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

Deadline for manuscript submissions: closed (31 January 2022) | Viewed by 23566

Special Issue Editors


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Guest Editor
Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Lodz, Poland
Interests: polymers; nanocomposites; polymer blends; materials science; shape memory effect; severe plastic deformation; lattice structure; 3D printing
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Special Issue Information

Dear Colleagues,

Plastic deformation and fracture processes, both in the laboratory conditions and in industrial practice, are largely dealt with at a phenomenological level, and often separately for different polymers, blends, composites, and less often from a mechanistic perspective. This makes the mechanisms governing the deformation and fracture resistance of polymers important to be well understood. At the same time, fundamental developments in polymer materials science and polymer physics are now making it possible to consider plastic deformation and fracture at an appropriate molecular and morphological level. Moreover, insight gained from computational simulations and mechanistic modeling is also broadening this perspective. The aim of this Special Issue is to present a coherent picture of the plastic deformation and fracture of polymer materials of different structures and architectures. I invite research articles, communication articles, or review articles covering various aspects of plastic deformation and fracture of polymer materials.

Dr. Yuri Voznyak
Dr. Ian Wyman
Guest Editor

Keywords

  • Plasticity of glassy/semicrystalline polymers
  • Mechanisms of plastic deformation
  • Deformation instabilities
  • Crazing in homo- and heteropolymers, blends, composites
  • Cracks and fracture
  • Craze initiation
  • cavitation
  • Toughening of polymers
  • New methods of plastic deformation
  • Deformation-induced structure and phase transformation
  • Simulation, micromechanics-based modeling

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Published Papers (6 papers)

