Special Issue "Polymeric Foams II"

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

Deadline for manuscript submissions: 25 December 2020.

Special Issue Editors

Prof. Dr. José Ignacio Velasco
Website
Guest Editor
Universitat Politecnica de Catalunya, Centre Català del Plàstic, Barcelona, Spain
Interests: polymers; composites; foams; nanocomposites
Special Issues and Collections in MDPI journals
Dr. Marcelo Antunes
Website
Guest Editor
Department of Materials Science and Metallurgy, School of Industrial, Aerospace and Audiovisual Engineering (ESEIAAT), Technical University of Catalonia (UPC BarcelonaTech), Terrassa Campus, Building TR5. C. Colom 11, E-08222 Terrassa, Barcelona, Spain
Interests: polymers; composites; foams; nanocomposites
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

Polymeric foams have been gaining increasing interest in emerging sectors that demand increasingly more efficient materials to fulfill complex technical requirements, including enhanced specific properties and reduced energy consumption, among others. Polymeric foams, in particular, have been shown to display great versatility in recent years, both in terms of microstructure control and final properties, such as secondary rigid phases. Control of microstructure and final properties are influenced by the constituent nanoparticles that are dispersed throughout the polymer matrix (“nanocomposite foams”), which have been carefully chosen based on these considerations. In addition, new advanced foaming technologies have also been developed in recent years. These two strategies have allowed for the generation of new polymer-based foams with micro-, submicro-, or even nanocellular structures, extending the already vast array of applications of polymer foams and opening brand new possibilities, such as in tissue engineering, high temperature applications, and catalysis.

This Special Issue is the continuation of a published Special Issue entitled “Polymeric Foams”, which contains a total of 23 articles that dealt with all aspects of some of the most recent research of novel polymer-based foams, from thermoset-based to thermoplastic and even syntactic foams, including their design, composition (focusing on the addition of functional nanoparticles), processing and fabrication, microstructure, applications, service behavior, or recycling and reuse. This first volume (Polymeric Foams) is a testament to the great deal of interest in these materials and fully justifies the expansion to a second Special Issue on this topic.
Manuscripts related to the following topics are of interest for this Special Issue:

  • Thermoplastic, thermosetting, and elastomeric polymer foams;
  • Syntactic foams;
  • Biopolymer foams;
  • High temperature polymer foams;
  • Nanocomposite foams;
  • Microcellular, submicrocellular, and nanocellular foams;
  • Closed-cell, open-cell, and interconnected-cell foams;
  • Unimodal and multimodal foams;
  • Chemical and physical foaming methods;
  • Novel foaming methods;
  • Foams for 3D printing;
  • Recycling of foams;
  • PLA-based and other biodegradable foams;
  • Flame-retardant foams;
  • Thermally and electrically conductive polymer foams;
  • Modeling of polymeric foams;
  • New applications of foams, including electronics, batteries, fuel cells, catalysis, separation and filtration, gas absorption, electromagnetic interference (EMI) shielding, electrostatic discharge (ESD), electrostatic painting, tissue engineering, sandwich-like materials, and many more.

Prof. José Ignacio Velasco
Dr. Marcelo Antunes
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. Polymers 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 1800 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

  • polymeric foams
  • cellular composites
  • microcellular foams
  • nanocomposite foams
  • functional foams
  • new applications of foams

Related Special Issue

Published Papers (6 papers)

