原位ATR-FTIR法研究丁二烯配位聚合反应动力学

将原位全反射傅立叶红外光谱(in situATR-FTIR)技术应用于研究稀土催化丁二烯配位聚合反应过程,探讨了采集FTIR谱图的背景、用于定量计算的特征峰的选择与确定、单体浓度和所确定的特征峰强度的关系及丁二烯溶液聚合反应动力学.在聚合过程中不同时间取样得到聚合物样品,采用GPC、FTIR、POM和DSC分别对这些样品进行分子量及其分布、微观结构及其含量、玻璃化温度及结晶特性的分析与表征.结果表明,选用溶剂正己烷为背景,采集的FTIR谱图(600~1800 cm-1)中仅出现丁二烯的3个特征峰1592、1010和904 cm-1,且基线更为平滑,计算误差小.在丁二烯浓度为0.46~3.88 mol.L-1的范围内,丁二烯的这3个特征峰的强度均与丁二烯浓度成正比,其中904 cm-1处的特征峰强,可选作定量计算的特征峰.聚合反应速率对单体浓度呈现一级动力学关系,表观增长活化能为56.5 kJ.moL-1.聚丁二烯产物的分子量随单体转化率呈线性增加,其GPC谱图表明所得聚合物的分子量呈单峰分布,分布指数(Mw/Mn)在2.5左右.聚丁二烯产物中顺-1,4结构含量大于98%,其玻璃化转变温度约为-109℃,可产生较明显的结晶现象.

KINETIC STUDIES ON COORDINATION POLYMERIZATION OF BUTADIENE VIA REAL-TIME ART-FTIR MONITORING

FTIR spectroscopy in combination with a diamond tipped attenuated total reflectance(ATR) immersion probe was utilized to study in situ coordination polymerization of butadiene(Bd) in hexane(HEX) with Neodymium-based catalyst.The relationship of their intensity at signal bands of Bd and its concentration were investigated.The kinetic studies of polymerization of Bd were conducted by in situ ATR-FTIR.The signal band at 1592 cm~(-1) was assigned to the stretching vibration of Bd,and the signal bands at 1010 cm...