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Showing papers on "Epoxy published in 2017"


Journal ArticleDOI
TL;DR: In this paper, the authors used cellulose nanofiber-supported 3D interconnected boron nitride nanosheet (3D-C-BNNS) aerogels for thermally conductive but electrically insulating epoxy nanocomposites.
Abstract: Thermally conductive but electrically insulating polymer composites are highly desirable for thermal management applications because of their wide range of utilization, ease of processing, and low cost. However, the traditional approaches to thermally conductive polymer composites usually suffer from the low thermal conductivity enhancement and/or the deterioration of electrical insulating property. In this study, using cellulose nanofiber-supported 3D interconnected boron nitride nanosheet (3D–C–BNNS) aerogels, a novel method for highly thermally conductive but electrically insulating epoxy nanocomposites is reported. The nanocomposites exhibit thermal conductivity enhancement of about 1400% at a low BNNS loading of 9.6 vol%. In addition, the epoxy nanocomposites are still highly insulating, having a volume electrical resistivity of 1015 Ω cm. The strong potential application for thermal management has been demonstrated by the surface temperature variations of the nanocomposites with time during heating and cooling.

580 citations


Journal ArticleDOI
TL;DR: In this article, a solvent-based epoxy coatings filled with graphene oxide nanosheets (GO) was developed to enhance the corrosion protection of mild steel substrates.

418 citations


Journal ArticleDOI
TL;DR: This study paves the way for thermally conductive polymer composites used as thermal interface materials for next-generation electronic packaging and 3D integration circuits.
Abstract: In this work, we report a fabrication of epoxy resin/ordered three-dimensional boron nitride (3D-BN) network composites through combination of ice-templating self-assembly and infiltration methods. The polymer composites possess much higher thermal conductivity up to 4.42 W m–1 K–1 at relatively low loading 34 vol % than that of random distribution composites (1.81 W m–1 K–1 for epoxy/random 3D-BN composites, 1.16 W m–1 K–1 for epoxy/random BN composites) and exhibit a high glass transition temperature (178.9–229.2 °C) and dimensional stability (22.7 ppm/K). We attribute the increased thermal conductivity to the unique oriented 3D-BN thermally conducive network, in which the much higher thermal conductivity along the in-plane direction of BN microplatelets is most useful. This study paves the way for thermally conductive polymer composites used as thermal interface materials for next-generation electronic packaging and 3D integration circuits.

361 citations


Journal ArticleDOI
01 Apr 2017-Carbon
TL;DR: In this paper, the authors used poly(2-butylaniline) (P2BA) as a dispersing agent to achieve stable dispersion of graphene in organic solvents via non-covalent π-π interactions between P2BA and graphene.

336 citations


Journal ArticleDOI
TL;DR: In this article, the authors presented a methodology for stochastic modeling of the fracture in polymer/particle nanocomposites, which is based on six uncertain parameters: the volume fraction and the diameter of the nanoparticles, Young's modulus and the maximum allowable principal stress of the epoxy matrix, the interphase zone thickness and its Youngs modulus.
Abstract: The fracture energy is a substantial material property that measures the ability of materials to resist crack growth. The reinforcement of the epoxy polymers by nanosize fillers improves significantly their toughness. The fracture mechanism of the produced polymeric nanocomposites is influenced by different parameters. This paper presents a methodology for stochastic modelling of the fracture in polymer/particle nanocomposites. For this purpose, we generated a 2D finite element model containing an epoxy matrix and rigid nanoparticles surrounded by an interphase zone. The crack propagation was modelled by the phantom node method. The stochastic model is based on six uncertain parameters: the volume fraction and the diameter of the nanoparticles, Young’s modulus and the maximum allowable principal stress of the epoxy matrix, the interphase zone thickness and its Young’s modulus. Considering the uncertainties in input parameters, a polynomial chaos expansion surrogate model is constructed followed by a sensitivity analysis. The variance in the fracture energy was mostly influenced by the maximum allowable principal stress and Young’s modulus of the epoxy matrix.

