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3D Printing and Customized Additive Manufacturing of Advanced Sustainable Polymers and Composites

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A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Polymer Processing and Engineering".

Deadline for manuscript submissions: closed (14 February 2024) | Viewed by 18031

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Dr. Mario Bragaglia

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Department of Enterprise Engineering “Mario Lucertini”, University of Rome “Tor Vergata” and INSTM RU Roma—Tor Vergata, via del Politecnico 1, 00133 Rome, Italy
Interests: 3D Printing, Advanced Materials, Multifunctional Composites; Mechanical Behavior of Materials; Material Characterization; Mechanical Testing; SEM Analysis; Materials; Microstructure.

Dr. Francesca Nanni

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Department of Enterprise Engineering “Mario Lucertini”, University of Rome “Tor Vergata”, and INSTM RU Roma-Tor Vergata, via del Politecnico 1, 00133 Rome, Italy
Interests: materials engineering; composite materials and nanocomposites; nanofibers and nanofillers in polymer matrices; self-aiding materials; electro-magnetic materials (shielding, absorbing)
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Dear Colleagues,

Additive manufacturing (AM) or 3D-printing allows for new freedom in the thermomechanical design of engineering components, and the realization of complex non-symmetric shapes that are otherwise impossible to achieve with the traditional manufacturing processes. Advanced polymers and composites have gained popularity in both research and industry and find a wide range of applications, from the aerospace sector to the biomedical sector, as well as the automotive, oil and gas, and energy sectors. The concept of advanced polymers and composites can be declined in different ways:

Polymers and composites showing high mechanical performance;
Multifunctional polymer matrix composites able to show “smart” properties (i.e., featured with the ability to autonomously show one or more functions other than the structural one, such as thermal conductivity, electrical conductivity, damping effect, magnetic properties, biocompatibility, and biodegradability);
Sustainable material derived from natural biobased sources;
Shape memory polymers allowing for 4D-printing.

The possibility to 3D-print advanced polymers and composites opens up new perspectives from a design point of view, but some critical issues can arise depending on the printing processing, as it can affect the microstructure (i.e., anisotropy, degree of crystallinity, filler orientation, etc.) and, hence, the final properties of the object. The aim of this Special Issue is to explore the latest achievements of the 3D-printing of advanced polymers, biopolymers, and composites, focusing on the development and/or modification of the polymers suitable for 3D-printing in all the aforementioned applications, but also to study the influence of the AM processes on the resulting physical, thermal, and mechanical properties of the 3D-printed products.

Dr. Mario Bragaglia
Dr. Francesca Nanni
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Polymers is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

additive manufacturing
3D printing
polymer matrix composites
multifunctional polymers
shape memory polymers
engineering polymers
biobased polymers
fused filament fabrication (FFF)
powder bed fusion
stereolythography
digital light processing

Published Papers (12 papers)

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Research

15 pages, 3673 KiB

Open AccessArticle

Development of a Polypropylene-Based Material with Flame-Retardant Properties for 3D Printing

by Eleonora Lorenzi, Rossella Arrigo and Alberto Frache

Polymers 2024, 16(6), 858; https://doi.org/10.3390/polym16060858 - 21 Mar 2024

Viewed by 611

Abstract

In this study, a nanocomposite based on a heterophasic polypropylene copolymer containing 5 wt% of nanoclays and 3 wt% of compatibilizer was formulated via melt compounding to obtain a material suitable for Fused Filament Fabrication (FFF) processing with enhanced flame-retardant properties. From rheological analyses, the nanocomposite showed an important increase in the non-Newtonian behavior, and, therefore, improved FFF printability compared to the pristine PP COPO. A filament with suitable characteristics for FFF was produced using a single-screw extruder and subsequently 3D printed. Finally, cone calorimeter and UL94 tests were carried out on both 3D-printed and compression-molded specimens. The obtained results showed that the 3D-printed samples exhibited even better flame-retardant properties than the compression-molded ones, thus demonstrating not only the possibility of successfully developing and using functionalized PP-based filaments in 3D printing but also the possibility of obtaining enhanced flame-retardant properties compared to conventional compression molding. Full article

(This article belongs to the Special Issue 3D Printing and Customized Additive Manufacturing of Advanced Sustainable Polymers and Composites)

