Study On Preparation And Flame Retardancy Of Solid Superacid Modified Mineral Materials

Functional plastics with different properties greatly meet the requirements of daily life and industrial production,the flammability and spread of the polymer will also have huge losses,which requires that the polymer materials used in mining must have flame retardancy.In this paper,a variety of solid super acids were successfully prepared.And the solid super acids were compounded with traditional flame retardants to modify flame retardant epoxy resin（EP）and polyvinyl chloride（PVC）.The oxygen index（LOI）,cone calorimeter（CCT）,thermogravimetric（TG）,electron microscopy（SEM）were used to analyze the flame retardancy and thermal stability,and to study the synergistic effect of solid superacid flame retardant.The main work and results of the paper are as follows:1.Using titanium tetrachloride and tetrabutyl titanate as raw materials,SO₄^2-/M_XO_Y and SO₄^2-/TiO₂-M_XO_Y solid super acids were prepared by precipitation method and sol-gel method,and X-ray diffraction analysis（XRD）,infrared spectroscopic analysis（FTIR）,elemental analysis（EDS）,acidity test（Hammett indicator）were characterized the structure and acidity,the solid superacid showed super strong Lewis acid or Br?nsted acid.2.Ammonium polyphosphate（APP）was selected as the main flame retardant of epoxy resin（EP）,and three super strong acids SO₄^2-/Fe₂O₃,SO₄^2-/ZrO₂ and SO₄^2-/TiO₂as flame retardants synergist were applied to flame retardant EP.The result showed that the flame retardant effect was better when the addition amount of super acid was2 wt%,in particular,the synergistic flame retardant of AM and SO₄^2-/TiO₂ were the best.Compared with the compound with different super acids,the oxygen index of EP/AM/SO₄^2-/TiO₂ at the maximum was 28.3%;and the lowest heat release rate（HRR）was 286 KW/m²,which was 45%lower than that of EP/APP composite system.TGA also showed that the thermal stability of the EP/SO₄^2-/TiO₂ composite was improved.At 700°C,the residual char of SO₄^2-/ZrO₂ and SO₄^2-/Fe₂O₃ were 21.07%and 19.61%,respectively,while the final residual char of EP/SO₄^2-/TiO₂ increased to26.22%.The SEM analysis of the morphology and structure of the residual char showed that SO₄^2-/TiO₂ was beneficial to enhance the char layer quality and strength of EP composites.3.Traditional Sb₂O₃ was selected as the main flame retardant of polyvinyl chloride（PVC）,and the single solid super-strong acid was prepared as the flame retardant synergist.The synergistic effect of SO₄^2-/TiO₂ was verified again.After exploration,the optimal ratio of Sb₂O₃ and SO₄^2-/M_XO_Y was 5:1,and the effect of SO₄^2-/TiO₂ was the best.The results showed that the LOI of PVC/Sb₂O₃/PO₄^3-/TiO₂,PVC/Sb₂O₃/SO₄^2-/ZrO₂ and PVC/Sb₂O₃/PO₄^3-/ZrO₂ were 32.3%,31.7%and 31.3%,respectively,after adding 1wt%SO₄^2-/TiO₂ into the PVC/Sb₂O₃ composites,the LOI was the biggest（32.5%）.The residual char of PVC/Sb₂O₃/SO₄^2-/TiO₂ was increased to19.8%at 700℃.The PHRR and THR were reduced to 247 KW/m² and 44 MJ/m²,respectively.At the same time,the char layer structure of PVC/Sb₂O₃/(SO₄^2-/TiO₂)was smooth and dense after combustion.4.As SO₄^2-/TiO₂ had better flame retardant synergistic effect,five different metals were compounded to explore the composite super strong acid to strengthen the flame retardant synergistic effect of acid source.Five complex superacids,SO₄^2-/TiO₂-CuO,SO₄^2-/TiO₂-ZrO₂,SO₄^2-/TiO₂-Fe₂O₃,SO₄^2-/TiO₂-MnO and SO₄^2-/TiO₂-MoO₃ were prepared by sol-gel method.Melamine coated ammonium polyphosphate（MAPP）was selected as the main flame retardant of epoxy resin（EP）,m-phenylenediamine as the curing agent,and SO₄^2-/TiO₂-M_XO_Y as the flame retardant synergist.The results showed that the LOI of EP/MAPP/(SO₄^2-/TiO₂-MnO)was up to34.5%,and the flame retardant effect of EP with other super strong acids was also good,with a LOI value of around 34%.In addition,PHRR,THR,and toxic gas release of the EP/MAPP/(SO₄^2-/TiO₂-MnO)were the lowest,its fire performance index（FPI）was the highest,and the fire danger was less.The TSP(1878 m²·m^-2)of EP/MAPP/(SO₄^2-/TiO₂-ZrO₂)was minimum,and its smoke suppression effect was better.When SO₄^2-/TiO₂-M_XO_Y was added,residual char was increased,and the char layer structure was more continuous and dense.The SO₄^2-/TiO₂-M_XO_Y strengthened the role of acid source in the expansion agent,and had a good synergistic effect with MAPP.The best flame retardant and smoke suppression effect was the EP/MAPP/(SO₄^2-/TiO₂-MnO)composite.