Viscoelastic Behavior of Polymer–Matrix Composites

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

Deadline for manuscript submissions: closed (1 October 2020) | Viewed by 6604

Special Issue Editor

Department of Mechanical Engineering, Faculty of Sciences and Technology of the University of Coimbra, University of Coimbra, 3000-370 Coimbra, Portugal
Interests: polymer-based composites; polymer-based nanocomposites; mechanical behavior
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Special Issue Information

Dear Colleagues,

It is common knowledge that polymer–matrix composites are currently one of the most important groups of materials, with applications on several engineering applications. Every day, these materials are replacing traditional metallic materials as a consequence of their excellent mechanical properties, including their high specific strength and stiffness, good static and dynamic properties, good resistance to corrosion, adjustable properties, competitive cost, and simplified fabrication.

More recently, nanoparticle-reinforced materials have been widely studied and applied due to their unique surface effects, increased chemical activity, and physical properties. For example, the literature has reported significant improvements in terms of mechanical performance when low concentrations of nanoparticles are added into polymers without compromising their density, toughness or the manufacturing process.

However, it is commonly agreed that polymer-based composites materials are sensitive to the strain rate, and consequently, the design of a structure is too conservative when the static properties are only considered. Even though this aspect for metals is widely studied over a wide range of strain rates, however, open literature is not as abundant for polymer–matrix composites. On the other hand, as a consequence of the inherent viscoelasticity of the matrix phase, polymer composites are prone to creep and stress relaxation, making it a great challenge when they are used in long-term applications. Therefore, a better understanding of the stress–relaxation behavior of composites enables us to predict the dimensional stability of load-bearing structures.

Therefore, this Special Issue of Polymers invites the submission of contributions that address topics related with the viscoelastic behavior of polymer–matrix composites. In this context, any original experimental or simulation work as well as review papers about the strain rate effects, stress relaxation, and/or creep behavior on polymer–matrix composites are welcome. We hope that this Special Issue of Polymers contributes to increasing the knowledge around this subject in order to predict the dimensional stability of load-bearing structures for long-term applications.

Prof. Paulo Nobre Balbis dos Reis
Guest Editor

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Keywords

  • Polymers 
  • Polymer-based composites
  • Polymer-based nanocomposites 
  • Strain rate effect 
  • Creep behavior 
  • Stress relaxation behavior 
  • Experimental test 
  • Numerical analysis

Published Papers (2 papers)

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Research

17 pages, 11627 KiB  
Article
Effect of Post-Cure on the Static and Viscoelastic Properties of a Polyester Resin
Polymers 2020, 12(9), 1927; https://doi.org/10.3390/polym12091927 - 26 Aug 2020
Cited by 8 | Viewed by 3176
Abstract
This work intends to study the effect of the curing parameters on the mechanical properties of a polyester resin without a complete curing reaction process. For this purpose, cures at room temperature, 40 °C, and 60 °C, and post-cures at 40 °C and [...] Read more.
This work intends to study the effect of the curing parameters on the mechanical properties of a polyester resin without a complete curing reaction process. For this purpose, cures at room temperature, 40 °C, and 60 °C, and post-cures at 40 °C and 60 °C, with different exposure times, were considered. Three-point bending tests were performed to assess the bending properties and both stress relaxation and creep behavior. The degree of crosslinking was estimated by evaluating the C = C ester bond, by Fourier infrared spectroscopy and complemented with the thermal characterization made by differential scanning calorimetry. The results showed that higher curing temperatures are preferable to methods involving curing and post-curing, which can be confirmed by the higher degree of conversion of unsaturated ester bonds at 60 °C. Compared to the resin cured at room temperature, the bending strength increased by 36.5% at 40 °C and 88.6% at 60 °C. A similar effect was observed for bending stiffness. In terms of stress relaxation and creep strain, the lowest values were obtained for samples cured at 60 °C. Full article
(This article belongs to the Special Issue Viscoelastic Behavior of Polymer–Matrix Composites)
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12 pages, 1214 KiB  
Article
Effect of Fibre Orientation and Hostile Solutions on Stress Relaxation of Glass/Polyamide Composites
Polymers 2020, 12(1), 20; https://doi.org/10.3390/polym12010020 - 20 Dec 2019
Cited by 5 | Viewed by 2627
Abstract
Polyamide creates high-performance composite materials, which are replacing the traditional epoxy composites in several applications. In this context, exposure to hostile environments is expected. On the other hand, due to the viscoelastic nature of the matrix, these composite materials are prone to stress [...] Read more.
Polyamide creates high-performance composite materials, which are replacing the traditional epoxy composites in several applications. In this context, exposure to hostile environments is expected. On the other hand, due to the viscoelastic nature of the matrix, these composite materials are prone to stress relaxation. Therefore, the stress relaxation behaviour of glass/polyamide 6 composites was studied considering different fibre directions, as well as exposure to NaOH and HCl solutions. Stress relaxation tests on the bending mode were carried out, and the stress recorded during the loading time (7200 s). All tests were characterized by a stress decrease over time, but laminates with higher fibre angles were more prone to stress relaxation. However, exposure to hostile solutions promoted more significant decreases, where the highest stress relaxation was achieved for alkaline environments with values that were three times higher for laminates with fibres at 0° and around one and half times higher for 45° fibre alignments when compared with the control samples. Finally, the Kohlrausch–Williams–Watts (KWW) model showed that it can be used to predict stress relaxation time, due to the accuracy that was obtained between the experimental and theoretical results. Full article
(This article belongs to the Special Issue Viscoelastic Behavior of Polymer–Matrix Composites)
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