Thermal performance, mechanical property and fire behavior of epoxy thermoset based on reactive phosphorus-containing epoxy monomer

Abstract

In this work, renewable diphenolic acid was used to prepare reactive phosphorus-containing epoxy monomer (PCDGEDP) and its chemical structure was characterized by FTIR, 1H-NMR and 31P-NMR spectra. Subsequently, PCDGEDP was reacted with diaminodiphenylmethane (DDM) to obtain phosphorus-containing PCDGEDP/DDM thermoset. The performances of corresponding thermoset in terms of thermal stability, mechanical property, combustion performance and fire behavior have been investigated in detail. It is worth noting that phosphorus-containing PCDGEDP/DDM thermoset showed high glass transition temperature (127 °C), good thermal stability with high mass residue (16.1 % at 700 °C) as well as good mechanical properties. Meanwhile, phosphorus-containing PCDGEDP/DDM thermoset exhibited improved flame retardant property with UL-94V-0 grade and high LOI value (29.6 %). Moreover, incorporating reactive phosphorus-containing epoxy monomer PCDGEDP into epoxy network can significantly decrease the heat release rate, total heat release, smoke produce rate, total smoke release and therefore enhance the fire safety of epoxy thermoset during combustion. It is implying that incorporating rigid phenyldiphosphate structure into epoxy molecular backbone can impart flame retardancy and smoke suppression properties to epoxy thermoset. It is tightly related to its higher phosphorus content (3.3 %) and higher mass residue (18.53 %) of phosphorus-containing PCDGEDP/DDM thermoset.