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Toughened Thermosets

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

Deadline for manuscript submissions: closed (30 September 2020) | Viewed by 19562

Special Issue Editor


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Guest Editor
Market Development Composites & Lightweight Construction, Evonik Nutrition & Care GmbH, Essen 21502, Germany
Interests: epoxy resins; vinyl ester resins; tougheners; nanosilica; material science

Special Issue Information

Dear Colleagues,

Thermosetting resins are a class of materials with a growing importance: key technologies that are of utmost importance for facing the challenges of the future are impossible without the use of thermosets. Lightweight construction in transportation including using high performance adhesives or fiber-reinforced composites or the miniaturization of electronic devices is an excellent example. New technologies to harvest renewable energies like wind, solar, geothermal, or tidal need them as well. Thermosetting materials are characterized by the three-dimensional network formed upon curing. Close-meshed networks provide excellent mechanical performance, but unfortunately they significantly increase brittleness. To meet the demands of applications, nearly all modern resin systems are toughened. Various different technologies and approaches can be used to obtain tough and stiff materials. It is crucial to balance chemistry and morphology and maintain optimal processability of toughened resins. Consequently the choice of toughening technology often depends on the process and/or the application of the thermosetting material. Although the use of established thermosetting resins derived from fossil resources is constantly growing, the next logical step in resin development is thermosets derived from renewable raw materials.

Miniaturization of electronics and new technologies enabling the harvest of renewable energies are just some of the growing applications fields for which thermosets are indispensable.

Dr. Sprenger Stephan
Guest Editor

Manuscript Submission Information

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Keywords

  • thermosets
  • toughener
  • epoxy

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Published Papers (4 papers)

