Studies on the effect of 4A zeolite on the properties of intumescent flame-retardant agent filled natural rubber composites

This investigation focused on the research of 4A zeolite on the properties of intumescent flame retardant (IFR) agent filled natural rubber (NR) systems. The first part focused on the evaluation of such characteristics as cure characteristics, tensile property, abrasion loss, and cross-linking density of NR composites. Experimental results demonstrated that the addition of 4A zeolite could increase the cross-linking density of the NR systems. The incorporation of 0.3 phr of 4A zeolite with 50 phr of IF Ragent could improve the elongation value from 480 to 610%, probably 27% increase. Also, the abrasion loss was decreased from 0.95 to 0.70 cm³, nearly 26%. The second part focused on the study of flame-retardant (FR) properties of 4A zeolite filled NR systems. The properties and structure of these composites were characterized by limited oxygen index (LOI), thermogravimetric analysis (TGA), and cone calorimeter. It was proved that the addition of 0.3 phr of 4A zeolite into the IFR filled NR systems could lead to an increase of LOI value and thermal stability, together with a decrease of mass loss ration, rate of heat release (RHR), carbon monoxide (CO) evolution and carbon dioxide (CO₂) evolution, and so on, in a word, an improvement of FR properties.