Synthesis and characterization of a novel modified expandable graphite and its application in rigid polyurethane foams

摘要

In this work, an intermediate product DOPO-A was firstly synthesized through an addition reaction between triethoxyvinylsilane and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO). Then DOPO-A was hydrolyzed to form DOPO-A' (silanol of DOPO-A) and the surface of expandable graphite (EG) was modified by DOPO-A' to prepare a novel modified expandable graphite (MEG). The effects of MEG on the flame-retardant and mechanical properties of rigid polyurethane (RPU) foams were investigated. It is found that MEG is more effective in improving the limiting oxygen index (LOI) of RPU foams than EG. The cone calorimeter studies indicate that MEG flame retarded RPU foams have lower peak heat release rate, total heat release, peak smoke production rate, and CO yield than those of the EG flame retarded RPU foams. Compressive strengths of the MEG flame retarded RPU foams have a great improvement compared with those of EG flame retarded RPU foams.