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Research

Open AccessArticle
Expanded Polycarbonate (EPC)—A New Generation of High-Temperature Engineering Bead Foams
Polymers 2020, 12(10), 2314; https://doi.org/10.3390/polym12102314 - 10 Oct 2020
Abstract
Bead foams serve in a wide variety of applications, from insulation and packaging to midsoles in shoes. However, the currently used materials are limited to somewhat low temperature or exhibit significant changes in modulus in the temperature range of many applications due to [...] Read more.
Bead foams serve in a wide variety of applications, from insulation and packaging to midsoles in shoes. However, the currently used materials are limited to somewhat low temperature or exhibit significant changes in modulus in the temperature range of many applications due to their glass transition. By comparison, polycarbonate (PC) exhibits almost constant mechanics for temperatures up to 130 °C. Therefore, it appears as an advantageous base material for bead foams. The aim of the publication is to provide comprehensive data on the properties of expanded PC (EPC) in comparison to already commercially available expanded polypropylene, EPP, and expanded polyethylene-terephthalate, EPET. A special focus is set on the thermo-mechanical properties as these are the most lacking features in current materials. In this frame, dynamic mechanical analysis, and tensile, bending, compression and impact tests at room temperature (RT), 80 °C, and 110 °C are conducted for the three materials of the same density. Already at RT, EPC exhibits superior mechanics compared to its peers, which becomes more pronounced toward higher temperature. This comes from the low sensitivity of properties to temperature as EPC is used below its glass transition. In summary, EPC proves to be an outstanding foam material over a broad range of temperatures for structural applications. Full article
(This article belongs to the Special Issue Polymeric Foams II)
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Open AccessArticle
Low-Density Polybutylene Terephthalate Foams with Enhanced Compressive Strength via a Reactive-Extrusion Process
Polymers 2020, 12(9), 2021; https://doi.org/10.3390/polym12092021 - 04 Sep 2020
Abstract
Due to their appealing properties such as high-temperature dimensional stability, chemical resistance, compressive strength and recyclability, new-generation foams based on engineering thermoplastics such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) have been gaining significant attention. Achieving low-density foams without sacrificing the mechanical [...] Read more.
Due to their appealing properties such as high-temperature dimensional stability, chemical resistance, compressive strength and recyclability, new-generation foams based on engineering thermoplastics such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) have been gaining significant attention. Achieving low-density foams without sacrificing the mechanical properties is of vital importance for applications in the field of transportation and construction, where sufficient compressive strength is desired. In contrast to numerous research studies on PET foams, only a limited number of studies on PBT foams and in particular, on extruded PBT foams are known. Here we present a novel route to extruded PBT foams with densities as low as 80 kg/m3 and simultaneously with improved compressive properties manufactured by a tandem reactive-extrusion process. Improved rheological properties and therefore process stability were achieved using two selected 1,3,5-benzene-trisamides (BTA1 and BTA2), which are able to form supramolecular nanofibers in the PBT melt upon cooling. With only 0.08 wt % of BTA1 and 0.02 wt % of BTA2 the normalized compressive strength was increased by 28% and 15%, respectively. This improvement is assigned to the intrinsic reinforcing effect of BTA fibers in the cell walls and struts. Full article
(This article belongs to the Special Issue Polymeric Foams II)
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Open AccessArticle
Foams with Enhanced Ductility and Impact Behavior Based on Polypropylene Composites
Polymers 2020, 12(4), 943; https://doi.org/10.3390/polym12040943 - 18 Apr 2020
Abstract
In this work, formulations based on composites of a linear polypropylene (L-PP), a long-chain branched polypropylene (LCB-PP), a polypropylene–graft–maleic anhydride (PP-MA), a styrene-ethylene-butylene-styrene copolymer (SEBS), glass fibers (GF), and halloysite nanotubes (HNT-QM) have been foamed by using the improved compression molding [...] Read more.
In this work, formulations based on composites of a linear polypropylene (L-PP), a long-chain branched polypropylene (LCB-PP), a polypropylene–graft–maleic anhydride (PP-MA), a styrene-ethylene-butylene-styrene copolymer (SEBS), glass fibers (GF), and halloysite nanotubes (HNT-QM) have been foamed by using the improved compression molding route (ICM), obtaining relative densities of about 0.62. The combination of the inclusion of elastomer and rigid phases with the use of the LCB-PP led to foams with a better cellular structure, an improved ductility, and considerable values of the elastic modulus. Consequently, the produced foams presented simultaneously an excellent impact performance and a high stiffness with respect to their corresponding solid counterparts. Full article
(This article belongs to the Special Issue Polymeric Foams II)
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Open AccessArticle
