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Polymers
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Polymers Physics: From Theory to Experimental Applications
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Polymers Physics: From Theory to Experimental Applications

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

Deadline for manuscript submissions: 15 September 2024 | Viewed by 23767

Special Issue Editors

Dr. Célio Pinto Fernandes

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Guest Editor
Institute for Polymers and Composites, University of Minho, Braga, Portugal
Interests: numerical simulation; openfoam; CFD; DEM; viscoelasticity; extrusion; injection molding
Special Issues, Collections and Topics in MDPI journals
Dr. Luís L. Ferrás

E-Mail Website
Guest Editor
Department of Mechanical Engineering (Section of Mathematics), FEUP, University of Porto, 4200-465 Porto, Portugal
Interests: applied mathematics; fluid mechanics; fractional calculus; numerical analysis; machine learning
Special Issues, Collections and Topics in MDPI journals
Dr. Alexandre M. Afonso

E-Mail Website
Guest Editor
CEFT-Transport Phenomena Research Center, Department of Mechanical Engineering, Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal
Interests: theoretical and computational rheology; complex flows of complex fluids; electrokinetics; multiphase flow; micro-combustion
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Polymer processing techniques are of paramount importance in the manufacture of plastic parts. The main concern is producing parts with the desired quality, which usually refers to mechanical performance, dimensional accuracy, and appearance. To maximize the overall efficiency of polymer processing techniques, new constitutive models and advanced modeling codes are needed along with experimental measurements to simulate, compare, and optimize processes. This is a complex task involving understanding the molecular theory behind such complex deformations, solving the problem numerically for small scales, transferring the molecular theory to a continuum medium, solving the resulting differential equations numerically, performing numerical experiments, and comparing the numerical and experimental results.

Thus, this Special Issue will welcome contributions which develop theories for new rheological constitutive equations and implementation of efficient algorithms to describe polymer physics. In addition, experimental studies for the preparation and characterization of new polymeric materials are also welcomed. Topics include but are not limited to the following:

  • Viscoelastic flow modeling;
  • Molecular simulation;
  • Heat transfer problems;
  • Machine learning techniques;
  • New materials, additives, and fillers;
  • Additive manufacturing and 3D printing;
  • Polymer rheology and mechanical properties.

Dr. Célio Pinto Fernandes
Dr. Luís L. Ferrás
Dr. Alexandre M. Afonso
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

  • multiphase flows
  • suspensions
  • viscoelasticity
  • heat transfer
  • machine learning
  • additive manufacturing
  • 3D printing
  • polymer rheology and mechanical properties

Published Papers (13 papers)

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Editorial

Jump to: Research, Review

4 pages, 177 KiB  
Editorial
Polymer Physics: From Theory to Experimental Applications
by Célio Fernandes, Luís L. Ferrás and Alexandre M. Afonso
Polymers 2024, 16(6), 768; https://doi.org/10.3390/polym16060768 - 11 Mar 2024
Viewed by 879
Abstract
The significance of polymer processing techniques cannot be overstated in the production of polymer components [...] Full article
(This article belongs to the Special Issue Polymers Physics: From Theory to Experimental Applications)

