Effect of a Curing Agent and an Accelerator on the Glass Transition of Brominatedand Unbrominated Diglycidyl Ether of Bisphenol A

摘要

Dicyandiamide-a solid with a melting point of 209 deg C-is one of a unique groupof curing agents that are insoluble in epoxy at room temperature. As a curing agent for epoxy resins, dicyandiamide can react through all four nitrogen groups--reacting with the resin at both epoxide and hydroxyl sites. When mixed with either diglycidyl ether of bisphenol A or diglycidyl ether of tetrabromobisphenol A, the formulation is stable enough to be stored for 6 to 12 months. Because dicyandiamide's solubility is low at room temperature, the curing reaction is limited until the temperature increases enough to dissolve the curing agent. To improve the ability to process the resin, an accelerator (such as diuron) can be added to reduce the curing temperature. The curing reaction then proceeds via a complex mechanism that is not dominated by a single reaction. Each compound's effect on the cured material was studied by measuring changes in the glass transition temperature.