336 citations


Journal ArticleDOI
TL;DR: In this paper, two bio-based epoxy monomers EP1 and EP2 were synthesized by one-pot reaction containing Schiff base formation and phosphorus-hydrogen addition between vanillin, diamines, and diethyl phosphite, followed by reacting with epichlorohydrin.
Abstract: Lignin derivative vanillin when coupled with diamines and diethyl phosphite followed by reaction with echichlorohydrin yields high-performance flame retardant epoxy resins. Biorenewable and environment-friendly flame retardant alternatives to bisphenol A epoxy resins (having plenty of applications such as coatings, adhesives, composites, etc.) have captured great attention due to their ecological and economic necessity. Vanillin, an industrial scale monoaromatic compound from lignin, is a promising sustainable candidate for high-performance polymers, while synthesis of diepoxies is challenging. Meanwhile, bio-based epoxy resins combining high performance and excellent fire resistance are more difficult to be achieved. In this paper, two novel bio-based epoxy monomers EP1 and EP2 were synthesized by one-pot reaction containing Schiff base formation and phosphorus–hydrogen addition between vanillin, diamines, and diethyl phosphite, followed by reacting with epichlorohydrin. Their reactivities are similar to...

311 citations


Journal ArticleDOI
TL;DR: In this article, a new thermosetting vitrimer epoxy ink and a 3D printing method that can 3D print epoxy into parts with complicated 3D geometries, which later can be recycled into a new ink for the next round of printing.
Abstract: 3D printing of polymeric materials for various applications has been quickly developed in recent years. In contrast to thermoplastics, 3D printed thermosets, although desirable, are inherently non-recyclable due to their permanently crosslinked networks. As 3D printing is becoming more popular, it is desirable to develop recycling approaches for 3D printed parts in view of increasing polymer wastes. Here, we present a new thermosetting vitrimer epoxy ink and a 3D printing method that can 3D print epoxy into parts with complicated 3D geometries, which later can be recycled into a new ink for the next round of 3D printing. In the first printing cycle, a high-viscous ink is first slightly cured and is then printed at an elevated temperature into complicated 3D structures, followed by an oven cure using a two-step approach. To be recycled, the printed epoxy parts are fully dissolved in an ethylene glycol solvent in a sealed container at a high temperature. The dissolved polymer solution is reused for the next printing cycle using similar printing conditions. Our experiments demonstrate that the ink can be printed four times and still retains very good printability. In addition, the vitrimer epoxy can be used for pressure-free repairs for the 3D printed parts.

297 citations


Journal ArticleDOI
22 Nov 2017-Polymer
TL;DR: In this article, a two-layer reinforced carbon fiber (CF) was prepared by an electrochemical deposition and electrophoretic deposition (EPD) and the modified fiber showed an increased interfacial shear strength (IFSS) and tensile strength.

294 citations


Journal ArticleDOI
TL;DR: In this paper, a unique eugenol-derived epoxy (Eu-EP) is synthesized, and then vitrimeric materials are prepared by reacting EuEP with succinic anhydride (SA) at various ratios (1: 0.5, 1:0.75, and 1:1) in the presence of zinc-containing catalysts.
Abstract: Conventional epoxy polymers are constructed by petro-based resources that are toxic and nonrenewable, and their permanent cross-links make them difficult to be reprocessed, reshaped, and recycled. In this study, a unique eugenol-derived epoxy (Eu-EP) is synthesized, and then vitrimeric materials are prepared by reacting Eu-EP with succinic anhydride (SA) at various ratios (1:0.5, 1:0.75, and 1:1) in the presence of zinc-containing catalysts. All vitrimers exhibit excellent shape changing, crack healing, and shape memory properties. Although vitrimers with 1:0.75 and 1:1 ratios cannot be physically reprocessed, they can be well reprocessed by the chemical method of being simply decomposed in a benign ethanol solution without loading additional catalyst. The collected decomposed polymers can form vitrimers again after exposure at 190 °C for 3 h. This work combines the concepts of vitrimer preparation, chemical recycling, and biobased polymer together, which would bring a feasible way to satisfy the demands ...

