Used as an active but also latent accelerator in thermosetting epoxy resin formulations. Its use is particularly suited in combination with micronized dicyandiamide [Dycure 8]. Dycure U400-22 does not contain halogens and may be preferred for applications in which halogen-free formulations are required. Dycure U400-22 is not considered a dangerous chemical substance for humans, providing additional safety and health benefits for product handling and processing. In thermosetting epoxy/dicyandiamide (DICY) formulation, the DICY is hardener which provides good processing, outstanding electrical, mechanical features, and extended shelf life. Nevertheless, this system needs elevated curing temperature as close as 200 ᵒC, which is high for most applications. Therefore, it is demanding to use accelerators to diminish the curing temperature significantly, whilst not sacrificing the shelf life of composite. In this regard, one of the best accelerators is Dycure U400 which is a substituted urea and most reactive one among them. Under the heat Dycure U400 decomposes to generate active species such as dimethylamine and isocyanate groups. These active groups could accelerate the epoxies curing process and also forming additional linkages as a result of reaction with epoxy groups in the network. In many one component thermosetting epoxy formulations, Dycure U400 is used as accelerator to activate dicyandiamide curing agents for:
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