淤浆法碱化试剂选择对PAC分子结构及其泥浆滤失性能影响

采用XRD和显微镜分析技术研究了高浴比淤浆法制备聚阴离子纤维素过程中, NaOH、KOH及其混合碱化体系对纤维素润胀度及结晶度的影响, 借助1H NMR方法分析了产物的取代度及取代基在葡萄糖环基C2、C3和C6位分布的均匀性. 通过泥浆实验研究了产品在高电解质含量中的高温滤失性能. 结果表明, 在相同摩尔浓度条件下, 棉纤维润胀度变化规律是: NaOH/KOH(摩尔比, 9∶1)>NaOH>NaOH/KOH(摩尔比, 1∶1)>NaOH/KOH(摩尔比, 1∶9)>KOH, 结晶度的顺序相反. 1H NMR测试结果表明, 含少量的K+时, 羧甲基在葡萄糖单元环内分布更均匀, 产品具有优良的耐酸、耐盐性和抗高温滤失性能; 当体系KOH成为主要碱化试剂时, 在酸碱介质中出现分层, 抗滤失性能急剧变差.

Effect of Alkali Agents on Molecular Structure of PAC and Drilling-mud Fluid Loss

During the polyanionic cellulose(PAC) manufacturing in slurry process,the influence of alkali agent on the structure and characterization of PAC was studied by producing PAC with NaOH,KOH and mixture thereof.The cellulose fibre swelling ratio in different alkali systems decreases in the order as follows: NaOH/KOH(molar ratio 9/1),NaOH,NaOH/KOH(molar ratio 1/1),NaOH/KOH(molar ratio 1/9),KOH.Crystalline grade of cellulose is in the reverse order.These results were obtained by means of X-ray diffraction and microscope.The degree of substitution of PAC and substituent distribution within anhydroglucose unit(AGU) were determined by means of 1H NMR spectrum.The results show that the degree of substitution of PAC is higher and the distribution of the substituents in the anhydroglucose unit of PAC is more even in the presence of a little KOH.These made PAC have an excellent viscosity stability in salt and lactic acid and fluid loss resistance.When KOH was a major alkali agent,solubility of PAC in salt and lactic acid became worse and fluid loss increased.