Mechanics of Polymeric Structures across Scales

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

Deadline for manuscript submissions: closed (25 November 2023) | Viewed by 12556

Special Issue Editors

Department of Physical Chemistry, Albert-Ludwigs-Universität Freiburg: Freiburg im Breisgau, Baden-Württemberg, Germany
Interests: single-molecule mechanics; polymer physics; nanotechnology

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Guest Editor
Advanced Research Center for Nanolithography, Science Park 106, 1098XG Amsterdam, The Netherlands
Interests: nanotriboligy; mechanochemistry; electrochemistry
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Biological Engineering Technology Innovation Center of Shandong Province, Heze Branch, Qilu University of Technology (Shandong Academy of Sciences), Heze 274000, China
Interests: biomedical materials; polymer synthesis; polymeric materials

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Guest Editor
School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, China
Interests: polymer chemistry; biopolymers; polymeric materials

Special Issue Information

Dear Colleagues,

Ubiquitous natural and synthetic polymers play an important role in both daily life and industrial manufacturing. Due to the unique long chain conformation, polymers display various structures, such as chains, assemblies, fibers, films and bulk materials, ranging from the nanometer scale to meter scale. Compared to small molecules, the polymeric structures produce special mechanical properties, which are strongly length scale-dependent.

The key topic of the current Special Issue is the mechanics of polymer-based structures and materials across all length scales. The main focus is on the biological, physical and chemical properties. These include but are not limited to the elastic and rheological behaviors of the polymeric structure; the adhesive and tribological behaviors at the polymeric or polymer-coated surface and interface; the relationship between functionality and mechanics in relevant applications. Papers presenting theoretical models, simulations and experimental results at any scale are all welcomed.

Dr. Wanhao Cai
Dr. Chen Xiao
Dr. Peichuang Li
Dr. Yuancong Zhao
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

  • polymer chain
  • polymeric materials
  • single-chain mechanics
  • supramolecular assembly
  • mechanical properties
  • polymer structures
  • physical properties
  • chemical properties
  • functionality

Published Papers (7 papers)

