Preparation And Properties Of Intumescent Flame Retardant Polypropylene Materials

Polypropylene (PP) is an important polyolefin and has been widely used in many fields. However, the use of PP is strongly limited because of its easy flammability and dripping tendency, therefore the flame retardancy of PP is essential. The intumescent flame retardant (IFR) have some advantages, such as lower smoke, no toxic, no corrosive gas and so on. At present, the flame retardant technology of PP is focused on the research and application of IFR system.In this paper, the IFR system was formed for polypropylene (PP), in which tris(2-hydroxyethyl) isocyanurate (THEIC) used as charring agent was combined with different amount of ammonium polyphosphate (APP) and other additives. Some important factors affecting the flame retardancy were studied, such as the ratio of THEIC to APP, type and amount of the synergistic agents such as Zeolites, rare earth oxides and so on. Water resistance of flame-retarded PP materials was also discussed. The experimental results demonstrated that when the IFR loading was 25 wt% in PP achieved V-0 rating and a 34.0 LOI value. The water resistant tests indicated IFR’s poor water resistant property and bad flame retardant durability had been improved evidently, and 4A,5A, H-Beta Zeolites, rare earth oxides and SiO2 etc all had good synergistic effects.TGA and SEM were used to evaluate the thermal degradation, char performance and the morphological structures of the burnt char layer of PP-IFR materials respectively. The results showed synergistic effect between THEIC and APP increased the amount of char residue, the synergists could accelerate the degradation of the systems, enhance the stabile char formation at high temperature. Therefore, a better flame retardancy was obtained.At last, we discussed the flame retardancy and properties of different type of PP-IFR materials. It was found that the IFR was quite effective in many types of PP resins. When the IFR loading was only 22 wt% in PP, the flame retardancy of PP-IFR can pass V-0 rating, and its LOI value could be higher than 30.0. However, there were some influences on the mechanical property of the PP-IFR materials.