Additive Manufacturing of Polymer Composites

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

Deadline for manuscript submissions: closed (25 October 2023) | Viewed by 20148

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editor


E-Mail Website
Guest Editor
Department of Mechanical and Construction Engineering, Northumbria University, Newcastle upon Tyne, UK
Interests: fibre composites; additive manufacturing; finite element analysis
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

It is our pleasure to invite articles for publication in this Special Issue on “Additive Manufacturing of Polymer Composites”. 3D-printed composites offer the opportunity for the rapid manufacture of complex components with bespoke material architectures that can be designed to prioritise performance in specific regions whilst focussing on weight savings elsewhere. Recent research in this field has demonstrated tremendous progress in overcoming some of the technical challenges associated with creating continuous fibre composites using additive manufacturing, and new-to-market commercial printers offer the promise of broader adoption of these materials. Some of the remaining key challenges limiting widespread use are an understanding of the key mechanisms of failure and how these materials perform over the long term in a wide range of environments.

We invite contributions to this Special Issue of Polymers on topics investigating all aspects of additive manufacturing of polymer composites including, but not limited to, material characterisation, the analysis of failure, modelling and simulation, novel approaches to printing, and an examination of the printed composite design approach. The goal of this Special Issue is to increase understanding of these novel material systems with the aim of increasing the performance and long-term viability of 3D-printed composites that will lead to wide-scale adoption.

Dr. Matthew Blacklock
Guest Editor

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 technology
  • 3D-printed fibre and polymer matrix systems
  • modelling and analysis: finite element, discrete element
  • material characterisation
  • constitutive modelling

Related Special Issue

Published Papers (11 papers)

Order results
Result details
Select all
Export citation of selected articles as:

Research

19 pages, 9486 KiB  
Article
The Effect of Zinc Oxide on DLP Hybrid Composite Manufacturability and Mechanical-Chemical Resistance
by Janis Baronins, Maksim Antonov, Vitalijs Abramovskis, Aija Rautmane, Vjaceslavs Lapkovskis, Ivans Bockovs, Saurav Goel, Vijay Kumar Thakur and Andrei Shishkin
Polymers 2023, 15(24), 4679; https://doi.org/10.3390/polym15244679 - 12 Dec 2023
Viewed by 1241
Abstract
The widespread use of epoxy resin (ER) in industry, owing to its excellent properties, aligns with the global shift toward greener resources and energy-efficient solutions, where utilizing metal oxides in 3D printed polymer parts can offer extended functionalities across various industries. ZnO concentrations [...] Read more.
The widespread use of epoxy resin (ER) in industry, owing to its excellent properties, aligns with the global shift toward greener resources and energy-efficient solutions, where utilizing metal oxides in 3D printed polymer parts can offer extended functionalities across various industries. ZnO concentrations in polyurethane acrylate composites impacted adhesion and thickness of DLP samples, with 1 wt.% achieving a thickness of 3.99 ± 0.16 mm, closest to the target thickness of 4 mm, while 0.5 wt.% ZnO samples exhibited the lowest deviation in average thickness (±0.03 mm). Tensile stress in digital light processed (DLP) composites with ZnO remained consistent, ranging from 23.29 MPa (1 wt.%) to 25.93 MPa (0.5 wt.%), with an increase in ZnO concentration causing a reduction in tensile stress to 24.04 MPa and a decrease in the elastic modulus to 2001 MPa at 2 wt.% ZnO. The produced DLP samples, with their good corrosion resistance in alkaline environments, are well-suited for applications as protective coatings on tank walls. Customized DLP techniques can enable their effective use as structural or functional elements, such as in Portland cement concrete walls, floors and ceilings for enhanced durability and performance. Full article
(This article belongs to the Special Issue Additive Manufacturing of Polymer Composites)
Show Figures

