氰酸酯/环氧树脂的固化反应历程

采用傅里叶红外光谱仪研究了4种不同比例的氰酸酯(CE)/环氧树脂(EP)混合体系在一系列固化温度下固化后的产物组成,结果证实了6步反应的存在。当EP含量高时,体系生成物主要是口恶唑烷酮和部分异氰酸脲,而三嗪环很不显著;EP含量低时,首先形成三嗪环,然后三嗪环与环氧生成口恶唑烷酮或异氰酸脲。反应温度较低时(≤160℃),CE首先生成三聚体,再同环氧反应生成口恶唑啉、口恶唑烷酮以及异氰酸脲;在较高温度下固化时(160℃～180℃),主要进行的是三聚氰酸酯重排生成异氰酸脲的反应以及异氰酸脲同环氧官能团生成口恶唑烷酮的反应。生成物组成的差异是影响固化物宏观性能,如耐热性的根本原因。

Curing Reaction Route Between Cyanate Ester and Epoxy

FT-IR was selected to analyze the curing products of cyanate ester(CE) modified epoxy(EP) systems with verified epoxy resin proportion and different curing conditions.IR spectra show that six different reactions are involved in the curing route between cyanate and the epoxy resin as reported.Cyanurate was mainly consumed to form oxazolidinone and partly isocyanurate in the system with higher epoxy content.In the system with fewer EP,however,there still a large part of cyanurate was reserved.When the curing temperature is below 160 ℃,the trimerization of cyanate ester dominated the curing reaction.Only a small part of cyanate reacted with epoxy group directly to form oxazoline,oxazolidinone and isocyanurate.The reaction involved the cyanurate rearrangement to isocyanurate was dominated when temperature was about 180 ℃.The obtained isocyanurate was sequently reacted with EP to form oxazolidinone.The different properties(especially thermal properties) of the curing products were determined by these diversely components.