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Polymers
Special Issues
Morphology and Aging of Polymers
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Morphology and Aging of Polymers

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

Deadline for manuscript submissions: closed (30 June 2022) | Viewed by 5634

Special Issue Editor

Prof. Dr. Alina Adams

E-Mail Website
Guest Editor
Institut für Technische und Makromolekulare Chemie, 52074 Aachen, Germany
Interests: multiphase polymers and polymer-based materials; morphology and aging of polymers; structure-property relationships; solid state NMR spectroscopy; compact NMR; non-destructive testing; cultural heritage; MOFs

Special Issue Information

Dear Colleagues,

Polymers are nowadays a driving force in our society. Unfortunately, they have a major drawback: independent of the application, they experience changes in their macroscopic properties with time upon the impact of various external factors including temperature, radiation, humidity, and mechanical load. While many researchers conduct accelerated aging studies, the reported results rarely match the observations from the natural aging. The main raisons for this discrepancy are currently attributed to the spatial dependence of the changes with the aging time and the combined effects of various types of aging.  

The macroscopic properties of polymers are largely determined by their morphology in terms of chemical structure, molecular dynamics, molecular weight, crystallinity degree etc. Thus, understanding and modeling the temporal and the spatial physical and chemical changes in the molecular network will provide the framework for establishing reliable structure-properties relationships requested for a better understanding of the experimental observations and for determining their lifetime. For this, one needs to take advantage of the capabilities of various modern analytical methods, which are able to probe different morphological aspects and to identify the most sensitive microscopic parameters towards aging. Moreover, there is great need for simple, robust, and low-cost analytical methods for onsite non-destructive morphological evaluation. In this way, systematic details about the microscopic changes associated with natural aging can be gained.

This special issue aims at collecting research and review articles covering all aspects of aging-induced morphological changes in polymer materials. It provides a platform for discussing challenges and open issues by presenting suitable morphological characterization techniques and modeling methods for improved structure-properties relationships.

Interim Professor, Dr. habil. Alina Adams
Guest Editor

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

  • structure, molecular dynamics, phase composition
  • molecular network
  • aging induced physical and chemical changes
  • natural and accelerated aging
  • heterogeneous aging
  • embrittlement criteria
  • standard and modern analytical methods for morphological studies
  • non-destructive testing and onsite analysis
  • structure-property relationships

Published Papers (3 papers)