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Research

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31 pages, 9573 KiB  
Article
Deformation of Poly-l-lactid acid (PLLA) under Uniaxial Tension and Plane-Strain Compression
by Alina Vozniak and Zbigniew Bartczak
Polymers 2021, 13(24), 4432; https://doi.org/10.3390/polym13244432 - 17 Dec 2021
Cited by 5 | Viewed by 2445
Abstract
The ability of PLLA, either amorphous or semicrystalline, to plastic deformation to large strain was investigated in a wide temperature range (Td = 70–140 °C). Active deformation mechanisms have been identified and compared for two different deformation modes—uniaxial drawing and plane-strain compression. [...] Read more.
The ability of PLLA, either amorphous or semicrystalline, to plastic deformation to large strain was investigated in a wide temperature range (Td = 70–140 °C). Active deformation mechanisms have been identified and compared for two different deformation modes—uniaxial drawing and plane-strain compression. The initially amorphous PLLA was capable of significant deformation in both tension and plane-strain compression. In contrast, the samples of crystallized PLLA were found brittle in tensile, whereas they proved to be ductile and capable of high-strain deformation when deformed in plane-strain compression. The main deformation mechanism identified in amorphous PLLA was the orientation of chains due to plastic flow, followed by strain-induced crystallization occurring at the true strain above e = 0.5. The oriented chains in amorphous phase were then transformed into oriented mesophase and/or oriented crystals. An upper temperature limit for mesophase formation was found below Td = 90 °C. The amount of mesophase formed in this process did not exceed 5 wt.%. An additional mesophase fraction was generated at high strains from crystals damaged by severe deformation. After the formation of the crystalline phase, further deformation followed the mechanisms characteristic for the semicrystalline polymer. Interlamellar slip supported by crystallographic chain slip has been identified as the major deformation mechanism in semicrystalline PLLA. It was found that the contribution of crystallographic slip increased notably with the increase in the deformation temperature. The most probable active crystallographic slip systems were (010)[001], (100)[001] or (110)[001] slip systems operating along the chain direction. At high temperatures (Td = 115–140 °C), the α→β crystal transformation was additionally observed, leading to the formation of a small fraction of β crystals. Full article
(This article belongs to the Special Issue Plastics)
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12 pages, 5740 KiB  
Article
Shear-Induced and Nanofiber-Nucleated Crystallization of Novel Aliphatic–Aromatic Copolyesters Delineated for In Situ Generation of Biodegradable Nanocomposites
by Ramin Hosseinnezhad
Polymers 2021, 13(14), 2315; https://doi.org/10.3390/polym13142315 - 14 Jul 2021
Cited by 4 | Viewed by 2373
Abstract
The shear-induced and cellulose-nanofiber nucleated crystallization of two novel aliphatic–aromatic copolyesters is outlined due to its significance for the in situ generation of biodegradable nanocomposites, which require the crystallization of nanofibrous sheared inclusions at higher temperatures. The shear-induced non-isothermal crystallization of two copolyesters, [...] Read more.
The shear-induced and cellulose-nanofiber nucleated crystallization of two novel aliphatic–aromatic copolyesters is outlined due to its significance for the in situ generation of biodegradable nanocomposites, which require the crystallization of nanofibrous sheared inclusions at higher temperatures. The shear-induced non-isothermal crystallization of two copolyesters, namely, poly(butylene adipate-co-succinate-co-glutarate-co-terephthalate) (PBASGT) and poly(butylene adipate-co-terephthalate) (PBAT), was studied following a light depolarization technique. To have a deep insight into the process, the effects of the shear rate, shear time, shearing temperature and cooling rate on the initiation, kinetics, growth and termination of crystals were investigated. Films of 60 μm were subjected to various shear rates (100–800 s−1) for different time intervals during cooling. The effects of the shearing time and increasing the shear rate were found to be an elevated crystallization temperature, increased nucleation density, reduced growth size of lamella stacks and decreased crystallization time. Due to the boosted nucleation sites, the nuclei impinged with each other quickly and growth was hindered. The effect of the cooling rate was more significant at lower shear rates. Shearing the samples at lower temperatures, but still above the nominal melting point, further shifted the non-isothermal crystallization to higher temperatures. As a result of cellulose nanofibers’ presence, the crystallization of PBAT, analyzed by DSC, was shifted to higher temperatures. Full article
(This article belongs to the Special Issue Plastics)
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12 pages, 3228 KiB  
Article
In Situ Generation of Green Hybrid Nanofibrillar Polymer-Polymer Composites—A Novel Approach to the Triple Shape Memory Polymer Formation
by Ramin Hosseinnezhad, Iurii Vozniak and Fahmi Zaïri
Polymers 2021, 13(12), 1900; https://doi.org/10.3390/polym13121900 - 8 Jun 2021
Cited by 12 | Viewed by 3173
Abstract
The paper discusses the possibility of using in situ generated hybrid polymer-polymer nanocomposites as polymeric materials with triple shape memory, which, unlike conventional polymer blends with triple shape memory, are characterized by fully separated phase transition temperatures and strongest bonding between the polymer [...] Read more.
The paper discusses the possibility of using in situ generated hybrid polymer-polymer nanocomposites as polymeric materials with triple shape memory, which, unlike conventional polymer blends with triple shape memory, are characterized by fully separated phase transition temperatures and strongest bonding between the polymer blends phase interfaces which are critical to the shape fixing and recovery. This was demonstrated using the three-component system polylactide/polybutylene adipateterephthalate/cellulose nanofibers (PLA/PBAT/CNFs). The role of in situ generated PBAT nanofibers and CNFs in the formation of efficient physical crosslinks at PLA-PBAT, PLA-CNF and PBAT-CNF interfaces and the effect of CNFs on the PBAT fibrillation and crystallization processes were elucidated. The in situ generated composites showed drastically higher values of strain recovery ratios, strain fixity ratios, faster recovery rate and better mechanical properties compared to the blend. Full article
(This article belongs to the Special Issue Plastics)
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14 pages, 5426 KiB  
Article
Microstructural Evolution of Poly(ε-Caprolactone), Its Immiscible Blend, and In Situ Generated Nanocomposites
by Iurii Vozniak, Ramin Hosseinnezhad, Jerzy Morawiec and Andrzej Galeski
Polymers 2020, 12(11), 2587; https://doi.org/10.3390/polym12112587 - 4 Nov 2020
Cited by 11 | Viewed by 2377
Abstract
Polymer–polymer systems with special phase morphology were prepared, leading to an exceptional combination of strength, modulus, and ductility. Two immiscible polymers: poly(ε-caprolactone) (PCL) and polyhydroxyalkanoate (PHA) were used as components for manufacturing a nanoblend and a nanocomposite characterized by nanodroplet-matrix and nanofibril-matrix morphologies, [...] Read more.
Polymer–polymer systems with special phase morphology were prepared, leading to an exceptional combination of strength, modulus, and ductility. Two immiscible polymers: poly(ε-caprolactone) (PCL) and polyhydroxyalkanoate (PHA) were used as components for manufacturing a nanoblend and a nanocomposite characterized by nanodroplet-matrix and nanofibril-matrix morphologies, respectively. Nanofibrils were formed by high shear of nanodroplets at sufficiently low temperature to stabilize their fibrillar shape by shear-induced crystallization. The effects of nanodroplet vs. nanofiber morphology on the tensile mechanical behavior of the nanocomposites were elucidated with the help of in situ 2D small-angle X-ray scattering, microcalorimetry and 2D wide-angle X-ray diffraction. For neat PCL and a PCL/PHA blend, the evolution of the structure under uniaxial tension was accompanied by extensive fragmentation of crystalline lamellae with the onset at strain e = 0.1. Limited lamellae fragmentation in the PCL/PHA composite occurred continuously over a wide range of deformations (e = 0.1–1.1) and facilitated plastic flow of the composite and was associated with the presence of a PHA nanofiber network that transferred local stress to the PCL lamellae, enforcing their local deformation. The PHA nanofibers acted as crystallization nuclei for PCL during their strain-induced melting–recrystallization. Full article
(This article belongs to the Special Issue Plastics)
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13 pages, 3832 KiB  
Article
Implementation of Circular Economy Principles in the Synthesis of Polyurethane Foams
by Maria Kurańska, Milena Leszczyńska, Elżbieta Malewska, Aleksander Prociak and Joanna Ryszkowska
Polymers 2020, 12(9), 2068; https://doi.org/10.3390/polym12092068 - 12 Sep 2020
Cited by 20 | Viewed by 3065
Abstract
The main strategy of the European Commission in the field of the building industry assumes a reduction of greenhouse gas emissions by up to 20% by 2020 and by up to 80% by 2050. In order to meet these conditions, it is necessary [...] Read more.
The main strategy of the European Commission in the field of the building industry assumes a reduction of greenhouse gas emissions by up to 20% by 2020 and by up to 80% by 2050. In order to meet these conditions, it is necessary to develop not only efficient thermal insulation materials, but also more environmentally friendly ones. This paper describes an experiment in which two types of bio-polyols were obtained using transesterification of used cooking oil with triethanolamine (UCO_TEA) and diethylene glycol (UCO_DEG). The bio-polyols were next used to prepare low-density rigid polyurethane (PUR) foams. It was found that the bio-polyols increased the reactivity of the PUR systems, regardless of their chemical structures. The reactivity of the system modified with 60% of the diethylene glycol-based bio-polyol was higher than in the case of the reference system. The bio-foams exhibited apparent densities of 41–45 kg/m3, homogeneous cellular structures and advantageous values of the coefficient of thermal conductivity. It was observed that the higher functionality of bio-polyol UCO_TEA compared with UCO_DEG had a beneficial effect on the mechanical and thermal properties of the bio-foams. The most promising results were obtained in the case of the foams modified in 60% with the bio-polyol based on triethanoloamine. In conclusion, this approach, utilizing used cooking oil in the synthesis of high-value thermal insulating materials, provides a sustainable municipal waste recycling solution. Full article
(This article belongs to the Special Issue Plastics)
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Review

