三氟甲烷磺酸稀土盐对聚丙烯热稳定性的影响及机理
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摘要
通过熔融共混将三氟甲烷磺酸镱[Yb(OTf)_3]和三氟甲烷磺酸镧[La(OTf)_3]添加至聚丙烯(PP)中,制得PP/Yb和PP/La材料,并对其热稳定性进行表征.热失重分析(TGA)和差示扫描量热分析(DSC)结果显示,Yb(OTf)_3和La(OTf)_3均可以显著提高聚丙烯的热稳定性.当Yb(OTf)_3添加量仅为1%(质量分数)时,PP的起始分解温度从275℃提高至305℃,最大分解温度从384℃提高至405℃,160℃下的氧化诱导时间从12.1 min延长至43.0 min,热焓从1907 J/g降低至483 J/g;而PP/La1的起始分解温度、最大分解温度、160℃下的氧化诱导时间和热焓分别为300℃,409℃,18.6 min和633 J/g.结果表明,La(OTf)_3对聚丙烯热稳定性的改善作用弱于Yb(OTf)_3,对2种稀土盐产生不同实验结果的原因进行分析并提出机制.由于阴离子和阳离子的共同作用,Yb(OTf)_3和La(OTf)_3均可提高PP的热氧稳定性.La(OTf)_3中三氟甲烷磺酸根的自由基捕捉能力和稀土离子的配位能力发挥主要作用,而Yb(OTf)_3中的稀土离子的高反应活性也起到关键作用.
The thermal degradation of polypropylene(PP)was a free radical chain reaction,in other words,free radicals were the primary cause of combustion and degradation.Rare earth trifluoromethanesulfonate[Yb(OTf)_3 and La(OTf)_3]can interfere degradation process of PP via capturing the free radicals,thus effectively improving the thermal stability of PP.PP composites filled with two kinds of rare earth trifluoromethanesulfonates were prepared via melt blending utilizing the free-radical trapping ability of Yb(OTf)_3 and La(OTf)_3 in this paper.The thermal-stability of PP was tested by thermogravimetric analysis(TGA),differential scanning calorimetry(DSC)and thermogravimetric analysis coupled to Fourier transform infrared spectroscopy(TGA-FTIR).The results showed that Yb(OTf)_3 and La(OTf)_3 could improve the thermal-stability of PP dramatically.Simply when the addition of Yb(OTf)_3 was 1%(mass fraction),the onset degradation temperature of PP was increased from 275℃ to 305℃,the temperature corresponding to the maximum rate of mass loss increased from 384℃ to 405℃,the oxidative induction time at 160℃ extended from 12.1 min to 43.0 min,and the enthalpy reduced from 1907 J/g to 483 J/g,respectively.Moreover,the onset degradation temperature,the maximum rate of mass loss,the oxidative induction time at 160℃ and the enthalpy of PP filled with 1% (mass fraction)La(OTf)_3 were 300℃,409℃,18.6 min and 633 J/g,respectively.The effect of La(OTf)_3 on the thermal stability of PP was weaker than that of Yb(OTf)_3.We tried to explain these differences and then propose the possible mechanism.Due to the combined action of anions and cations,Yb(OTf)_3 and La(OTf)_3 could improve the thermal stability of PP.For La(OTf)_3,the free radical trapping ability of trifluoromethanesulfonate and the coordination ability of rare earth ions played a major role.For Yb(OTf)_3,in addition to the above reasons,the high reactivity of rare earth ions also played a key role.
