چكيده به لاتين
In this study, we aimed to improve the thermal properties of copolymer ethyl vinyl acetate (EVA), which is used as the primary polymer of electrical cables. For this reason, an expanded graphite flame retardant (EG) was used. Expandable graphite was selected for its thermal stability at high temperatures, low cost, and the formation of carbon in many of the work used in flame retardant applications. On the other hand, due to its low compatibility in the polymer matrix and the instability of its char layer, it was modified. For this reason, at first, expandable graphite annealed in a furnace to eliminate some functional groups that intensify the chain reactions and graphite layers are spaced apart. So, the phosphorus-based (ammonium polyphosphate (APP)) flame retardant was used for cross-linking with expanded graphite. Then, various empirical methods for expanding graphite phosphorus have been investigated. In this regard, a modified and straightforward manner is proposed for the development of a high quantity of expandable graphite phosphorus to be used in flame retardant substances. To this end, a modified and straightforward method is proposed for the development of high-quantity expanded graphite phosphorus to be used in flame retardant works. To prove the existence of a chemical bond between expanded graphite and ammonium polyphosphate, Fourier-transform infrared spectroscopy (FTIR), X-ray Diffraction (XRD), scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDAX), thermogravimetric analysis (TGA) and (DTG) was used. The results exhibited that, at 6.5 weight percent, phosphorus was bonded to the expandable graphite surface, which is due to the appearance of the P-O-C bond. The product identified for flame retardant properties with ethylene-vinyl acetate polymer matrix (EVA) was combined in percentages 10, 20 and 30. Then, modified composites were compared with neat EVA and expanded graphite composites, expanded graphite with ammonium polyphosphate (two-hybrid systems) composites in the same composition percentages using TGA, vertical burning (UL-94) and micro-cone calorimeter (PCFC) has been compared. The results displayed that the modified composite with 30 wt% filler remind more char than other specimens, and, and also, the UL-94 was rated to V-0, and the results of the micro calorimeter were indicated that the heat released peak corresponds to the modified specimen is 40% better than neat EVA sample.
Keywords: expandable graphite, ammonium polyphosphate, phosphorous, flame retardant
