Research

20 pages, 3405 KiB

Open AccessArticle

Antimicrobial Efficacy of a Vegetable Oil Plasticizer in PVC Matrices

by Greta Bajetto, Sara Scutera, Francesca Menotti, Giuliana Banche, Giuseppe Chiaradia, Caterina Turesso, Marco De Andrea, Marta Vallino, Daan S. Van Es, Matteo Biolatti, Valentina Dell’Oste and Tiziana Musso

Polymers 2024, 16(8), 1046; https://doi.org/10.3390/polym16081046 - 10 Apr 2024

Viewed by 425

Abstract

The growing prevalence of bacterial and viral infections, highlighted by the recent COVID-19 pandemic, urgently calls for new antimicrobial strategies. To this end, we have synthesized and characterized a novel fatty acid epoxy-ester plasticizer for polymers, named GDE. GDE is not only sustainable [...] Read more.

The growing prevalence of bacterial and viral infections, highlighted by the recent COVID-19 pandemic, urgently calls for new antimicrobial strategies. To this end, we have synthesized and characterized a novel fatty acid epoxy-ester plasticizer for polymers, named GDE. GDE is not only sustainable and user-friendly but also demonstrates superior plasticizing properties, while its epoxy components improve the heat stability of PVC-based matrices. A key feature of GDE is its ability to confer antimicrobial properties to surfaces. Indeed, upon contact, this material can effectively kill enveloped viruses, such as herpes simplex virus type 1 (HSV-1) and the β-coronavirus prototype HCoV-OC43, but it is ineffective against nonenveloped viruses like human adenovirus (HAdV). Further analysis using transmission electron microscopy (TEM) on HSV-1 virions exposed to GDE showed significant structural damage, indicating that GDE can interfere with the viral envelope, potentially causing leakage. Moreover, GDE demonstrates antibacterial activity, albeit to a lesser extent, against notorious pathogens such as Staphylococcus aureus and Escherichia coli. Overall, this newly developed plasticizer shows significant potential as an antimicrobial agent suitable for use in both community and healthcare settings to curb the spread of infections caused by microorganisms contaminating physical surfaces. Full article

(This article belongs to the Special Issue Advanced Epoxy-Based Materials IV)

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17 pages, 4313 KiB

Open AccessArticle

Catalysis of Silver and Bismuth in Various Epoxy Resins

by Hayun Jeong and Keon-Soo Jang

Polymers 2024, 16(3), 439; https://doi.org/10.3390/polym16030439 - 05 Feb 2024

Viewed by 821

Abstract

Epoxy resins find extensive utility across diverse applications owing to their exceptional adhesion capabilities and robust mechanical and thermal characteristics. However, the demanding reaction conditions, including extended reaction times and elevated reaction temperature requirements, pose significant challenges when using epoxy resins, particularly in [...] Read more.

Epoxy resins find extensive utility across diverse applications owing to their exceptional adhesion capabilities and robust mechanical and thermal characteristics. However, the demanding reaction conditions, including extended reaction times and elevated reaction temperature requirements, pose significant challenges when using epoxy resins, particularly in advanced applications seeking superior material properties. To surmount these limitations, the conventional approach involves incorporating organic catalysts. Within the ambit of this investigation, we explored the catalytic potential of metallic powders, specifically bismuth (Bi) and silver (Ag), in epoxy resins laden with various curing agents, such as diacids, anhydrides, and amines. Metallic powders exhibited efficacious catalytic activity in epoxy–diacid and epoxy–anhydride systems. In contrast, their influence on epoxy–amine systems was rendered negligible, attributed to the absence of requisite carboxylate functional groups. Additionally, the catalytic performance of Bi and Ag are different, with Bi displaying superior efficiency owing to the presence of inherent metal oxide layers on its powder surfaces. Remarkably, the thermal and mechanical properties of uncatalyzed, fully cured epoxy resins closely paralleled those of their catalyzed counterparts. These findings accentuate the potential of Bi and Ag metal catalysts, particularly in epoxy–diacid and epoxy–anhydride systems, spanning a spectrum of epoxy-based applications. In summary, this investigation elucidates the catalytic capabilities of Bi and Ag metal powders, underscoring their ability to enhance the curing rate of epoxy resin systems involving diacids and anhydrides but not amines. This research points toward a promising trajectory for multifarious epoxy-related applications. Full article

(This article belongs to the Special Issue Advanced Epoxy-Based Materials IV)

