LAUSR

A series of flame-retardant epoxy resin (EP) composites, with different mass ratio of intumescent flame-retardant (IFR) and hollow glass microspheres (HGM), have been prepared. The synergistic flame-retardant effects of HGM between IFR in EP blends have been examined through several conventional methods, such as limiting oxygen index (LOI) test, UL-94 test, cone calorimeter test (CCT), scanning electron microscopy (SEM), and thermogravimetric analysis (TG), respectively. The LOI and UL-94 results show that when 2.0 mass% IFR is replaced by HGM, the LOI value can be increased to the maximum value of 34.7 among all samples. The data obtained from the CCT test indicate the peak value of heat release rate of EP/IFR/HGM sample with 2.0 mass% HGM reduced to 177.6 from 851.1 kW m−2 (pure EP). The digital photographs and SEM of char residues after CCT give positive evidence of the synergistic flame-retardant effects between HGM and IFR. Firstly, HGM could promote the formation of dense and compact charred layers. Secondly, it could prevent the charred layers from cracking. The TG results reveal that EP/IFR/HGM samples show higher thermal stability at high temperature than EP/IFR sample.