Effect of aluminium hydroxide, chlorinated polyethylene, decabromo biphenyl oxide and expanded graphite on thermal, mechanical and sorption properties of oil-extended ethylene–propylene–diene terpolymer rubber

Oil-extended EPDM composites with different flame retardant fillers like aluminium hydroxide (ATH), chlorinated polyethylene (CPE), decabromobiphenyl oxide (DBBO) and expanded graphite (EG) were prepared by conventional mill mixing. Thermal, mechanical and sorption characteristics of the vulcanizates were studied. The effect of different fillers on the flammability of the composites was measured using Limiting Oxygen Index (LOI) and UL-94 HB tests. Scanning Electron Microscopic (SEM) studies of the composites were also conducted. ATH and CPE improve the thermal stability of the composite substantially. Among the four fillers ATH has the highest reinforcing effect on the EPDM rubber. Sorption studies of the composite showed that ATH reduced the swelling rate of the microcomposite considerably. All the four fillers were effective in improving the flame retardant property. Filler dispersion studies and SEM images point to a uniform dispersion of filler in the matrix which is in good agreement with significant improvement in mechanical properties.

► Cure characteristics are not affected by the addition of ATH, CPE, DBBO and EG.
► Even 25 phr ATH loaded EPDM exhibit a sharp increase in tensile strength.
► EPDM/ATH compounds exhibited reduced swelling rate compared to other systems.
► The thermal stability of EPDM increased with the addition of all fillers.
► SEM supports the filler dispersion which is in good agreement with the mechanical properties.