Figure 1

18 pages, 7508 KiB  
Article
Tensile and Compression Strength Prediction and Validation in 3D-Printed Short-Fiber-Reinforced Polymers
by Timothy Russell and David A. Jack
Polymers 2023, 15(17), 3605; https://doi.org/10.3390/polym15173605 - 30 Aug 2023
Viewed by 835
Abstract
In the current study, a methodology is validated for predicting the internal spatially varying strength properties in a single 3D-printed bead composed of 13%, by weight, carbon-fiber-filled acrylonitrile butadiene styrene. The presented method allows for the characterization of the spatially varying microstructural behavior [...] Read more.
In the current study, a methodology is validated for predicting the internal spatially varying strength properties in a single 3D-printed bead composed of 13%, by weight, carbon-fiber-filled acrylonitrile butadiene styrene. The presented method allows for the characterization of the spatially varying microstructural behavior yielding a local anisotropic stiffness and strength that can be integrated in a finite element framework for a bulk estimate of the effective stiffness and strength. The modeling framework is presented with a focus on composite structures made from large area additive manufacturing (LAAM). LAAM is an extrusion-based process yielding components on the order of meters, with a typical raster size of 10 mm. The presented modeling methods are applicable to other short-fiber-reinforced polymer processing methods as well. The results provided indicate the modeling framework yields results for the effective strength and stiffness that align with experimental characterization to within ∼1% and ∼10% for the longitudinal compressive and tensile strength, respectively, and to within ∼3% and ∼50% for the longitudinal compressive and tensile stiffness, respectively. Full article
(This article belongs to the Special Issue Additive Manufacturing of Polymer Composites)
Show Figures

Figure 1

13 pages, 2916 KiB  
Article
Influence of Post-Processing on the Properties of Multi-Material Parts Obtained by Material Projection AM
by Pablo Zapico, Pablo Rodríguez-González, Pablo Robles-Valero, Ana Isabel Fernández-Abia and Joaquín Barreiro
Polymers 2023, 15(9), 2089; https://doi.org/10.3390/polym15092089 - 27 Apr 2023
Viewed by 893
Abstract
The great geometric complexity that additive manufacturing allows in parts, together with the possibility of combining several materials in the same part, establishes a new design and manufacturing paradigm. Despite the interest of many leading sectors, the lack of standardization still makes it [...] Read more.
The great geometric complexity that additive manufacturing allows in parts, together with the possibility of combining several materials in the same part, establishes a new design and manufacturing paradigm. Despite the interest of many leading sectors, the lack of standardization still makes it necessary to carry out characterization work to enjoy these advantages in functional parts. In many of these techniques, the process does not end with the end of the machine cycle, but different post-processing must be carried out to consider the part finished. It has been found that the type of post process applied can have a similar effect on part quality as other further studied process parameters. In this work, the material projection technique was used to manufacture multi-material parts combining resins with different mechanical properties. The influence of different post-processing on the tensile behavior of these parts was analyzed. The results show the detrimental effect of ultrasonic treatment with isopropyl alcohol in the case of the more flexible resin mixtures, being advisable to use ultrasonic with mineral oil or furnace treatment. For more rigid mixtures, the furnace is the best option, although the other post-processing techniques do not significantly deteriorate their performance. Full article
(This article belongs to the Special Issue Additive Manufacturing of Polymer Composites)
Show Figures

Graphical abstract

27 pages, 12260 KiB  
Article
Prediction of Mechanical Properties for Carbon fiber/PLA Composite Lattice Structures Using Mathematical and ANFIS Models
by Mustafa Saleh, Saqib Anwar, Abdulrahman M Al-Ahmari and Abdullah Yahia AlFaify
Polymers 2023, 15(7), 1720; https://doi.org/10.3390/polym15071720 - 30 Mar 2023
Cited by 5 | Viewed by 1867
Abstract
This study investigates the influence of design, relative density (RD), and carbon fiber (CF) incorporation parameters on mechanical characteristics, including compressive modulus (E), strength, and specific energy absorption (SEA) of triply periodic minimum surface (TPMS) lattice structures. The TPMS lattices were 3D-printed by [...] Read more.
This study investigates the influence of design, relative density (RD), and carbon fiber (CF) incorporation parameters on mechanical characteristics, including compressive modulus (E), strength, and specific energy absorption (SEA) of triply periodic minimum surface (TPMS) lattice structures. The TPMS lattices were 3D-printed by fused filament fabrication (FFF) using polylactic acid (PLA) and carbon fiber-reinforced PLA(CFRPLA). The mechanical properties of the TPMS lattice structures were evaluated under uniaxial compression testing based on the design of experiments (DOE) approach, namely, full factorial design. Prediction modeling was conducted and compared using mathematical and intelligent modeling, namely, adaptive neuro-fuzzy inference systems (ANFIS). ANFIS modeling allowed the 3D printing imperfections (e.g., RD variations) to be taken into account by considering the actual RDs instead of the designed ones, as in the case of mathematical modeling. In this regard, this was the first time the ANFIS modeling utilized the actual RDs. The desirability approach was applied for multi-objective optimization. The mechanical properties were found to be significantly influenced by cell type, cell size, CF incorporation, and RD, as well as their combination. The findings demonstrated a variation in the E (0.144 GPa to 0.549 GPa), compressive strength (4.583 MPa to 15.768 MPa), and SEA (3.759 J/g to 15.591 J/g) due to the effect of the studied variables. The ANFIS models outperformed mathematical models in predicting all mechanical characteristics, including E, strength, and SEA. For instance, the maximum absolute percent deviation was 7.61% for ANFIS prediction, while it was 21.11% for mathematical prediction. The accuracy of mathematical predictions is highly influenced by the degree of RD deviation: a higher deviation in RD indicates a lower accuracy of predictions. The findings of this study provide a prior prediction of the mechanical behavior of PLA and CFRPLA TPMS structures, as well as a better understanding of their potential and limitations. Full article
(This article belongs to the Special Issue Additive Manufacturing of Polymer Composites)
Show Figures