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Research

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10 pages, 1758 KiB  
Article
Effect of Environmental pH on the Mechanics of Chitin and Chitosan: A Single-Molecule Study
by Song Zhang, Yunxu Ji, Yiwei He, Juan Dong, Haohang Li and Shirui Yu
Polymers 2024, 16(7), 995; https://doi.org/10.3390/polym16070995 - 5 Apr 2024
Viewed by 728
Abstract
Chitin and chitosan are important structural macromolecules for most fungi and marine crustaceans. The functions and application areas of the two molecules are also adjacent beyond their similar molecular structure, such as tissue engineering and food safety where solution systems are involved. However, [...] Read more.
Chitin and chitosan are important structural macromolecules for most fungi and marine crustaceans. The functions and application areas of the two molecules are also adjacent beyond their similar molecular structure, such as tissue engineering and food safety where solution systems are involved. However, the elasticities of chitin and chitosan in solution lack comparison at the molecular level. In this study, the single-molecule elasticities of chitin and chitosan in different solutions are investigated via atomic force microscope (AFM) based single-molecule spectroscopy (SMFS). The results manifest that the two macromolecules share the similar inherent elasticity in DOSM due to their same chain backbone. However, obvious elastic deviations can be observed in aqueous conditions. Especially, a lower pH value (acid environment) is helpful to increase the elasticity of both chitin and chitosan. On the contrary, the tendency of elastic variation of chitin and chitosan in a larger pH value (alkaline environment) shows obvious diversity, which is mainly determined by the side groups. This basic study may produce enlightenment for the design of intelligent chitin and chitosan food packaging and biomedical materials. Full article
(This article belongs to the Special Issue Mechanics of Polymeric Structures across Scales)
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13 pages, 14714 KiB  
Article
Approaches to Control Crazing Deformation of PHA-Based Biopolymeric Blends
by Ramin Hosseinnezhad, Dhanumalayan Elumalai and Iurii Vozniak
Polymers 2023, 15(21), 4234; https://doi.org/10.3390/polym15214234 - 26 Oct 2023
Viewed by 969
Abstract
The mechanical behavior of polymer materials is heavily influenced by a phenomenon known as crazing. Crazing is a precursor to damage and leads to the formation of cracks as it grows in both thickness and tip size. The current research employs an in [...] Read more.
The mechanical behavior of polymer materials is heavily influenced by a phenomenon known as crazing. Crazing is a precursor to damage and leads to the formation of cracks as it grows in both thickness and tip size. The current research employs an in situ SEM method to investigate the initiation and progression of crazing in all-biopolymeric blends based on Polyhydroxyalkanoates (PHAs). To this end, two chemically different grades of PHA, namely poly(hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBHV), were melt-blended with polybutyrate adipate terephthalate (PBAT). The obtained morphologies of blends, the droplet/fibrillar matrix, were highly influenced by the plasticity of the matrices as well as the content of the minor phase. Increasing the concentration of PBAT from 15 to 30 wt.% resulted in the brittle to ductile transition. It changed the mechanism of plastic deformation from single craze-cracking to homogeneous and heterogeneous intensified crazing for PHB and PHBHV matrices, respectively. Homogeneous tensile crazes formed perpendicularly to the draw direction at the initial stages of deformation, transformed into shear crazes characterized by oblique edge propagation for the PHBHV/PBAT blend. Such angled crazes suggested that the displacement might be caused by shear localized deformation. The crazes’ strength and the time to failure increased with the minor phase fibers. These fibers, aligned with the tensile direction and spanning the width of the crazes, were in the order of a few micrometers in diameter depending on the concentration. The network of fibrillar PBAT provided additional integrity for larger plastic deformation values. This study elucidates the mechanism of crazing in PHA blends and provides strategies for controlling it. Full article
(This article belongs to the Special Issue Mechanics of Polymeric Structures across Scales)
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15 pages, 4620 KiB  
Article
Examining the Quasi-Static Uniaxial Compressive Behaviour of Commercial High-Performance Epoxy Matrices
by J. F. Gargiuli, G. Quino, R. Board, J. C. Griffith, M. S. P. Shaffer, R. S. Trask and I. Hamerton
Polymers 2023, 15(19), 4022; https://doi.org/10.3390/polym15194022 - 8 Oct 2023
Viewed by 1025
Abstract
Four commercial high-performance aerospace aromatic epoxy matrices, CYCOM®890, CYCOM®977-2, PR520, and PRISM EP2400, were cured to a standardised 2 h, 180 °C cure cycle and evaluated in quasi-static uniaxial compression, as well as by dynamic scanning calorimetry (DSC) and [...] Read more.
Four commercial high-performance aerospace aromatic epoxy matrices, CYCOM®890, CYCOM®977-2, PR520, and PRISM EP2400, were cured to a standardised 2 h, 180 °C cure cycle and evaluated in quasi-static uniaxial compression, as well as by dynamic scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The thermoplastic toughened CYCOM®977-2 formulation displayed an overall increase in true axial stress values across the entire stress–strain curve relative to the baseline CYCOM®890 sample. The particle-toughened PR520 sample exhibited an overall decrease in true axial stress values past the yield point of the material. The PRISM EP2400 resin, with combined toughening agents, led to true axial stress values across the entire plastic region of the stress–strain curve, which were in line with the stress values observed with the CYCOM®890 material. Interestingly, for all formulations, the dilation angles (associated with the volume change during plastic deformation), recorded at 0.3 plastic strain, were close to 0°, with the variations reflecting the polymer structure. Compression data collected for this series of commercial epoxy resins are in broad agreement with a selection of model epoxy resins based on di- and tetra-functional monomers, cured with polyamines or dicarboxylic anhydrides. However, the fully formulated resins demonstrate a significantly higher compressive modulus than the model resins, albeit at the expense of yield stress. Full article
(This article belongs to the Special Issue Mechanics of Polymeric Structures across Scales)
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21 pages, 14155 KiB  
