TiO₂/PO₄^3– solid superacid was synthesized by using the precipitation immersion method and characterized by means of X-ray diffraction (XRD) and an energy-dispersive spectrometer; it was added into flexible poly(vinyl chloride) (PVC) composites as a flame retardant. The smoke suppression and flame retardance of TiO₂/PO₄^3– accompanied by Sb₂O₃ were investigated through the limiting oxygen index (LOI), cone calorimetry test, and thermogravimetry analysis (TGA). The results indicated that the LOI value of PVC/Sb₂O₃/(TiO₂/PO₄^3–) reached to 32.3%, which is higher by 6% than that of neat PVC (26.3%). In addition, Sb₂O₃/(TiO₂/PO₄^3–) greatly reduced the peak heat release rate and total heat release simultaneously in comparison to using Sb₂O₃ separately, suggesting a significant synergistic effect between TiO₂/PO₄^3– and Sb₂O₃ on improving the flame retardancy of the PVC. Further, results of TGA and differential thermal analysis showed that the thermal stability of the composites was greatly improved. For the Fourier transform infrared analysis, Sb₂O₃/(TiO₂/PO₄^3–) leads to a large amount of functional group surplus, which specifically indicates that its carbon residue increases. The surface of the char formed after combusting of the PVC compounds was observed through scanning electron microscopy. It is found that the solid superacid can promote decomposition, pyrolysis, and cross-linking of PVC into the compact and continuous char layer on the surface of the material, which improved the flame retardancy and smoke suppression of PVC.

中文翻译：

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固体超强酸的合成及其在阻燃聚氯乙烯材料中的应用

采用沉淀浸没法合成了TiO ₂ / PO ₄ ^3-固体超强酸，并利用X射线衍射（XRD）和能谱仪对其进行了表征。将其作为阻燃剂添加到柔性聚氯乙烯（PVC）复合材料中。通过极限氧指数（LOI），锥形量热试验和热重分析（TGA）研究了TiO ₂ / PO ₄ ^3–伴随Sb ₂ O _3的抑烟性和阻燃性。结果表明，PVC / Sb ₂ O ₃ /（TiO ₂ / PO ₄ ^3–）达到32.3％，比纯PVC（26.3％）高6％。此外，锑₂ ö ₃ /（二氧化钛₂ / PO ₄ ^3-）的峰值热释放速率和在比较同时总放热量大大降低使用的Sb ₂ ö ₃分开，提示显著协同作用的TiO之间₂ / PO ₄ ^{3 –}和Sb ₂ O ₃对改善PVC的阻燃性。另外，TGA和差示热分析的结果表明，复合材料的热稳定性大大提高。对于傅立叶变换红外分析，Sb ₂ O₃ /（TiO ₂ / PO ₄ ^3–）导致大量的官能团过剩，这具体表明其碳残基增加。通过扫描电子显微镜观察PVC化合物燃烧后形成的炭的表面。已经发现，固体超强酸可以促进PVC的分解，热解和交联成材料表面上的致密且连续的炭层，从而改善了PVC的阻燃性和抑烟性。