Modification Of Intumescent Flame-retardant Agent And Its Application In Polypropylene

In recent years, with the wide application of polypropylene(PP) in many industries such as electric, automobile, its flame retardancy become more and more important. The impact on health and the environment due to the evolution of corrosive and obscuring smoke from halogenated flame retardants force the market to develop alternative fire retardant systems.Based on the demands of low smoke, corrodibility, and toxicity for flame-retardant polymeric materials, intumescent flame retardants have been developed as the replacement for the traditional halogen-containing flame retardants. The disadvantages of intumescent flame-retardant system, such as bad matrix compatibility, poor mechanical properties, moisture sensitivity, and migration., have restrict the its application. In this thesis, flame-retardant has been synthesized through reaction of ammonium polyphosphate(APP) and melamine(MEL) to overcome these problems.This work focused on the mechanism and kinetics of the reaction between APP and MEL, and the properties of the resulted products. IR and element analysis were employed to investigate the reaction processes. The effects of reactant ratio, reaction time and temperature were studied. The molecular structure, particle size and the water solubility of the APP before and after the reaction were compared. It has been found that the optimum reaction condition is: weight ratio of MEL to APP 0.5, reaction temperature 260℃, reaction time 2h,A kinetics model has also been developed. It has been found that the reaction order of APP is 1, the reaction order of MEL is 2, the apparent activation energy is 47.8KJ/mol and the frequency factory is 5.42×10⁶s^-1The TGA results showed that thermo-stability of reacted APP have been improved. The initial decomposition temperature was increased to 300℃ from 170℃. This means that the reacted APP can meet the processing requirements of plastics. The XPS results showed that the crystalline form of heated APP was changed from form Ito the mixture of form I and form II.Burning test of flame retardant PP system showed that those IFR can improve the flame retardancy of PP. The experimental results indicated the LOI was more than 30 and passed the UL94V-0 flame retardancy examination when the addition of IFR was more than 30%. The dripping was also prevented to certain extent.The flame retardancy of flame retarded PP using TGA and DTG show that the IFR systems can act at both condensed and gas phases and possessed excellent thermal stabilities and char-forming properties.To improve the miscibility between IFR and substrate, the addition of styrene-maleic anhydride copolymers were employed. That improved the tensile strength property.