二乙酰己二胺与异氰酸酯合成聚脲反应动力学

采用酰基化方法对扩链剂1,6-己二胺进行了改性,并用凯氏定氮法,傅立叶红外光谱(FT-IR)和核磁共振氢谱(1H-NMR)分析了改性产物,确定产物为二乙酰己二胺.以二乙酰己二胺为扩链剂,与半预聚物4,4'-二苯甲烷二异氰酸酯(MDI)反应合成新型聚脲,考察了扩链剂1,6-己二胺改性对聚脲凝胶时间的影响,并采用FT-IR研究聚脲合成的反应动力学.结果表明,采用二乙酰己二胺为扩链剂,反应活性降低,凝胶时问延长,有利于动力学反应研究.在常温下,二乙酰己二胺与MDI合成聚脲的反应为二级反应,表观活化能为43.414 kJ/mol.

Kinetics of Synthesis of Polyurea from Diacetyl Hexamethylene Diamine and Isocyanates

The chain extender, 1,6-hexylenediamime, was modified with acetic acid and phosphoric acid, and the modified product was analyzed by Micro-Kjeldahl method, Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (~1H-NMR). It was found that the modified product was diacetyl hexamethylene-diamine. The polyurea was synthesized from diacetyl hexamethylene-diamine and 4, 4'-diphenyl diisocyanate, and the effect of modification of 1, 6-hexylenediamime on gelation time of polyurea and the kinetics of synthesis of polyurea from diacetyl hexamethylene diamine and isocyanate were investigated. The results showed that the reaction activity decreased and gelation time of polyurea increased when diacetyl hexamethylene-diamine was used as chain extender instead of hexamethylene-diamine, which was suitable to study of reaction kinetics. The synthesis of polyurea from diacetyl hexamethylene-diamine and 4,4'-diphenyl diisocyanate was second-order reaction and its apparent activation energy was 43. 414 kJ/mol at room temperature.