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Special Issue "Recycled Materials, Eco-design and 3D Printing"

A special issue of Materials (ISSN 1996-1944).

Deadline for manuscript submissions: 31 January 2018

Special Issue Editors

Guest Editor
Prof. Dr. Francesco Colangelo

Univ Naples Parthenope, Department of Civil Engineering Ctr Direz, Isola C4, 80143 Naples, Italy
Website | E-Mail
Interests: recycled materials; waste treatment; green composites; ecodesign; LCA
Guest Editor
Prof. Dr. Fernando Fraternali

University of Salerno, Department of Civil Engineering, Via G. Paolo II, 13, 84084 - Fisciano (SA), Italy
Website | E-Mail
Interests: mechanics of solids and structures; multiscale mechanics; computational mechanics; lattice materials; mechanical metamaterials
Guest Editor
Prof. Dr. Luciano Feo

University of Salerno, Department of Civil Engineering, Via G. Paolo II, 13, 84084 - Fisciano (SA), Italy
Website | E-Mail
Interests: mechanics of solids and structures, multiscale mechanics, computational mechanics, advanced mechanical modeling of new materials and structures, innovative composite materials

Special Issue Information

Dear Colleagues,

Human activities use a huge amount of raw materials which often implicates high energy consumption. The manufacturing, transport, use, and disposal of the materials employed, in fact, require a large quantity of energy, in spite of them contributing, in minimal part, to the ultimate cost of the object produced.

Unluckily, industrial activities do not often allow for a true cradle-to-cradle itinerary during a material lifecycle. Instead, in many cases, downcycling of high quality to low-quality material is the only available option. Ecodesign is an approach to designing products with special consideration for the environmental impacts of the product during its whole lifecycle. One of the most hopeful prospects to improve the recycling of materials is to study also the possibility to use wastes for the 3D printing process. The Ecodesign Directive provides consistent EU-wide rules for improving the environmental performance of products.

In a life cycle assessment, the life cycle of a product is usually divided into transport, manufacture, use, and disposal. The goal of the Special Issue “Recycled Materials, Eco-Design and 3D Printing” is to encourage and foster research and development in the broad field of innovative materials and to provide a forum for innovative applications of sustainable material recycling and upcycling. This Special Issue aims to collect the most recent advances from the global research regarding recycling in engineering, eco-friendly building materials (cement and geopolymer based), eco-design, energy storage material, durability and service life, hybrid innovative materials, multiscale innovative materials and structures, lattice 3D printing materials, Life Cycle Assessment (LCA) and material science, as well as innovative strategies for Recycling, “Closed loop recycling”,  Re-Use, and Upcycling.

Prof. Dr. Francesco Colangelo
Prof. Dr. Fernando Fraternali
Prof. Dr. Luciano Feo
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 papers will be 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. Materials is an international peer-reviewed open access monthly 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 1500 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

  • Eco-friendly building materials
  • Green materials
  • Life Cycle Assessment
  • 3D printing materials
  • Multiscale innovative materials and structures
  • Innovative composite materials

Published Papers (6 papers)

