Synthesis, characteristic of a novel flame retardant containing phosphorus, silicon and its application in ethylene vinyl-acetate copolymer (EVM) rubber

A novel flame retardant (SPDV) containing phosphorus and silicon elements at the same time was synthesized. Spirocyclic pentaerythritol bisphosphorate disphosphoryl chloride (SPDPC) synthesized through simple dehydrochlorination reaction of pentaerythritol (PER) and phosphorus oxychloride (POCl₃) was introduced into 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)/ vinylmethyldimethoxy silane (VMDMS) oligomer (DV) to form a novel flame retardant. The structure and properties of SPDPC, DV and SPDV were characterized by FT-IR, NMR and TGA. After blended with EVM, the flame retardance of EVM/SPDV composites was estimated by cone calorimeter, limited oxygen index (LOI) and UL-94, and thermal stability was investigated using TGA. The morphological structure of the char formed after combustion in cone calorimeter was investigated by Scanning Electron Microscopy (SEM). The results indicate that the flame retardant and thermal stability were improved by incorporation of SPDV. The rich foamed char layers were observed in the residues after combustion in cone calorimeter test, which exactly benefits the thermal stability and flame retardant of EVM materials.