Preparation Of Modified Basic Magnesium Carbonate And Ammonium Polyphosphate And Their Influence On PP Properties

As an important thermoplastic resin,polypropylene(PP)has widely used in the fields of automobile,packaging and machinery because of its excellent performance and low cost.However,PP is a flammable material with limiting oxygen index of approximate 18%,burns violently and produce dense smoke with melting drops,which severely limited its application.Therefore,the study of non-halogenated flame retardant for polypropylene has drawn great attention from the current scientific community.Basic magnesium carbonate is an important new non halogen flame retardant,despite the basic advantages of which,such as non-toxic,non-volatile,good thermal stability,low cost,no secondary pollution,as inorganic matter,it has a poor compatibility with the polymer.In this study,the Basic magnesium carbonate and ammonium polyphosphate(APP)are modified and blended with PP at different proportions to improve the flame-retardant property of the blends.Firstly,titanate coupling agent was used to modify the Basic magnesium carbonate and APP,and the optimum conditions for surface modification were obtained.Fourier transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM),thermogravimetric analysis(TG),differential scanning calorimetry(DSC),water contact angle,vertical burning and cone calorimetry were used to characterize the structure and properties of the samples.The results showed that the titanate coupling agent 201 was successfully connected to the surface of the Basic magnesium carbonate and APP,and the optimum amount of the titanate coupling agent 201 was obtained.When the modified Basic magnesium carbonate with 30 wt%titanate and modifying APP with 10 wt%titanate,they showed good compatibility and dispersibility with PP.The flame retardancy and thermal stability of the blends were improved significantly.The highest limit oxygen index and UL-94 of the blends reached 30.5%and V-0 level,respectively,therefore they are classified as the flame retardant materials.In addition,the temperature resistance of the blends was improved,the heat release during combustion was inhibited,and the entire burning time was prolonged,but the mechanical properties and rheological properties of the blended materials all degraded.Although it achieved good flame retardancy,there was still a great amount of smoke and poisonous gas when the blends were burning.To suppress the smoke,the Basic magnesium carbonate and ammonium polyphosphate were microencapsulated by tetraethyl orthosilicate in this study:Hexadecyl trimethyl ammonium bromide(CTAB)surfactant was used to disperse the inorganic particles evenly in reaction solvent and the SiO2 gel core-shell structure was formed in alkaline conditions.Then the titanate coupling agent 201 was used to modify the surface of the SiO2 gel.Finally,the modified microencapsulated Basic magnesium carbonate and APP were blended with PP at different proportions.The results showed that SiO2 gel successfully coated on the Basic magnesium carbonate and APP,and the poisonous gas and smoke were reduced by using these flame retardant,which had a positive effect on the smoke suppression of the blends.This study provides useful theoretical exploration for the further research of Basic magnesium carbonate.