Synergetic effect of LDH and glass fiber on the properties of two- and three-component epoxy composites

Epoxy resins display excellent properties such as high thermal and mechanical stability along with good chemical resistance, but usually perform poorly under fire, burning easily and violently. The focus of the present work is to investigate the use of glycinate intercalated layered double hydroxides (LDH) for the preparation of two-component (LDH) and three-component (LDH/glass fiber) epoxy composites in order to achieve fire retardancy. The solution method was used to synthesize LDH, and the three-component epoxy/LDH/glass fiber composites were molded by resin transfer molding (RTM). The mechanical properties were investigated with tensile, flexural, impact and hardness testing. The flame-retardant characteristics were evaluated by horizontal (UL 94 HB) and vertical burning (UL 94 V), and the burnt sample residues were examined for morphological changes by scanning electron microscopy. The best mechanical performance was obtained when glass fiber (three-component) was used as reinforcement, and all samples containing LDH showed self-extinguishing behavior with lower burning rate than pristine epoxy or epoxy/glass fiber.