Nonaqueous Suspensions of Surface-Modified Kaolin

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• 作者：Yan Zhang ; David I. Gittins ; David Skuse ; Terence Cosgrove ; Jeroen S. van Duijneveldt
• 刊名：Langmuir
• 出版年：2007
• 出版时间：March 13, 2007
• 年：2007
• 卷：23
• 期：6
• 页码：3424 - 3431
• 全文大小：556K
• 年卷期：v.23,no.6(March 13, 2007)
• ISSN：1520-5827

文摘

A range of different stabilizers have been used to render natural kaolin clay particles hydrophobic and dispersiblein nonpolar solvents such as heptane. Both silanol and aluminol groups are known to be present at the kaolin surface.Use of a Hammett indicator showed that silanes would not neutralize the acidic aluminol sites, whereas amines wouldneutralize these sites. Both types of stabilizer adsorbed chemically onto the clay. In addition, a combined silane +amine treatment and a polyisobutylene-based stabilizer with a succinimide/amine head group (SAP230) were alsoconsidered. Both would neutralize the acid sites. The final sediment density after settling under gravity was used togauge suspension stability, which varied with the kaolin surface treatment as silanes < amines < silane + amine SAP230. This behavior was very similar for suspensions in heptane and in a higher molecular weight branched alkane,polydecene. This trend of increasing stability correlated very well with an increase in surface coverage of the stabilizingmoieties, a decrease in particle size found using small-angle light scattering, and a decrease in Bingham yield stressobtained by fitting rheological data.