纤维级聚酯切片中羧基值测定方法的改进

Improvement on the determination methods of carboxyl end group value in fiber grade PET chip

对国标GB/T14190 93测定方法进行改进。为防止在滴定过程中玻璃电极表面成膜,搅拌速度调节到旋起的旋涡约1/5溶液高,加液速度为1mL/min,直接用在蒸馏水中浸泡的电极测样,连续测量2个平行试样之间,将电极用乙醇、氯仿清洗后在蒸馏水中浸泡6min以上,在样品溶液中预加3～4滴饱和氯化锂溶液等。回收率可达95%～105%,相对误差最大为3.1%。

The improvements on the determination methods of GB/T1419093 are carried out.To prevent the surface on the glass electrode from filmforming during the titrating,the stirring speed is adjusted to the height of volute is one fifth of the solution,the adding speed is 1 mL/min, the electrodes steeping in the distillation water are used to determination directly.Between the determinations of two parallel samples,the electrode should be washed with alcohol, chloroform solution,then it will be steeping in the distillation water over 6 min,3 or 4 drops of LiCl saturation solution is preadded to the sample solution.The recovery ratio is 95%～105%,the maximum relative error is 3.1%.