二维红外相关光谱在双氰胺固化环氧树脂体系中的应用

Application of Two-Dimensional Fourier Transform Infrared Correlation Spectroscopy on Dicyandiamide-Epoxy Network

利用原位红外加热炉模拟双氰胺固化环氧树脂体系的固化反应过程,实时测试并记录反应过程中官能团结构的变化;将一维红外光谱和二维红外光谱相结合进行分析,给出固化过程中各官能团的变化顺序和趋势。在双氰胺固化环氧树脂体系中,双氰胺首先分解成氰基胺,然后再和环氧树脂发生开环加成反应,生成亚胺结构,通过重排生成酰胺结构。双氰胺分解为氰基胺的反应是可逆反应。将原位红外、一维红外与二维红外三者结合是阐明热固性树脂固化反应机理的非常有效的手段。

In-situ IR has been applied to study the curing reaction process of dicyandiamide（ DICY） with epoxy resin. The combination of FTIR and its generalized two-dimensional infrared correlation spectroscopy（ 2D-IR） to analyze the curing reaction process can effectively enhance the spectral resolution and reveal the details about the reaction mechanism. Four reactions were detected in the resin network：（ i） reversible decomposition of DICY and cyanamide;（ ii） copolymerization of cyanamide and epoxy resin to form the intermediate product;（ iii） copolymerization of cyanamide and the intermediate product to form imines;（ iv） rearrangement of the imine structure to form the amide structure. It is very effective to explain the curing mechanism of thermosetting resin by using in-situ IR,FTIR and 2D-IR.