Preparation and characterization of double shell microencapsulated ammonium polyphosphate and its flame retardance in polypropylene

Microencapsulated ammonium polyphosphate (MUFAPP) with a double shell is prepared by in situ polymerization, and is characterized by FTIR, XPS and SEM, etc. The microencapsulation of APP can increase its flame retardance and water resistance in PP. The flame retardant action of MUFAPP and APP in PP are studied using LOI and UL 94 test, and their thermal stability is evaluated by TG. The LOI value of the PP/MUFAPP composite at the same loading is higher than that of PP/APP composite. The LOI values of the PP/MUFAPP/ dipentaerythritol are higher than that of the PP/MUFAPP, and UL 94 ratings of most ternary composites are raised to V-0 at 30 wt.% loading. The results of the cone calorimeter also indicate that MUFAPP is an effective flame retardant in PP. The thermal degradation behaviors of APP and MUFAPP are studied using TG and dynamic FTIR.