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Research

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18 pages, 11623 KiB  
Article
General-Purpose Coarse-Grained Toughened Thermoset Model for 44DDS/DGEBA/PES
by Michael M. Henry, Stephen Thomas, Mone’t Alberts, Carla E. Estridge, Brittan Farmer, Olivia McNair and Eric Jankowski
Polymers 2020, 12(11), 2547; https://doi.org/10.3390/polym12112547 - 30 Oct 2020
Cited by 7 | Viewed by 3035
Abstract
The objective of this work is to predict the morphology and material properties of crosslinking polymers used in aerospace applications. We extend the open-source dybond plugin for HOOMD-Blue to implement a new coarse-grained model of reacting epoxy thermosets and use the 44DDS/DGEBA/PES system [...] Read more.
The objective of this work is to predict the morphology and material properties of crosslinking polymers used in aerospace applications. We extend the open-source dybond plugin for HOOMD-Blue to implement a new coarse-grained model of reacting epoxy thermosets and use the 44DDS/DGEBA/PES system as a case study for calibration and validation. We parameterize the coarse-grained model from atomistic solubility data, calibrate reaction dynamics against experiments, and check for size-dependent artifacts. We validate model predictions by comparing glass transition temperatures measurements at arbitrary degree of cure, gel-points, and morphology predictions against experiments. We demonstrate for the first time in molecular simulations the cure-path dependence of toughened thermoset morphologies. Full article
(This article belongs to the Special Issue Toughened Thermosets)
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16 pages, 11209 KiB  
Article
Lithographic Performance of Aryl Epoxy Thermoset Resins as Negative Tone Photoresist for Microlithography
by Vitor Vlnieska, Margarita Zakharova, Andrey Mikhaylov and Danays Kunka
Polymers 2020, 12(10), 2359; https://doi.org/10.3390/polym12102359 - 14 Oct 2020
Cited by 3 | Viewed by 3076
Abstract
Photoresists (or photo-resins) are the main and most important raw material used for lithography techniques such as deep X-ray (DXRL), ultraviolet (UVL), deep-UV (DUVL), and extreme UV (EUVL). In previous work, we showed how complicated could be the synthesis of the resins used [...] Read more.
Photoresists (or photo-resins) are the main and most important raw material used for lithography techniques such as deep X-ray (DXRL), ultraviolet (UVL), deep-UV (DUVL), and extreme UV (EUVL). In previous work, we showed how complicated could be the synthesis of the resins used to produce photoresist. In this study, we follow up on the strategy of tuning deep and macro levels of properties to formulate photo-resins. They were developed from a primary basis, using epoxy resins, a solvent, and a photoinitiator in several concentrations. The formulations were evaluated initially by the UVL technique, using a squared pattern of 2.3 mm2. The most suitable compositions were then studied in a pattern structure varying from 50 down to 1 µm width, applying UVL and DUVL. The patterned structures were compared with the chemical composition of the photo-resins. Considering the deep level of properties, polydispersion, and epoxidation degree were evaluated. Regarding the macro level of properties, the concentration of photoinitiator was studied. Promising results have been achieved with the control of the deep and macro levels methodology. By means of UV lithography, it was possible to note, for a large feature size above 2.0 mm2, the formulations presented good quality structures with a broad range of epoxidation degrees and photoinitiator concentrations, respectively from 3 to 100% (mol·molpolymer−1) and from 10 to 40% (mol·molpolymer−1). For structures smaller than 50 µm width, the composition of the photo-resins may be restricted to a narrow range of values regarding the formulation. The results indicate that the polydispersion of the oligomers might be a significant property to control. There is a tendency to better outcome with a low polydispersity (resins P1 and P2). Regarding UV and deep-UV irradiation, the best results were achieved with UV. Nevertheless, for DUV, the sensitivity seems to be more intense, leading to well-defined structures with over-exposure effects. Full article
(This article belongs to the Special Issue Toughened Thermosets)
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9 pages, 9062 KiB  
Article
Dimensional Accuracy of Dental Casting Patterns Fabricated Using Consumer 3D Printers
by Yoshiki Ishida, Daisuke Miura, Taira Miyasaka and Akikazu Shinya
Polymers 2020, 12(10), 2244; https://doi.org/10.3390/polym12102244 - 29 Sep 2020
Cited by 11 | Viewed by 2803
Abstract
Consumer 3D printers have improved considerably due to the evolution of additive manufacturing. This study aimed to examine the accuracy of consumer printers in dental restoration. Cylindrical patterns mimicking a full crown were created and enlarged from 100% to 105% of the original [...] Read more.
Consumer 3D printers have improved considerably due to the evolution of additive manufacturing. This study aimed to examine the accuracy of consumer printers in dental restoration. Cylindrical patterns mimicking a full crown were created and enlarged from 100% to 105% of the original size. Two types of consumer 3D printers, including a fused deposition modeling (FDM) device and a stereolithography (SLA) device, and two types of dental 3D printers, including a multi-jet device and an SLA device, were used to fabricate the patterns. Then, the outer and inner diameters and depths, and surface roughness of the patterns were measured. The changing rates of the outer diameter of models created using dental printers were significantly smaller than those of the models created using consumer printers (p < 0.05). Significantly greater surface roughness was obtained in the tooth axis of the model fabricated using the consumer FDM device (p < 0.05). However, no significant differences were observed on the surface roughness of both axes between the consumer SLA device and the dental devices (p > 0.05). However, FDM showed larger surface roughness than dental devices in both axes (p < 0.05). Thus, the SLA consumer printer can be applied to fabricate resin patterns with enlargement editing of 1–3% along the horizontal axis. Full article
(This article belongs to the Special Issue Toughened Thermosets)
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Review

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27 pages, 7601 KiB  
Review
Nanosilica-Toughened Epoxy Resins
by Stephan Sprenger
Polymers 2020, 12(8), 1777; https://doi.org/10.3390/polym12081777 - 8 Aug 2020
Cited by 59 | Viewed by 10097
Abstract
Surface-modified silica nanoparticles are available as concentrates in epoxy resins in industrial quantities for nearly 20 years. Meanwhile, they are used in many epoxy resin formulations for various applications like fiber-reinforced composites, adhesives or electronic components; even in space vehicles like satellites. Some [...] Read more.
Surface-modified silica nanoparticles are available as concentrates in epoxy resins in industrial quantities for nearly 20 years. Meanwhile, they are used in many epoxy resin formulations for various applications like fiber-reinforced composites, adhesives or electronic components; even in space vehicles like satellites. Some of the drawbacks of “classic” epoxy toughening using elastomers as a second phase, like lower modulus or a loss in strength can be compensated by using nanosilica together with such tougheners. Apparently, there exists a synergy as toughness and fatigue performance are increased significantly. This work intends to provide an overview regarding the possibilities of nanotoughening with silica, the industrial applications of such epoxy resin formulations and the most recent research results. Full article
(This article belongs to the Special Issue Toughened Thermosets)
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