Polymers

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12 pages, 4274 KiB

Open AccessArticle

Incorporation of Graphene Oxide Modified with Polyamide Curing Agent into the Epoxy–Zinc Composite Coating for Promoting Its Corrosion Resistance

by Shengjun He, Guangxiong Wei, Zhengnan Zhang, Lifeng Yang, Yuebin Lin, Longji Du and Xusheng Du

Polymers 2023, 15(8), 1873; https://doi.org/10.3390/polym15081873 - 13 Apr 2023

Cited by 2 | Viewed by 1884

Abstract

To promote the anticorrosion performance of epoxy/zinc (EP/Zn) coating, graphene oxide (GO) was directly incorporated into dual-component paint. Interestingly, it was found that the method of incorporating GO during the fabrication of the composite paints strongly influenced their performance. The samples were characterized [...] Read more.

To promote the anticorrosion performance of epoxy/zinc (EP/Zn) coating, graphene oxide (GO) was directly incorporated into dual-component paint. Interestingly, it was found that the method of incorporating GO during the fabrication of the composite paints strongly influenced their performance. The samples were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and Raman spectroscopy. The results indicated that GO could be intercalated and modified with the polyamide curing agent while preparing component B of the paint, for which the interlayer spacing of the resulting polyamide modified GO (PGO) increased, and its dispersion in organic solvent was improved. The corrosion resistance of the coatings was studied through potentiodynamic polarization testing, electrochemical impedance spectroscopy (EIS), and immersion testing. Among the three types of as-prepared coatings, i.e., neat EP/Zn coating, GO modified EP/Zn coating (GO/EP/Zn), and PGO-modified EP/Zn coating (PGO/EP/Zn), the order of the corrosion resistance of the coatings was PGO/EP/Zn > GO/EP/Zn > neat EP/Zn. This work demonstrates that although the in situ modification of GO with a curing agent is a simple method, it evidently promotes the shielding effect of the coating and enhances its corrosion resistance. Full article

(This article belongs to the Special Issue Advances in Graphene-Epoxy Nanocomposites)

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19 pages, 3185 KiB

Open AccessArticle

Evaluation of Surfactants on Graphene Dispersion and Thermal Performance for Heat Dissipation Coating

by Chia Cheng, Wen-Hao Shi, Tun-Ping Teng and Chii-Rong Yang

Polymers 2022, 14(5), 952; https://doi.org/10.3390/polym14050952 - 27 Feb 2022

Cited by 7 | Viewed by 3152

Abstract

With the development of thin and high-power electronic devices, heat dissipation has become an important and urgent issue in thermal management. In this study, a water-based epoxy was used as a polymer matrix to prepare heat dissipation coatings utilizing low volatile organic compounds, [...] Read more.

With the development of thin and high-power electronic devices, heat dissipation has become an important and urgent issue in thermal management. In this study, a water-based epoxy was used as a polymer matrix to prepare heat dissipation coatings utilizing low volatile organic compounds, which were environmentally friendly and had a high heat-dissipating performance. Graphene flakes, multi-walled carbon nanotubes and aluminum oxide particles were used as fillers for preparing the heat dissipation coating. The graphene flakes and multi-walled carbon nanotubes were dispersed in a water-based epoxy by adding sodium dihexyl sulfosuccinate and poly (dimethyldiallylammonium chloride). These two surfactants were combined as a dispersant to improve the dispersibility of the carbon nanomaterials in the water-based epoxy. The synergistic effect of the well-dispersed fillers improved the heat-dissipating performance. The experimental results show that the infrared emissivity of the heat dissipation film was 0.96 after filling 30 wt% aluminum oxide particles, 2 wt% graphene flakes and 2 wt% multi-walled carbon nanotubes into a water-based epoxy. The heat dissipation film reduced the thermal equilibrium temperature of the bare copper panel by 17.8 °C under a heating power of 10 W. The film was applied in a heat dissipation test on a 15 W LED bulb, and the thermal equilibrium temperature was reduced by 21.3 °C. The results demonstrate that the carbon nanomaterial-based heat dissipation coating with a water-based epoxy could significantly reduce the thermal equilibrium temperature, giving a high potential for the application of thermal management. Full article