Research

Jump to: Editorial, Review

32 pages, 9182 KiB  
Article
Improved Approach for ab Initio Calculations of Rate Coefficients for Secondary Reactions in Acrylate Free-Radical Polymerization
by Fernando A. Lugo, Mariya Edeleva, Paul H. M. Van Steenberge and Maarten K. Sabbe
Polymers 2024, 16(7), 872; https://doi.org/10.3390/polym16070872 - 22 Mar 2024
Viewed by 713
Abstract
Secondary reactions in radical polymerization pose a challenge when creating kinetic models for predicting polymer structures. Despite the high impact of these reactions in the polymer structure, their effects are difficult to isolate and measure to produce kinetic data. To this end, we [...] Read more.
Secondary reactions in radical polymerization pose a challenge when creating kinetic models for predicting polymer structures. Despite the high impact of these reactions in the polymer structure, their effects are difficult to isolate and measure to produce kinetic data. To this end, we used solvation-corrected M06-2X/6-311+G(d,p) ab initio calculations to predict a complete and consistent data set of intrinsic rate coefficients of the secondary reactions in acrylate radical polymerization, including backbiting, β-scission, radical migration, macromonomer propagation, mid-chain radical propagation, chain transfer to monomer and chain transfer to polymer. Two new approaches towards computationally predicting rate coefficients for secondary reactions are proposed: (i) explicit accounting for all possible enantiomers for reactions involving optically active centers; (ii) imposing reduced flexibility if the reaction center is in the middle of the polymer chain. The accuracy and reliability of the ab initio predictions were benchmarked against experimental data via kinetic Monte Carlo simulations under three sufficiently different experimental conditions: a high-frequency modulated polymerization process in the transient regime, a low-frequency modulated process in the sliding regime at both low and high temperatures and a degradation process in the absence of free monomers. The complete and consistent ab initio data set compiled in this work predicts a good agreement when benchmarked via kMC simulations against experimental data, which is a technique never used before for computational chemistry. The simulation results show that these two newly proposed approaches are promising for bridging the gap between experimental and computational chemistry methods in polymer reaction engineering. Full article
(This article belongs to the Special Issue Polymers Physics: From Theory to Experimental Applications)
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16 pages, 373 KiB  
Article
Analytical Solutions to the Unsteady Poiseuille Flow of a Second Grade Fluid with Slip Boundary Conditions
by Evgenii S. Baranovskii
Polymers 2024, 16(2), 179; https://doi.org/10.3390/polym16020179 - 7 Jan 2024
Cited by 3 | Viewed by 968
Abstract
This paper deals with an initial-boundary value problem modeling the unidirectional pressure-driven flow of a second grade fluid in a plane channel with impermeable solid walls. On the channel walls, Navier-type slip boundary conditions are stated. Our aim is to investigate the well-posedness [...] Read more.
This paper deals with an initial-boundary value problem modeling the unidirectional pressure-driven flow of a second grade fluid in a plane channel with impermeable solid walls. On the channel walls, Navier-type slip boundary conditions are stated. Our aim is to investigate the well-posedness of this problem and obtain its analytical solution under weak regularity requirements on a function describing the velocity distribution at initial time. In order to overcome difficulties related to finding classical solutions, we propose the concept of a generalized solution that is defined as the limit of a uniformly convergent sequence of classical solutions with vanishing perturbations in the initial data. We prove the unique solvability of the problem under consideration in the class of generalized solutions. The main ingredients of our proof are a generalized Abel criterion for uniform convergence of function series and the use of an orthonormal basis consisting of eigenfunctions of the related Sturm–Liouville problem. As a result, explicit expressions for the flow velocity and the pressure in the channel are established. The constructed analytical solutions favor a better understanding of the qualitative features of time-dependent flows of polymer fluids and can be applied to the verification of relevant numerical, asymptotic, and approximate analytical methods. Full article
(This article belongs to the Special Issue Polymers Physics: From Theory to Experimental Applications)
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18 pages, 2345 KiB  
Article
Knot Formation on DNA Pushed Inside Chiral Nanochannels
by Renáta Rusková and Dušan Račko
Polymers 2023, 15(20), 4185; https://doi.org/10.3390/polym15204185 - 22 Oct 2023
Cited by 1 | Viewed by 8269
Abstract
We performed coarse-grained molecular dynamics simulations of DNA polymers pushed inside infinite open chiral and achiral channels. We investigated the behavior of the polymer metrics in terms of span, monomer distributions and changes of topological state of the polymer in the channels. We [...] Read more.
