To further improve the dispersibility of fumed silica,a pilot-scale fluidized bed is utilized for its dry modification by using polydimethylsiloxane(PDMS)with a high carbon content as the modifying agent.The influences of pre-activation,modification temperature,time,gas velocity,and the mass fraction of the modifying agent on the hydrophobic properties of fumed silica are studied.Results indicate that the optimal process conditions are as follows:pre-activation temperature is at 200℃,pre-activation time is 30 min,water mass fraction is 10％,nitrogen gas velocity is 4Nm3·h-1,modification temperature is at 300℃,PDMS mass fraction is 25％,and reaction time is 90 min.After modification,carbon content of fumed silica is 4.89％,surface hydroxyl group content declines to 0.15 groups·nm-2,and the wettable rate is 0％,which enhances the hydrophobicity of fumed silica.Furthermore,the reinforcing performance of the modified fumed silica on silicone rubber is explored.As fumed silica with a carbon content of 2.5％is used to reinforce,the tensile elongation at break of silicone rubber increases by 24.8％,the reinforcement coefficient increases by 18.0％,and the tensile strength up 8.0％,showing the best reinforcement effect and effectively improving the comprehensive mechanical properties of silicone rubber.
fumed silicaPDMSfluidized beddry modificationperformance of silicon rubber
维普
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