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Special Issue "Polymers Physics: From Theory to Experimental Applications"

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

Deadline for manuscript submissions: 25 February 2024 | Viewed by 15258

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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

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Guest Editor

1. Department of Mechanical Engineering (Section of Mathematics), FEUP, University of Porto, 4200-465 Porto, Portugal
2. Center for Mathematics, University of Minho, 4710-057 Braga, Portugal
Interests: numerical analysis; integro-differential equations; mathematical modelling; viscoelastic flows; anomalous diffusion; machine learning
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Dr. Alexandre M. Afonso

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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 (10 papers)

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Research

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18 pages, 2345 KiB

Open AccessArticle

Knot Formation on DNA Pushed Inside Chiral Nanochannels

Renáta Rusková

and

Dušan Račko

Polymers 2023, 15(20), 4185; https://doi.org/10.3390/polym15204185 - 22 Oct 2023

Viewed by 7335

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 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

Open AccessArticle

Effectiveness of the Use of Polymers in High-Performance Concrete Containing Silica Fume

and

Polymers 2023, 15(18), 3730; https://doi.org/10.3390/polym15183730 - 11 Sep 2023

Viewed by 527

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 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

Open AccessArticle

Numerical Simulation of Three-Dimensional Free Surface Flows Using the K–BKZ–PSM Integral Constitutive Equation

and

Polymers 2023, 15(18), 3705; https://doi.org/10.3390/polym15183705 - 08 Sep 2023

Viewed by 405

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 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

Open AccessArticle

Analysis of the Dynamic Cushioning Property of Expanded Polyethylene Based on the Stress–Energy Method

Yueqing Xing

Deqiang Sun

and

Guoliang Chen

Polymers 2023, 15(17), 3603; https://doi.org/10.3390/polym15173603 - 30 Aug 2023

Viewed by 416

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 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

Open AccessArticle

A Phenomenological Model for Enthalpy Recovery in Polystyrene Using Dynamic Mechanical Spectra

Koh-hei Nitta

Kota Ito

and

Asae Ito

Polymers 2023, 15(17), 3590; https://doi.org/10.3390/polym15173590 - 29 Aug 2023

Cited by 1 | Viewed by 550

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 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 T_g peak is used as the recovery function of the endothermic overshoot of specific heat. In addition, the sub-T_g shoulder peak around the T_g 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 T_g, as well as the kinetic process of the sub-T_g 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

Open AccessArticle

Cellulose Nanocrystal Embedded Composite Foam and Its Carbonization for Energy Application

So Yeon Ahn

Chengbin Yu

and

Young Seok Song

Polymers 2023, 15(16), 3454; https://doi.org/10.3390/polym15163454 - 18 Aug 2023

Viewed by 634

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 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

Open AccessCommunication

Key Factors in Enhancing Pseudocapacitive Properties of PANI-InO_x Hybrid Thin Films Prepared by Sequential Infiltration Synthesis

Jiwoong Ham

Hyeong-U Kim

and

Nari Jeon

Polymers 2023, 15(12), 2616; https://doi.org/10.3390/polym15122616 - 08 Jun 2023

Viewed by 847

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)-InO_x composite thin films prepared using SIS for application in electrochemical energy storage. In this study, we investigated the effects of the number of InO_x SIS cycles on the chemical and electrochemical properties of PANI-InO_x 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-InO_x 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-InO_x 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

Open AccessArticle

Numerical Modeling of the Mixing of Highly Viscous Polymer Suspensions in Partially Filled Sigma Blade Mixers

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

Viewed by 986

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 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

Open AccessArticle

Multiphase Flow Production Enhancement Using Drag Reducing Polymers

Abdelsalam Alsarkhi

and

Mustafa Salah

Polymers 2023, 15(5), 1108; https://doi.org/10.3390/polym15051108 - 23 Feb 2023

Cited by 1 | Viewed by 817

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 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

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26 pages, 5353 KiB

Open AccessReview

The Elasticity of Polymer Melts and Solutions in Shear and Extension Flows

Andrey V. Subbotin

Alexander Ya. Malkin

and

Valery G. Kulichikhin

Polymers 2023, 15(4), 1051; https://doi.org/10.3390/polym15041051 - 20 Feb 2023

Viewed by 1543

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 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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