Effects of kaolin on the thermal stability and flame retardancy of polypropylene composite
writer：張勝；姜鵬；劉喜山；谷曉昱*； 趙倩；扈中武；唐武飛
keywords：polypropylene; kaolin; flammability; char formation
source：期刊
specific source：POLYMERS FOR ADVANCED TECHNOLOGIES
Issue time：2014年
Kaolin clay was introduced into an intumescent flame retardant (IFR) system containing ammonium polyphosphate as an acid source and pentaerythritol as a carbonization agent in order to improve the thermal stability and flame retardancy of polypropylene (PP) composite. The flame retardancy and smoke suppression was evaluated by the limiting oxygen index, vertical burning UL-94, and cone calorimeter (CONE) tests. The limiting oxygen index value was increased from 30 to 33 at the presence of 2 phr kaolin. Thepeak heat release rate value decreased from 1002 kW/m(2) of neat PP to 318 kW/m(2) of PP/40 phr IFR and then to 222 kW/m(2) ofPP/38 phr IFR/2 phr kaolin. The time of the peak heat release rate was significantly prolonged after the introduction of kaolin. Themorphology of char after combustion was characterized by a scanning electron microscope, and it revealed more compact char structure that was obtained at the presence of kaolin. The mechanism of kaolin on improving the retardancy and smoke suppression of PP/IFR composite was proposed on the basis of X-ray photoelectron spectroscopy analysis.