| GAO Chao,ZENG Yi-bing,WU Xiao-feng,FAN Hai-bo,ZHAO Lu-lu.Modification of Silica Sols and Its Reinforcing Effects on Water-based Silicone Rubber Coatings[J],47(5):148-153 |
| Modification of Silica Sols and Its Reinforcing Effects on Water-based Silicone Rubber Coatings |
| Received:December 06, 2017 Revised:May 20, 2018 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2018.05.022 |
| KeyWord:KH-560 modified silica sols volume exclusion effect storage stability water-based silicone coatings mechanical properties |
| Author | Institution |
| GAO Chao |
Aerospace Research Institute of Materials & Technology, Beijing , China |
| ZENG Yi-bing |
Aerospace Research Institute of Materials & Technology, Beijing , China |
| WU Xiao-feng |
Aerospace Research Institute of Materials & Technology, Beijing , China |
| FAN Hai-bo |
Aerospace Research Institute of Materials & Technology, Beijing , China |
| ZHAO Lu-lu |
Aerospace Research Institute of Materials & Technology, Beijing , China |
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| Abstract: |
| The work aims to improve the storage stability of silica sols and enhance the mechanical properties of water-based silicone rubber coatings. Silane coupling agent, KH-560, was added into silica sols and stirred gently at 60 ℃ to establish chemical bonds. The modification mechanism was analyzed by the change of the pH value and macroscopic morphology. The morphology, size, thermal stability, Zeta potential and freeze-thaw stability were before and after modification were characterized. The modified silica sols and heat-resistant fibers were blended with the self-made silicone emulsions to prepare the water-based silicone coatings. The tensile strength, elongation at break, shear strength and pull strength of the cured coatings were tested to detect the reinforcing effects of silica sols. The methoxy group of KH-560 reacted with silica-O or silica-OH on the surface of silica sol particles to establish new Si—O—Si bonds. The volume exclusion effect of silica sol particles was increased and the double layer effect was weakened. The modified silica sols restored the colloidal state quickly through 5 freeze-thaw cycles. The morphology, size and distribution of particles did not change significantly. With the modified silica sols as reinforcing filler, the mechanical strength of water-based silicone coatings increased as the addition amount of silica sols improved. When 30% silica sol was added, the tensile strength, elongation at break, shear strength, and pull strength of the coatings were 3.03 MPa, 37.1%, 1.68 MPa, 1.85 MPa, respectively. Silane coupling agent KH-560 can effectively improve the storage stability of the silica sols. The modified silica sols have a good reinforcing effect on water-based silicone coatings. |
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