水溶性高分子PVP对陶瓷凝胶注模成型坯体表面起皮的抑制作用与机理

Inhibitive Role and Mechanism of Water-Soluble Polymer PVP on the Surface-Exfoliation Problem of Ceramic Green Bodies Prepared byGelcasting

在凝胶注模成型的丙烯酰胺单体溶液中加入适量的聚乙烯吡咯烷酮(ＰＶＰ),可有效地克服在空气气氛下单体聚合形成凝胶网络的氧阻聚问题,从而消除了坯体表面起皮现象,达到精确控制坯体尺寸的目的．本文研究了加入ＰＶＰ对Ａｌ２Ｏ３粉料的分散性、陶瓷浆料的静/动态流变特性、生坯的强度以及显微结构的影响;并通过红外光谱初步分析了ＰＶＰ消除陶瓷坯体表面起皮现象的作用机制,即利用ＰＶＰ增稠作用和ＰＶＰ分子间的氢键作用在表面处起到粘结粉体的作用．

The inhibition of oxygen, which occurred in gelcasting during the formation of polymer networks by in-situ polymerization of monomers in air, was successfully prevented by adding a proper amount of polyvinylpyrrolidone (PVP) to the aqueous acrylamide solution. Thus, the surface-exfoliation problem of green bodies was eliminated and the aim of precisely controlling the size of the formed green bodies was achieved by gelcasting in air. The influence of PVP on the dispersion of alumina, the static and dynamic rheological properties of alumina slurry and the strength and microstructure of green bodies was investigated. Furthermore, the mechanism of PVP in eliminating the surface-exfoliation problem of green bodies gelcast in air, namely the role of PVP in thickening and the hydrogen bonding between the molecules of PVP, which serve as a ceramic binder for the particles on the sample surface, was analyzed via the infrared spectra.