| WANG Xiaoming,ZHU Gengzeng,JIN Yijie,JIA Dan,DUAN Haitao,ZHAN Shengpeng,YANG Tian,TU Jiesong,ZHANG Wulin,MA Lixin.Fire Resistance and Thermal Insulation of in Situ-grown CNTs@MoS2 Hybrids Enhanced Waterborne Intumescent Flame-retardant Coatings[J],53(4):200-210 |
| Fire Resistance and Thermal Insulation of in Situ-grown CNTs@MoS2 Hybrids Enhanced Waterborne Intumescent Flame-retardant Coatings |
| Received:February 25, 2023 Revised:August 24, 2023 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2024.04.019 |
| KeyWord:carbon nanotubes (CNTs) molybdenum disulfide (MoS2) synergistic effect fire resistance flame-retardant mechanism |
| Author | Institution |
| WANG Xiaoming |
State Grid Shandong Electric Power Research Institute, Jinan , China |
| ZHU Gengzeng |
State Grid Shandong Electric Power Research Institute, Jinan , China |
| JIN Yijie |
State Key Laboratory of Special Surface Protection Materials and Application Technology, Wuhan Research Institute of Materials Protection, Wuhan , China |
| JIA Dan |
State Key Laboratory of Special Surface Protection Materials and Application Technology, Wuhan Research Institute of Materials Protection, Wuhan , China |
| DUAN Haitao |
State Key Laboratory of Special Surface Protection Materials and Application Technology, Wuhan Research Institute of Materials Protection, Wuhan , China |
| ZHAN Shengpeng |
State Key Laboratory of Special Surface Protection Materials and Application Technology, Wuhan Research Institute of Materials Protection, Wuhan , China |
| YANG Tian |
State Key Laboratory of Special Surface Protection Materials and Application Technology, Wuhan Research Institute of Materials Protection, Wuhan , China |
| TU Jiesong |
State Key Laboratory of Special Surface Protection Materials and Application Technology, Wuhan Research Institute of Materials Protection, Wuhan , China |
| ZHANG Wulin |
State Key Laboratory of Special Surface Protection Materials and Application Technology, Wuhan Research Institute of Materials Protection, Wuhan , China |
| MA Lixin |
State Key Laboratory of Special Surface Protection Materials and Application Technology, Wuhan Research Institute of Materials Protection, Wuhan , China |
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| Abstract: |
| Fire is one of the most significant issues affecting the durability of steel constructions, which not only limits their application in industrial engineering but also seriously threatens the safety of personnel present. The latest ecologically friendly and aesthetic flame-retardant technology is a intumescent flame-retardant coating made from a triple system composed of ammonium polyphosphate, pentaerythritol, and melamine (P-C-N). However, its fire resistance and protective capacity are still insufficient. To address this problem, a waterborne intumescent flame-retardant coating with outstanding fire resistance and thermal insulation properties was designed and developed. The carbon nanotubes (CNTs), hexadecyl trimethyl ammonium bromide (CTAB), and thiourea were used as basic materials to synthesize novel CNTs@MoS2 hybrids through a straightforward one-step hydrothermal method. The composite hybrids were characterized using FT-IR, XRD, Raman spectroscopy and SEM techniques. FT-IR spectra showed that the CNTs were compounded with MoS2, and the absorption peaks of both CNTs and MoS2 were observed on the curves of the CNTs@MoS2 hybrids. XRD spectra confirmed the diffraction peaks at 2θ=14.2°, 25.8°, 32.5°, 37.4° and 57.2° for the CNTs@MoS2 hybrids, respectively. The Raman spectrum showed a higher ID/IG= 0.63 of CNTs@MoS2 samples than that of CNTs (ID/IG=0.52) since the partial filling of the CNTs surface with MoS2 matrix. It was found that the hybrid of CNTs@MoS2 was composed of CNTs nanowires and molybdenum disulfide microspheres. Afterward, the synergist CNTs@MoS2 hybrid was dispersed in waterborne intumescent fireproofing coatings (CNTs@MoS2/WES), and their fire resistance and thermal insulation properties were evaluated by large-plate experiments and surface analyses of the coating and charred layers. SEM images showed that there were obvious cracks and pores on the WES, CNTs/WES and MoS2/WES coating surfaces. However, CNTs@MoS2/WES coatings displayed a smooth and dense surface, which could improve the barrier effect of the coatings. In general, the difficulty of heat transfer from the air to the substrate rose with the thickness of the expansion layer. It was confirmed that the expansion ratio of CNTs@MoS2/WES, CNTs/WES and MoS2/WES coatings were 8.88 times, 6.04 times and 4.59 times, respectively, which was much higher than that of the WES coating (3.90 times), which indicated that CNTs@MoS2 hybrids preferably promoted the fire resistance of the WES coating. In addition, CNTs@MoS2/WES coatings exhibited the lowest backside temperature (133.3 ℃) after 40 min of combustion, which confirmed their better thermal insulation properties. The morphology of the char layer of the coating was observed using the SEM technique. Results displayed that the char layer of CNTs@MoS2/WES coatings presented a more complete carbon coke layer with uniform and stable expansion structures and smaller pores, which effectively inhibited the transfer of external heat and oxygen to the steel surface. In brief, the prepared CNTs@MoS2 hybrids display a stable network hybridization structure, which effectively improves their dispersion performance in coatings. In addition, the excellent fire and thermal insulation properties of CNTs@MoS2/WES coatings are mainly attributed to 1) denser and more complete surfaces of coatings and their char layers; 2) dilution of heat and oxygen by carbon dioxide released during combustion; and 3) reduction of cracks and porosity via catalytic carbonation of MoS2. |
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