Synthesis and characterization of a functional polyhedral oligomeric silsesquioxane and its flame retardancy in epoxy resin

A functional polyhedral oligomeric silsesquioxane (NPOSS) with two epoxy ring groups was synthesized via the reaction between trisilanolisobutyl-POSS and triglycidyl isocyanurate, and then a halogen-free epoxy composite containing silicon/nitrogen was prepared. The results of microscale combustion calorimeter indicate that the presence of NPOSS (10% weight ratio) in epoxy resin (EP) can decrease its peak heat release rate by about 30%. The thermal oxidation and degradation behaviors of EP and EP/NPOSS composites were characterized by DSC, TG, FTIR-TG and dynamic FTIR. Scanning electron microscopy and X-ray photoelectron spectroscopy were used to explore the char residues of composites. The thermal degradation and flame retardant mechanism has been evaluated. NPOSS can retard the movement and scission of polymeric chains of EP and form a stable charred layer in the condensed phase to prevent the underlying materials from further combustion.