Coupling agents are the most commonly used modifiers in the surface modification of sericite. The coupling agent has two functional groups with different chemical properties, one of which can form a chemical bond with the surface group of sericite, and the other can form a chemical bond or physical entanglement with the organic matrix, thereby improving the compatibility and dispersion of sericite in the organic matrix. Methacryloyloxypropyltrimethoxysilane (KH570) belongs to the organic functional group silane coupling agent, the appearance is colorless or yellowish transparent liquid, soluble in ethanol, acetone, toluene and other organic solvents, hydrolysis produces methanol, boiling point 255, flash point 88, density 1043～1.053g/cm3。KH570 is often used as a surface modifier for inorganic fillers such as sericite, silica, kaolin and attapulgite, which can increase the surface hydrophobicity of inorganic fillers and improve their compatibility and dispersion in organic matrices. Xiao et al. used KH550, KH560, KH570 and other silane coupling agents to modify seridolite, and prepared polyimide modified sericite composites by in-situ polymerization, and the effect of silane coupling agent modified sericite on the morphology and properties of polyimide composites showed that KH570 modified sericite had good compatibility with polyimide matrix, and polyimide KH570 modified sericite composites had good heat resistance and mechanical properties. Wang Xiaoyan et al. used KH550, KH560 and KH570 silane coupling agents to modify the surface of sericite, and the results showed that the modification effect of KH550 and KH570 was better, the modification effect of KH560 was relatively poor, and the modification effect of KH550 and KH570 composite modification was the best.
Zhang Zhen et al. prepared the silane coupling agent KH570 modified sericite by wet process, and investigated the changes of turbidity, activation index, contact angle and oil absorption value of sericite before and after modification. 1. Preparation of KH570 modified sericite The sericite is placed in a vacuum drying oven and dried at 80 for 2hWeigh a certain quality of dry sericite, add deionized water according to the mass ratio of 1:5, and disperse ultrasonically for 30minKH570 was mixed with ethanol solution at a mass ratio of 1:10 and poured into a three-mouth flask, and hydrolyzed at 60 for 30minThe ultrasonically dispersed sericite and hydrolyzed KH570 were mixed evenly in a three-mouth flask, and then the wet modification experiment was performed at a set time and temperature using a thermostatic magnetic stirrerAfter the wet modification was completed, the prepared products were washed and filtered for many times, and vacuum dried to constant weight, and finally KH570 modified sericite was obtained. 2. Modification mechanism of silane coupling agent KH570 surface modification sericite
As shown in the figure, KH570 undergoes hydrolysis reaction with a small amount of water additives and dehydrates and condenses to form silane oligomersSilane oligomers react with hydroxyl groups on the surface of mica and dehydrate and condense to form silicon-oxygen bonds. 3. Test results (1) The optimal process conditions of KH570 modified sericite are: KH570 dosage 15%, reaction temperature 60 and reaction time 2h, at this time, its turbidity is 587, the activation index is 80%, the contact angle is 50°, and the oil absorption value is 46%. Compared with the unmodified sericite, the turbidity of KH570 modified sericite was increased by 115%, the activation index was increased by 134%, the contact angle was increased by 194%, the oil absorption value was increased by 71%, and the hydrophobicity and dispersion were improved. (2) FT-IR analysis showed that KH570 had a coupling reaction with hydroxyl groups on the surface of sericite, and KH570 was introduced into the surface of sericite to obtain KH570 modified sericite. (3) Laser particle size analysis and SEM analysis showed that the average particle size of KH570 modified sericite was smaller, the agglomeration phenomenon was weakened, and the dispersion was more uniform. 
4) XRD analysis showed that KH570 modified sericite did not change the original crystal structure of sericite, but reduced its crystallinity. (5) TG analysis showed that the surface KH570 content of KH570 modified sericite was about 5%, and the heat resistance temperature was about 680, which had good thermal processing performance, thermal stability and high temperature resistance. Material**: Zhang Zhen, Hu Yingmo, Pang Baobao, etc. Preparation and characterization of silane coupling agent KH570 surface modified sericite[J].New Chemical Materials,2022,50(S1):241-245+251", edited and sorted out by [Powder Technology Network], **Please indicate the source!