We performed coarse-grained molecular dynamics simulations of DNA polymers pushed inside infinite open chiral and achiral channels. We investigated the behavior of the polymer metrics in terms of span, monomer distributions and changes of topological state of the polymer in the channels. We also compared the regime of pushing a polymer inside the infinite channel to the case of polymer compression in finite channels of knot factories investigated in earlier works. We observed that the compression in the open channels affects the polymer metrics to different extents in chiral and achiral channels. We also observed that the chiral channels give rise to the formation of equichiral knots with the same handedness as the handedness of the chiral channels. Full article
(This article belongs to the Special Issue Polymers Physics: From Theory to Experimental Applications)
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13 pages, 3238 KiB  
Article
Effectiveness of the Use of Polymers in High-Performance Concrete Containing Silica Fume
by Alya Harichane, Nadhir Toubal Seghir, Paweł Niewiadomski, Łukasz Sadowski and Michał Cisiński
Polymers 2023, 15(18), 3730; https://doi.org/10.3390/polym15183730 - 11 Sep 2023
Cited by 2 | Viewed by 920
Abstract
The incorporation of polycarboxylate ether superplasticizer (PCE)-type polymers and silica fume (SF) in high-performance concretes (HPC) leads to remarkable rheological and mechanical improvements. In the fresh state, PCEs are adsorbed on cement particles and dispersants, promoting the workability of the concrete. Silica fume [...] Read more.
The incorporation of polycarboxylate ether superplasticizer (PCE)-type polymers and silica fume (SF) in high-performance concretes (HPC) leads to remarkable rheological and mechanical improvements. In the fresh state, PCEs are adsorbed on cement particles and dispersants, promoting the workability of the concrete. Silica fume enables very well-compacted concrete to be obtained, which is characterized by high mechanical parameters in its hardened state. Some PCEs are incompatible with silica fume, which can result in slump loss and poor rheological behavior. The main objective of this research is to study the influence of three types of PCEs, which all have different molecular architectures, on the rheological and mechanical behavior of high-performance concretes containing 10% SF as a partial replacement of cement. The results show that the carboxylic density of PCE has an influence on its compatibility with SF. Full article
(This article belongs to the Special Issue Polymers Physics: From Theory to Experimental Applications)
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19 pages, 1379 KiB  
Article
Numerical Simulation of Three-Dimensional Free Surface Flows Using the K–BKZ–PSM Integral Constitutive Equation
by Juliana Bertoco, Antonio Castelo, Luís L. Ferrás and Célio Fernandes
Polymers 2023, 15(18), 3705; https://doi.org/10.3390/polym15183705 - 8 Sep 2023
Cited by 1 | Viewed by 777
Abstract
This work introduces a novel numerical method designed to address three-dimensional unsteady free surface flows incorporating integral viscoelastic constitutive equations, specifically the K–BKZ–PSM (Kaye–Bernstein, Kearsley, Zapas–Papanastasiou, Scriven, Macosko) model. The new proposed methodology employs a second-order finite difference approach along with the deformation [...] Read more.
This work introduces a novel numerical method designed to address three-dimensional unsteady free surface flows incorporating integral viscoelastic constitutive equations, specifically the K–BKZ–PSM (Kaye–Bernstein, Kearsley, Zapas–Papanastasiou, Scriven, Macosko) model. The new proposed methodology employs a second-order finite difference approach along with the deformation fields method to solve the integral constitutive equation and the marker particle method (known as marker-and-cell) to accurately capture the evolution of the fluid’s free surface. The newly developed numerical method has proven its effectiveness in handling complex fluid flow scenarios, including confined flows and extrudate swell simulations of Boger fluids. Furthermore, a new semi-analytical solution for velocity and stress fields is derived, considering fully developed flows of a K–BKZ–PSM fluid in a pipe. Full article
(This article belongs to the Special Issue Polymers Physics: From Theory to Experimental Applications)
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16 pages, 2539 KiB  
Article
Analysis of the Dynamic Cushioning Property of Expanded Polyethylene Based on the Stress–Energy Method
by Yueqing Xing, Deqiang Sun and Guoliang Chen
Polymers 2023, 15(17), 3603; https://doi.org/10.3390/polym15173603 - 30 Aug 2023
Cited by 1 | Viewed by 861
Abstract
This paper aimed to experimentally clarify the dynamic crushing performance of expanded polyethylene (EPE) and analyze the influence of thickness and dropping height on its mechanical behavior based on the stress–energy method. Hence, a series of impact tests are carried out on EPE [...] Read more.
