It is found that in the presence of butyl titanate or stannous oxalate as a polycondensationcatalyst the carboxyl content is not always on the increase in all high vacuum stage.
发现，钛酸四丁酯或草酸亚锡作为缩聚催化剂时，在整个高真空阶段羧基含量并不是一直增加的。
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A comparison has been made between systems of stannous oxalate and antimony trioxide, the result shows the former has a bright future as a polycondensationcatalyst in practical production.
Poly(succinimide)(PSI) was synthesized by polycondensation of L-aspartic acid in a solvent. The effects of the catalyst, reaction time and solvent on the reaction were studied.