Unique hybridized carbon nanotubes and their high performance flame retarding composites with high smoke suppression, good toughness and low curing temperature

Abstract

High curing temperature, poor flame retardancy and high brittleness are three critical disadvantages of the available heat-resistant resins. To simultaneously overcome these problems, unique phosphorus-containing hybridized multi-walled carbon nanotubes (MWCNTs), coded as PMWCNTs, were synthesized through a ring-opening reaction between epoxidated MWCNTs and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO). The structure of the PMWCNTs were fully characterized. On this basis, novel flame retarding PMWCNT/cyanate ester (CE) composites with simultaneously improved integrated performance were developed. The influence of the loading of PMWCNTs (from 0.5 to 3.5 wt%) on the integrated performance of the composites was systematically investigated. The results show that the curing temperatures of the PMWCNT/CE composites are 45–71 °C lower than that of CE; the impact strengths of the PMWCNT/CE composites are 1.3–1.6 times that of the CE resin. Meanwhile, the PMWCNT/CE composites have very good flame retardancy and smoke suppression, mainly reflected by the remarkably decreased average heat release rate and average smoke production rate. Note that the PMWCNT/CE composites also have much better integrated performance than the DOPO/CE and MWCNT/CE composites. The origin of these interesting results was intensively studied, which was proved to be attributed to the unique structure of the PMWCNTs and their interaction with the CE resin. The investigation provides a new approach to synthesizing hybridized MWCNTs and related high performance resins.