Figure 1

19 pages, 4949 KiB  
Article
Effect of Manufacture-Induced Interfaces on the Tensile Properties of 3D Printed Polyamide and Short Carbon Fibre-Reinforced Polyamide Composites
by Yingwei Hou and Ajit Panesar
Polymers 2023, 15(3), 773; https://doi.org/10.3390/polym15030773 - 02 Feb 2023
Cited by 2 | Viewed by 1493
Abstract
This study aims to elucidate the structure–property–process relationship of 3D printed polyamide and short carbon fibre-reinforced polyamide composites. The macroscopic properties (tensile modulus) of the 3D printed samples are quantitatively correlated to the printing process-induced intrinsic microstructure with multiple interfaces. The samples were [...] Read more.
This study aims to elucidate the structure–property–process relationship of 3D printed polyamide and short carbon fibre-reinforced polyamide composites. The macroscopic properties (tensile modulus) of the 3D printed samples are quantitatively correlated to the printing process-induced intrinsic microstructure with multiple interfaces. The samples were printed with different layer thicknesses (0.1, 0.125 and 0.2 mm) to obtain the varied number of interface densities (number of interfaces per unit sample thickness). The result shows that the printed short carbon fibre-reinforced polyamide composites had inferior partially bonded interfaces compared to the printed polyamide, and consequently exhibited interface-dependent elastic performance. The tensile modulus of 3 mm thick composites decreased up to 18% as a function of interface density, whilst the other influencing aspects including porosity, crystallinity and fibre volume fraction (9%) were the same. Injection moulding was also employed to fabricate samples without induced interfaces, and their tensile properties were used as a benchmark. Predictions based on the shear-lag model were in close agreement (<5%) with the experimental data for the injection-moulded composites, whereas the tensile modulus of the printed composites was up to 38% lower than the predicted modulus due to the partial bonded interfaces. Full article
(This article belongs to the Special Issue Additive Manufacturing of Polymer Composites)
Show Figures

Figure 1

13 pages, 3100 KiB  
Article
A Comparative Analysis of Chemical, Plasma and In Situ Modification of Graphene Nanoplateletes for Improved Performance of Fused Filament Fabricated Thermoplastic Polyurethane Composites Parts
by Xiaojie Zhang, Jianhua Xiao, Jinkuk Kim and Lan Cao
Polymers 2022, 14(23), 5182; https://doi.org/10.3390/polym14235182 - 28 Nov 2022
Cited by 2 | Viewed by 1218
Abstract
The limited number of materials and mechanical weakness of fused deposition modeling (FDM) parts are deficiencies of FDM technology. The preparation of polymer composites parts with suitable filler is a promising method to improve the properties of the 3D printed parts. However, the [...] Read more.
The limited number of materials and mechanical weakness of fused deposition modeling (FDM) parts are deficiencies of FDM technology. The preparation of polymer composites parts with suitable filler is a promising method to improve the properties of the 3D printed parts. However, the agglomerate of filler makes its difficult disperse in the matrix. In this work, graphene nanoplatelets (GnPs) were surface modified with chemical, low-temperature plasma and in situ methods, in order to apply them as fillers for thermoplastic polyurethane (TPU). Following its modification, the surface chemical composition of GnPs was analyzed. Three wt% of surface-modified GnPs were incorporated into TPU to produce FDM filaments using a melting compounding process. Their effects on rheology properties and electrical conductivity on TPU/GnPs composites, as well as the dimensional accuracy and mechanical properties of FDM parts, are compared. The images of sample facture surfaces were examined by scanning electron microscope (SEM) to determine the dispersion of GnPs. Results indicate that chemical treatment of GnPs with zwitterionic surfactant is a good candidate to significantly enhance TPU filaments, when considering the FDM parts demonstrated the highest mechanical properties and lowest dimensional accuracy. Full article
(This article belongs to the Special Issue Additive Manufacturing of Polymer Composites)
Show Figures

