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Polymers
Special Issues
State-of-the-Art Polymer Science and Technology in Portugal (2020,2021)
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State-of-the-Art Polymer Science and Technology in Portugal (2020,2021)

A special issue of Polymers (ISSN 2073-4360).

Deadline for manuscript submissions: closed (30 April 2022) | Viewed by 17520

Special Issue Editors

Dr. Fernão D. Magalhães

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Guest Editor
1. LEPABE, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal
2. ALiCE, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal
Interests: synthetic and natural adhesives; lignocellulosic composites; graphene-based biomaterials
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Geoffrey R. Mitchell

E-Mail Website
Guest Editor
Centre for Rapid and Sustainable Product Development, Institute Polytechnic of Leiria, Rua de Portugal, 2430-028 Marinha Grande, Portugal
Interests: energy storage devices; additive manufacturing; X-ray and neutron scattering; functional materials; electrically conductive polymers; electrochemistry; digital twins
Special Issues, Collections and Topics in MDPI journals
Dr. Marta Otero

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Guest Editor
Department of Applied Chemistry and Physics, University of León, León, Spain
Interests: water pollution and contamination; water and wastewater treatment: global treatment systems; sustainable treatment processes; clean and alternative technologies; waste management and valorization; alternative adsorbent materials; alternative photocatalysts
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. José António Covas

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Guest Editor
Department of Polymer Engineering, University of Minho, Campus de Azurém, 4800-058 Guimarães, Portugal
Interests: polymer processing and micro-processing (monitoring, optimization, technology, biodegradable materials); compounding (preparation of composites and nanocomposites, polymer blending and modification); additive manufacturing; polymer characterization (rheology and morphology)
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Portugal is a rapidly developing country that aims to be the manufacturing powerhouse of Europe. Traditional industries, such as glass-making, have morphed into the third-largest centre of mould-making for plastic processing. Portugal has an emerging biomedical and pharmaceutical industry and is a leader in the implementation of 3G and 5G. As a country that borders both the Atlantic and the Mediterranean, Portugal has a strong interest in the marine industries and in environmental issues. In recent times, Portugal has generated all of its electrical energy from renewable sources, including wind and hydroelectric sources, and solar farms are emerging. In the same vein, there is a focus in many research centres on biopolymers and other natural resources and the entire circular economy.  A network of almost 400 publically funded research units in Universities and Polytechnics provides the core of research together with the Ministry of Science through the Foundation for Science and Technology. Other notable research institutes include the Instituto Gulbenkian de Ciência, which is an international centre for biomedical research and graduate education in Oeiras, the Champalimaud Foundation, which is based in Lisbon and focused on neuroscience and oncology, and the International Iberian Nanotechnology Laboratory in Braga. A particular feature of research in Portugal is the multidisciplinary nature of the research teams and the diverse areas of Polymer Science including  Chemistry, Physics, Polymer Engineering, Chemical Engineering, Mechanical Engineering, Bioengineering and Materials Science, and Medical Applications. The focus of the research ranges from synthesis and characterization to processing and fabrication, involving work with synthetic, artificial, and natural polymers. Novel developments very often translate into innovative real-world products and processes, thanks to close collaborations with industry, in fields such as coatings, adhesives, foams, paper, textiles, packaging, and composites, which are often supported by the Agência Nacional de Inovação (ANI).

This Special Issue intends to present a collection of original research and review articles that provide an overview of current work on Polymer Science in Portugal. Potential research topics include, but are not limited to:

  • polymer synthesis and modification;
  • physical characterization;
  • biodegradability;
  • functional polymers;
  • biosourced polymers;
  • biomaterials;
  • supramolecular structures;
  • property–structure relationships;
  • composites and nanocomposites;
  • modeling of reaction engineering and processing;
  • technological applications;
  • environmental applications;
  • additive manufacturing;
  • polymers for a circular economy

Prof. Dr. Fernão D. Magalhães
Prof. Dr. Geoffrey R. Mitchell
Dr. Marta Otero
Prof. Dr. José António Covas
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

  • Synthesis and modification
  • Characterization
  • Biodegradability
  • Biosourced polymers
  • Composites
  • Modelling
  • Processing
  • Circular economy

Published Papers (6 papers)

