What is the powder in the plastic coated steel pipe

the powder in the plastic-coated steel pipe is a kind of epoxy resin powder, so what are the characteristics of this epoxy resin powder? what is the role of plastic-coated steel pipes?

epoxy resins generally refer to organic polymer compounds containing two or more epoxy groups in their molecules, and their relative molecular weights are not high except for a few. the molecular structure of epoxy resin is characterized by active epoxy groups in the molecular chain, and the epoxy groups can be located at the end, middle, or ring structure of the molecular chain. due to the active epoxy groups in the molecular structure, they can undergo cross-linking reactions with various types of curing agents to form insoluble, infusible high polymers with a three-dimensional network structure.