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14 pages, 2802 KiB

Open AccessArticle

Fabrication of a Controlled-Release Core-Shell Floating Tablet of Ketamine Hydrochloride Using a 3D Printing Technique for Management of Refractory Depressions and Chronic Pain

by Tahmineh Karami, Emad Ghobadi, Mohammad Akrami and Ismaeil Haririan

Polymers 2024, 16(6), 746; https://doi.org/10.3390/polym16060746 - 8 Mar 2024

Viewed by 607

Abstract

In this study, a novel floating, controlled-release and core-shell oral tablet of ketamine hydrochloride (HCl) was produced using a dual extrusion by 3D printing method. A mixture of Soluplus^® and Eudragit^® RS-PO was extruded by a hot-melt extrusion (HME) nozzle at 150–160 °C to fabricate the tablet shell, while a second nozzle known as a pressure-assisted syringe (PAS) extruded the etamine HCl in carboxymethyl cellulose gel at room temperature (25 °C) inside the shell. The resulting tablets were optimized based on the United States pharmacopeia standards (USP) for solid dosage forms. Moreover, the tablet was characterized using Fourier-transform infrared (FTIR) spectrum, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and buoyancy techniques. The results showed a desired dissolution profile for a 100% infill optimized tablet with total drug release (100%) during 12 h. Weight variation and content uniformity of the tablets achieved the USP requirements. SEM micrographs showed a smooth surface with acceptable layer diameters. According to the FTIR analysis, no interference was detected among peaks. Based on DSC analysis, the crystallinity of ketamine HCl did not change during melt extrusion. In conclusion, the floating controlled-release 3D-printed tablet of ketamine HCl can be a promising candidate for management of refractory depressions and chronic pain. Additionally, the additive manufacturing method enables the production of patient-tailored dosage with tunable-release kinetics for personalized medicine in point-of care setting. Full article

(This article belongs to the Special Issue 3D Printing and Customized Additive Manufacturing of Advanced Sustainable Polymers and Composites)

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18 pages, 13702 KiB

Open AccessArticle

Experimental Study of a 3D Printing Strategy for Polymer-Based Parts for Drone Equipment Using Bladeless Technology

by Florin Popișter, Horea Ștefan Goia, Paul Ciudin and Diana Dragomir

Polymers 2024, 16(4), 533; https://doi.org/10.3390/polym16040533 - 16 Feb 2024

Viewed by 758

Abstract

The present study focuses on an up-to-date topic regarding flying equipment identified within the category of drones that use, for propulsion and air movements, the power generated by electric motors. In this paper, researchers focus on implementing bladeless technology to calculate, develop, and construct flying equipment known in the literature as drones. The entire structure of the prototype, all the needed parts, is to be obtained using additive manufacturing technologies, which assumes practical realization using 3D-printing equipment. Nowadays, the 3D-printing process has been proven to be a reliable solution when it comes to manufacturing complex shape parts in quite a short time and with reduced costs. The practical study within the present research aims to obtain polymer-based, lightweight parts with complex shapes inside to be implemented in the propulsion of a drone. The complex surface geometry of the parts that this research used is influenced by the ventilation technology offered by the “Air Multiplier” technology. The entire structure of the final drone equipment, all the parts, is to be manufactured using fused filament fabrication (FFF). The main purpose of the fusion is to use the advantages offered by this technology in drones to obtain advantages such as augmented values of thrust, a more agreeable and muffled sound signature, or an increased level of safety. Full article

(This article belongs to the Special Issue 3D Printing and Customized Additive Manufacturing of Advanced Sustainable Polymers and Composites)

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29 pages, 227522 KiB

Open AccessArticle

Influence of 3D Printing Direction in PLA Acoustic Guitars on Vibration Response

by Álvaro Burgos-Pintos, Francisco Fernández-Zacarías, Pedro F. Mayuet, Ricardo Hernández-Molina and Lucía Rodríguez-Parada

Polymers 2023, 15(24), 4710; https://doi.org/10.3390/polym15244710 - 14 Dec 2023

Cited by 1 | Viewed by 878

Abstract

The design of musical instruments is a discipline that is still carried out in an artisanal way, with limitations and high costs. With the additive manufacturing technique, it is possible to obtain results for the generation of not only electrical but also acoustic instruments. However, it is necessary to generate a procedure to evaluate the influence of the process on the final result of the acoustics obtained. This study focuses on investigating the relationship between the construction of acoustic guitars and their final sound. The reinforcement structures at the top of the instrument are analysed, as well as how this design affects the vibratory behaviour of the top in the first five vibratory modes. Specifically, this article presents a procedure for the design of customised acoustic guitars using additive manufacturing through parametrisation and a vibrational analysis of the designed tops using finite element (FEA) and experimental physical tests, in order to develop a methodology for the study of stringed instruments. As a result, an 11% increase in the high-frequency response was achieved with a printing direction of +45°, and a reduction in the high-frequency response with ±45°. In addition, at high frequencies, a relative error of 5% was achieved with respect to the simulation. This work fulfils an identified need to study the manufacture of acoustic guitars using polylactic acid (PLA), and to be able to offer the musician a customised instrument. This represents a breakthrough in the use of this manufacturing technology, extending its relationship with product design. Full article

