Study On The Synergistic Effects Of Intumescent Flame-Retardant Polyethylene

According to the formation process of intumescent char layer, there are two kinds of intumescent flame retardant, chemically intumescent flame retardant (CIFR) and physically intumescent one (PIFR). Intumescent flame retardant (IFR) based on the components of ammonium polyphosphate (APP), pentaerythritol (PER) and melamine (MN), as traditional CIFR, has been widely studied while expandable graphite (EG) as typical PIFR has been paid much attention to recently. However, few reports on the study of the synergistic effect of EG and IFR can be found. The paper aims at the study on the synergistic effect of two kinds of intumescent systems. The flame retardant properties, thermal degradation process and structure of char layer of two kinds of intumescent flame retardant polyethylene (PE), PE/EG and PE/IFR, are investigated by means of limiting oxygen index (LOI), thermogravimetric analysis (TG) and scanning electron microscope (SEM). By comparison of the synergistic effects of EG/APP and EG/IFR, the synergistic mechanism is revealed and a compound flame retardant system of high flame retardant efficiency is obtained. Furthermore, new EG of self synergistic effect is prepared by using the synergistic effect of two kinds of intumescent systems.Following results can be obtained in the paper: (1) Although two kinds of intumescent flame retardan systems show different flame retardant properties and mechanism, the properties of intumescent char layer play an important role in flame retardant mechanism. The better flame retardant efficiency of EG should be ascribed to the thermal stable expanded graphite layer which greatly decreased the weight loss rate and improved the char mass during thermal degradation...