【摘要】 以KNG–180石墨烯微片(GNSs)为导电填料,双酚A型环氧树脂(EP)E–54为基体,并分别用2-乙基-4-甲基咪唑(2,4-EMI)和甲基四氢邻苯二甲酸酐(Me THPA)为固化剂,采用超声分散法制备了EP/GNSs导电复合材料。研究了不同固化剂及GNSs含量对EP/GNSs复合材料电性能的影响。结果表明,两种固化剂固化的复合材料均具有明显的导电逾渗行为和正温度系数(PTC)效应;2,4-EMI固化的复合材料的逾渗阈值为5.1%,Me THPA固化的为4.5%;Me THPA固化的复合材料具有更强的PTC效应和更低的室温电阻率,但大量实验发现Me THPA固化的复合材料电性能实验结果重复性相对较差,且易存在负温度系数效应,故仍采用2,4-EMI作为EP/GNSs导电复合材料的固化剂。随GNSs含量增加,2,4–EMI固化的复合材料室温电阻率逐渐降低,PTC强度先升高后降低,当GNSs质量分数达到8%时,复合材料的PTC强度最高,达到2.3,且经过3次热循环之后,其阻–温曲线的热循环稳定性变好。更多还原

【Abstract】 Using KNG-180 graphen nanosheets(GNSs) as the conductive filler,bisphenol A type epoxy resin(EP) E-54 as the matrix material,2-ethyl-4-methyl imidazole(2,4-EMI) and methyl tetrahydro phthalic anhydride(Me THPA) as curing agent respectively,EP/GNSs conductive composites were prepared by ultrasonic dispersion. The influences of the two curing agents and GNSs contents on electrical properties of the composites were studied. The results show that the composites cured by the two curing agents all have obvious conductive percolation behaviors and positive temperature coefficient(PTC) effects. The percolation threshold of the composite cured by 2,4-EMI and Me THPA is 5.1% and 4.5% respectively. When using Me THPA as curing agent,the composites has a lower room temperature resistivity and stronger PTC effect,but it is found that the composite cured by Me THPA has poor repeatability of the electrical properties experiment results and is easy to exist negative temperature coefficient(NTC) effect through a large number of repeatability experiments,so 2,4-EMI is still used as curing agent of the composites. With the increase of GNSs content,the room temperature resistivity of the composite cured by 2,4-EMI decreases and the PTC intensity increases firstly and decreases lastly. When the mass fraction of GNSs is 8%,the PTC intensity of the composite cured by 2,4-EMI reaches 2.3,and after three thermal cycles,the thermal cycle stability of the resistance-temperature characteristics curves for the composite cured by 2,4-EMI becomes better.更多还原