Figure 1

19 pages, 5063 KiB  
Article
Improved Electrical Signal of Non-Poled 3D Printed Zinc Oxide-Polyvinylidene Fluoride Nanocomposites
by Sharmad Joshi, Enrique Gazmin, Jayden Glover, Nathan Weeks, Fazeel Khan, Scott Iacono and Giancarlo Corti
Polymers 2022, 14(20), 4312; https://doi.org/10.3390/polym14204312 - 13 Oct 2022
Cited by 4 | Viewed by 1560
Abstract
Polyvinylidene fluoride (PVDF) presents highly useful piezo and pyro electric properties but they are predicated upon the processing methods and the ensuing volume fraction of the β-phase. Production of PVDF with higher β-phase content for additive manufacturing (AM) is particularly desirable [...] Read more.
Polyvinylidene fluoride (PVDF) presents highly useful piezo and pyro electric properties but they are predicated upon the processing methods and the ensuing volume fraction of the β-phase. Production of PVDF with higher β-phase content for additive manufacturing (AM) is particularly desirable because it can enable the creation of custom parts with enhanced properties. Necessary steps from compounding to the testing of a 3D printed piezo sensitive sensor are presented in this paper. AM process variables and the influence of zinc oxide (ZnO) nanofiller on crystallinity, viscosity, and electromechanical properties of PVDF, have been explored. Fourier-transform infrared spectroscopy (FTIR) measurements confirm that a high cooling rate (HCR) of 30 °C min−1 promotes the conversion of the α-into the β-phase, reaching a maximum of 80% conversion with 7.5–12.5% ZnO content. These processing conditions increase the elastic modulus up to 40%, while maintaining the ultimate strength, ≈46 MPa. Furthermore, HCR 10% ZnO-PVDF produces four times higher volts per Newton when compared to low cooling rate, 5 °C min−1, pristine PVDF. A piezoelectric biomedical sensor application has been presented using HCR and ZnO nanofiller. This technique also reduces the need for post-poling which can reduce manufacturing time and cost. Full article
(This article belongs to the Special Issue Additive Manufacturing of Polymer Composites)
Show Figures

Graphical abstract

17 pages, 4553 KiB  
Article
Development and Processing of New Composite Materials Based on High-Performance Semicrystalline Polyimide for Fused Filament Fabrication (FFF) and Their Biocompatibility
by Igor Polyakov, Gleb Vaganov, Andrey Didenko, Elena Ivan’kova, Elena Popova, Yuliya Nashchekina, Vladimir Elokhovskiy, Valentin Svetlichnyi and Vladimir Yudin
Polymers 2022, 14(18), 3803; https://doi.org/10.3390/polym14183803 - 11 Sep 2022
Cited by 6 | Viewed by 1654
Abstract
Samples of composite materials based on high-performance semicrystalline polyimide R-BAPB (based on the dianhydride R: 1,3-bis-(3′,4,-dicarboxyphenoxy)benzene and diamine BAPB: 4,4′-bis-(4″-aminophenoxy)diphenyl)) filled with carbon nanofibers and micron-sized discrete carbon fibers were obtained by FFF printing for the first time. The viscosity of melts of [...] Read more.
Samples of composite materials based on high-performance semicrystalline polyimide R-BAPB (based on the dianhydride R: 1,3-bis-(3′,4,-dicarboxyphenoxy)benzene and diamine BAPB: 4,4′-bis-(4″-aminophenoxy)diphenyl)) filled with carbon nanofibers and micron-sized discrete carbon fibers were obtained by FFF printing for the first time. The viscosity of melts of the composites based on R-BAPB, thermal, mechanical characteristics of the obtained composite samples, their internal structure, and biocompatibility were studied. Simultaneously with FFF printing, samples were obtained by injection molding. The optimal concentrations of carbon fillers in polyimide R-BAPB for their further use in FFF printing were determined. The effect of the incorporation of carbon fillers on the porosity of the printed samples was investigated. It was shown that the incorporation of carbon nanofibers reduces the porosity of the printed samples, which leads to an increase in deformation at break. Modification of polyimide with discrete carbon fibers increases the strength and Young’s modulus sufficiently but decreases the deformation at break. The cytotoxicity analysis showed that the obtained composite materials are bioinert. Full article
(This article belongs to the Special Issue Additive Manufacturing of Polymer Composites)
Show Figures

