Research And Development Of Efficient Flame Retardant Polypropylene

Polypropylene (PP) is an important raw material in the plastics processing industry. However,many fires broke out by products made of flammable polypropylene.Therefore, researches in flame retardant modification of polypropylene are of great practical significance. Intumescent and halogen-free flame retardant has always been research hotspot.This reasearch was based on the typical intumescent flame retardant system of ammonium polyphosphate (APP)/pentaerythritol (PER).In order to reduce hygroscopicity of ammonium polyphosphate (APP),APP was encapsulated with melamine-formaldehyde resin (MF).The effect of pH value,the ratio of the shell layer material to the core material,temperature and the reaction time were studied.The optimal coating conditions was determined by the evalution of the particle size,solubility and thermal stability.The prepared microencapsulation ammonium polyphosphate (MAPP) had excellent water resistance.The influence of the ratio of APP to PER on the flame retardance of PP was studied. Through the evaluation of oxygen index test,vertical burning test and thermal stability analysis,the paper decided which ratio was employed.The results showed that the flame retardance of PP/APP/PER was best when the ratio of APP/PER was3/1.Then the prepared MFAPP was applied to flame-retardant PP.The results indicated that the flame retardance of PP/MFAPP/PER was better than that of PP/APP/PER.The samples of PP/MFAPP/PER also achieved good results in the mechanical properties,water resistance and smoke density.To improve efficiency of MFAPP/PER/PP,4A zeolite was employed as a synergistic agent of the flame retardant system of MFAPP/PER/PP.The effect of the amount of4A Zeolite on the flame retardance of MFAPP/PER/PP was studied.The optimum amount of4A Zeolite was decided by the results of oxygen index test,vertical burning test and thermal stability analysis.The results showed that the flame retardance of MFAPP/PER/PP/4A Zeolite achieved best performance when the mass fraction of4A zeolite was1%.The samples of MFAPP/PER/PP/4A Zeolite (1wt%) also achieved good results in the mechanical properties and smoke density.