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Research

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14 pages, 5279 KiB  
Article
Changing the Paradigm-Controlling Polymer Morphology during 3D Printing Defines Properties
by Daniel P. da Silva, João Pinheiro, Saba Abdulghani, Christina Kamma Lorger, Juan Carlos Martinez, Eduardo Solano, Artur Mateus, Paula Pascoal-Faria and Geoffrey R. Mitchell
Polymers 2022, 14(9), 1638; https://doi.org/10.3390/polym14091638 - 19 Apr 2022
Cited by 3 | Viewed by 2635
Abstract
Direct digital manufacturing consists of a set of techniques that enable products to be fabricated directly from their digital definition, without the use of complex tooling or moulds. This manufacturing approach streamlines prototyping and small-scale production, as well as the mass customization of [...] Read more.
Direct digital manufacturing consists of a set of techniques that enable products to be fabricated directly from their digital definition, without the use of complex tooling or moulds. This manufacturing approach streamlines prototyping and small-scale production, as well as the mass customization of parts with complex designs immediately fixed before fabrication. With broad applicability, there are clearly opportunities in the field of medical devices for its use. However, many of the developments of direct digital manufacturing focus on simply specifying the shape or the form of the product, and this limited scope throws away many of the particular advantages of direct digital manufacturing. This work is focused on remedying this situation so that the digital specification of the fabricated product includes the properties as well as the form of the product. We use in situ time-resolving small-angle X-ray scattering measurements performed at the ALBA Synchrotron Light Source in Barcelona to evaluate the control that can be exerted on the morphology of a semi-crystalline polymer during extruder-based 3D printing. We use this as a methodology for printing the patterns of the morphology of the polymer to realise the patterns of properties of the polymeric material, specifically the modulus of the polymer. We give an example of products produced in this manner that contain spatial variation in their properties. Full article
(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Portugal (2020,2021))
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19 pages, 5648 KiB  
Article
On-Line Optical Monitoring of the Mixing Performance in Co-Rotating Twin-Screw Extruders
by Felipe Bernardo, José A. Covas and Sebastião V. Canevarolo
Polymers 2022, 14(6), 1152; https://doi.org/10.3390/polym14061152 - 14 Mar 2022
Cited by 4 | Viewed by 2261
Abstract
The use of real-time techniques to evaluate the global mixing performance of co-rotating twin-screw extruders is well consolidated, but much less is reported on the specific contribution of individual screw zones. This work uses on-line flow turbidity and birefringence to ascertain the mixing [...] Read more.
The use of real-time techniques to evaluate the global mixing performance of co-rotating twin-screw extruders is well consolidated, but much less is reported on the specific contribution of individual screw zones. This work uses on-line flow turbidity and birefringence to ascertain the mixing performance of kneading blocks with different geometries. For this purpose, one of the barrel segments of the extruder was modified in order to incorporate four sampling devices and slit dies containing optical windows were attached to them. The experiments consisted in reaching steady extrusion and then adding a small amount of tracer. Upon opening each sampling device, material was laterally detoured from the local screw channel, and its turbidity and birefringence were measured by the optical detector. Residence time distribution curves (RTD) were obtained at various axial positions along three different kneading blocks and under a range of screw speeds. It is hypothesized that K, a parameter related to the area under each RTD curve, is a good indicator of dispersive mixing, whereas variance can be used to assess distributive mixing. The experimental data confirmed that these mixing indices are sensitive to changes in processing conditions, and that they translate the expected behavior of each kneading block geometry. Full article
(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Portugal (2020,2021))
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14 pages, 13940 KiB  
Article
Nonlinear Thermopower Behaviour of N-Type Carbon Nanofibres and Their Melt Mixed Polypropylene Composites
by Antonio J. Paleo, Beate Krause, Maria F. Cerqueira, Enrique Muñoz, Petra Pötschke and Ana M. Rocha
Polymers 2022, 14(2), 269; https://doi.org/10.3390/polym14020269 - 10 Jan 2022
Cited by 5 | Viewed by 1496
Abstract
The temperature dependent electrical conductivity σ (T) and thermopower (Seebeck coefficient) S (T) from 303.15 K (30 °C) to 373.15 K (100 °C) of an as-received commercial n-type vapour grown carbon nanofibre (CNF) powder and its melt-mixed polypropylene (PP) [...] Read more.
The temperature dependent electrical conductivity σ (T) and thermopower (Seebeck coefficient) S (T) from 303.15 K (30 °C) to 373.15 K (100 °C) of an as-received commercial n-type vapour grown carbon nanofibre (CNF) powder and its melt-mixed polypropylene (PP) composite with 5 wt.% of CNFs have been analysed. At 30 °C, the σ and S of the CNF powder are ~136 S m−1 and −5.1 μV K−1, respectively, whereas its PP/CNF composite showed lower conductivities and less negative S-values of ~15 S m−1 and −3.4 μV K−1, respectively. The σ (T) of both samples presents a dσ/dT < 0 character described by the 3D variable range hopping (VRH) model. In contrast, their S (T) shows a dS/dT > 0 character, also observed in some doped multiwall carbon nanotube (MWCNT) mats with nonlinear thermopower behaviour, and explained here from the contribution of impurities in the CNF structure such as oxygen and sulphur, which cause sharply varying and localized states at approximately 0.09 eV above their Fermi energy level (EF). Full article
(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Portugal (2020,2021))
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15 pages, 3290 KiB  
Article
Process Development for Flexible Films of Industrial Cellulose Pulp Using Superbase Ionic Liquids
by Diana C. M. Ribeiro, Rafael C. Rebelo, Francesco De Bon, Jorge F. J. Coelho and Arménio C. Serra
Polymers 2021, 13(11), 1767; https://doi.org/10.3390/polym13111767 - 28 May 2021
Cited by 5 | Viewed by 2916
Abstract
Due to environmental concerns, more attention has been given to the development of bio-based materials for substitution of fossil-based ones. Moreover, paper use is essential in daily routine and several applications of industrial pulp can be developed. In this study, transparent films were [...] Read more.
Due to environmental concerns, more attention has been given to the development of bio-based materials for substitution of fossil-based ones. Moreover, paper use is essential in daily routine and several applications of industrial pulp can be developed. In this study, transparent films were produced by industrial cellulose pulp solubilization in tetramethylguanidine based ionic liquids followed by its regeneration. Films were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), UV/Vis spectroscopy, proton nuclear magnetic resonance (1H-NMR), dynamic scanning calorimetry (DSC), thermal analysis (TG), and X-ray diffraction (XRD). Mechanical tests showed that films have a good elongation property, up to 50%, depending on ionic liquid incorporation. The influence of the conjugated acid and dissolution temperature on mechanical properties were evaluated. These results revealed the potential of this methodology for the preparation of new biobased films. Full article
(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Portugal (2020,2021))
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Review

