聚乙烯/聚并苯复合物PTC/NTC效应及辐射交联对其影响的研究

【作者】 孙海珠；

【导师】 谢德民；

【作者基本信息】 东北师范大学 ， 物理化学， 2003， 硕士

【摘要】 本文以聚并苯替代碳黑作导电填料制备聚乙烯／聚并苯复合物，对其导电机理和渗流转变现象做深入研究。初步探讨聚乙烯／聚并苯复合物的PTC(Positive Temperature Coefficient)效应及产生机理。通过辐射交联的方法降低聚乙烯／聚并苯复合物室温电阻率，提高PTC强度，减弱NTC(Negative Temperature Coefficient)效应，增强其稳定性。最后将其与出碳黑制备的复合物性质进行比较。指出：活化的聚并苯浓度为20％-40％是聚乙烯／聚并苯复合物的渗流转变区；未活化的聚并苯浓度为30％-40％是聚乙烯／聚并苯复合物的渗流转变区。在渗流转变区，少量增加聚并苯浓度就会引起复合物电阻率的急剧下降。热处理可以降低聚乙烯／聚并苯复合物室温电阻率。聚并苯添加到聚乙烯中可以得到PTC效应，不同聚并苯浓度的复合物得到的PTC强度并不相同。在高于或低于渗阈浓度复合物都会发生PTC转变，但只有在渗阈浓度附近，复合物才可以得到最佳的PTC效应。辐射交联可以降低聚乙烯／聚并苯复合物室温电阻率，提高聚乙烯／聚并苯复合物PTC效应，减小NTC效应，增强复合物的稳定性。与聚乙烯／碳黑复合物相比较，聚乙烯／聚并苯复合物具有较高的渗流转变值和室温电阻率，较强的PTC效应。这是出于聚并苯相对于碳黑具有较低的结构：即粒径较大、比表面积较小、室温电阻率较高的结果。更多还原

【Abstract】 Polyacenic semiconductor (PAS) is used as fillers instead of carbon black(CB) in order to prepare polyethylene(PE)/PAS Composites. The mechanisms of conductivity and phenomena of percolation threshold are studied. Effect of PTC (Positive Temperature Coefficient) of PE/PAS has been introduced and the mechanism of PTC is also pilot studied. Radiation crosslinking can increase the intensity of PE/PAS composites, decrease the effect of NTC (Negative Temperature Coefficient) and hence the stability of composites. At the end of this paper, the properties of PE/PAS composites are compared with PE/CB composites. Conclusions have been drawn that:The percolation threshold of PE/PAS(activated) composites is 20%-40% and inactivated PAS is 30%-40%. In the percolation threshold, little increase of PAS can make the acute decreasing of resistivity of composites. Thermal-treatment can make the crystal of PE and conductive chain completed and decrease the resistivity of composites. PAS added to PE can make the composites has the property of effect of PTC, but the intensity of PTC of composites varies with the concentration of PAS. When the concentration of PAS is in the percolation threshold, the composites can gain the maximum effect of PTC. Radiation crosslinking can increase the intensity of PE/PAS composites, decrease the effect of NTC and hence the stability of composites. Compared with PE/CB composites, PE/PAS composites have the higher concentration of percolation threshold, resistivity and more intensive effect of PTC. This is resulted from the low structure of PAS such as bigger grain diameter, smaller surface area, and higher resistivity etc.更多还原