Preparation of halogen‐free flame‐retardant expandable polystyrene foam by suspension polymerization

Abstract

ABSTRACTIn this research, using hexaphenoxycyclotriphosphazene (HPCTP) as the halogen‐free flame retardant, we prepared flame‐retardant expandable polystyrene (EPS) beads by suspension polymerization. The effects of process parameters and the amount of flame retardant on polystyrene (PS)/HPCTP composite beads were investigated. The results show that the change in HPCTP content has little effect on the particle size distribution of composite beads. When the oil–water ratio is 1/4, TCP dosage is 3 wt %, stirring rate is 350 rpm, initiator dosage is 1.25 wt %, and HPCTP dosage is 15 wt %, the size of the composite beads is uniform, and the average particle size is 1.12 mm. HPCTP formed nanodispersed particles in the PS matrix with an average particle size of 44.86 nm. In addition, the thermogravimetric behavior and heat‐release properties of composite beads were evaluated. The results showed that HPCTP mainly acted in the gaseous phase, which can effectively decrease the maximum mass‐loss rate of the PS/HPTCP composite beads and significantly reduce the heat‐release rate and heat‐release capacity. The EPS foams were obtained by a prefoaming method. The average cell diameter was 62.15 μm, and the foaming ratio was 11 times. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47779.