The thermal degradation of polypropylene(PP)was a free radical chain reaction,in other words,free radicals were the primary cause of combustion and degradation.Rare earth trifluoromethanesulfonate[Yb(OTf)_3 and La(OTf)_3]can interfere degradation process of PP via capturing the free radicals,thus effectively improving the thermal stability of PP.PP composites filled with two kinds of rare earth trifluoromethanesulfonates were prepared via melt blending utilizing the free-radical trapping ability of Yb(OTf)_3 and La(OTf)_3 in this paper.The thermal-stability of PP was tested by thermogravimetric analysis(TGA),differential scanning calorimetry(DSC)and thermogravimetric analysis coupled to Fourier transform infrared spectroscopy(TGA-FTIR).The results showed that Yb(OTf)_3 and La(OTf)_3 could improve the thermal-stability of PP dramatically.Simply when the addition of Yb(OTf)_3 was 1%(mass fraction),the onset degradation temperature of PP was increased from 275℃ to 305℃,the temperature corresponding to the maximum rate of mass loss increased from 384℃ to 405℃,the oxidative induction time at 160℃ extended from 12.1 min to 43.0 min,and the enthalpy reduced from 1907 J/g to 483 J/g,respectively.Moreover,the onset degradation temperature,the maximum rate of mass loss,the oxidative induction time at 160℃ and the enthalpy of PP filled with 1% (mass fraction)La(OTf)_3 were 300℃,409℃,18.6 min and 633 J/g,respectively.The effect of La(OTf)_3 on the thermal stability of PP was weaker than that of Yb(OTf)_3.We tried to explain these differences and then propose the possible mechanism.Due to the combined action of anions and cations,Yb(OTf)_3 and La(OTf)_3 could improve the thermal stability of PP.For La(OTf)_3,the free radical trapping ability of trifluoromethanesulfonate and the coordination ability of rare earth ions played a major role.For Yb(OTf)_3,in addition to the above reasons,the high reactivity of rare earth ions also played a key role.
引文
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[17]Zhang W.W.,Xue Z.X.,Liu J.J.,Yan M.,Xia Y.Z.,Chem.J.Chinese Universities,2017,38(2),303-311(张伟伟,薛志欣,刘晶晶,燕苗,夏延致.高等学校化学学报,2017,38(2),303-311)
[2]Liu J.C.,Xu M.J.,Li B.,Chem.J.Chinese Universities,2015,36(6),1228-1235(刘建超,许苗军,李斌.高等学校化学学报,2015,36(6),1228-1235)
[3]Zhao L.P.,Guo Z.H.,Cao Z.H.,Zhang T.,Fang Z.P.,Peng M.,Polym.Degrad Stabil.,2013,98(10),1953-1962
[4]Wei Y.Z.,Chen Y.M.,Zhang Y.,Zhu M.F.,Polymer Materials Science&Engineering,2005,21(1),52-56(魏延志,陈彦模,张瑜,朱美芳.高分子材料科学与工程,2005,21(1),52-56)
[5]Wang L.,Yang W.,Wang B.B.,Wu Y.,Hu Y.,Song L.,Yuen R.K.K.,Ind.Eng.Chem.Res.,2012,51(23),7884-7890
[6]Liu Y.,Cao Z.H.,Zhang Y.,Fang Z.P.,Ind.Eng.Chem.Res.,2013,52(15),5334-5340
[7]Ran S.Y.,Guo Z.H.,Chen C.,Fang Z.P.,J.Mater.Chem.A,2014,2(9),2999-3007
[8]Wu Y.,Kan Y.,Song L.,Hu Y.,Polym.Advan.Technol.,2012,23,1612-1619
[9]Lv G.M.,Wang Y.J.,Liu R.,Sun L.D.,Huang Y.H.,Yan C.H..,Science China:Chemistry,2013,43,1-13(吕广明,王艳杰,刘瑞,孙聆东,黄云辉,严纯华.中国科学:化学,2013,43,1-13)
[10]Ran S.Y.,Zhao L.,Han L.G.,Guo Z.H.,Fang Z.P.,Thermochim.Acta,2015,612,55-62
[11]Ran S.Y.,Guo Z.H.,Fang Z.P.,Li J.,Wang H.,Composites Communications,2018,8,19-23
[12]Díaz M.F.,Barbosa S.E.,Capiati N.J.,Polymer,2005,46(16),6096-6101
[13]Díaz M.F.,Barbosa S.E.,Capiati N.J.,Journal of Polymer Science,Part B:Polymer Physics,2004,42(3),452-462
[14]Ran S.Y.,Guo Z.H.,Han L.G.,Fang Z.P.,Industrial&Engineering Chemistry Research,2014,53(36),4711-4717
[15]Guo Z.H.,Fang Z.P.,Chen C.,Chem.J.Chinese Universities,2017,38(2),284-293(郭正虹,方征平,陈超.高等学校化学学报,2017,38(2),284-293)
[16]Babushok V.,Tsang W.,Combust Flam,2000,123(4),488-506
[17]Zhang W.W.,Xue Z.X.,Liu J.J.,Yan M.,Xia Y.Z.,Chem.J.Chinese Universities,2017,38(2),303-311(张伟伟,薛志欣,刘晶晶,燕苗,夏延致.高等学校化学学报,2017,38(2),303-311)