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12 pages, 4532 KiB

Open AccessArticle

Enhancing Thermomechanical Strength and Thermal Stability of Poly(dicyclopentadiene) Composites through Cost-Effective Fly Ash Reinforcement for Structural and Impact Applications

by Henry A. Colorado, Wei Yuan, Juan Meza, Franklin Jaramillo and Elkin I. Gutierrez-Velasquez

Polymers 2023, 15(22), 4418; https://doi.org/10.3390/polym15224418 - 16 Nov 2023

Cited by 1 | Viewed by 666

Abstract

Poly(dicyclopentadiene) (poly-DCPD) is a thermoset with potential for high-performance applications. In this research, epoxy resin was blended with different concentrations of fly ash class F particles at 0.0, 1.0, 10.0, and 50.0 wt.%, aiming to improve its use as a high-volume structural material [...] Read more.

Poly(dicyclopentadiene) (poly-DCPD) is a thermoset with potential for high-performance applications. In this research, epoxy resin was blended with different concentrations of fly ash class F particles at 0.0, 1.0, 10.0, and 50.0 wt.%, aiming to improve its use as a high-volume structural material by decreasing costs and reducing its negative environmental impact through using fly ash particles. A planetary Thinky mixer was used to initially mix the resin with the curing agent, followed by incorporating a Grubbs catalyst. The microstructures were analyzed using scanning electron microscopy (SEM), where particles were found to be homogeneously distributed over the polymer matrix. The thermomechanical behavior was evaluated via curing, compression, dynamic mechanical analysis (DMA), and thermo-gravimetric analysis (TGA). Nanoindentation tests were also conducted. Fly ash was found to decelerate the curing of the resin through the release of calcium ions that enhanced the exothermic reaction. Full article

(This article belongs to the Special Issue Advanced Epoxy-Based Materials IV)

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16 pages, 5514 KiB

Open AccessArticle

Reinforced Epoxy Binder Modified with Borpolymer

by Aleksei G. Tuisov, Aisen Kychkin, Anatoly K. Kychkin and Elena S. Anan’eva

Polymers 2023, 15(12), 2632; https://doi.org/10.3390/polym15122632 - 09 Jun 2023

Viewed by 873

Abstract

Polymer binders based on epoxy resins have unique properties that contribute to their use in many composite industries. The potential of using epoxy binders is due to their high elasticity and strength characteristics, thermal and chemical resistance, and resistance to climatic aging. This [...] Read more.

Polymer binders based on epoxy resins have unique properties that contribute to their use in many composite industries. The potential of using epoxy binders is due to their high elasticity and strength characteristics, thermal and chemical resistance, and resistance to climatic aging. This is the reason for the existing practical interest in modifying the composition of epoxy binders and understanding the strengthening mechanisms in order to form reinforced composite materials with a required set of properties based on them. This article presents the results of a study of the process of dissolving the modifying additive of polymethylene-p-triphenyl ether of boric acid in the components of an epoxyanhydride binder applicable to the production of fibrous composite materials. The temperature and time conditions for the dissolution of polymethylene-p-triphenyl ether of boric acid in anhydride-type isomethyltetrahydrophthalic anhydride hardeners are presented. It has been established that the complete dissolution of the borpolymer-modifying additive in iso-MTHPA occurs at a temperature of 55 ± 2 °C for 20 h. The effect of the modifying additive of polymethylene-p-triphenyl ether of boric acid on the strength properties and structure of the epoxyanhydride binder has been studied. Increases in transverse bending strength up to 190 MPa, elastic modulus up to 3200 MPa, tensile strength up to 0.8 MPa, and impact strength (Charpy) up to 5.1 kJ/m² are observed when the content of the borpolymer-modifying additive in the composition of the epoxy binder is 0.50 mass. %. Full article

(This article belongs to the Special Issue Advanced Epoxy-Based Materials IV)

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21 pages, 13485 KiB

Open AccessArticle

Method of Manufacturing Structural, Optically Transparent Glass Fiber-Reinforced Polymers (tGFRP) Using Infusion Techniques with Epoxy Resin Systems and E-Glass Fabrics

by Klaus Heudorfer, Johannes Bauer, Yavuz Caydamli, Bruno Gompf, Jens Take, Michael R. Buchmeiser and Peter Middendorf

Polymers 2023, 15(9), 2183; https://doi.org/10.3390/polym15092183 - 04 May 2023

Viewed by 2163

Abstract

Recently, fiber-reinforced, epoxy-based, optically transparent composites were successfully produced using resin transfer molding (RTM) techniques. Generally, the production of structural, optically transparent composites is challenging since it requires the combination of a very smooth mold surface with a sufficient control of resin flow [...] Read more.