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Research

Open AccessArticle Characterization of Sheep Wool as a Sustainable Material for Acoustic Applications
Materials 2017, 10(11), 1277; doi:10.3390/ma10111277
Received: 29 September 2017 / Revised: 2 November 2017 / Accepted: 3 November 2017 / Published: 7 November 2017
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Abstract
In recent years, natural materials are becoming a valid alternative to traditional sound absorbers due to reduced production costs and environmental protection. This paper reports the acoustical characterization of sheep wool. Measurements on normal incidence and diffuse-incidence sound absorption coefficients of different samples
[...] Read more.
In recent years, natural materials are becoming a valid alternative to traditional sound absorbers due to reduced production costs and environmental protection. This paper reports the acoustical characterization of sheep wool. Measurements on normal incidence and diffuse-incidence sound absorption coefficients of different samples are reported. The airflow resistance has also been measured. The results prove that sheep wool has a comparable sound absorption performance to that of mineral wool or recycled polyurethane foam. An empirical model is used to calculate the sound absorption of sheep wool samples. A reasonable agreement on the acoustic absorption of all sheep wool samples is obtained. Full article
(This article belongs to the Special Issue Recycled Materials, Eco-design and 3D Printing)
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Open AccessArticle On the Role of Processing Parameters in Producing Recycled Aluminum AA6061 Based Metal Matrix Composite (MMC-AlR) Prepared Using Hot Press Forging (HPF) Process
Materials 2017, 10(9), 1098; doi:10.3390/ma10091098
Received: 20 June 2017 / Revised: 25 August 2017 / Accepted: 28 August 2017 / Published: 19 September 2017
PDF Full-text (5933 KB) | HTML Full-text | XML Full-text
Abstract
Solid-state recycling, which involves the direct recycling of scrap metal into bulk material using severe plastic deformation, has emerged as a potential alternative to the conventional remelting and recycling techniques. Hot press forging has been identified as a sustainable direct recycling technique that
[...] Read more.
Solid-state recycling, which involves the direct recycling of scrap metal into bulk material using severe plastic deformation, has emerged as a potential alternative to the conventional remelting and recycling techniques. Hot press forging has been identified as a sustainable direct recycling technique that has fewer steps and maintains excellent material performance. An experimental investigation was conducted to explore the hardness and density of a recycled aluminum-based metal matrix composite by varying operating temperature and holding time. A mixture of recycled aluminum, AA6061, and aluminum oxide were simultaneously heated to 430, 480, and 530 °C and forged for 60, 90, and 120 min. We found a positive increase in microhardness and density for all composites. The hardness increased approximately 33.85%, while density improved by about 15.25% whenever the temperature or the holding time were increased. Based on qualitative analysis, the composite endures substantial plastic deformation due to the presence of hardness properties due to the aluminum oxide embedded in the aluminum matrix. These increases were significantly affected by the operating temperature; the holding time also had a subordinate role in enhancing the metal matrix composite properties. Furthermore, in an effort to curb the shortage of primary resources, this study reviewed the promising performance of secondary resources produced by using recycled aluminum and aluminum oxide as the base matrix and reinforcement constituent, respectively. This study is an outline for machining practitioners and the manufacturing industry to help increase industry sustainability with the aim of preserving the Earth for our community in the future. Full article
(This article belongs to the Special Issue Recycled Materials, Eco-design and 3D Printing)
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Open AccessArticle Bonding Behavior of Deformed Steel Rebars in Sustainable Concrete Containing both Fine and Coarse Recycled Aggregates
Materials 2017, 10(9), 1082; doi:10.3390/ma10091082
Received: 15 August 2017 / Revised: 12 September 2017 / Accepted: 13 September 2017 / Published: 14 September 2017
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Abstract
In order to assess the bond behavior of deformed steel rebars in recycled-aggregate concrete (RAC) incorporating both fine and coarse recycled aggregate, pull-out tests were carried out in this study on 16-mm diameter deformed steel rebars embedded concentrically in RAC. The concrete was
[...] Read more.
In order to assess the bond behavior of deformed steel rebars in recycled-aggregate concrete (RAC) incorporating both fine and coarse recycled aggregate, pull-out tests were carried out in this study on 16-mm diameter deformed steel rebars embedded concentrically in RAC. The concrete was designed using equivalently mixed proportions of both recycled coarse aggregate and recycled fine aggregate. The tests employed five types of recycled aggregate replacement combinations and three types of rebar placement orientation (i.e., vertical bars and two-tiered and three-tiered horizontal bars). Based on the pull-out test results, the maximum bond strength tended to decrease and the slip at the maximum bond strength increased as the average water absorption of the aggregate increased, irrespective of the rebar orientation or placement location within the concrete member. The pull-out test results for the horizontal steel rebars embedded in RAC indicate that the casting position effect could be determined from the mid-depth of the concrete member, irrespective of the member’s height. The normalized bond versus slip relationship between the deformed rebar and the RAC could be predicted using an empirical model based on regression analysis of the experimental data. Full article
(This article belongs to the Special Issue Recycled Materials, Eco-design and 3D Printing)