(This article belongs to the Special Issue 3D Printing and Customized Additive Manufacturing of Advanced Sustainable Polymers and Composites)

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17 pages, 7766 KiB

Open AccessArticle

Experimental and Numerical Study of Printing Strategy Impact on the Mechanical Properties of Sustainable PLA Materials

by Emil Spišák, Ema Nováková-Marcinčínová, Janka Majerníková, Peter Mulidrán and Ľudmila Nováková-Marcinčínová

Polymers 2023, 15(24), 4639; https://doi.org/10.3390/polym15244639 - 7 Dec 2023

Cited by 1 | Viewed by 957

Abstract

This article is focused on a mechanical properties investigation of three types of sustainable poly lactic acid materials manufactured using the fused filament fabrication process. The purpose of this work was to study the impact of printing strategies on the mechanical properties and predict mechanical behavior under tensile loading using finite element analysis. The testing of mechanical properties was conducted according to the ISO 527 standard. The numerical simulations were conducted in Simufact Forming 2022 software. Analysis of the experimental data showed a dependance of mechanical properties on the used printing strategy. The Clear PLA samples printed in the XY plane exhibited a 43% reduction in tensile strength and a 49% reduction in elongation compared to samples printed from the same material in YZ plane. The experimental results show the influence of the printing orientation on the mechanical properties of 3D-printed samples. Full article

(This article belongs to the Special Issue 3D Printing and Customized Additive Manufacturing of Advanced Sustainable Polymers and Composites)

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13 pages, 3096 KiB

Open AccessArticle

Enhancing the Mechanical Properties and Aging Resistance of 3D-Printed Polyurethane through Polydopamine and Graphene Coating

by Chien-Chiang Tung, Yen-Hong Lin, Yi-Wen Chen and Fu-Ming Wang

Polymers 2023, 15(18), 3744; https://doi.org/10.3390/polym15183744 - 13 Sep 2023

Cited by 2 | Viewed by 1060

Abstract

Three-dimensional (3D) printing is a versatile manufacturing method widely used in various industries due to its design flexibility, rapid production, and mechanical strength. Polyurethane (PU) is a biopolymer frequently employed in 3D printing applications, but its susceptibility to UV degradation limits its durability. To address this issue, various additives, including graphene, have been explored to enhance PU properties. Graphene, a two-dimensional carbon material, possesses remarkable mechanical and electrical properties, but challenges arise in its dispersion within the polymer matrix. Surface modification techniques, like polydopamine (PDA) coating, have been introduced to improve graphene’s compatibility with polymers. This study presents a method of 3D printing PU scaffolds coated with PDA and graphene for enhanced UV stability. The scaffolds were characterized through X-ray diffraction, Fourier-transform infrared spectroscopy, mechanical testing, scanning electron microscopy, and UV durability tests. Results showed successful PDA coating, graphene deposition, and improved mechanical properties. The PDA–graphene-modified scaffolds exhibited greater UV resistance over time, attributed to synergistic effects between PDA and graphene. These findings highlight the potential of combining PDA and graphene to enhance the stability and mechanical performance of 3D-printed PU scaffolds. Full article

(This article belongs to the Special Issue 3D Printing and Customized Additive Manufacturing of Advanced Sustainable Polymers and Composites)

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14 pages, 3842 KiB

Open AccessArticle

Self-Monitoring Performance of 3D-Printed Poly-Ether-Ether-Ketone Carbon Nanotube Composites

by Lorenzo Paleari, Mario Bragaglia, Francesco Fabbrocino, Raimondo Luciano and Francesca Nanni