Article
The Analysis of Stress Raisers Affecting the GFRP Strength at Quasi-Static and Cyclic Loads by the Theory of Critical Distances, Digital Image Correlation, and Acoustic Emission
by Dmitrii Lobanov, Andrey Yankin, Maksim Mullahmetov, Ekaterina Chebotareva and Valeriya Melnikova
Polymers 2023, 15(9), 2087; https://doi.org/10.3390/polym15092087 - 27 Apr 2023
Cited by 4 | Viewed by 1256
Abstract
The purpose of this work is to analyze the stress-raisers that affect the tensile strength and fatigue resistance of GFRP parts using the point and line methods of the theory of critical distances (TCD) to obtain a quantitative measure of the defect size [...] Read more.
The purpose of this work is to analyze the stress-raisers that affect the tensile strength and fatigue resistance of GFRP parts using the point and line methods of the theory of critical distances (TCD) to obtain a quantitative measure of the defect size that can be tolerated by the composite before it fails. In the course of the work, a method combining TCD and the Weibull function was developed. In the course of the work, GFRP structural fiberglass for electrical purposes was tested under uniaxial quasi-static and cyclic loading with digital image correlation (DIC) and acoustic emission (AE), as well as a numerical simulation of deformation. The studied specimens were plain (without a stress-raiser) and notched (V-shaped) with different notch root radii and depths. The results were used to determine the material critical distances. In this case, two approaches to TCD were used: line (LM) and point (PM) methods. To analyze the experimental results, finite element modeling was applied using the ANSYS software package. As a result, the linearized maximum principal stresses were obtained on the central line passing through the top of the stress raiser. Thus, the values of the critical distances of the material were determined by PM and LM. Based on the data obtained, the sizes of permissible defects in the studied fiberglass were established that do not affect the tensile and fatigue strength of the material. The paper illustrates the cumulative energy, peak amplitudes, and distributions of the frequency of the spectral maximum of acoustic emission signals obtained after the destruction of specimens by fatigue test. Evolutions of deformation fields on the specimen surface were recorded using a Vic-3D contactless optical video system and the DIC. Full article
(This article belongs to the Special Issue Mechanics of Polymeric Structures across Scales)
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11 pages, 2498 KiB  
Article
Physical Aging Behavior of the Side Chain of a Conjugated Polymer PBTTT
by Tengfei Qu, Fanzhang Meng, Linling Li, Chen Zhang, Xiaoliang Wang, Wei Chen, Gi Xue, Evgeny Zhuravlev, Shaochuan Luo and Dongshan Zhou
Polymers 2023, 15(4), 794; https://doi.org/10.3390/polym15040794 - 4 Feb 2023
Cited by 3 | Viewed by 1679
Abstract
This paper provides a viewpoint of the technology of the fast-scanning calorimetry with the relaxation behavior of disordered side chains of poly[2,5-bis(3-dodecylthiophen-2-yl)thieno[3,2-b]thiophene] (PBTTT-C12) around the glass transition temperature of the side chains (Tg). PBTTT is an ideal model of [...] Read more.
This paper provides a viewpoint of the technology of the fast-scanning calorimetry with the relaxation behavior of disordered side chains of poly[2,5-bis(3-dodecylthiophen-2-yl)thieno[3,2-b]thiophene] (PBTTT-C12) around the glass transition temperature of the side chains (Tg). PBTTT is an ideal model of the high-performance copolymer of poly(alkylthiophenes) with side chains. The γ1 relaxation process of the disordered side chains of PBTTT was detected as a small endothermic peak that emerges before the γ2 relaxation process. It shows an increase with increasing temperature as it approaches the glass transition temperature of the disordered side chains of PBTTT. The ductile–brittle transition of PBTTT in low temperatures originating from the thermal relaxation process is probed and illustrated by physical aging experiments. The signature is shown that the relaxation process of the disordered side chain of PBTTT at low temperatures varies from Arrhenius temperature dependence to super Arrhenius temperature dependence at high temperatures. These observations could have significant consequences for the stability of devices based on conjugated polymers, especially those utilized for stretchable or flexible applications, or those demanding mechanical robustness during tensile fabrication or use in a low-temperature environment. Full article
(This article belongs to the Special Issue Mechanics of Polymeric Structures across Scales)
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25 pages, 11336 KiB  
Article
Mechanical Response of Fiber-Filled Automotive Body Panels Manufactured with the Ku-FizzTM Microcellular Injection Molding Process
by Sara Andrea Simon, Jörg Hain, Michael W. Sracic, Hridyesh R. Tewani, Pavana Prabhakar and Tim A. Osswald
Polymers 2022, 14(22), 4916; https://doi.org/10.3390/polym14224916 - 14 Nov 2022
Cited by 1 | Viewed by 1900
Abstract
To maximize the driving range and minimize the associated energy needs and, thus, the number of batteries of electric vehicles, OEMs have adopted lightweight materials, such as long fiber-reinforced thermoplastics, and new processes, such as microcellular injection molding. These components must withstand specific [...] Read more.
To maximize the driving range and minimize the associated energy needs and, thus, the number of batteries of electric vehicles, OEMs have adopted lightweight materials, such as long fiber-reinforced thermoplastics, and new processes, such as microcellular injection molding. These components must withstand specific loading conditions that occur during normal operation. Their mechanical response depends on the fiber and foam microstructures, which in turn are defined by the fabrication process. In this work, long fiber thermoplastic door panels were manufactured using the Ku-FizzTM microcellular injection molding process and were tested for their impact resistance, dynamic properties, and vibration response. Material constants were compared to the properties of unfoamed door panels. The changes in mechanical behavior were explained through the underlying differences in their respective microstructures. The specific storage modulus and specific elastic modulus of foamed components were within 10% of their unfoamed counterparts, while specific absorbed energy was 33% higher for the foamed panel by maintaining the panel’s mass/weight. Full article
(This article belongs to the Special Issue Mechanics of Polymeric Structures across Scales)
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Review