276 citations


Journal ArticleDOI
TL;DR: In this article, a polypyrrole functionalized nano-magnetite (Fe3O4-PPy) was used to enhance the electromagnetic wave absorption performance and flame retardancy.
Abstract: Epoxy nanocomposites reinforced with polypyrrole functionalized nano-magnetite (Fe3O4–PPy) showed significantly enhanced electromagnetic wave absorption performance and flame retardancy. The Fe3O4–PPy nanocomposites were prepared by the surface initiated polymerization method. The epoxy/(30.0 wt%)Fe3O4–PPy nanocomposites possess a minimum reflection loss (RL) value of −35.7 dB, which is much lower than that of either epoxy/(7.5 wt%)PPy nanocomposites with a minimum RL value of −11.0 dB or epoxy/(30.0 wt%)Fe3O4 with a minimum RL value of −17.8 dB at the same thickness (1.7 mm). Meanwhile, the bandwidth of epoxy/(30.0 wt%)Fe3O4–PPy nanocomposites for RL < −10 dB and RL < −20 dB is 4.0 GHz and 0.8 GHz, respectively. The increased interface area, eddy current loss and anisotropic energy are essentially important to achieve higher reflection loss and broader absorption bandwidth for epoxy/(30.0 wt%)Fe3O4–PPy nanocomposites. Moreover, the significantly reduced flammability was observed in the epoxy/(30.0 wt%)Fe3O4–PPy nanocomposites compared with pure epoxy. The total heat release of epoxy/(30.0 wt%)Fe3O4–PPy nanocomposites decreased from 25.5 kJ g−1 of pure epoxy to just 12.3 kJ g−1. The tensile strength of the epoxy nanocomposites was reported as well. These new nanocomposites with an enhanced electromagnetic wave absorption property and flame retardancy possess great potential for safer electromagnetic wave absorbers in the electronic industry to satisfy stringent industrial standards.

239 citations


Journal ArticleDOI
TL;DR: In this paper, a facile strategy was reported to fabricate vertically oriented and densely packed hexagonal boron nitride (h-BN)/epoxy (EP) composites via vacuum filtration followed by slicing up.
Abstract: A facile strategy was reported to fabricate vertically oriented and densely packed hexagonal boron nitride (h-BN)/epoxy (EP) composites via vacuum filtration followed by slicing up. This route is simple and high-efficient without special treatment and/or chemical modification. A high through-plane thermal conductivity of 9 W/m K was obtained at a h-BN loading of 44 vol% in the composites. Laser flash thermal analyzer (LFA) and thermogravimetric analysis (TGA) results indicated that the through-plane thermal conductivity of the composites increased with the fraction of the fillers. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) tests indicated that h-BN microplatelets were mainly vertically oriented in the composites. In addition, as-made composites showed good mechanical strength. Therefore, it has great potential as thermal interface materials, which is very important in the thermal management of electronics, especially in electronic packages where electrical insulation is required.

Journal ArticleDOI
TL;DR: In this paper, homogeneous dispersion of hexagonal boron nitride (h-BN) in epoxy matrix was achieved with a water-soluble carboxylated aniline trimer derivative (CAT−) as a dispersant, which was attributed to the strong π-π interaction between h-BN and CAT−, as proved by Raman and UV-vis spectra.

Journal ArticleDOI
TL;DR: In this paper, unidirectional carbon fiber/epoxy composites where CNTs were introduced to enhance the hierarchical composites by two alternative strategies: mixing into the epoxy or attaching onto carbon fibers by electrophoretic deposition.

Journal ArticleDOI
TL;DR: In this article, a surface treatment approach of steel substrate by covalent modification of graphene oxide (fGO) nanosheets with 3-aminopropyltriethoxysilane to improve the adhesion and corrosion protection properties of an epoxy coating was introduced.

Journal ArticleDOI
TL;DR: In this article, tetraethyl orthosilicate (TEOS) is used as organosilane to decorate the surface of graphene oxide (GO) nanosheets by SiO2 nanospheres via a facile method.
Abstract: In this research, tetraethyl orthosilicate (TEOS) is used as organosilane to decorate the surface of graphene oxide (GO) nanosheets by SiO2 nanospheres via a facile method. Results of X-ray diffraction analysis, Raman spectroscopy, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, and atomic force microscopy reveal that SiO2 nanospheres have covered the surface of GO sheets through covalent bonding and SiO2-GO nanohybrids are successfully synthesized. Further, the effect of incorporating 0.1 wt% GO nanosheets and/or SiO2-GO nanohybrids on properties of epoxy coatings is investigated. The results show that the pull-off adhesion strength of epoxy coatings to mild steel substrates and the water contact angle on coatings significantly increase via adding SiO2-GO nanohybrids. The potentiodynamic polarization test, electrochemical impedance spectroscopy (EIS) and salt spray test results demonstrate that corrosion protection performance of epoxy coatings remarkably enhances by embedding well-distributed SiO2-GO nanohybrids compared to GO nanosheets.

