Flame retardant and mechanical properties of core-shell-like polybutylene terephthalate/intumescent flame retardant through controlling injection time

This study prepared layered intumescent flame retardant (IFR)-graphene oxide (GO) via the esterification of GO and IFR. Then the distribution of IFR-GO in polybutylene terephthalate (PBT) was regulated via an injection molding process, while the tensile strength and combustion were explored. The results showed that the flame retardant distribution in PBT presented high external concentrations and low internal concentrations when the injection time was reduced. The lowest flame retardant content of 20 wt% was evident at an injection time of 2 s while displaying a high limiting oxygen index of 27.1. Although this resulted in a V-0 flame-retardant level, the mechanical properties were not affected. Therefore, the flame retardant was proportionately reduced by a shorter injection time to form a concentration gradient core-shell-like macrostructure, significantly increasing the flame-resistant efficiency while retaining the mechanical properties.