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17 pages, 2649 KiB  
Review
Structure–Elastic Properties Relationships in Gelling Carrageenans
by Loïc Hilliou
Polymers 2021, 13(23), 4120; https://doi.org/10.3390/polym13234120 - 26 Nov 2021
Cited by 11 | Viewed by 2163
Abstract
Gelling carrageenans are polysaccharides extracted from the Gigartinales order of red algae. These are additives used essentially in the food industry for texturizing, stabilizing or gelling various formulations. Although a consensual gel mechanism has been reached which encompasses a coil-to-helix transition followed by [...] Read more.
Gelling carrageenans are polysaccharides extracted from the Gigartinales order of red algae. These are additives used essentially in the food industry for texturizing, stabilizing or gelling various formulations. Although a consensual gel mechanism has been reached which encompasses a coil-to-helix transition followed by the self-assembling of helices in a network, the structure–elastic relationships in the network are still to be clearly established. This paper reviews the reports in which carrageenan gel structures have been systematically compared with gel elastic properties. The focus is on the sizes documented for structural units, such as strands, aggregates, voids or network meshes, as well as on the reported linear and nonlinear elastic characteristics. The insufficient rationalization of carrageenan gel elasticity by models which take on board mechanically relevant structural features is underlined. After introducing selected linear and nonlinear elastic models, preliminary results comparing such models to structural and rheological data are presented. In particular, the concentration scaling of the strain hardening exhibited by two types of carrageenan gels is discussed. Full article
(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Portugal (2020,2021))
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34 pages, 10174 KiB  
Review
Mussel-Inspired Catechol Functionalisation as a Strategy to Enhance Biomaterial Adhesion: A Systematic Review
by Pedro M. Costa, David A. Learmonth, David B. Gomes, Mafalda P. Cautela, Ana C. N. Oliveira, Renato Andrade, João Espregueira-Mendes, Tiago R. Veloso, Cristiana B. Cunha and Rui A. Sousa
Polymers 2021, 13(19), 3317; https://doi.org/10.3390/polym13193317 - 28 Sep 2021
Cited by 17 | Viewed by 4306
Abstract
Biomaterials have long been explored in regenerative medicine strategies for the repair or replacement of damaged organs and tissues, due to their biocompatibility, versatile physicochemical properties and tuneable mechanical cues capable of matching those of native tissues. However, poor adhesion under wet conditions [...] Read more.
Biomaterials have long been explored in regenerative medicine strategies for the repair or replacement of damaged organs and tissues, due to their biocompatibility, versatile physicochemical properties and tuneable mechanical cues capable of matching those of native tissues. However, poor adhesion under wet conditions (such as those found in tissues) has thus far limited their wider application. Indeed, despite its favourable physicochemical properties, facile gelation and biocompatibility, gellan gum (GG)-based hydrogels lack the tissue adhesiveness required for effective clinical use. Aiming at assessing whether substitution of GG by dopamine (DA) could be a suitable approach to overcome this problem, database searches were conducted on PubMed® and Embase® up to 2 March 2021, for studies using biomaterials covalently modified with a catechol-containing substituent conferring improved adhesion properties. In this regard, a total of 47 reports (out of 700 manuscripts, ~6.7%) were found to comply with the search/selection criteria, the majority of which (34/47, ~72%) were describing the modification of natural polymers, such as chitosan (11/47, ~23%) and hyaluronic acid (6/47, ~13%); conjugation of dopamine (as catechol “donor”) via carbodiimide coupling chemistry was also predominant. Importantly, modification with DA did not impact the biocompatibility and mechanical properties of the biomaterials and resulting hydrogels. Overall, there is ample evidence in the literature that the bioinspired substitution of polymers of natural and synthetic origin by DA or other catechol moieties greatly improves adhesion to biological tissues (and other inorganic surfaces). Full article
(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Portugal (2020,2021))
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