Studies On The Preparation And Performance Of Palygorskite-based Phosphorus,Boron,and Titanium-containing Flame Retardants For EVA And EP Composites

With the development of modern technology,more and more novel polymer appeared in our daily life.But its flammability prevents polymer material from using in many flammable or high-temperatured fields.Therefore,an appropriate flame retardant agent was always added to reduce the flammability of the polymer.For the meeting of the non-toxicity and green environment requirement,green flame retardants have been prepared to substitute halogenated flame retandants.In recent years,metal hydroxides fillers have replaced the halogen-based fire retardants in many applications because of their environmental friendly.However,the flame retardant efficiency was always low when using the metal hydroxides alone.In order to achieve the effective flame retardant?UL-94,V-0?,the addition of metal hydroxides was up to 50%.Unfortunately,it would lead to poor dispersibility for polymer with such high addition,and the mechanical property declined dramatically.So we could modify metal hydroxides by organics component,e.g.polymers,to improve its compatibility and mechanical properties.On the other hand,inorganic-inorganic compound were usually prepared in order to enhance the flame retardance of polymer material.In view of that,we prepared inorganic-inorganic hybrid PGS-based flame retardant due to its excellent adsorption property.We also modify the prepared material with organic reagents to promote its compatibility.The main contents and results of present study were as follows:1.Alumium hypophospite was precipitated on PGS to form PGS-AlHP,it was subsequently grafted by O-carboxyl benzoyl octadecylamine which was prepared by the reaction of octadecylamine and phthalic anhydride successfully.A novel organic-inorganic hybrid flame retardant named N@PGS-AlHP was prepared.Through FTIR,XRD,SEM,TGA,LOI and CCT characterization,it found that the prepared composite of EVA/N@PGS-AlHP/EG obtained a LOI value of 40.1%with the addition of 30 wt%of flame retardant of N@PGS-AlHP/EG.From the analysis of the mechanism,it was known that the phosphorus-based radicals?PO₂·,PO·,etc?were efficient trap for the capture of H·and HO·radicals in the vapor phase.The introduction of AlHP and N element could contribute to improve the formation of char residue to improve the flame retardancy of EVA.2.Through the simple precipitation of PGS by zinc borate?to made PGS@ZB,where PGS=palygorskite,ZB=zinc borate?and the decoration of PGS@ZB by dodecylamine?N?,a new compound of PGS@ZB-N was prepared and was incorporated with EVA to enhance its flame retardance.The prepared EVA/PGS@ZB-N/EG composite obtained a LOI value of 41.2%with the addition of30 wt%PGS@ZB-N/EG.The result of thermal stability indicated that the EVA/PGS@ZB-N/EG composite was more stable than the EVA/N@PGS-AlHP/EG composite.It was found that the B₂O₃ was released during the the combustion,and EVA/PGS@ZB-N/EG was mainly protected through condensedt mechanism.3.In this part,a new flame retardant element of Ti was introduced on the basis of the previous work.Through the co-precipitation method,titanium dioxide was loaded on PGS?to made PGS-Ti,where Ti=titanium dioxide?and through the decoration of PGS-Ti by P-g-C₃N₄,a novel 3D hybrid flame retardant named P-g-C₃N₄@PGS-Ti which could improve the flame retardancy of EP?epoxy resins?was prepared.It was found that the peak heat releasing rate?PHRR?of EP/P-g-C₃N₄@PGS-Ti composite reduced by 36%with the addition of 5 wt%of P-g-C₃N₄@PGS-Ti.The char residue increasing obviously due to the synergistic effect of PGS,TiO₂ and the introduced P element.