Warp-Knitted Spacer Fabric Reinforced Syntactic Foam: A Compression Modulus Meso-Mechanics Theoretical Model and Experimental Verification
Polymers 2020, 12(2), 286; https://doi.org/10.3390/polym12020286 - 01 Feb 2020
Cited by 1
Abstract
In this study, a new type ternary composite, called warp-knitted spacer fabric reinforced syntactic foam (WKSF-SF), with the advantages of high mechanical properties and a lower density, was proposed. Then, a meso-mechanics theoretical model based on the Eshelby–Mori–Tanaka equivalent inclusion method, average stress [...] Read more.
In this study, a new type ternary composite, called warp-knitted spacer fabric reinforced syntactic foam (WKSF-SF), with the advantages of high mechanical properties and a lower density, was proposed. Then, a meso-mechanics theoretical model based on the Eshelby–Mori–Tanaka equivalent inclusion method, average stress method and composite hybrid theory was established to predict the compression modulus of WKSF-SF. In order to verify the validity of this model, compression modulus values of theoretical simulations were compared with the quasi-static compression experiment results. The results showed that the addition of suitable WKSF produces at least 15% improvement in the compressive modulus of WKSF-SF compared with neat syntactic foam (NSF). Meanwhile, the theoretical model can effectively simulate the values and variation tendency of the compression modulus for different WKSF-SF samples, and is especially suitable for the samples with smaller wall thickness or a moderate volume fraction of microballoons (the deviations is less than 5%). The study of the meso-mechanical properties of WKSF-SF will help to increase understanding of the compression properties of this new type composite deeply. It is expected that WKSF-SF can be used in aerospace, marine, transportation, construction, and other fields. Full article
(This article belongs to the Special Issue Polymeric Foams II)
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Open AccessArticle
A Novel Hybrid Foaming Method for Low-Pressure Microcellular Foam Production of Unfilled and Talc-Filled Copolymer Polypropylenes
Polymers 2019, 11(11), 1896; https://doi.org/10.3390/polym11111896 - 17 Nov 2019
Cited by 3
Abstract
Unfilled and talc-filled Copolymer Polypropylene (PP) samples were produced through low-pressure foam-injection molding (FIM). The foaming stage of the process has been facilitated through a chemical blowing agent (C6H7NaO7 and CaCO3 mixture), a physical blowing agent (supercritical [...] Read more.
Unfilled and talc-filled Copolymer Polypropylene (PP) samples were produced through low-pressure foam-injection molding (FIM). The foaming stage of the process has been facilitated through a chemical blowing agent (C6H7NaO7 and CaCO3 mixture), a physical blowing agent (supercritical N2) and a novel hybrid foaming (combination of said chemical and physical foaming agents). Three weight-saving levels were produced with the varying foaming methods and compared to conventional injection molding. The unfilled PP foams produced through chemical blowing agent exhibited the strongest mechanical characteristics due to larger skin wall thicknesses, while the weakest were that of the talc-filled PP through the hybrid foaming technique. However, the hybrid foaming produced superior microcellular foams for both PPs due to calcium carbonate (CaCO3) enhancing the nucleation phase. Full article
(This article belongs to the Special Issue Polymeric Foams II)
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Open AccessArticle
Fabrication of Poly(butylene succinate)/Carbon Black Nanocomposite Foams with Good Electrical Conductivity and High Strength by a Supercritical CO2 Foaming Process
Polymers 2019, 11(11), 1852; https://doi.org/10.3390/polym11111852 - 10 Nov 2019
Cited by 5
Abstract
Lightweight, high-strength and electrically conductive poly(butylene succinate) (PBS)/ carbon black (CB) nanocomposite foams with a density of 0.107–0.344 g/cm3 were successfully fabricated by a solid-state supercritical CO2 (ScCO2) foaming process. The morphology, thermal and dynamic mechanical properties, and rheological [...] Read more.
Lightweight, high-strength and electrically conductive poly(butylene succinate) (PBS)/ carbon black (CB) nanocomposite foams with a density of 0.107–0.344 g/cm3 were successfully fabricated by a solid-state supercritical CO2 (ScCO2) foaming process. The morphology, thermal and dynamic mechanical properties, and rheological behavior of the PBS/CB nanocomposites were studied. The results indicate that the CB nanofiller was well dispersed in the PBS matrix and the presence of a proper CB nanofiller can accelerate the rate of crystallization, improve the thermal stability, enhance the stiffness, and increase the complex viscosity of PBS/CB nanocomposites. These improved properties were found to play an important role in the foaming process. The results from foaming experiments showed that the PBS/CB nanocomposite foams had a much smaller cell size, a higher cell density, and a more uniform cell morphology as compared to neat PBS foams. Furthermore, the PBS/CB nanocomposite foams also possessed low density (0.107–0.344 g/cm3), good electrical conductivity (~0.45 S/cm at 1.87 vol % CB loading), and improved compressive strength (108% increase), which enables them to be used as lightweight and high-strength functional materials. Full article
(This article belongs to the Special Issue Polymeric Foams II)
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