Journal ArticleDOI
TL;DR: In this paper, the effect of amino-silane modified graphene oxide (A-GO) on performance of nanocomposite coatings was investigated, and the results of electrochemical impedance spectroscopy showed that A-GO can provide superior corrosion protection performance and maximum corrosion resistance.
Abstract: Epoxy coatings containing graphene oxide (GO) and amino-silane modified GO (A-GO) with various weight fractions (0.05, 0.1, 0.3, and 0.5 wt%) are prepared to investigate the effect of silane modified GO on performance of nanocomposite coatings. (3-Aminopropyl) triethoxysilane (APTES) is used as organosilane for A-GO synthesis. A-GO is characterized by FTIR, XRD, FE-SEM, and EDS. The dispersion quality of nanosheets in epoxy coating is examined by FE-SEM, revealing the interfacial interaction of GO in coating has improved via silane modification. Besides, the pull-off adhesion strength of epoxy coating to substrate increases by about two times via adding A-GO. The results of electrochemical impedance spectroscopy show that epoxy/A-GO coatings can provide superior corrosion protection performance and maximum corrosion resistance is achieved via adding 0.1 wt% A-GO. By increasing the loading of A-GO, the barrier properties decrease due to agglomeration of nanosheets in polymer matrix.

Journal ArticleDOI
TL;DR: It is concluded that 0.75% CNFs loading is the minimal to enhance both thermal and dynamic mechanical properties of the epoxy composites and can be utilized for advance material applications where thermal stability along with renewability are prime requirements.

Journal ArticleDOI
TL;DR: In this paper, the CNTs are functionalized by attaching melamine to improve the dispersibility in epoxy matrix and to enhance the interfacial bonding between CNT and matrix, and a significant increase of fracture toughness was observed for 2wt% M-CNT/Epoxy nanocomposite.
Abstract: Carbon nanotubes (CNTs) are considered as high potential filler material to improve the mechanical properties of epoxy nanocomposites. The CNTs are functionalized by attaching melamine to improve the dispersibility in epoxy matrix and to enhance the interfacial bonding between CNTs and matrix. The tensile tests and single edge notch bending (SENB) tests were performed for CNT/Epoxy and M-CNT/Epoxy nanocomposites at various weight fraction of functionalized CNTs. The M-CNT/Epoxy nanocomposites with addition of 2wt% functionalized CNTs exhibited enhancements of Young's modulus by 64% and ultimate tensile strength by 22%. Furthermore, a significant increase of fracture toughness by 95% was observed for 2wt% M-CNT/Epoxy nanocomposite. The homogeneity of CNTs in epoxy matrix has been analyzed and related to the improvement of modulus and strength. The phenomena of crack propagation has been investigated and related to the improvement of fracture toughness.

Journal ArticleDOI
TL;DR: It appeared that epoxy composites filled with DGTR have better mechanical properties than those filled with untreated GTR, which agrees with scanning electron microscopy observations which highlighted a better interface coherence between DGTR and epoxy.

Journal ArticleDOI
TL;DR: In this article, the surface of a graphene oxide (GO) nanofiller was modified with a silane coupling agent to enhance the corrosion inhibiting performance of the nano-coating in epoxy coatings.