This paper aimed to experimentally clarify the dynamic crushing performance of expanded polyethylene (EPE) and analyze the influence of thickness and dropping height on its mechanical behavior based on the stress–energy method. Hence, a series of impact tests are carried out on EPE foams with different thicknesses and dropping heights. The maximum acceleration, static stress, dynamic stress and dynamic energy of EPE specimens are obtained through a dynamic impact test. Then, according to the principle of the stress–energy method, the functional relationship between dynamic stress and dynamic energy is obtained through exponential fitting and polynomial fitting, and the cushion material constants a, b and c are determined. The maximum acceleration-static stress curves of any thickness and dropping height can be further fitted. By the equipartition energy domain method, the range of static stress can be expanded, which is very fast and convenient. When analyzing the influence of thickness and dropping height on the dynamic cushioning performance curves of EPE, it is found that at the same drop height, with the increase of thickness, the opening of the curve gradually becomes larger. The minimum point on the maximum acceleration-static stress curve also decreases with the increase of the thickness. When the dropping height is 400 mm, compared to foam with a thickness of 60 mm, the tested maximum acceleration value of the lowest point of the specimen with a thickness of 40 mm increased by 45.3%, and the static stress is both 5.5 kPa. When the thickness of the specimen is 50 mm, compared to the dropping height of 300 mm, the tested maximum acceleration value of the lowest point of the specimen with a dropping height of 600 mm increased by 93.3%. Therefore, the dynamic cushioning performance curve of EPE foams can be quickly obtained by the stress–energy method when the precision requirement is not high, which provides a theoretical basis for the design of cushion packaging. Full article
(This article belongs to the Special Issue Polymers Physics: From Theory to Experimental Applications)
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18 pages, 4473 KiB  
Article
A Phenomenological Model for Enthalpy Recovery in Polystyrene Using Dynamic Mechanical Spectra
by Koh-hei Nitta, Kota Ito and Asae Ito
Polymers 2023, 15(17), 3590; https://doi.org/10.3390/polym15173590 - 29 Aug 2023
Cited by 3 | Viewed by 1092
Abstract
This paper studies the effects of annealing time on the specific heat enthalpy of polystyrene above the glass transition temperature. We extend the Tool–Narayanaswamy–Moynihan (TNM) model to describe the endothermic overshoot peaks through the dynamic mechanical spectra. In this work, we accept the [...] Read more.
This paper studies the effects of annealing time on the specific heat enthalpy of polystyrene above the glass transition temperature. We extend the Tool–Narayanaswamy–Moynihan (TNM) model to describe the endothermic overshoot peaks through the dynamic mechanical spectra. In this work, we accept the viewpoint that the enthalpy recovery behavior of glassy polystyrene (PS) has a common structural relaxation mode with linear viscoelastic behavior. As a consequence, the retardation spectrum evaluated from the dynamic mechanical spectra around the primary Tg peak is used as the recovery function of the endothermic overshoot of specific heat. In addition, the sub-Tg shoulder peak around the Tg peak is found to be related to the structural relaxation estimated from light scattering measurements. The enthalpy recovery of annealed PS is quantitatively described using retardation spectra of the primary Tg, as well as the kinetic process of the sub-Tg relaxation process. Full article
(This article belongs to the Special Issue Polymers Physics: From Theory to Experimental Applications)
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15 pages, 3228 KiB  
Article
Cellulose Nanocrystal Embedded Composite Foam and Its Carbonization for Energy Application
by So Yeon Ahn, Chengbin Yu and Young Seok Song
Polymers 2023, 15(16), 3454; https://doi.org/10.3390/polym15163454 - 18 Aug 2023
Cited by 1 | Viewed by 1124
Abstract
In this study, we fabricated a cellulose nanocrystal (CNC)-embedded aerogel-like chitosan foam and carbonized the 3D foam for electrical energy harvesting. The nanocrystal-supported cellulose foam can demonstrate a high surface area and porosity, homogeneous size ranging from various microscales, and a high quality [...] Read more.
In this study, we fabricated a cellulose nanocrystal (CNC)-embedded aerogel-like chitosan foam and carbonized the 3D foam for electrical energy harvesting. The nanocrystal-supported cellulose foam can demonstrate a high surface area and porosity, homogeneous size ranging from various microscales, and a high quality of absorbing external additives. In order to prepare CNC, microcrystalline cellulose (MCC) was chemically treated with sulfuric acid. The CNC incorporates into chitosan, enhancing mechanical properties, crystallization, and generation of the aerogel-like porous structure. The weight percentage of the CNC was 2 wt% in the chitosan composite. The CNC/chitosan foam is produced using the freeze-drying method, and the CNC-embedded CNC/chitosan foam has been carbonized. We found that the degree of crystallization of carbon structure increased, including the CNCs. Both CNC and chitosan are degradable materials when CNC includes chitosan, which can form a high surface area with some typical surface-related morphology. The electrical cyclic voltammetric result shows that the vertical composite specimen had superior electrochemical properties compared to the horizontal composite specimen. In addition, the BET measurement indicated that the CNC/chitosan foam possessed a high porosity, especially mesopores with layer structures. At the same time, the carbonized CNC led to a significant increase in the portion of micropore. Full article
(This article belongs to the Special Issue Polymers Physics: From Theory to Experimental Applications)
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9 pages, 2127 KiB  
Communication
Key Factors in Enhancing Pseudocapacitive Properties of PANI-InOx Hybrid Thin Films Prepared by Sequential Infiltration Synthesis
by Jiwoong Ham, Hyeong-U Kim and Nari Jeon
