(四川大学 材料科学与工程学院,成都 610064)
摘 要: 为了提高Al2O3超微粉在水介质中的分散稳定性,先采用硅烷偶联剂KH570对Al2O3进行表面改性,再对Al2O3粒子锚固偶氮引发剂偶氮二异丁基脒盐酸盐(AIBA),进而引发丙烯酰胺(AM)单体聚合而制备聚丙烯酰胺(PAM)/Al2O3复合粒子。利用XPS、FT-IR、激光粒度仪、微电泳仪、分光光度计、SEM及XRD等对Al2O3复合粒子结构及分散性能等进行表征。结果表明:在40 ℃下加入水溶性偶氮引发剂,可以得到在水介质中分散稳定性良好,以聚丙烯酰胺为壳,以Al2O3为核的复合磨粒。与未改性的Al2O3超微粉相比,经AM接枝聚合改性后的颗粒表面团聚现象得到改善,颗粒的D50减小;接枝改性后Al2O3的等电点IEP发生迁移,在pH值为9时颗粒表面Zeta电位绝对值达到最大。
关键字: Al2O3超微粉;偶氮引发剂;分散性;表面改性;复合磨粒
(College of Materials Science and Engineering, Sichuan University, Chengdu 610064, China)
Abstract:In order to enhance the dispersion stability of ultra-fine Al2O3 powder in aqueous medium, Al2O3 particles were modified with silane coupling agent KH570 at first, then 2,2′-azobis(2-amidinopropane) dihydrochloride (AIBA) was anchored onto the modified Al2O3 to initiate the graft polymerization of acrylamide monomer (AM), and PAM/Al2O3 composite particles were obtained finally. The structure and dispersion property of Al2O3 composite particles were characterized by XPS, FT-IR, laser particle size analyzer, micro electrophoresis apparatus, spectrophotometer and SEM as well as XRD. The results indicate that the attained composite abrasive shows good dispersion stability in aqueous medium with PAM as shell and Al2O3 as core when water-soluble azo initiator is added at 40 ℃. Compared with unmodified Al2O3, the reunion phenomenon of grafting polymerization modified Al2O3 powder is improved by AM, the D50 of the modified particles is reduced. The isoelectric point (IEP) of the grafting modified particles is migrated, and the Zeta potential of the modified particles reaches the maximum value when the pH value is 9.
Key words: Al2O3 ultrafine powders; azo initiator; dispersion; surface modification; composite abrasive