Improved Thermal Stability and Flame Retardancy of Polyethylene with Rare Earth Trifluoromethanesulfonate
作者：Ran SY, Guo ZH*, Fang ZP, Li J, Wang H
關鍵字：Flame retardancy; Thermal stability; Rare earth; Radical trapping
論文來源：期刊
具體來源：Composites Communications, 2018.3, 8: 19-23
發表時間：2018年
The thermal degradation of polyethylene (PE) is a free radical chain reaction, in other words, free radicals are the primary cause of combustion and degradation. Discovering proper compounds with radical trapping ability is critical for developing flame retardant PE composites. Herein, we introduced rare earth trifluoromethanesulfonate (RE(OTf)3), with radical trapping ability, into PE. The effects of ytterbium (Yb(OTf)3) and lanthanum (La(OTf)3) on the thermal stability and flame retardancy of polyethylene (PE) were investigated systemically. Electron spin resonance (ESR) spectroscopy proved the free radical-trapping ability of La(OTf)3 and Yb(OTf)3. The results of thermogravimetric analysis (TG) and differential scanning calorimetry (DSC) showed that Yb(OTf)3 could improve the thermal stability of PE more significantly compared with La(OTf)3. The flame retardancy of PE/intumescent flame retardant (IFR) composite was improved when 0.4 wt% IFR was substituted by RE(OTf)3. It changed the PE/IFR26 from UL-94 non-rated to V-0. Vertical flame test, limited oxygen index (LOI) and microscale combustion calorimeter (MCC) indicated that the effect of Yb(OTf)3 on the flame retardancy of PE was better than La(OTf)3. The improvement on the thermal stability and flame retardancy of PE is due to the combined action of anion and cation of RE(OTf)3. However, the different effects are attributed to the different reactivity of rare earth elements.