Studies on the effects of kaolin and modified kaolin on the flammability of APP/PP system

Abstract

THIS WORK is a continuation of the previous works by the authors to increase the efficiency of ammonium polyphosphate (APP) as flame retardant for polypropylene(PP). In this work a more abundant kaolin was used. Also to improve the efficiency of kaolin, an acid modification by sulfuric acid was used. XRD, XRF, IR, SEM and BET were used to characterization the samples. TGA and DTA were used to evaluate the prepared samples as flame retardant. For comparison, five samples of (APP/ Kaolin ore)/PP were prepared and other five samples (APP/Modified kaolin)/PP have the same composition also were prepared. The analysis of the XRD, IR and SEM results indicate that the acid treatment of kaolin increases the SiO2 content which lead to increase the surface area. In the same time the acid leaching causes some distortion in the crystalline and the layers. The evaluation of the flammability of the system by using the TGA indicate that the presence of kaolin increases the time of degradation of PP. On other hand, the modification of kaolin by sulfuric acid improves the role of the kaolin when added to the APP.