-Printed Acrylonitrile–Butadiene–Styrene TiO2 and ATO Nanocomposites. Polymers 2020, 12, 1589 .

AMA Style

Nectarios Vidakis, Markos Petousis, Athena Maniadi, Emmanuel Koudoumas, Marco Liebscher, Lazaros Tzounis. Mechanical Properties of 3D-Printed Acrylonitrile–Butadiene–Styrene TiO2 and ATO Nanocomposites. Polymers. 2020; 12 (7):1589.

Chicago/Turabian Style

Nectarios Vidakis; Markos Petousis; Athena Maniadi; Emmanuel Koudoumas; Marco Liebscher; Lazaros Tzounis. 2020. "Mechanical Properties of 3D-Printed Acrylonitrile–Butadiene–Styrene TiO2 and ATO Nanocomposites." Polymers 12, no. 7: 1589.

Journal article
Published: 25 June 2020 in Micromachines
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In order to expand the mechanical and physical capabilities of 3D-printed structures fabricated via commercially available 3D printers, nanocomposite and microcomposite filaments were produced via melt extrusion, 3D-printed and evaluated. The scope of this work is to fabricate physically and mechanically improved nanocomposites or microcomposites for direct commercial or industrial implementation while enriching the existing literature with the methodology applied. Zinc Oxide nanoparticles (ZnO nano) and Zinc Oxide micro-sized particles (ZnO micro) were dispersed, in various concentrations, in Acrylonitrile Butadiene Styrene (ABS) matrices and printable filament of ~1.75mm was extruded. The composite filaments were employed in a commercial 3D printer for tensile and flexion specimens’ production, according to international standards. Results showed a 14% increase in the tensile strength at 5% wt. concentration in both nanocomposite and microcomposite materials, when compared to pure ABS specimens. Furthermore, a 15.3% increase in the flexural strength was found in 0.5% wt. for ABS/ZnO nano, while an increase of 17% was found on 5% wt. ABS/ZnO micro. Comparing the two composites, it was found that the ABS/ZnO microcomposite structures had higher overall mechanical strength over ABS/ZnO nanostructures.

ACS Style

Nectarios Vidakis; Markos Petousis; Athena Maniadi; Emmanuel Koudoumas; George Kenanakis; Cosmin Romanitan; Oana Tutunaru; Mirela Suchea; John Kechagias. The Mechanical and Physical Properties of 3D-Printed Materials Composed of ABS-ZnO Nanocomposites and ABS-ZnO Microcomposites. Micromachines 2020, 11, 615 .

AMA Style

Nectarios Vidakis, Markos Petousis, Athena Maniadi, Emmanuel Koudoumas, George Kenanakis, Cosmin Romanitan, Oana Tutunaru, Mirela Suchea, John Kechagias. The Mechanical and Physical Properties of 3D-Printed Materials Composed of ABS-ZnO Nanocomposites and ABS-ZnO Microcomposites. Micromachines. 2020; 11 (6):615.

Chicago/Turabian Style

Nectarios Vidakis; Markos Petousis; Athena Maniadi; Emmanuel Koudoumas; George Kenanakis; Cosmin Romanitan; Oana Tutunaru; Mirela Suchea; John Kechagias. 2020. "The Mechanical and Physical Properties of 3D-Printed Materials Composed of ABS-ZnO Nanocomposites and ABS-ZnO Microcomposites." Micromachines 11, no. 6: 615.

Journal article
Published: 27 April 2020 in Sustainability
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Sustainability in additive manufacturing refers mainly to the recycling rate of polymers and composites used in fused filament fabrication (FFF), which nowadays are rapidly increasing in volume and value. Recycling of such materials is mostly a thermomechanical process that modifies their overall mechanical behavior. The present research work focuses on the acrylonitrile-butadiene-styrene (ABS) polymer, which is the second most popular material used in FFF-3D printing. In order to investigate the effect of the recycling courses on the mechanical response of the ABS polymer, an experimental simulation of the recycling process that isolates the thermomechanical treatment from other parameters (i.e., contamination, ageing, etc.) has been performed. To quantify the effect of repeated recycling processes on the mechanic response of the ABS polymer, a wide variety of mechanical tests were conducted on FFF-printed specimens. Regarding this, standard tensile, compression, flexion, impact and micro-hardness tests were performed per recycle repetition. The findings prove that the mechanical response of the recycled ABS polymer is generally improved over the recycling repetitions for a certain number of repetitions. An optimum overall mechanical behavior is found between the third and the fifth repetition, indicating a significant positive impact of the ABS polymer recycling, besides the environmental one.

ACS Style

Nectarios Vidakis; Markos Petousis; Athena Maniadi; Emmanuel Koudoumas; Achilles Vairis; John Kechagias. Sustainable Additive Manufacturing: Mechanical Response of Acrylonitrile-Butadiene-Styrene over Multiple Recycling Processes. Sustainability 2020, 12, 3568 .

AMA Style

Nectarios Vidakis, Markos Petousis, Athena Maniadi, Emmanuel Koudoumas, Achilles Vairis, John Kechagias. Sustainable Additive Manufacturing: Mechanical Response of Acrylonitrile-Butadiene-Styrene over Multiple Recycling Processes. Sustainability. 2020; 12 (9):3568.

Chicago/Turabian Style

Nectarios Vidakis; Markos Petousis; Athena Maniadi; Emmanuel Koudoumas; Achilles Vairis; John Kechagias. 2020. "Sustainable Additive Manufacturing: Mechanical Response of Acrylonitrile-Butadiene-Styrene over Multiple Recycling Processes." Sustainability 12, no. 9: 3568.