Journal ArticleDOI
TL;DR: In this article, a new biobased epoxy resin, EUFU-EP/MHHPA, was prepared by using methyl hexahydrophthalic anhydride as the curing agent and 2-ethyl-4-methylimidazole as the accelerator.
Abstract: Preparing a biobased (biomass-based) high performance epoxy resin with extremely large biomass content is of great importance for sustainable development. Herein, a new epoxy resin with a precise structure, bis(2-methoxy-4-(oxiran-2-ylmethyl)phenyl)furan-2,5-dicarboxylate (EUFU-EP), was synthesized from two biobased green and low toxic compounds (2,5-furandicarboxylic acid and eugenol) and the biomass content of EUFU-EP is as large as 93.3%. In addition, a new biobased epoxy resin, EUFU-EP/MHHPA, was prepared by using methyl hexahydrophthalic anhydride (MHHPA) as the curing agent and 2-ethyl-4-methylimidazole as the curing accelerator. The curing reactivity and integrated performances including thermal and mechanical properties as well as flame retardancy of the cured resin were systematically researched and compared with those of petrochemical resource-based epoxy resin (DGEBA/MHHPA) consisting of commercial diglycidyl ether of bisphenol A (DGEBA), MHHPA and 2-ethyl-4-methylimidazole. Results show that E...

Journal ArticleDOI
TL;DR: In this paper, a biobased flame retardant toughening agent, phosphaphenanthrene groups-containing triscardanyl phosphate (PTCP), was successfully synthesized via debydrochlorination, epoxidation and ring opening reaction from renewable resource cardanol.
Abstract: A biobased flame retardant toughening agent, phosphaphenanthrene groups-containing triscardanyl phosphate (PTCP), was successfully synthesized via debydrochlorination, epoxidation and ring opening reaction from renewable resource cardanol. The chemical structure of PTCP was confirmed by the proton and phosphorus nuclear magnetic resonance. Epoxy resins (EPs) with different contents of PTCP were prepared through a simple mixing method. Thermogravimetric analysis results indicated that the earlier degradation of PTCP catalyzed the char formation of epoxy resins that was beneficial to protecting underlying polymers from further decomposition. The flame retardant properties were enhanced with the increase of the PTCP content. The EP composite containing 30 wt % PTCP showed a limiting oxygen index of 30.5%. Meanwhile, its peak heat release rate, total heat release and average effective heat of combustion values were decreased by 50%, 27% and 32%, respectively, in comparison to those of neat EP. The enhanced fl...

Journal ArticleDOI
TL;DR: In this article, a novel hyperbranched poly(aminomethylphosphine oxide-amine) (HPAPOA) was synthesized from α -amino-thylation reaction of trihydroxymethylphosphines (THP) with piperazine before oxidation.

Journal ArticleDOI
TL;DR: In this paper, the physical and mechanical properties of GFRP bars made with vinyl-ester, isophthalic polyester, or epoxy resins were evaluated first, and the long-term performance of these bars under alkaline exposure simulating a concrete environment was then assessed in accordance with ASTM D7705.
Abstract: In the last decade, noncorrosive glass fiber-reinforced-polymer (GFRP) bars have become more widely accepted as cost-effective alternatives to steel bars in many applications for concrete structures (bridges, parking garages, and water tanks). Also, these reinforcing bars are valuable for temporary concrete structures such as soft-eyes in tunneling works. The cost of the GFRP bars can be optimized considering the type of resin according the application. Yet limited research seems to have investigated the durability of GFRP bars manufactured with different types of resin. In this study, the physical and mechanical properties of GFRP bars made with vinyl-ester, isophthalic polyester, or epoxy resins were evaluated first. The long-term performance of these bars under alkaline exposure simulating a concrete environment was then assessed in accordance with ASTM D7705 . The alkaline exposure consisted in immersing the bars in an alkaline solution for 1000, 3000 and 5000 h at elevated temperature (60 °C) to accelerate the effects. Subsequently, the bar properties were assessed and compared with the values obtained on unconditioned reference specimens. The test results reveal that the vinyl-ester and epoxy GFRP bars had the best physical and mechanical properties and lowest degradation rate after conditioning in alkaline solution, while the polyester GFRP bars evidenced the lowest physical and mechanical properties and exhibited significant degradation of physical and mechanical properties after conditioning.