Recently, fiber-reinforced, epoxy-based, optically transparent composites were successfully produced using resin transfer molding (RTM) techniques. Generally, the production of structural, optically transparent composites is challenging since it requires the combination of a very smooth mold surface with a sufficient control of resin flow that leads to no visible voids. Furthermore, it requires a minimum deviation of the refractive indices (RIs) of the matrix polymer and the reinforcement fibers. Here, a new mold design is described and three plates of optically transparent glass fiber-reinforced polymers (tGFRP) with reproducible properties as well as high fiber volume fractions were produced using the RTM process and in situ polymerization of an epoxy resin system enclosing E-glass fiber textiles. Their mechanical (flexural), microstructural (fiber volume fraction, surface roughness, etc.), thermal (DSC, TGA, etc.), and optical (dispersion curves of glass fibers and polymer as well as transmission over visible spectra curves of the tGFRP at varying tempering states) properties were evaluated. The research showed improved surface quality and good transmission data for samples manufactured by a new Optical-RTM setup compared to a standard RTM mold. The maximum transmission was reported to be ≈74%. In addition, no detectable voids were found in these samples. Furthermore, a flexural modulus of 23.49 ± 0.64 GPa was achieved for the Optical-RTM samples having a fiber volume fraction of ≈42%. Full article

(This article belongs to the Special Issue Advanced Epoxy-Based Materials IV)

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26 pages, 3848 KiB

Open AccessArticle

Seawater Effects on Thermally Aged Ambient Cured Carbon/Epoxy Composites: Moisture Kinetics and Uptake Characteristics

by Vistasp M. Karbhari, Rabina Acharya and SoonKook Hong

Polymers 2023, 15(9), 2138; https://doi.org/10.3390/polym15092138 - 29 Apr 2023

Viewed by 1546

Abstract

Carbon fiber-reinforced epoxy matrix composites using ambient- and moderate-temperature curing non-autoclave processes have broad applicability in marine, offshore, and naval applications. This research focuses on the characterization of moisture kinetics of ambient cured carbon/epoxy composites subject to immersion in seawater for up to [...] Read more.

Carbon fiber-reinforced epoxy matrix composites using ambient- and moderate-temperature curing non-autoclave processes have broad applicability in marine, offshore, and naval applications. This research focuses on the characterization of moisture kinetics of ambient cured carbon/epoxy composites subject to immersion in seawater for up to 72 weeks after prior periods of extended thermal aging. A two-stage model is shown to best describe the overall kinetics and response. The level of maximum moisture uptake shows an increasing trend with the temperature and time of prior thermal aging, reaching asymptotic levels at the highest levels. The transition point is seen to represent a shift between the diffusion and relaxation-/deterioration-based dominant regimes, and the ratio of uptake at the transition point to the maximum uptake can be correlated to the relaxation coefficient. Diffusivity, as expected, generally increases with the temperature of prior aging and shows changes based on the level of post-curing and network changes with time. Moisture uptake kinetics and characteristics developed through the sequence of exposures provide a better understanding of phenomena towards the development of a future comprehensive model capable of long-term prediction based on the sequential prior history of exposure to elevated temperatures and immersion in seawater. Full article

(This article belongs to the Special Issue Advanced Epoxy-Based Materials IV)

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20 pages, 5460 KiB

Open AccessArticle

Microwave Modification of an Epoxy Basalt-Filled Oligomer to Improve the Functional Properties of a Composite Based on It

by Amirbek Bekeshev, Ekaterina Vasinkina, Svetlana Kalganova, Yulia Kadykova, Anton Mostovoy, Andrey Shcherbakov, Marina Lopukhova and Zukhra Aimaganbetova

Polymers 2023, 15(9), 2024; https://doi.org/10.3390/polym15092024 - 24 Apr 2023

Cited by 2 | Viewed by 1283

Abstract

The purpose of this work is to study the influence of the electric field strength of an electromagnetic wave with the maximum modifying effect on an epoxy basalt-filled oligomer, which is of great scientific and practical importance for the development of microwave oligomer [...] Read more.

