聚异戊二烯橡胶环化反应动力学研究

THE KINETIC STUDIES ON INTRAMOLECULAR CYCLIZATION OF POLYISOPRENE

以红外光谱为主要手段研究了聚异戊二烯的环化反应动力学。测定了环化反应动力学参数：反应级数ｎ＝１，活化能Ｅａ＝８３．１ｋＪ·ｍｏｌ－１，指前因于Ａ＝２．７５×１０１０ｍｉｎ－１．并测定了标准活化熵和活化焓，分别为△ｒ≠Ｓｍ＝－６９．１Ｊ·ｍｏｌ－１·Ｋ－１和△ｒ≠Ｈｍ＝８０．４ｋＪ·ｍｏｌ－１，提出了该环化反应的可能机理。用１ＨＮＭＲ分析了环化聚异戊二烯的结构。

The kinetics of the cyclization of polyisoprene are investigated by IR spectrum. Some kinetic parameters of this cyclization are determined. Reaction order n= 1,activation energy Ea = 83. 1 kJ·mol-1, preexponential factor A= 2.75 × 10 10 min-1. Entropy of activation and enthalpy of activation of this cyclization are determined too,△r≠Sm=- 69.1 J·mol-1·K-1, △r≠Hm = 80.4 kJ · mol-1. The possible mechanisms of this cyclization are suggested. The structure of cyclized polyisoprene is analysed by 1 HNMR spectroscopy.