Journal ArticleDOI
TL;DR: In this paper, the thermal and physical properties of a composite reinforced with nanodiamonds and epitaxial boron nitride in an epoxy matrix were evaluated using 4,4′-methylene diphenyl diisocyanate as the coupling agent.
Abstract: This research focused on evaluating the thermal and physical properties of a composite reinforced with nanodiamonds and epitaxial boron nitride in an epoxy matrix. Nanodiamond-attached exfoliated hexagonal boron nitride nanoplates were fabricated using 4,4′-methylene diphenyl diisocyanate as the coupling agent. The morphology and structure of boron nitride (BN), exfoliated hexagonal BN nanoplates (EBN), and nanodiamond-attached EBN nanoplates (NDEBN) were determined. Epoxy composites were fabricated by in-situ polymerization and reinforced with various concentrations of either EBN or NDEBN nanoplates. These composites exhibited high thermal stability and high thermal conductivity, attributed to the exceptional thermal stability and thermal conductivity inherent in nanodiamond materials. In addition, inserting nanodiamond particles between BN layers prevented the BN nanosheet from forming agglomerates. We also found that nanodiamond particles improved dynamic mechanical properties by acting as a crack pinning role, which could restrict the molecular mobility of the epoxy.

Journal ArticleDOI
TL;DR: In this article, carbon-epoxy composites were subjected to accelerated aging in an aging chamber with controlled conditions of temperature, humidity and UV-radiation, and changes within the material were evaluated by Fourier-Transform Infrared (FTIR) Spectroscopy, Dynamic Mechanical Analysis (DMA), interlaminar shear strength and compressive strength, Scanning Electron Microscopy (SEM), and also in terms of mass variation.
Abstract: The influence of operational environments on the long-term durability of structural components fabricated with carbon fiber reinforced composites is an ongoing concern. Exposures to ultraviolet radiation, temperature cycles and moisture are known to degrade the polymeric matrix. In this work, carbon-epoxy composites were subjected to accelerated aging in an aging chamber with controlled conditions of temperature, humidity and UV-radiation. Changes within the material are evaluated by Fourier-Transform Infrared (FTIR) Spectroscopy, Dynamic Mechanical Analysis (DMA), interlaminar shear strength and compressive strength, Scanning Electron Microscopy (SEM), and also in terms of mass variation. Although significant changes in mechanical properties were not observed, the effects of accelerated aging on the composite material were evidenced by mass loss, fiber exposure, chemical alterations, increased crack density in interlaminar shear tests and fiber buckling in fractured specimens after compression testing.

Journal ArticleDOI
TL;DR: In this paper, a vacuum filtration method was used to fabricate sandwiched carbon nanotubes/polysulfone nanofiber (CNTs/PSF) paper as an interleaf to improve the interlaminar fracture toughness of carbon fiber/epoxy composite laminates.

Journal ArticleDOI
Tao Shao1, Feng Liu1, Bin Hai1, Yunfei Ma1, Ruixue Wang1, Chengyan Ren1 
TL;DR: In this article, an atmospheric-pressure dielectric barrier discharge is used to modify the surface of the epoxy material and enhance the dissipation of surface charge to reduce the accumulation of surface charges.
Abstract: In this paper, an atmospheric-pressure dielectric barrier discharge is used to modify the surface of the epoxy material and enhance the dissipation of surface charge to reduce the accumulation of surface charge. In the experiments, atmospheric-pressure air dielectric barrier discharge is driven by a microsecond pulse generator. Surface properties of epoxy before and after the plasma treatment are characterized by water contact angle, surface potential, and surface/volume conductivity measurements. Atomic force microscope and X-ray photoelectron spectroscopy are used to investigate the changes of the morphology and the chemical composition of the epoxy surface. Experimental results indicate that the surface of epoxy is etched by the plasma and the increase of the surface roughness enhances the surface insulation ability. The O radicals in plasma and the carbonyl groups formed on the surface make the surface charge trap shallower, change the epoxy surface composition then increase the surface conductivity and accelerate surface charge dissipation. When the epoxy is treated for an appropriate time, the epoxy surface insulation performance will be enhanced obviously and the surface charge dissipation will be accelerated.

Journal ArticleDOI
Hongpeng Zheng1, Yawei Shao1, Yanqiu Wang1, Guozhe Meng1, Bin Liu1 
TL;DR: In this article, a modified graphene oxide (GO) coating was prepared by anchoring a prepolymer of urea-formaldehyde (UF) resin onto GO sheets through in situ polycondensation.