The purpose of this work is to study the influence of the electric field strength of an electromagnetic wave with the maximum modifying effect on an epoxy basalt-filled oligomer, which is of great scientific and practical importance for the development of microwave oligomer modification technology. The optimal modes of microwave modification, under which the highest values of the mechanical properties of an epoxy basalt-filled polymer composite material are obtained, are identified: power of 400 W and an exposure time of 24 s. At the same time, the breaking stress in bending increases by 20%, the impact strength increases by 2 times, and hardness increases by 31%. A slight increase of 4.5% in heat resistance is noted compared to the composite obtained on the basis of an oligomer unmodified in the microwave electromagnetic field. The results of resistance to various aggressive environments are obtained, which show that the studied physical and mechanical characteristics of the epoxy basalt-filled material after exposure to an aggressive environment decrease by less than 14%, which corresponds to their good resistance to an aggressive environment. It is established that the effect of the microwave electromagnetic field on an epoxy basalt-filled oligomer is an effective modification method that improves physical and mechanical characteristics with a high level of temporal stability to climatic influences, with a coefficient of property retention of more than 90%. Full article

(This article belongs to the Special Issue Advanced Epoxy-Based Materials IV)

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15 pages, 4789 KiB

Open AccessArticle

Effect of the Simultaneous Addition of Polycaprolactone and Carbon Nanotubes on the Mechanical, Electrical, and Adhesive Properties of Epoxy Resins Cured with Ionic Liquids

by Lidia Orduna, Itziar Otaegi, Nora Aranburu and Gonzalo Guerrica-Echevarría

Polymers 2023, 15(7), 1607; https://doi.org/10.3390/polym15071607 - 23 Mar 2023

Cited by 1 | Viewed by 1198

Abstract

Electrically-conductive epoxy nanocomposites (NCs) with improved mechanical and adhesive properties were achieved through the combined addition of poly(ε-caprolactone) (PCL) and carbon nanotubes (CNTs). Three different ionic liquids (ILs) were used as dual role agents, i.e., as both curing and dispersing agents. Regardless of [...] Read more.

Electrically-conductive epoxy nanocomposites (NCs) with improved mechanical and adhesive properties were achieved through the combined addition of poly(ε-caprolactone) (PCL) and carbon nanotubes (CNTs). Three different ionic liquids (ILs) were used as dual role agents, i.e., as both curing and dispersing agents. Regardless of the IL used, the epoxy/PCL matrix of the NCs showed a single-phase behaviour and similar glass transition (T_g) and crosslinking density (ν_e) values to the unfilled epoxy/PCL/IL systems. Although the CNTs were more poorly dispersed in the epoxy/PCL/CNT/IL NCs than in the reference epoxy/CNT/IL NCs, which led to slightly lower electrical conductivity values, the epoxy/PCL/CNT/IL NCs were still semiconductive. Their low-strain mechanical properties (i.e., flexural modulus and flexural strength) were similar or better than those of the reference epoxy/IL systems and their high-strain mechanical properties (i.e., deformation at break and impact strength) were significantly better. In addition, the positive effects of the PCL and the CNTs on the adhesive properties of the epoxy/IL system were combined. The substitution of ILs for traditional amine-based curing agents and biodegradable PCL for part of the epoxy resin represents an important advance on the road towards greater sustainability. Full article

(This article belongs to the Special Issue Advanced Epoxy-Based Materials IV)

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12 pages, 3562 KiB

Open AccessArticle

Thermal and Mechanical Characterization of Epoxy/Polyimide Blends via Postcuring Process

by Yong-Min Lee, Kwan-Woo Kim and Byung-Joo Kim

Polymers 2023, 15(5), 1072; https://doi.org/10.3390/polym15051072 - 21 Feb 2023

Cited by 1 | Viewed by 2154

Abstract

In this study, the effects of polyimide (PI) content and postcuring on thermal and mechanical properties in PI and epoxy (EP) blending systems were investigated. EP/PI (EPI) blending reduced the crosslinking density and improved the flexural and impact strength due to ductility. On [...] Read more.

In this study, the effects of polyimide (PI) content and postcuring on thermal and mechanical properties in PI and epoxy (EP) blending systems were investigated. EP/PI (EPI) blending reduced the crosslinking density and improved the flexural and impact strength due to ductility. On the other hand, in the postcuring of EPI, the thermal resistance improved due to the increased crosslinking density and the flexural strength increased by up to 57.89% due to the enhanced stiffness, but the impact strength decreased by up to 59.54%. EPI blending induced the improvement in the mechanical properties of EP, and the postcuring process of EPI was shown to be an effective method to improve heat resistance. It was confirmed that EPI blending induces improvement in the mechanical properties of EP, and the postcuring process of EPI is an effective method for improving heat resistance. Full article

(This article belongs to the Special Issue Advanced Epoxy-Based Materials IV)

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