Polymers 2023, 15(12), 2616; https://doi.org/10.3390/polym15122616 - 8 Jun 2023
Cited by 1 | Viewed by 1172
Abstract
Sequential infiltration synthesis (SIS) is an emerging vapor-phase synthetic route for the preparation of organic–inorganic composites. Previously, we investigated the potential of polyaniline (PANI)-InOx composite thin films prepared using SIS for application in electrochemical energy storage. In this study, we investigated the [...] Read more.
Sequential infiltration synthesis (SIS) is an emerging vapor-phase synthetic route for the preparation of organic–inorganic composites. Previously, we investigated the potential of polyaniline (PANI)-InOx composite thin films prepared using SIS for application in electrochemical energy storage. In this study, we investigated the effects of the number of InOx SIS cycles on the chemical and electrochemical properties of PANI-InOx thin films via combined characterization using X-ray photoelectron spectroscopy, ultraviolet–visible spectroscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, and cyclic voltammetry. The area-specific capacitance values of PANI-InOx samples prepared with 10, 20, 50, and 100 SIS cycles were 1.1, 0.8, 1.4, and 0.96 mF/cm², respectively. Our result shows that the formation of an enlarged PANI-InOx mixed region directly exposed to the electrolyte is key to enhancing the pseudocapacitive properties of the composite films. Full article
(This article belongs to the Special Issue Polymers Physics: From Theory to Experimental Applications)
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12 pages, 4595 KiB  
Article
Numerical Modeling of the Mixing of Highly Viscous Polymer Suspensions in Partially Filled Sigma Blade Mixers
by Michael Roland Larsen, Tobias Ottsen, Erik Tomas Holmen Olofsson and Jon Spangenberg
Polymers 2023, 15(8), 1938; https://doi.org/10.3390/polym15081938 - 19 Apr 2023
Cited by 2 | Viewed by 1480
Abstract
This paper presents a non-isothermal, non-Newtonian Computational Fluid Dynamics (CFD) model for the mixing of a highly viscous polymer suspension in a partially filled sigma blade mixer. The model accounts for viscous heating and the free surface of the suspension. The rheological model [...] Read more.
This paper presents a non-isothermal, non-Newtonian Computational Fluid Dynamics (CFD) model for the mixing of a highly viscous polymer suspension in a partially filled sigma blade mixer. The model accounts for viscous heating and the free surface of the suspension. The rheological model is found by calibration with experimental temperature measurements. Subsequently, the model is exploited to study the effect of applying heat both before and during mixing on the suspension’s mixing quality. Two mixing indexes are used to evaluate the mixing condition, namely, the Ica Manas-Zlaczower dispersive index and Kramer’s distributive index. Some fluctuations are observed in the predictions of the dispersive mixing index, which could be associated with the free surface of the suspension, thus indicating that this index might not be ideal for partially filled mixers. The Kramer index results are stable and indicate that the particles in the suspension can be well distributed. Interestingly, the results highlight that the speed at which the suspension becomes well distributed is almost independent of applying heat both before and during the process. Full article
(This article belongs to the Special Issue Polymers Physics: From Theory to Experimental Applications)
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18 pages, 8414 KiB  
Article
Multiphase Flow Production Enhancement Using Drag Reducing Polymers
by Abdelsalam Alsarkhi and Mustafa Salah
Polymers 2023, 15(5), 1108; https://doi.org/10.3390/polym15051108 - 23 Feb 2023
Cited by 2 | Viewed by 1134
Abstract
This paper presents a comprehensive experimental investigation concerning the effect of drag reducing polymers (DRP) on enhancing the throughput and reducing the pressure drop for a horizontal pipe carrying two-phase flow of air and water mixture. Moreover, the ability of these polymer entanglements [...] Read more.
This paper presents a comprehensive experimental investigation concerning the effect of drag reducing polymers (DRP) on enhancing the throughput and reducing the pressure drop for a horizontal pipe carrying two-phase flow of air and water mixture. Moreover, the ability of these polymer entanglements to damp turbulence waves and changing the flow regime has been tested at various conditions, and a clear observation showed that the maximum drag reduction always occurs when the highly fluctuated waves were reduced effectively by DRP (and that, accordingly, phase transition (flow regime changed) appeared. This may also help in improving the separation process and enhancing the separator performance. The present experimental set-up has been constructed using a test section of 1.016-cm ID; an acrylic tube section was used to enable visual observations of the flow patterns. A new injection technique has been utilized and, with the use of different injection rates of DRP, the results have shown that the reduction in pressure drop occurred in all flow configurations. Furthermore, different empirical correlations have been developed which improve the ability to predict the pressure drop after the addition of DRP. The correlations showed low discrepancy for a wide range of water and air flow rates. Full article
(This article belongs to the Special Issue Polymers Physics: From Theory to Experimental Applications)
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Review

