取代基及分子量对非离子型纤维素醚表面特性的影响

根据Washburn的浸渍理论(Penetration Theory)和van Oss-Good- Chaudhury的组合理论(Combining Theory)及应用柱状灯芯技术(Column Wicking Technique),对几种非离子型纤维素醚,如甲基纤维素、羟丙基纤维素和羟丙基甲基纤维素的表面特性进行了测试。由于这些纤维素醚的取代基、取代度和分子量不同,所以它们的表面能及其组成部分有着明显的差异。数据说明,非离子型纤维素醚Lewis碱大于Lewis酸,表面自由能的主要成分是Lifshitz-van der Waals力。羟丙基的表面能及其成分都大于羟甲基。而在相同取代基和取代度的前提下,羟丙基纤维素的表面自由能正比于分子量;而羟丙基甲基纤维素的表面自由能则正比于取代度,反比于分子量。实验还发现非离子型纤维素醚中的取代基羟丙基和羟丙基甲基的表面能似乎都大于纤维素的表面能,而实验证明所测试得出的纤维素的表面能及其成分的数据是与文献所吻合的。

The Influence of the Substitution Group and Molecular Weight on the Surface Properties of Non-ionic Cellulosic Ether

Applying the Washburn penetration theory and the van OssGoodChaudhury combining rules, as well as the column wicking technique, the surface properties of some kinds of non-ionic celluloses ethers, e.g. methylcellulose (MC), hydroxypropylcellulose (HPC) and methylhydroxypropylcellulose (MHPC), have been determined. Results showed that the kind of substitute group, the degree of substitute and molecular weight are factors to influence the surface free energy and related components of cellulose ethers. In addition to comparison of these factors, another comparison of to cellulose indicated that most of these cellulose ethers are larger in the surface free energy due to the greater in the Lifshitz-van der Waals component and the Lewis base component, respectively. This paper also indicated that the etherification of cellulose may raise the Lifshitz-van der Waals component and the Lewis base component, but the Lewis acid component on the contrary.