Abstract:

Flame retardants could enhance the flame retardancy of polypropylene（PP）,but also reduce its mechanical prop-erties,so it is important to modify the flame retardants in order to improve the mechanical properties of PP.PP flame retardants are mainly the traditional intumescent flame retardants（IFR） including ammonium polyphosphate（APP）,pentaerythritol （PER） and melamine（MA）.Organic montmorillonite（OMt） was introduced in the synthesis of APP.APP formed around OMt,and OMt was stripped to make it dispersed smoothly in flame retardants.Ultrasonic was introduced in the solution of diammonium hydrogen phosphate（DAP）,urea and OMt for better dispersion.Then the compounds（DAP-UREA-OMt） which dried from the solution reacted with P₂O₅ and APP was obtained.Adding modified flame retardants to PP could improve the flame retardancy of PP and slow down the decline of mechanical properties.When 30%（the mass fraction of flame retardant in total mass） flame retardant was added,the oxygen index（LOI） reached 29.8%,and the tensile strength of 22.0 MPa was higherthan that of 0.7 MPa by the traditional method by V-0 test.

Key words: ultrasonic, polypropylene, organic montmorillonite, flame retardant, polyammonium phosphate