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23 pages, 7587 KiB  
Review
Properties and Applications of Self-Healing Polymeric Materials: A Review
by Kiwon Choi, Ahyeon Noh, Jinsil Kim, Pyong Hwa Hong, Min Jae Ko and Sung Woo Hong
Polymers 2023, 15(22), 4408; https://doi.org/10.3390/polym15224408 - 14 Nov 2023
Cited by 1 | Viewed by 3844
Abstract
Self-healing polymeric materials, engineered to autonomously self-restore damages from external stimuli, are at the forefront of sustainable materials research. Their ability to maintain product quality and functionality and prolong product life plays a crucial role in mitigating the environmental burden of plastic waste. [...] Read more.
Self-healing polymeric materials, engineered to autonomously self-restore damages from external stimuli, are at the forefront of sustainable materials research. Their ability to maintain product quality and functionality and prolong product life plays a crucial role in mitigating the environmental burden of plastic waste. Historically, initial research on the development of self-healing materials has focused on extrinsic self-healing systems characterized by the integration of embedded healing agents. These studies have primarily focused on optimizing the release of healing agents and ensuring rapid self-healing capabilities. In contrast, recent advancements have shifted the focus towards intrinsic self-healing systems that utilize their inherent reactivity and interactions within the matrix. These systems offer the advantage of repeated self-healing over the same damaged zone, which is attributed to reversible chemical reactions and supramolecular interactions. This review offers a comprehensive perspective on extrinsic and intrinsic self-healing approaches and elucidates their unique properties and characteristics. Furthermore, various self-healing mechanisms are surveyed, and insights from cutting-edge studies are integrated. Full article
(This article belongs to the Special Issue Mechanics of Polymeric Structures across Scales)
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