Figure 1

14 pages, 5047 KiB  
Article
Influence of Rapid Consolidation on Co-Extruded Additively Manufactured Composites
by Chethan Savandaiah, Stefan Sieberer, Bernhard Plank, Julia Maurer, Georg Steinbichler and Janak Sapkota
Polymers 2022, 14(9), 1838; https://doi.org/10.3390/polym14091838 - 29 Apr 2022
Cited by 4 | Viewed by 1923
Abstract
Composite filament co-extrusion (CFC) additive manufacturing (AM) is a bi-matrix rapid fabrication technique that is used to produce highly customisable composite parts. By this method, pre-cured, thermoset-based composite carbon fibre (CCF) is simultaneously extruded along with thermoplastic (TP) binding melt as the matrix. [...] Read more.
Composite filament co-extrusion (CFC) additive manufacturing (AM) is a bi-matrix rapid fabrication technique that is used to produce highly customisable composite parts. By this method, pre-cured, thermoset-based composite carbon fibre (CCF) is simultaneously extruded along with thermoplastic (TP) binding melt as the matrix. Like additive manufacturing, CFC technology also has inherent challenges which include voids, defects and a reduction in CCF’s volume in the fabricated parts. Nevertheless, CFC AM is an emerging composite processing technology, a highly customisable and user-oriented manufacturing unit. A new TP-based composites processing technique has the potential to be synergised with conventional processing techniques such as injection moulding to produce lightweight composite parts. Thus, CFC AM can be a credible technology to replace unsustainable subtractive manufacturing, if only the defects are minimised and processing reliability is achieved. The main objective of this research is to investigate and reduce internal voids and defects by utilising compression pressing as a rapid consolidation post-processing technique. Post-processing techniques are known to reduce the internal voids in AM-manufactured parts, depending on the TP matrices. Accordingly, the rapid consolidated neat polylactic acid (PLA) TP matrix showed the highest reduction in internal voids, approximately 92%. The PLA and polyamide 6 (PA6) binding matrix were reinforced with short carbon fibre (SCF) and long carbon fibre (LCF), respectively, to compensate for the CCF’s fibre volume reduction. An increase in tensile strength (ca. 12%) and modulus (ca. 30%) was observed in SCF-filled PLA. Furthermore, an approximately 53% increase in tensile strength and a 76% increase in modulus for LCF-reinforced PA6 as the binding matrix was observed. Similar trends were observed in CFC and rapidly consolidated CFC specimens’ flexural properties, resulting due to reduced internal voids. Full article
(This article belongs to the Special Issue Additive Manufacturing of Polymer Composites)
Show Figures

