低聚倍半硅氧烷基铁络合物阻燃剂的合成及改性环氧树脂

Synthesis of Oligosilsesquioxane-Based Iron Complex Flame Retardant and Its Modified Epoxy Resin

采用Kabachnik-Fields反应合成出含有邻苯二酚功能团、磷杂菲基团和笼型倍半硅氧烷结构基元的新型配体POSS-DOPO-Catechol(PDC),再与Fe^3+配位络合形成低聚倍半硅氧烷基铁络合物Fe(PDC)3,进一步加入双酚A型环氧树脂(EP)进行固化制备出EP/Fe(PDC)3复合材料。利用红外、质谱和核磁共振表征配体及络合物的化学结构;通过差示扫描量热分析、热重分析、氧指数测定、微形量热、动态力学实验等方法研究铁络合物Fe(PDC)3的引入对环氧树脂固化温度、热性能、阻燃性能、力学性能及介电性能的影响。结果表明,添加Fe(PDC)3可以降低环氧树脂的固化温度、热释放速率及总热释放量,提高残炭量、氧指数,这是由于铁络合物可以有效促进材料在高温下形成稳定性良好的致密炭层,起到隔氧隔热作用,从而在燃烧过程中阻止材料进一步燃烧。

A novel ligand POSS-DOPO-catechol (PDC) containing catechol functional groups, phosphaphenanthroline groups and caged silsesquioxane structura was synthesized by Kabachnik Fields reaction and then complexed with Fe^3+ to obtained an oligomeric silsesquioxane-based iron complex Fe(PDC)3. The bisphenol A epoxy resin (EP) was further added for curing to prepare an EP/Fe(PDC)3 composite material. The chemical structures of POSS-DOPO-catechol and Fe(PDC)3 were characterized by IR, MS and NMR. The curing temperature, flame retardancy, mechanical and dielectric properties of the EP/Fe(PDC)3 composite material were characterized by differential scanning calorimetry, thermogravimetric analysis, limiting oxygen index measurement, cone calorimetry and dynamic mechanical tests. The results show that the addition of Fe(PDC)3 can reduce the curing temperature, heat release rate and total heat release of epoxy resin, and increase the residual carbon content, oxygen index and flexural modulus. Scanning electron microscopy results indicate that the iron complex can effectively promote the formation of a dense carbon layer at high temperatures which plays an important role in oxygen barrier and heat insulation to prevent the materials from further burning during the combustion process. In a word, the incorporation of the prepared Fe(PDC)3 is helpful to improve thermal and flame retardants as well as mechanical properties of epoxy resins.