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Research

13 pages, 2931 KiB  
Article
Sterilization Induced Changes in Polypropylene-Based Ffp2 Masks
by Emmanuel Richaud, Muriel Ferry, Floriane Carpentier, Sophie Rouif, Laurent Cortella and Stéphane Esnouf
Polymers 2021, 13(23), 4107; https://doi.org/10.3390/polym13234107 - 25 Nov 2021
Cited by 1 | Viewed by 1620
Abstract
In the context of the SARS-CoV2 pandemic and because of the surgical and FFP2 mask (equivalent to the American N95 masks) shortages, studies on efficient sterilization protocols were initiated. As sterilization using irradiation is commonly used in the medical field, this method was [...] Read more.
In the context of the SARS-CoV2 pandemic and because of the surgical and FFP2 mask (equivalent to the American N95 masks) shortages, studies on efficient sterilization protocols were initiated. As sterilization using irradiation is commonly used in the medical field, this method was among those that were evaluated. In this work, we tested irradiation under vacuum and under air (under both γ-rays and e-beams), but also, for acceptance purposes, undertook washing prior to the e-beam irradiation sterilization process. This article deals with the modifications induced by the sterilization processes at the molecular and the macromolecular scales on an FFP2 mask. Fourier transform infrared spectroscopy in attenuated total reflectance mode, size-exclusion chromatography and thermal-desorption–gas chromatography–mass spectrometry were used to characterize possible damage to the materials. It appeared that the modifications induced by the different sterilization processes under vacuum were relatively tenuous and became more significant when irradiation was performed using γ-rays under air. Full article
(This article belongs to the Special Issue Morphology and Aging of Polymers)
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26 pages, 9478 KiB  
Article
Bimodal 1H Double Quantum Build-Up Curves by Fourier and Laplace-like Transforms on Aged Cross-Linked Natural Rubber
by Dumitrița Moldovan and Radu Fechete
Polymers 2021, 13(20), 3523; https://doi.org/10.3390/polym13203523 - 13 Oct 2021
Cited by 2 | Viewed by 1385
Abstract
The 1H DQ Fourier and Laplace-like spectra for a series of cross-linked natural rubber (NR) samples naturally aged during six years are presented and characterized. The DQ build-up curves of these samples present two peaks which cannot be described by classical functions. [...] Read more.
The 1H DQ Fourier and Laplace-like spectra for a series of cross-linked natural rubber (NR) samples naturally aged during six years are presented and characterized. The DQ build-up curves of these samples present two peaks which cannot be described by classical functions. The DQ Fourier spectra can be obtained after a numeric procedure which introduces a correction time which depends less on the chosen approximation, spin-½ and isolated CH2 and CH3 functional groups. The DQ Fourier spectra are well described by the distributions of the residual dipolar coupling correlated with the distribution of the end-to-end vector of the polymer network, and with the second and fourth van Vleck moments. The deconvolution of DQ Fourier spectra with a sum of four Gaussian variates show that the center and the width of Gaussian functions increase linearly with the increase in the cross-link density. The Laplace-like spectra for the natural aged NR DQ build-up curves are presented. The centers of four Gaussian distributions obtained via both methods are consistent. The differences between the Fourier and Laplace-like spectra consist mainly of the spectral resolution in the favor of Laplace-like spectra. The last one was used to discuss the effect of natural aging for cross-linked NR. Full article
(This article belongs to the Special Issue Morphology and Aging of Polymers)
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11 pages, 4178 KiB  
Article
Electrical Property of Polypropylene Films Subjected to Different Temperatures and DC Electric Fields
by Chuyan Zhang, Weichen Shi, Qiao Wang, Mingguang Diao and Huseyin R. Hiziroglu
Polymers 2021, 13(17), 2956; https://doi.org/10.3390/polym13172956 - 31 Aug 2021
Cited by 2 | Viewed by 1731
Abstract
A polypropylene (PP) film is usually used as a dielectric material in capacitors as well as cables. However, PP films may degrade because of the combined effect of temperature and electric field. In an earlier study, plain PP films and PP films loaded [...] Read more.
A polypropylene (PP) film is usually used as a dielectric material in capacitors as well as cables. However, PP films may degrade because of the combined effect of temperature and electric field. In an earlier study, plain PP films and PP films loaded with nano-metric natural clay were studied under sinusoidal (AC) electric fields at power frequency and temperatures above the ambient. To better understand the electrical characteristics of PP film under various conditions, the objective of this study is to determine the time-to-breakdown of the plain PP and PP filled with 2% (wt) natural nano-clay when subjected to time-invariant (DC) electric fields at elevated temperatures. In order to achieve this objective, the effects of uniform as well as non-uniform electric fields were compared at the same temperature for the PP film. In this study, experimental results indicated that the time-to-breakdown of all PP films, plain or filled with nano-clay, decreases with the increase in electric field intensity, non-uniformity of the electric field, and temperature. It was also found that the time-to-breakdown of PP film filled with 2% (wt) natural nano-clay under DC electric field is longer and less sensitive to temperature. Furthermore, when compared with the results under the uniform electric field, PP film filled with 2% (wt) nano-metric natural clay indicates shorter time-to-failure under non-uniform DC electric fields. Finally, the morphology of the samples was observed by digital camera, optical micrography, and SEM, to better understand the mechanism of the breakdown. Full article
(This article belongs to the Special Issue Morphology and Aging of Polymers)
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