Investigation of novel intumescent flame retardant low-density polyethylene based on SiO₂@MAPP and double pentaerythritol

To improve the flame-retardant property of low-density polyethylene (LDPE) composites, a novel intumescent flame retardant (IFR) consisting of ammonium polyphosphate (APP) covered by silicon dioxide and 3-(Methylacryloxyl) propyltrimethoxy silane (KH-570) (SiO₂@MAPP) and double pentaerythritol (DPER) was synthesized. Various methods were applied to structural characterization and property investigations of different samples. The results indicated that the solubility of APP decreased after coating with silicon dioxide (SiO₂) and KH-570. The flame retardancy of LDPE composites was improved with addition of IFR containing SiO₂@MAPP/DPER. With 30 wt% addition of IFR containing SiO₂@MAPP /DPER, the limiting oxygen index reached 26.8% and the tensile strength was 3.30 MPa. The tensile strength was 7.14% higher than that of 30 wt% IFR without SiO₂@MAPP. The smoke density test showed that the flue gas emission was obviously improved. The addition of SiO₂@MAPP effectively increased the residual carbon content of composites and thermal stability of the composites.