(This article belongs to the Special Issue Advances in Graphene-Epoxy Nanocomposites)

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15 pages, 11714 KiB

Open AccessArticle

Enhanced Heat Dissipation Performance of Automotive LED Lamps Using Graphene Coatings

by Tun-Ping Teng, Wei-Jen Chen and Chun-Hsin Chang

Polymers 2022, 14(1), 50; https://doi.org/10.3390/polym14010050 - 23 Dec 2021

Cited by 3 | Viewed by 2680

Abstract

Graphene heat-dissipating coating (GNHC) of 0.6 wt % GN concentration is utilized to promote the cooling performance of automotive light-emitting diode (LED) lamps. Three cases are studied as follows: Case 0 is the original automotive LED lamp as the baseline. Case 1 is [...] Read more.

Graphene heat-dissipating coating (GNHC) of 0.6 wt % GN concentration is utilized to promote the cooling performance of automotive light-emitting diode (LED) lamps. Three cases are studied as follows: Case 0 is the original automotive LED lamp as the baseline. Case 1 is to apply GNHC to reduce the thermal resistance of the junction surfaces between the components of automotive LED lamps. The aluminum fin radiator of Case 1 is further coated with GNHC on the surface that becomes Case 2. The spectrum, illuminance, power consumption, and surface temperature are measured at different ambient temperatures (T_a) to fully evaluate the feasibility of applying GNHC to improve cooling performance and the impacts on the related characteristics of automotive LED lamps. The results show that the maximum illuminance efficacy of Case 1 and Case 2 with high beam, irradiation angle of 0 degrees, and T_a of 80 °C is 11.03% and 8.70% higher than that of Case 0, respectively. The minimum temperature difference of heat dissipation path of Case 1 and Case 2 with high beam, irradiation angle of 90 degrees, and T_a of 80 °C is 6.41% and 5.33% lower than that of Case 0, respectively, indicating GNHC as a promising coating material for improving the cooling performance of automotive LED lamps. Full article

(This article belongs to the Special Issue Advances in Graphene-Epoxy Nanocomposites)

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23 pages, 5694 KiB

Open AccessArticle

Structural and Dipole-Relaxation Processes in Epoxy–Multilayer Graphene Composites with Low Filler Content

by Borys M. Gorelov, Oleksandr V. Mischanchuk, Nadia V. Sigareva, Sergey V. Shulga, Alla M. Gorb, Oleksiy I. Polovina and Volodymyr O. Yukhymchuk

Polymers 2021, 13(19), 3360; https://doi.org/10.3390/polym13193360 - 30 Sep 2021

Cited by 5 | Viewed by 1878

Abstract

Multilayered graphene nanoplatelets (MLGs) were prepared from thermally expanded graphite flakes using an electrochemical technique. Morphological characterization of MLGs was performed using scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), Raman spectroscopy (RS), and the Brunauer–Emmett–Teller (BET) method. DGEBA-epoxy-based nanocomposites filled with synthesized [...] Read more.

Multilayered graphene nanoplatelets (MLGs) were prepared from thermally expanded graphite flakes using an electrochemical technique. Morphological characterization of MLGs was performed using scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), Raman spectroscopy (RS), and the Brunauer–Emmett–Teller (BET) method. DGEBA-epoxy-based nanocomposites filled with synthesized MLGs were studied using Static Mechanical Loading (SML), Thermal Desorption Mass Spectroscopy (TDMS), Broad-Band Dielectric Spectroscopy (BDS), and Positron Annihilation Lifetime Spectroscopy (PALS). The mass loading of the MLGs in the nanocomposites was varied between 0.0, 0.1, 0.2, 0.5, and 1% in the case of the SML study and 0.0, 1.0, 2, and 5% for the other measurements. Enhancements in the compression strength and the Young’s modulus were obtained at extremely low loadings (

C \leq

0.01%). An essential increase in thermal stability and a decrease in destruction activation energy were observed at

C \leq

5%. Both the dielectric permittivity (

ε_{1}

) and the dielectric loss factor (

ε_{2}

) increased with increasing

C

over the entire frequency region tested (4 Hz–8 MHz). Increased

ε_{2}

is correlated with decreased free volume when increasing

C

. Physical mechanisms of MLG–epoxy interactions underlying the effects observed are discussed. Full article

