PET固相缩聚反应机理的研究

对ＰＥＴ固相聚合的反应机理进行了较深入地研究。并首次对副产物ＥＧ表面扩散控制机理进行了探讨。通过研究发现：固相聚合机理与温度、预聚体尺寸、惰性气体的流量（或真空度）有关。当反应温度较低时（如１６０～１８０℃），ＰＥＴ固相聚合总是化学反应控制的过程。当反应温度较高（如≥２２０℃），且预聚体的尺寸较大时，ＰＥＴ的固相聚合实际上是由副产物ＥＧ从样品内部向表面的扩散控制的。当反应温度较高，且预聚体的尺寸很小（如几十微米）时，又惰性气体流量较小（或真空度较差），ＰＥＴ固相缩聚反应为副产物ＥＧ从样品表面向外的扩散所控制；若惰性气体流量较大（或真空度较好），反应又转化为化学反应控制。

STUDIES ON THE MECHANISM OF SOLID-STATE POLYMERIZATION(SSP)OF PET

In order to get higher molecular weight PET,the mechanism of SSP has been studied thoughtfully in the paper.It is found that polymerization temperature,size of polymer particle and rate of inert gas play an important role in determining the mechanism of SSP.That is to say,if the polymerization temperature is low(e.g.less than 200℃),the SSP is generally controlled by chemical reaction process.While in the case of using highploymerization temperature(e.g.220 ℃ or higher),if the particle size is smaller enough(e.g.70μm in diameter),the case may be more complicated;if the flow rate of inert gas is very small,the SSP is controled by diffusion of reaction by-product EG from the surface to the inert gas;If the flow rate of inert gas is high enough,the SSP would be controlled by chemical reaction process.