Curing mechanism of epoxides by imidazoles

✍ Scribed by Václava Jíšová

• Publisher: John Wiley and Sons
• Year: 1987
• Tongue: English
• Weight: 483 KB
• Volume: 34
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/app.1987.070340718

✦ Synopsis

The courses of the reactions of the epoxides with the various derivatives of imidazole in the concentration range 0.5-25 epox. weight eq./mol imidazole and in the temperature range 80-155°C were studied. All imidazoles form adducts with epoxides very quickly, namely the 1-substituted imidazole 1:l adducts, in case of the 1,3-unsubstituted imidazoles the reaction continues to the 1 : 2 adducts. The polymerization effectiveness of the imidazoles falls in order 2-ethyl-4-methylimidazole (EMI) > 1-n-butylimidazole (BI) > 2-phenylimidazole (PI) > imidazole (I) B 1-vinylimidazole (VL) > benzimidazole (BZJ). The effect of temperature, epoxide, and imidazole concentrations on the overall curing rate and the limiting conversion were investigated. In the concentration and temperature range studied the overall curing rate is directly proportional to the imidazole and epoxide concentrations and follows the Arrhenius ratio with similar values of the overall activation energy E,, = 70 to 79 kJ/mol for all active tested imidazoles in the studied concentration and temperature range.