Synthesis Of New MOFs Rich In P And N Elements And Their Flame Retardant Application In EP

Epoxy resin（EP）is a kind of polymer material with good thermal stability,corrosion resistance,good insulation performance and excellent mechanical properties.It is widely used in all aspects of our life.However,because it contains a large amount of elements such as C,H,O and other elements,making it easy to burn,it releases a lot of heat,smoke,toxic,harmful gases and other substances when burning,which affects its use in some fields.Therefore,it is necessary to conduct in-depth research on flame retardancy and smoke suppression of EP.Metal-organic frameworks（MOFs）is a class of porous materials with a networked framework structure formed by metal ions and organic ligands through coordination bonds.MOFs have relatively high thermal stability,and better compatibility.The contained metal elements can reduce flue gas emissions and catalyze the carbon-forming reaction of polymer substrates;however,the MOFs currently used in flame retardant generally have organic ligands that do not contain flame retardant elements or have a low content of flame retardant elements,so MOFs have poor flame retardant efficiency when used alone,and often need to be modified with flame raterdant grafting or used in combination with other flame retardants.Therefore,we use high content of flame retardant elements2,4,6-tris（p-aminobenzoic acid）-1,3,5-triazine and hexa（4-carboxyphenoxy）cyclotri phosphazene were used as organic ligands to synthesize novel MOFs,and they were applied in EP to explore the effect of MOFs on the flame retardant properties of EP,and analyze the flame retardant mechanism.The specific research contents are as follows:Part one:Synthesis of 2,4,6-tris（p-aminobenzoic acid）-1,3,5-triazine（R1）with relatively high nitrogen content using cyanuric chloride and p-aminobenzoic acid as raw materials,and using it as a ligand and zinc chloride（Zn Cl₂）to prepare a new type of MOF by solvothermal method,and using X-ray single crystal diffraction,scanning electron microscope（SEM）,X-ray diffractometer（XRD）,thermogravimetry It was characterized by analysis（TGA）and thermogravimetric infrared（TG-IR）.These test results show that we have successfully prepared a novel MOF（R1-MOF）with a regular hexahedral structure,uniform particle size,good dispersion,and no agglomeration.TGA test results show that R1-MOF has good thermal stability and can meet the curing requirements of EP.And applied to EP,the results of cone calorimetry test（CCT）showed that the peak heat release rate（p HRR）of the EP composite samples decreased by 51.3%,the peak smoke release rate（p SPR）decreased by 41.5%,and carbon monoxide was generated.The production of carbon dioxide（COP）and carbon dioxide production（CO₂P）decreased by 45.3%and 39.1%,respectively.Part two:Hexa（4-carboxyphenoxy）cyclotriphosphazene with relatively high content of P and N was synthesized from hexachlorocyclotriphosphazene and methyl p-hydroxybenzoate.A new type of MOF（R2-MOF）was prepared by solvothermal method with the ligand and zinc perchlorate hexahydrate（Zn（Cl O₄）₂·6H₂O）,and analyzed by X-ray single crystal diffraction,XRD,SEM,TGA and TG-It was characterized by IR et al.The test results showed that a new type of MOF with a lamellar structure was successfully prepared.The TGA test results showed that the R2-MOF was stable enough to meet the processing and curing requirements of EP.The CCT results showed that the p HRR of the EP composite samples decreased by29.9%,the p SPR decreased by 45.9%,and the COP and CO₂P decreased by 38.4%and 38.1%,respectively.