Polymers 2023, 15(1), 8; https://doi.org/10.3390/polym15010008 - 20 Dec 2022

Cited by 4 | Viewed by 1258

Abstract

In this paper, poly-ether-ether-ketone (PEEK) carbon-nanotube (CNT) self-monitoring composites at different levels of filler loading (i.e., 3, 5 and 10% by weight) have been extruded as 3D-printable filaments, showing gauge factor values of 14.5, 3.36 and 1.99, respectively. CNT composite filaments of 3 and 5 wt% were 3D-printed into tensile samples, while the PEEK 10CNT filament was found to be barely printable. The 3D-printed PEEK 3CNT and PEEK 5CNT composites presented piezo-resistive behavior, with an increase in electrical resistance under mechanical stress, and showed an average gauge factor of 4.46 and 2.03, respectively. Mechanical tests highlighted that 3D-printed samples have a laminate-like behavior, presenting ultimate tensile strength that is always higher than 60 MPa, hence they offer the possibility to detect damages in an orthogonal direction to the applied load wit high sensitivity. Full article

(This article belongs to the Special Issue 3D Printing and Customized Additive Manufacturing of Advanced Sustainable Polymers and Composites)

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15 pages, 3752 KiB

Open AccessArticle

Recycling of Bottle Grade PET: Influence of HDPE Contamination on the Microstructure and Mechanical Performance of 3D Printed Parts

by Joanne Vaucher, Adrien Demongeot, Véronique Michaud and Yves Leterrier

Polymers 2022, 14(24), 5507; https://doi.org/10.3390/polym14245507 - 15 Dec 2022

Cited by 11 | Viewed by 2788

Abstract

As part of a project that aims to provide people with disabilities with simple assistive devices in Colombia, the possibility of creating a PET filament that can be printed by Fused Deposition Modelling (FDM) from beverage bottle waste was investigated, with the aim to remain as simple as possible in terms of plastic collection, sorting, processing, and printing. Recycled PET filaments were thus produced by extrusion from collected PET bottles, with the potential addition of HDPE, which comes from caps and rings. The microstructure, mechanical performance, and printing quality of parts produced with these filaments were investigated in comparison to commercial PET virgin and recycled filaments. HDPE presence as an immiscible blend did not affect the ease of extrusion or the quality of the printing, which were all satisfactory. In some conditions, the addition of 5 wt% of HDPE to recycled PET had a toughening effect on otherwise brittle samples. This behavior was attributed to the presence of elongated HDPE inclusions resulting from shear forces induced by the layer-by-layer printing, provided that the interface temperature remained high between layer depositions. This confirms that the mechanical performance of recycled PET is very sensitive to the processing conditions, especially in the case of 3D printing. Nonetheless, this low-cost process that did not require sophisticated compatibilization schemes allowed for the printing of parts with mechanical properties comparable to those obtained with high purity, commercially recycled filaments, opening interesting perspectives for a low-cost PET recycling process. Full article

(This article belongs to the Special Issue 3D Printing and Customized Additive Manufacturing of Advanced Sustainable Polymers and Composites)

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19 pages, 5926 KiB

Open AccessArticle

Enhancing the Mechanical Properties of 3D-Printed Waterborne Polyurethane-Urea and Cellulose Nanocrystal Scaffolds through Crosslinking

by Julen Vadillo, Izaskun Larraza, Tamara Calvo-Correas, Loli Martin, Christophe Derail and Arantxa Eceiza

Polymers 2022, 14(22), 4999; https://doi.org/10.3390/polym14224999 - 18 Nov 2022

Cited by 2 | Viewed by 1705

Abstract

In this work, shape-customized scaffolds based on waterborne polyurethane-urea (WBPUU) were prepared via the combination of direct ink writing 3D-printing and freeze-drying techniques. To improve the printing performance of the ink and guarantee a good shape fidelity of the scaffold, cellulose nanocrystals (CNC) were added during the synthesis of the WBPUU and some of the printed constructs were immersed in CaCl₂ prior to the freeze-drying process to promote ionic crosslinking between calcium ions and the polyurethane. The results showed that apart from allowing the ink to be successfully printed, obtaining scaffolds with good shape fidelity, the addition of the CNC resulted in a greater homogeneity of the porous structure as well as an increase of the swelling capacity of the scaffolds. Additionally, the CNC has a reinforcement effect in the printed systems, presenting a higher compression modulus as the CNC content increases. In the case of samples crosslinked by calcium ions, a rigid shell was observed by scanning electron microscopy, which resulted in stiffer scaffolds that presented a lower water absorption capacity as well as an enhancement of the thermal stability. These results showed the potential of this type of post-printing process to tune the mechanical properties of the scaffold, thus widening the potential of this type of material. Full article

(This article belongs to the Special Issue 3D Printing and Customized Additive Manufacturing of Advanced Sustainable Polymers and Composites)