(This article belongs to the Special Issue Advances in Graphene-Epoxy Nanocomposites)

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10 pages, 2387 KiB

Open AccessArticle

Preparation of Modified Fluorographene Oxide with Interlayer Supporting Structure

by Chengbing Yu, Kaiqin Shi, Jinyan Ning and Jun Liu

Polymers 2021, 13(18), 3126; https://doi.org/10.3390/polym13183126 - 16 Sep 2021

Viewed by 1779

Abstract

Fluorinated graphene (FGi) is easy to agglomerate, after which it turns into a curly and wavy shape, which results in a great decrease in the properties of the resultant composite materials and coatings. In this study, fluorinated graphene oxide (FGO) modified with p-phenylenediamine [...] Read more.

Fluorinated graphene (FGi) is easy to agglomerate, after which it turns into a curly and wavy shape, which results in a great decrease in the properties of the resultant composite materials and coatings. In this study, fluorinated graphene oxide (FGO) modified with p-phenylenediamine (PPD) was prepared, but with a view to avoid its agglomeration and retain a sheet-like structure. Through the reaction between PPD and the epoxy groups of FGO, the modified FGO with an amino group (N-PGO) had a larger interlayer d-spacing than FGO. The stability of N-PGO was also improved, and nitrogen, fluorine, oxygen, and carbon were evenly distributed in the N-PGO sheets. All the results indicate that PPD can act as an effective spacer to separate graphene sheets for good anti-agglomeration properties. This method produced modified graphene with fluorine, amino, and carbonyl groups. It shows potential in introducing N-PGO as a reactive modifier in composite materials and coatings for a variety of industrial applications including waterborne epoxy materials. Full article

(This article belongs to the Special Issue Advances in Graphene-Epoxy Nanocomposites)

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23 pages, 12192 KiB

Open AccessArticle

Experimental Characterization and Modeling Multifunctional Properties of Epoxy/Graphene Oxide Nanocomposites

by Kakur Naresh, Kamran A. Khan and Rehan Umer

Polymers 2021, 13(16), 2831; https://doi.org/10.3390/polym13162831 - 23 Aug 2021

Cited by 20 | Viewed by 3448

Abstract

Thermomechanical modeling of epoxy/graphene oxide under quasi-static and dynamic loading requires thermo-mechanical properties such as Young’s modulus, Poisson’s ratio, thermal conductivity, and frequency-temperature dependent viscoelastic properties. In this study, the effects of different graphene oxide (GO) concentrations (0.05, 0.1, and 0.2 wt%) within [...] Read more.

Thermomechanical modeling of epoxy/graphene oxide under quasi-static and dynamic loading requires thermo-mechanical properties such as Young’s modulus, Poisson’s ratio, thermal conductivity, and frequency-temperature dependent viscoelastic properties. In this study, the effects of different graphene oxide (GO) concentrations (0.05, 0.1, and 0.2 wt%) within an epoxy matrix on several mechanical and thermal properties were investigated. The distribution of GO fillers in the epoxy was investigated using transmission electron microscopy (TEM). The digital image correlation (DIC) technique was employed during the tensile testing to determine Young’s modulus and Poisson’s ratio. Analytical models were used to predict Young’s modulus and thermal conductivity, with an error of less than 13% and 9%, respectively. Frequency–temperature dependent phenomenological models were proposed to predict the storage moduli and loss tangent, with a reasonable agreement with experimental data. A relatively high storage modulus, heat-resistance index (T_HRI), and thermal conductivity were observed in 0.2 wt% nanocomposite samples compared with pure epoxy and other lower concentration GO nanocomposites. A high T_HRI and derivative of thermogravimetric analysis peak temperatures (T_m1 and T_m2) were exhibited by adding nano-fillers in the epoxy, which confirms higher thermal stability of nanocomposites than that of pristine epoxy. Full article

(This article belongs to the Special Issue Advances in Graphene-Epoxy Nanocomposites)

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22 pages, 11514 KiB

Open AccessArticle

Research on the Anticorrosion Properties of CeO₂-GO/EP Nanocomposite Coating in Simulated Sea Water

by Xiaoyan Liu, Ruidan Liu, Tianyu Li, Yanqi Liu, Li Liu, Kai Lyu and Surendra P. Shah

Polymers 2021, 13(13), 2072; https://doi.org/10.3390/polym13132072 - 24 Jun 2021

Cited by 13 | Viewed by 2820

Abstract

Graphene is a two-dimensional sheet of regular hexagonal honeycomb lattice formed by sp² hybrid orbital bonding, with only one layer thickness of a single atom, which is known as the “super king” of the 21st century. Previous studies have shown that cerium [...] Read more.

