| The reason and control conditions of THF, which was the by-products of direct PBS esterification process, was researched in this paper, as well as the influence on the polymerization process.The influence of the formation of THF on the Mn of PBS in post-polymerization process was studied; In the direct esterification of succinic acid and 1,4-butanediol, the changes of esterification rate and THF production rate with time and different factors was researched under different processing conditions; in the transesterification of dimethyl succinate and 1,4-butanediol, the changes of esterification rate and THF production rate with time was investigated, and the contribution of the hydroxybutyl end groups removal reaction on the generation of THF was disscussed.The results showed that:(1) Ratio of raw materials which actually participated in the esterification was be changed because of the generation of THF, and the side reaction could influence the de-alcohol reaction in condensation. In the same ratio of raw materials which actually participated in the esterification, Mn of end product in condensation was value closed. (2) When the stirring speed was less than 200 r/min, the generation rate of THF was increased with the increased speed in the initial reaction. But when the esterification rate reached a certain value, the generation rate of THF was decreased. In the same esterification rate, the generation of THF was increased with the higher temperature and the bigger molar ratio of 1,4-butanediol and succinate, and it can be decreased in the N2 atmosphere. The effect of Ti(OBu)4 on esterafication and THF generation were both not obvious.The d72 resin could both accelerate esterafication rate and THF generation rate,Na3PO4 could accelerate esterafication rate effectively and reduce THF generation rate,making generation of THF was increased in the same esterification rate, (3)THF generated in the reaction of 1,4-butanediol cyclization catalyticed by acid, which was the main reason of THF generation in the PBS esterification, was much more than the hydroxybutyl end groups removal reaction. Ti(OBu)4 and Na3PO4 could accelerate the esterification reaction, and decreased thethe hydroxybutyl end groups removal reaction, which could reduce the generation of THF in the same esterification rate. The generation rate of THF could be increased by the acid. |
