层剥离高岭土改性煤沥青的结构与热稳定性

Structure and Thermal Stability of Delaminated Kaolinite Modified Coal Tar Pitch

在超声波作用下,以二甲基亚砜（DMSO）插层处理高岭土,通过熔融复合法改性煤沥青。采用XRD、FTIR、SEM、TEM、TG、DSC表征测试了插层高岭土的层间距、层间相互作用、层分散形态,以及改性煤沥青的热稳定性。结果表明,DMSO削弱了层间铝羟基与硅氧键间的氢键作用,插层高岭土的层间距由0.716 nm增加至1.124nm,插层率达到98.57%;熔融复合后,高岭土发生层剥离,（001）衍射峰消失,以薄片形态分散于煤沥青中。薄片形态的高岭土通过延缓空气传输速率的方式改善了煤沥青的热稳定性,当插层高岭土掺杂质量分数为6%时,插层高岭土改性煤沥青的最大失重速率所对应温度为650℃,对应的失重为78.04%,而最大失重速率处原煤沥青失重85.41%。原煤沥青失重50%时的温度为490℃,而改性煤沥青达到550℃。未掺杂高岭土时,煤沥青软化点为42.3℃,改性煤沥青软化点增加到45.4℃,继续增加高岭土质量分数,软化点上升幅度减小。

The kaolinite was first intercalated with dimethyl sulfoxide（DMSO） under ultrasonic field,and then used to modify coal tar pitch through melt composite. The interlayer spacing,interlayer interaction,dispersion morphology of intercalated kaolinite,and the thermal stability of modified coal tar pitch were characterized by X-ray diffraction（XRD）,FTIR,electron microscope and thermal analysis.The results showed that DMSO weakened the hydrogen bonds between aluminum hydroxyl and silicon oxygen bond. The interlayer space of kaolinite expanded from 0. 716 nm to 1. 124 nm and the intercalation rate reached 98. 57%. After melt composition,the（001） diffraction peak disappeared,which indicated the kaolinite was delaminated by coal tar pitch molecules. The delaminated kaolinite were dispersed in coal tar pitch in the form of thin layers and improve the thermal stability of coal tar pitch by delaying air transmission. The maximum weight loss rate temperature of intercalated kaolinite modified coal tar pitch was 650 ℃,the corresponding weight loss was 78. 04%,while that of raw coal tar pitch（RCTP） was as high as 85. 41%. For RCTP,the 50% weight loss temperature appeared at490 ℃,lower than that of modified pitch（550 ℃）. The softening point of modified coal tar pitch with6% mass fraction of intercalated kaolinite reached 45. 4 ℃,higher than that of RCTP（42. 3 ℃）.However,the further increase of intercalated kaolinite dosage did not greatly improve the softening point of modified coal tar pitch.