Graphene is a two-dimensional sheet of regular hexagonal honeycomb lattice formed by sp² hybrid orbital bonding, with only one layer thickness of a single atom, which is known as the “super king” of the 21st century. Previous studies have shown that cerium oxide-graphene oxide (CeO₂-GO(4:1)) nanocomposites eliminated the agglomeration of graphene to some extent and the CeO₂-GO(4:1) epoxy coating could be prepared with good anti-corrosion performance. In this paper, CeO₂-GO(4:1) nanocomposites were prepared by the hydrothermal synthesis method, and the three-electrode method was used for electrochemical tests. The state evolution of CeO₂-GO(4:1)/EP coating and the synergy between CeO₂-GO(4:1)/EP and corrosion inhibitor in simulated seawater solution with different concentrations (20%, 40%, 60%) were analyzed and illustrated by Optical Microscope (OM) characterization, Open Circuit Potential (OCP), Electrochemical alternating current Impedance Spectroscopy (EIS), Mott–Schottky curve and Tafel curve. The results indicated that CeO₂-GO(4:1) nanocomposites showed good corrosion resistance in a marine environment. This research lays a solid theoretical foundation for the application of cerium oxide-modified graphene oxide anticorrosive coating in marine engineering. Full article

(This article belongs to the Special Issue Advances in Graphene-Epoxy Nanocomposites)

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Review

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21 pages, 5092 KiB

Open AccessReview

An Overview on Carbon Fiber-Reinforced Epoxy Composites: Effect of Graphene Oxide Incorporation on Composites Performance

by Harsh Sharma, Ajay Kumar, Sravendra Rana and Liberata Guadagno

Polymers 2022, 14(8), 1548; https://doi.org/10.3390/polym14081548 - 11 Apr 2022

Cited by 42 | Viewed by 8472

Abstract

Carbon fiber-reinforced polymer (CFRP) composites are used in a variety of applications such as aircraft, automobiles, body armors, and the sports sector owing to their ultra-strong and lightweight characteristics. However, the incorporation of an untreated pristine carbon fiber surface leads to a weak [...] Read more.

Carbon fiber-reinforced polymer (CFRP) composites are used in a variety of applications such as aircraft, automobiles, body armors, and the sports sector owing to their ultra-strong and lightweight characteristics. However, the incorporation of an untreated pristine carbon fiber surface leads to a weak interfacial interaction with the polymeric matrix, thus triggering catastrophic failure of the composite material. Graphene oxide, a 2D-macromolecule consisting of several polar functional groups such as hydroxyl, carboxyl, and carbonyl on the basal planes and edges, tends to increase the surface area and has thus been applied between the fiber and matrix, helping to improve CFRP properties. Herein, we condense different routes of functionalization of GO nanosheets and their incorporation onto a fiber surface or in a carbon fiber-reinforced epoxy matrix, helping to improve the interfacial adhesion between the fiber and matrix, and thus allowing effective stress transfer and energy absorption. The improvement of the interfacial adhesion between the fiber and carbon fiber-reinforced epoxy matrix is due to the peculiar structure of GO nanoparticles composed of polar groups, especially on the edges of the nanosheets, able to provide strong interaction with the hosting cured epoxy matrix, and the “core” part similar to the structure of CFs, and hence able to establish strong π-π interactions with the reinforcing CFs. The article also covers the effect of functionalized graphene oxide incorporation on the mechanical, thermal, electrical, and viscoelastic properties of composite materials reinforced with carbon fibers. Full article

(This article belongs to the Special Issue Advances in Graphene-Epoxy Nanocomposites)

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