乌氏黏度计铜氨溶液法测定棉纤维的聚合度

Determination of Polymerization Degrees of Cotton Fiber by Using Ubbelohde Viscometer–Copper Ammonia Solution Method

采用铜氨溶液乌氏黏度计法测定棉纤维聚合度。聚合度在1 000以上时,纤维素在铜氨溶液的质量浓度为0.75~1.0 g/L;聚合度在1 000以下时,纤维素质量浓度为1.5 g/L。用棉纤维平衡样品制备纤维素铜氨溶液,将铜氨溶液加入到0.5 mol/L的硫酸标准溶液中,过量的硫酸以甲基橙为指示剂,用1 mol/L氢氧化钠标准溶液滴定,测定铜氨溶液中NH4+浓度,然后计算棉纤维的平均聚合度。在选定条件下,测量结果的相对标准偏差均小于3%(n=4)。该方法检测速度快,测定结果稳定,可用于测定棉纤维聚合度。

The method for determination of polymerization degree of cotton fi ber by using copper ammonia solution Ubbelohde viscometer was established. When the polymerization degree of cellulose was more than 1 000,cellulose concentration in copper ammonia solution was 0.75–1.0 g/L;when the polymerization degree was below 1 000,the cellulose concentration was 1.5 g/L. With cotton fi ber balance sample preparation cellulose copper ammonia solution, copper ammonia solution was joined into 0.5 mol/L sulfuric acid standard solution, the excess sulfuric acid was titrated by using 1 mol/L sodium hydroxide standard solution with methyl orange as the indicator, the concentration of NH4+ in copper ammonia solution was determined, then the average degree of polymerization was calculated. The relative standard deviation of determination results was less than 3%(n=4). The method is fast with stabilization determination result, it is suitable for determination of polymerization degree cotton fi bre.