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Open AccessArticle Green Composites Based on Blends of Polypropylene with Liquid Wood Reinforced with Hemp Fibers: Thermomechanical Properties and the Effect of Recycling Cycles
Materials 2017, 10(9), 998; doi:10.3390/ma10090998
Received: 20 July 2017 / Revised: 22 August 2017 / Accepted: 23 August 2017 / Published: 26 August 2017
Cited by 1 | PDF Full-text (4953 KB) | HTML Full-text | XML Full-text
Abstract
Green composites from polypropylene and lignin-based natural material were manufactured using a melt extrusion process. The lignin-based material used was the so called “liquid wood”. The PP/“Liquid Wood” blends were extruded with “liquid wood” content varying from 20 wt % to 80 wt
[...] Read more.
Green composites from polypropylene and lignin-based natural material were manufactured using a melt extrusion process. The lignin-based material used was the so called “liquid wood”. The PP/“Liquid Wood” blends were extruded with “liquid wood” content varying from 20 wt % to 80 wt %. The blends were thoroughly characterized by flexural, impact, and dynamic mechanical testing. The addition of the Liquid Wood resulted in a great improvement in terms of both the flexural modulus and strength but, on the other hand, a reduction of the impact strength was observed. For one blend composition, the composites reinforced with hemp fibers were also studied. The addition of hemp allowed us to further improve the mechanical properties. The composite with 20 wt % of hemp, subjected to up to three recycling cycles, showed good mechanical property retention and thermal stability after recycling. Full article
(This article belongs to the Special Issue Recycled Materials, Eco-design and 3D Printing)
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Open AccessArticle Hot Press as a Sustainable Direct Recycling Technique of Aluminium: Mechanical Properties and Surface Integrity
Materials 2017, 10(8), 902; doi:10.3390/ma10080902
Received: 5 June 2017 / Revised: 18 July 2017 / Accepted: 19 July 2017 / Published: 3 August 2017
Cited by 1 | PDF Full-text (9217 KB) | HTML Full-text | XML Full-text
Abstract
Meltless recycling technique has been utilized to overcome the lack of primary resources, focusing on reducing the usage of energy and materials. Hot press was proposed as a novel direct recycling technique which results in astoundingly low energy usage in contrast with conventional
[...] Read more.
Meltless recycling technique has been utilized to overcome the lack of primary resources, focusing on reducing the usage of energy and materials. Hot press was proposed as a novel direct recycling technique which results in astoundingly low energy usage in contrast with conventional recycling. The aim of this study is to prove the technical feasibility of this approach by characterizing the recycled samples. For this purpose, AA6061 aluminium chips were recycled by utilizing hot press process under various operating temperature (Ts = 430, 480, and 530 °C) and holding times (ts = 60, 90, and 120 min). The maximum mechanical properties of recycled chip are Ultimate tensile strength (UTS) = 266.78 MPa, Elongation to failure (ETF) = 16.129%, while, for surface integrity of the chips, the calculated microhardness is 81.744 HV, exhibited at Ts = 530 °C and ts = 120 min. It is comparable to theoretical AA6061 T4-temper where maximum UTS and microhardness is increased up to 9.27% and 20.48%, respectively. As the desired mechanical properties of forgings can only be obtained by means of a final heat treatment, T5-temper, aging after forging process was employed. Heat treated recycled billet AA6061 (T5-temper) are considered comparable with as-received AA6061 T6, where the value of microhardness (98.649 HV) at 175 °C and 120 min of aging condition was revealed to be greater than 3.18%. Although it is quite early to put a base mainly on the observations in experimental settings, the potential for significant improvement offered by the direct recycling methods for production aluminium scrap can be clearly demonstrated. This overtures perspectives for industrial development of solid state recycling processes as environmentally benign alternatives of current melting based practices. Full article
(This article belongs to the Special Issue Recycled Materials, Eco-design and 3D Printing)
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Open AccessFeature PaperArticle Investigations for Thermal and Electrical Conductivity of ABS-Graphene Blended Prototypes
Materials 2017, 10(8), 881; doi:10.3390/ma10080881
Received: 2 July 2017 / Revised: 16 July 2017 / Accepted: 25 July 2017 / Published: 31 July 2017
Cited by 1 | PDF Full-text (3516 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The thermoplastic materials such as acrylonitrile-butadiene-styrene (ABS) and Nylon have large applications in three-dimensional printing of functional/non-functional prototypes. Usually these polymer-based prototypes are lacking in thermal and electrical conductivity. Graphene (Gr) has attracted impressive enthusiasm in the recent past due to its natural
[...] Read more.
The thermoplastic materials such as acrylonitrile-butadiene-styrene (ABS) and Nylon have large applications in three-dimensional printing of functional/non-functional prototypes. Usually these polymer-based prototypes are lacking in thermal and electrical conductivity. Graphene (Gr) has attracted impressive enthusiasm in the recent past due to its natural mechanical, thermal, and electrical properties. This paper presents the step by step procedure (as a case study) for development of an in-house ABS-Gr blended composite feedstock filament for fused deposition modelling (FDM) applications. The feedstock filament has been prepared by two different methods (mechanical and chemical mixing). For mechanical mixing, a twin screw extrusion (TSE) process has been used, and for chemical mixing, the composite of Gr in an ABS matrix has been set by chemical dissolution, followed by mechanical blending through TSE. Finally, the electrical and thermal conductivity of functional prototypes prepared from composite feedstock filaments have been optimized. Full article
(This article belongs to the Special Issue Recycled Materials, Eco-design and 3D Printing)
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