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Keywords: Liggin graphene water-based epoxy anti-corrosion
background:
graphene as a single layer of flat carbon atoms in a sp2 hybrid way closely combined to form a two-dimensional atomic crystal, due to its unique structure, excellent electrical properties and barrier properties, is considered to be a promising new material, its applications include batteries, solar cells, nanocomposites, capacitors. Due to the barrier properties of graphene coating, a lot of anti-corrosion research has been done on it. However, due to its high-ratio surface area and strong Van der Worrest, graphene is likely to come together during use, limiting its widespread use in many water-based
. As a result, many researchers have increased the dispersion of graphene in the substation through co-price modification and non-common-price modification.
, as a renewable biomass material, accounts for 35% of wood. The use of woody products to produce high value-added products is attracting more and more attention. In order to maintain the sp2 hybridization of graphene, many researchers have tried to disperse graphene with ligands to obtain high-performance composites through compounding. According to previous studies, the affinity of ligands and the π-π interaction between ligands and graphene have made it possible for ligands to disperse graphene in water. At present, it is a very meaningful study to study the corrosion resistance of dispersed graphene in water-based epoxy resin with the aid of modified ligands.
Shan Wang, a key laboratory of cellulose chemistry at the Chinese Academy of Sciences, reported on a new method of preparing graphene-based water-based epoxy nanocomposites using ligands. There is a non-co-price interaction between modified ligands and graphene, which improves the dispersion and stability of nanocomposites. The ligand/graphene dispersion is added as an additive to the water-based epoxy resin, enhancing the corrosion resistance of nanocomposites.
the content of the
1. Synthesis of hydroxyl lignin-OH
In order to increase the hydroxyl content of lignin-OH, lignin-OH has been prepared based on previous studies. Add 10g of ligands dissolved in 40mL DMF, 50g 48% of hydrobromoic acid solution to the reactor, and react at 115C for 20h. Finally, the post-treatment resulted in 3.22g dark black powder.
2. The preparation of water-based graphene dispersions
based on previous research, graphene dispersions were modified. The method is to add 0.5 mg/mL of lignin-OH to the glass crusher. Solution pH is maintained at 8-9, lignin-OH solution soaked ultrasonic 15min. Add 40mg/mL graphite to the lignin-OH solution, stir 15min at 25C, ice bath ultrasound 6h. Place the resulting dispersion for 24 hours and centrifuge at 1000 rpm for 30 minutes. Get the upper liquid. The lignin-OH/graphene dispersion is vacuum filtered through a nitroculose membrane (aperture 0.22 m, diameter 47mm) and washed several times to remove the free lignin-OH. The resulting material is then dispersed into water to obtain a saturated dispersion without free lignin-OH. Dispersion solubility is 1.07 mg/mL.
3. Preparation of anti-corrosion coatings (hydroxygen/graphene/water-based epoxy resin)
adds a certain amount of saturated hydroxyhydroxy lilac/graphene dispersion to the water-based curing agent PLR736, mixing 5min, ultrasonic 5min. Add the water-based epoxy resin and a small amount of isopropyl alcohol to the mixture, then ultrasound for 15 minutes in an ice bath below 30 degrees C to form a uniform system. Degass 10min at room temperature in a vacuum drying chamber to remove bubbles. Apply the mixture to the q235 steel surface with a coating machine and bake 5h at 50 degrees C. The coating thickness is controlled at 50±5 m, and the prepared coatings are named 0.5% hydroxygen/graphene/water-based epoxy resins (0.5% of ligands account for 0.5% of total mass) and 1% hydroxy-based lilac/graphene/water-based epoxy resins, respectively. For comparison, 0.5% graphene/water-based epoxy resins are named in a similar way. The specific preparation method for the nanocomposate coating is shown in Figure 1.
the results of
1. Dispersion study of ligand demethylated preparation hydroxygen
2, hydroxygen-modified graphene:
3, hydroxy-based lilac/graphene appearance:
4, coating surface appearance:
5, coating surface deformation:
6, coating surface shape:
7, corrosion-repulsive properties of hydroxygen/graphene coatings:
Conclusion: The
research process prepared hydroxygenic lilac/graphene/water-based epoxy nanocomposites through a simple, green production route. Compared with graphene/water-based epoxy resins and pure water-based epoxy resins, the composite coating has good corrosion resistance, thermal stability and regenerative properties due to its good dispersion in the substation. The corrosion resistance of nanocomposites is improved due to the ultra-high barrier properties of hydroxylated ligands/graphene coatings and the "maze effect" of corrosion paths. The nanocomposates prepared have potential application value in the corrosion prevention of metal substations, and provide a new strategy for the high value-added utilization of wood quality.
:
WangS, Hu Z, Shi J, et al. Green synthesis of graphene with the assistance ofmodified lignin and its application in anticorrosive waterborne epoxycoatings[J]. Applied Surface Science, 2019,484:759-770.