High density polyethylene filled with condutuctive carbon black was prepared by conventional meltmixing method. The effect of unidirectional pressure on the conductivity was studied. Wide angle X-ray diffraction （ WA...High density polyethylene filled with condutuctive carbon black was prepared by conventional meltmixing method. The effect of unidirectional pressure on the conductivity was studied. Wide angle X-ray diffraction （ WAXD ） was used to slum： the influence of pressure on the aggregate structure of the polymer filled with carbon black （CB） fillers. A model on the basis of the formation and destruction of conductive networks was proposed to explain the change in the conductivity with the application of pressure.展开更多
The carbon nanotubes (CNTs) periodically decorated by high-density polyethylene (HDPE) composites with nanohybrid shish kebabs (NHSK) structures were prepared by CNTs-initiated solution crystalli-zation. The disc-shap...The carbon nanotubes (CNTs) periodically decorated by high-density polyethylene (HDPE) composites with nanohybrid shish kebabs (NHSK) structures were prepared by CNTs-initiated solution crystalli-zation. The disc-shaped HDPE crystalline lamellae were periodically located on the surface of CNTs in the direction perpendicular to the nanotube axis. Observations from scanning electron microscopy and transmission electron microscopy showed that with the increasing of crystallization temperature, the lateral dimension of the lamellae was decreased and the distance between two neighboring lamellae was increased. However, the thickness of the lamellae did not vary with the crystallization temperature. The formation mechanism of the NHSK structures was also explained. The one-dimensional structure and the ultra-high curved surface of CNTs lead to strong geometry confinement, which plays a main role in the formation of the NHSKs.展开更多
通过对多壁碳纳米管(MWNTS)／高密度聚乙烯(High density polyethylene,HDPE)复合材料的电阻- 温度特性进行了研究。发现MWNTs填充质量分数为1％-2％时,复合体系呈现渗流行为,表现出优异的导电性。同时体系存在特殊的V形温度系数特性(V-...通过对多壁碳纳米管(MWNTS)／高密度聚乙烯(High density polyethylene,HDPE)复合材料的电阻- 温度特性进行了研究。发现MWNTs填充质量分数为1％-2％时,复合体系呈现渗流行为,表现出优异的导电性。同时体系存在特殊的V形温度系数特性(V-PTC特性),即当MWNTs质量分数超过渗流阈值后,体系的电阻率随温度的升高先下降,出现负温度系数特性(NTC转变),然后才出现通常的正温度系数特性(PTC 转变),且具有很好的循环稳定性。V-PTC这种特性源于基体体积膨胀、MWNTs缠结链松弛以及基体的“退火”效应的协同作用。马来酸酐接枝苯乙烯-(乙烯-丁烯)-苯乙烯共聚物(MA-g-SEBS)的加入,可改善MWNTs 和HDPE之间的相互作用,并可基本上消除V-PTC特性,改善导电性。展开更多
文摘High density polyethylene filled with condutuctive carbon black was prepared by conventional meltmixing method. The effect of unidirectional pressure on the conductivity was studied. Wide angle X-ray diffraction （ WAXD ） was used to slum： the influence of pressure on the aggregate structure of the polymer filled with carbon black （CB） fillers. A model on the basis of the formation and destruction of conductive networks was proposed to explain the change in the conductivity with the application of pressure.
基金Supported by the National Natural Science Foundation of China (Grant No. 50772031)the Chinese Program for New Century Excellent Talents in University (Grant No. NCET-05-0678)+1 种基金the Scientific Research Foundation for the Returned Overseas Chinese Scholars of Ministry of Education, Hubei Provincial Department of Education (Grant No. Q200610005)Hubei Provincial Science & Technology Department (Grant No. 2006ABA020)
文摘The carbon nanotubes (CNTs) periodically decorated by high-density polyethylene (HDPE) composites with nanohybrid shish kebabs (NHSK) structures were prepared by CNTs-initiated solution crystalli-zation. The disc-shaped HDPE crystalline lamellae were periodically located on the surface of CNTs in the direction perpendicular to the nanotube axis. Observations from scanning electron microscopy and transmission electron microscopy showed that with the increasing of crystallization temperature, the lateral dimension of the lamellae was decreased and the distance between two neighboring lamellae was increased. However, the thickness of the lamellae did not vary with the crystallization temperature. The formation mechanism of the NHSK structures was also explained. The one-dimensional structure and the ultra-high curved surface of CNTs lead to strong geometry confinement, which plays a main role in the formation of the NHSKs.
