| DENG Long,HE Hui,ZHANG Liguo,GUAN Zhenwei,WANG Zhiyong.Effect of Hollow Glass Microspheres Modification on Spray-type Epoxy Coating Properties[J],53(16):129-138 |
| Effect of Hollow Glass Microspheres Modification on Spray-type Epoxy Coating Properties |
| Received:September 05, 2023 Revised:November 19, 2023 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2024.16.010 |
| KeyWord:hollow glass microspheres epoxy coating filler modification terminal carboxyl polybutadiene low density adhesion anti-corrosion properties |
| Author | Institution |
| DENG Long |
AECC Beijing Institute of Aeronautical Materials, Beijing , China |
| HE Hui |
AVIC The First Aircraft Institute, Xi'an , China |
| ZHANG Liguo |
AVIC The First Aircraft Institute, Xi'an , China |
| GUAN Zhenwei |
AECC Beijing Institute of Aeronautical Materials, Beijing , China |
| WANG Zhiyong |
AECC Beijing Institute of Aeronautical Materials, Beijing , China |
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| Abstract: |
| To improve the dispersion of hollow glass microspheres (HGM) in the spray-type epoxy coating by surface modification and analyze the effect of modified HGM on the coating performance, in this paper, KH560 was used as the bridging unit linked to the hydroxyl group on the surface of HGM after NaOH etching with the terminal carboxyl group of CTPB to prepare HGM-CTPB. The surface morphology, grafting groups, and dispersion in the epoxy matrix of each surface-modified HGM were analyzed by SEM, FTIR, TGA, and UV. Then, HGM-CTPB was added as a low-density filler into the epoxy matrix, and the effects on the adhesion, flexibility, impact resistance, surface roughness, and corrosion resistance were studied. According to the analysis result, the characteristic peaks of —C═C— and —CH2 belonging to CTPB could be seen respectively in the FT-IR spectra of HGM-CTPB which were located at 3 100-3 000 cm−1 and 3 000-2 700 cm−1. In thermogravimetric analysis, HGM-CTPB lost the highest mass, reaching 7.2%, and HGM-CTPB had the fastest weight loss rate during the heating process from 200 to 500 ℃, mainly due to the largest molecular weight of the CTPB segment grafted with HGM after the sample was removed by the bound water addition. An obvious morphological difference between HGM-CTPB and bare HGM could also be seen in the SEM images. Such results proved that KH560 could successfully bridge CTPB to the surface of NaOH-etched HGM. Through the SEM images of the cross section of coatings, HGM-CTPB could achieve better dispersion without migration and enrichment in the epoxy matrix compared with bare HGM, NaOH-etched HGM, and KH560 grafted HGM, which were also confirmed by the coating transmittance curve. The result showed that CTPB groups could provide sufficient steric hindrance for dispersion and react with epoxy groups to firmly anchor HGM. The epoxy coating prepared performed best when HGM-CTPB was used as filler and its additional mass ratio of epoxy resin was 0.08 and 0.16. The density was 5.6% and 11.3% lower than the pure epoxy coating; Where the average adhesion was increased by 0.97 and 2.14 MPa, reaching 15.57 and 16.74 MPa. Such coatings could withstand forward and reverse impacts of 50 cm.kg, and 1 mm flexibility was passed without cracks. After soaking in 5wt.% NaCl solution at 60 ℃ for 144 h, low-frequency impedance could be maintained above 108 Ω, which was 2 orders of magnitude higher than the pure epoxy coating. Above all, the successful grafting of CTPB can enable HGM to achieve optimal dispersion and a good combination with the epoxy matrix. The density of fabricated coatings can be significantly reduced, while the adhesion and anti-corrosion properties can be improved with a proper amount of HGM-CTPB. At present, epoxy-based protective coatings for large-scale equipment are mostly applied by the spraying process. This study provides a new strategy for the lightweight of such coatings, which can effectively solve the serious migration and phase separation problems of low-density fillers in the dilution, especially during the curing process, due to the low viscosity of the epoxy matrix, so as to ensure the performance and uniformity of coatings. |
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