Preparation and characterization of TiO2-coated hollow glass microsphere and its flame-retardant property in thermoplastic polyurethane

In this paper, a novel and efficient halogen-free flame retardant, HGM@TiO2, was synthesized by coating hollow glass microspheres (HGM) with TiO2. The flame-retardant and smoke suppression properties of HGM@TiO2 in thermoplastic polyurethane (TPU) have been investigated using several techniques including cone calorimeter test (CCT), smoke density test (SDT), thermogravimetric analysis (TGA) and fourier infrared, respectively. The CCT results showed that HGM@TiO2 could greatly improve the flame-retardant properties of TPU composites. The peak heat release rate of the sample with 0.5 wt% HGM@TiO2 (405 kW m−2) was reduced by 64% compared with the sample with the same loading HGM (1117 kW m−2), and the structure of char residue layer of TPU composites was obviously changed. The SDT results showed that HGM@TiO2 could effectively decrease the amount of smoke production in the test. Furthermore, the TGA results indicated that HGM@TiO2 could decrease the initial decomposition temperature and improve the thermal stability of TPU. And the FTIR results revealed that HGM@TiO2 could promote the composites to release inflammable gas such as CO2 earlier to suppress the combustion. According to this study, there may be some new methods to obtain flame-retardant polymer with low loading level.