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13 pages, 4220 KiB  
Review
Covalent Adaptable Network and Self-Healing Materials: Current Trends and Future Prospects in Sustainability
by Ajmir Khan, Naveed Ahmed and Muhammad Rabnawaz
Polymers 2020, 12(9), 2027; https://doi.org/10.3390/polym12092027 - 5 Sep 2020
Cited by 64 | Viewed by 8766
Abstract
This work estimates that if the growth of polymer production continues at its current rate of 5% each year, the current annual production of 395 million tons of plastic will exceed 1000 million tons by 2039. Only 9% of the plastics that are [...] Read more.
This work estimates that if the growth of polymer production continues at its current rate of 5% each year, the current annual production of 395 million tons of plastic will exceed 1000 million tons by 2039. Only 9% of the plastics that are currently produced are recycled while most of these materials end up in landfills or leak into oceans, thus creating severe environmental challenges. Covalent adaptable networks (CANs) materials can play a significant role in reducing the burden posed by plastics materials on the environment because CANs are reusable and recyclable. This review is focused on recent research related to CANs of polycarbonates, polyesters, polyamides, polyurethanes, and polyurea. In particular, trends in self-healing CANs systems, the market value of these materials, as well as mechanistic insights regarding polycarbonates, polyesters, polyamides, polyurethanes, and polyurea are highlighted in this review. Finally, the challenges and outlook for CANs are described herein. Full article
(This article belongs to the Special Issue Plastics)
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