Figure 1

22 pages, 10382 KiB  
Article
Development of 3D Printed Biodegradable Mesh with Antimicrobial Properties for Pelvic Organ Prolapse
by Jiongyu Ren, Rebecca Murray, Cynthia S. Wong, Jilong Qin, Michael Chen, Makrina Totsika, Andrew D. Riddell, Andrea Warwick, Nicholas Rukin and Maria A. Woodruff
Polymers 2022, 14(4), 763; https://doi.org/10.3390/polym14040763 - 16 Feb 2022
Cited by 10 | Viewed by 3214
Abstract
To address the increasing demand for safe and effective treatment options for pelvic organ prolapse (POP) due to the worldwide ban of the traditional polypropylene meshes, this study introduced degradable polycaprolactone (PCL)/polyethylene glycol (PEG) composite meshes fabricated with melt-electrowriting (MEW). Two PCL/PEG mesh [...] Read more.
To address the increasing demand for safe and effective treatment options for pelvic organ prolapse (POP) due to the worldwide ban of the traditional polypropylene meshes, this study introduced degradable polycaprolactone (PCL)/polyethylene glycol (PEG) composite meshes fabricated with melt-electrowriting (MEW). Two PCL/PEG mesh groups: 90:10 and 75:25 (PCL:PEG, wt%) were fabricated and characterized for their degradation rate and mechanical properties, with PCL meshes used as a control. The PCL/PEG composites showed controllable degradation rates by adjusting the PEG content and produced mechanical properties, such as maximal forces, that were higher than PCL alone. The antibacterial properties of the meshes were elicited by coating them with a commonly used antibiotic: azithromycin. Two dosage levels were used for the coating: 0.5 mg and 1 mg per mesh, and both dosage levels were found to be effective in suppressing the growth of S. aureus bacteria. The biocompatibility of the meshes was assessed using human immortalized adipose derived mesenchymal stem cells (hMSC). In vitro assays were used to assess the cell viability (LIVE/DEAD assay), cell metabolic activity (alamarBlue assay) and cell morphology on the meshes (fluorescent and electron microscopy). The cell attachment was found to decrease with increased PEG content. The freshly drug-coated meshes showed signs of cytotoxicity during the cell study process. However, when pre-released for 14 days in phosphate buffered saline, the initial delay in cell attachment on the drug-coated mesh groups showed full recovery at the 14-day cell culture time point. These results indicated that the PCL/PEG meshes with antibiotics coating will be an effective anti-infectious device when first implanted into the patients, and, after about 2 weeks of drug release, the mesh will be supporting cell attachment and proliferation. These meshes demonstrated a potential effective treatment option for POP that may circumvent the issues related to the traditional polypropylene meshes. Full article
(This article belongs to the Special Issue Additive Manufacturing of Polymer Composites)
Show Figures

Figure 1

16 pages, 5222 KiB  
Article
Additive Manufacturing and Characterization of Metal Particulate Reinforced Polylactic Acid (PLA) Polymer Composites
by Ved S. Vakharia, Lily Kuentz, Anton Salem, Michael C. Halbig, Jonathan A. Salem and Mrityunjay Singh
Polymers 2021, 13(20), 3545; https://doi.org/10.3390/polym13203545 - 14 Oct 2021
Cited by 18 | Viewed by 2845
Abstract
Affordable commercial desktop 3-D printers and filaments have introduced additive manufacturing to all disciplines of science and engineering. With rapid innovations in 3-D printing technology and new filament materials, material vendors are offering specialty multifunctional metal-reinforced polymers with unique properties. Studies are necessary [...] Read more.
Affordable commercial desktop 3-D printers and filaments have introduced additive manufacturing to all disciplines of science and engineering. With rapid innovations in 3-D printing technology and new filament materials, material vendors are offering specialty multifunctional metal-reinforced polymers with unique properties. Studies are necessary to understand the effects of filament composition, metal reinforcements, and print parameters on microstructure and mechanical behavior. In this study, densities, metal vol%, metal cross-sectional area %, and microstructure of various metal-reinforced Polylactic Acid (PLA) filaments were characterized by multiple methods. Comparisons are made between polymer microstructures before and after printing, and the effect of printing on the metal-polymer interface adhesion has been demonstrated. Tensile response and fracture toughness as a function of metal vol% and print height was determined. Tensile and fracture toughness tests show that PLA filaments containing approximately 36 vol% of bronze or copper particles significantly reduce mechanical properties. The mechanical response of PLA with 12 and 18 vol% of magnetic iron and stainless steel particles, respectively, is similar to that of pure PLA with a slight decrease in ultimate tensile strength and fracture toughness. These results show the potential for tailoring the concentration of metal reinforcements to provide multi-functionality without sacrificing mechanical properties. Full article
(This article belongs to the Special Issue Additive Manufacturing of Polymer Composites)
Show Figures

Figure 1

Back to TopTop