环氧树脂包覆聚磷酸铵微胶囊的制备及其对聚丙烯的阻燃效果

为了探究环氧树脂包覆聚磷酸(EP@APP)微胶囊对聚丙烯(PP)的阻燃效果,首先,采用原位聚合法以EP为外壳包覆APP,制备了EP@APP微胶囊,并将其与PP进行复合,制备了EP@APP/PP复合材料。然后,测试了EP@APP微胶囊的溶解性,探讨了工艺参数对溶解性的影响;考察了EP@APP微胶囊的耐水性,并借助红外光谱分析了EP@APP微胶囊的表面官能团。最后,测试了PP复合材料的极限氧指数、拉伸强度和热重曲线,并分析了PP复合材料的热分解动力学。结果表明:当EP的加入量为APP的10wt%、固化剂加入量为EP加入量的15wt%时,采用先于40℃下维持1h、再于70℃下维持1h的阶跃升温方法可制备包覆完全的EP@APP微胶囊;该种微胶囊在水中溶解度低,且具有良好的耐水性。在PP中添加EP@APP微胶囊后,PP复合材料的极限氧指数为35.5%,达到V-0燃烧等级,燃烧后的残炭量增多,成炭效果明显优于直接添加APP的PP复合材料。与APP相比,EP@APP微胶囊对PP拉伸强度的破坏程度明显降低。EP@APP微胶囊的加入使PP复合材料的表观活化能由100.8kJ/mol提高到127.5kJ/mol,改变了PP复合材料的热降解氧化过程,且生成的残炭形成了稳定的保护炭层。研究结果表明EP@APP微胶囊可有效提高PP复合材料的阻燃性能。

Preparation of epoxy resin coated ammonium polyphosphate microcapsules and their flame retardant effects on polypropylene

In order to study the flame retardant effects of epoxy resin coated ammonium polyphosphate (EP@APP) microcapsules on polypropylene (PP), firstly, EP was used as the shell to coat APP by in situ polymerization method, then the EP@APP microcapsules were prepared, and it was compound with PP to prepare the EP@APP/PP composites. Secondly, solubility of EP@APP microcapsules was tested to explore the effects of process parameters on solubility. The water resistance was also investigated. With infrared spectroscopy, surface functional groups of EP@APP microcapsules were analyzed. Finally, limited oxygen index, tensile strength and thermogravimetric curves were tested and the thermal degradation kinetics of PP composites was analyzed. The results show that when the addition of EP is 10wt% of APP, and curing agent addition is 15wt% of EP, the completely coated EP@APP microcapsules were prepared by step heating method of maintaining 40 ℃ for 1 h, followed by maintaining 70 ℃ for 1 h. The solubility of the microcapsules in water is lower and the water resistance is good. After adding EP@APP microcapsules into PP, the limited oxygen index of PP composites is 35.5% and reaches V-0 burning class, the mass of residual char after burning increases, and the carbonize effect is better than that of PP composites which adding APP directly. Comparing with APP, the destructiveness of EP@APP microcapsules toward tensile strength of PP reduces obviously. The addition of EP@APP microcapsules makes the apparent activation energy of PP composites increases from 100.8 kJ/mol to 127.5 kJ/mol, and changes the thermal degradation oxidation process of PP composites, and a stable protecting carbon layer is formed by the generated residual char. The research results show that EP@APP microcapsules can improve the flame retardancy of PP composites effectively.