Jump to: Editorial, Research

26 pages, 5353 KiB  
Review
The Elasticity of Polymer Melts and Solutions in Shear and Extension Flows
by Andrey V. Subbotin, Alexander Ya. Malkin and Valery G. Kulichikhin
Polymers 2023, 15(4), 1051; https://doi.org/10.3390/polym15041051 - 20 Feb 2023
Cited by 3 | Viewed by 2573
Abstract
This review is devoted to understanding the role of elasticity in the main flow modes of polymeric viscoelastic liquids—shearing and extension. The flow through short capillaries is the central topic for discussing the input of elasticity to the effects, which are especially interesting [...] Read more.
This review is devoted to understanding the role of elasticity in the main flow modes of polymeric viscoelastic liquids—shearing and extension. The flow through short capillaries is the central topic for discussing the input of elasticity to the effects, which are especially interesting for shear. An analysis of the experimental data made it possible to show that the energy losses in such flows are determined by the Deborah and Weissenberg numbers. These criteria are responsible for abnormally high entrance effects, as well as for mechanical losses in short capillaries. In addition, the Weissenberg number determines the threshold of the flow instability due to the liquid-to-solid transition. In extension, this criterion shows whether deformation takes place as flow or as elastic strain. However, the stability of a free jet in extension depends not only on the viscoelastic properties of a polymeric substance but also on the driving forces: gravity, surface tension, etc. An analysis of the influence of different force combinations on the shape of the stretched jet is presented. The concept of the role of elasticity in the deformation of polymeric liquids is crucial for any kind of polymer processing. Full article
(This article belongs to the Special Issue Polymers Physics: From Theory to Experimental Applications)
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