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16 pages, 6422 KiB

Open AccessArticle

Effect of Infill Density in FDM 3D Printing on Low-Cycle Stress of Bamboo-Filled PLA-Based Material

by Miroslav Müller, Petr Jirků, Vladimír Šleger, Rajesh Kumar Mishra, Monika Hromasová and Jan Novotný

Polymers 2022, 14(22), 4930; https://doi.org/10.3390/polym14224930 - 15 Nov 2022

Cited by 12 | Viewed by 2218

Abstract

In this paper, the fatigue behavior of polylactic acid (PLA) material with bamboo filler printed by 3D additive printing using fused deposition modelling (FDM) technology at different infill densities and print nozzle diameters is investigated. The mechanical test results are supported by the findings from SEM image analysis. The fatigue behavior was tested at four consecutive 250 cycles at loads ranging from 5 to 20, 30, 40, and 50% based on the limits found in the static tensile test. The results of the static tensile and low-cycle fatigue tests confirmed significant effects of infill density of 60%, 80%, and 100% on the tensile strength of the tested specimens. In particular, the research results show a significant effect of infill density on the fatigue properties of the tested materials. The influence of cyclic tests resulted in the strengthening of the tested material, and at the same time, its viscoelastic behavior was manifested. SEM analysis of the fracture surface confirmed a good interaction between the PLA matrix and the bamboo-based filler using nozzle diameters of 0.4 and 0.6 mm and infill densities of 60%, 80%, and 100%. Low-cycle testing showed no reductions in the mechanical properties and fatigue lives of the 3D printed samples. Full article

(This article belongs to the Special Issue 3D Printing and Customized Additive Manufacturing of Advanced Sustainable Polymers and Composites)

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14 pages, 3053 KiB

Open AccessArticle

New Approach for Extrusion Additive Manufacturing of Soft and Elastic Articles from Liquid-PVC-Based Consumable Materials

by Bohdan Savchenko, Nadiya Sova, Victor Beloshenko, Bohdan Debeluy, Aleksander Slieptsov and Iurii Vozniak

Polymers 2022, 14(21), 4683; https://doi.org/10.3390/polym14214683 - 2 Nov 2022

Cited by 2 | Viewed by 2096

Abstract

The article deals with the experimental development of a novel additive manufacturing (AM) process using a liquid consumable based on polyvinyl chloride plastisol. A conventional additive manufacturing system designed for deposition of melt filaments was converted to deposition of liquid material. Additive manufacturing with liquid plastisol enables the production of parts with low Shore A hardness and high ductility, surpassing the performance of the conventional filament process. The novel AM process enables the production of articles with a Shore A hardness of 5 to 60, and the mechanical properties of the additively manufactured articles are similar to those produced in the mold. This was achieved by varying the parameters of the AM process as well as the composition of the plastisol composition, including those filled with an inorganic filler. The application of different material distribution patterns also has a significant effect on the mechanical properties of the samples. A potential application of the investigated AM method was proposed and practically evaluated. Full article

(This article belongs to the Special Issue 3D Printing and Customized Additive Manufacturing of Advanced Sustainable Polymers and Composites)

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18 pages, 9668 KiB

Open AccessArticle

Evaluation of the Orthotropic Behavior in an Auxetic Structure Based on a Novel Design Parameter of a Square Cell with Re-Entrant Struts

by Rodrigo Valle, Gonzalo Pincheira, Víctor Tuninetti, Cesar Garrido, Cecilia Treviño and Jorge Morales

Polymers 2022, 14(20), 4325; https://doi.org/10.3390/polym14204325 - 14 Oct 2022

Cited by 3 | Viewed by 1852

Abstract

In this research, a three-dimensional auxetic configuration based on a known re-entrant cell is proposed. The 3D auxetic cell is configured from a new design parameter that produces an internal rotation angle to its re-entrant elements to study elastic properties in its three orthogonal directions. Through a topological analysis using Timoshenko beam theory, the bending of its re-entrant struts is modeled as a function of the new design parameter to manipulate Poisson’s ratio and Young’s modulus. Experimental samples were fabricated using a fused filament fabrication system using ABS and subsequently tested under quasi-static compression and bending tests. Additionally, an orthotropy factor is applied that allows for measuring the deviation between the mechanical properties of each structure. The experimental results validate the theoretical design and show that this new unit cell can transmit an orthotropic mechanical behavior to the macrostructure. In addition, the proposed structure can provide a different bending stiffness behavior in up to three working directions, which allows the application under different conditions of external forces, such as a prosthetic ankle. Full article

(This article belongs to the Special Issue 3D Printing and Customized Additive Manufacturing of Advanced Sustainable Polymers and Composites)

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