INVESTIGATION OF MICROSTRUCTURE AND CONDUCTIVE MECHANISM OF HIGH DENSITY POLYETHYLENE/CARBON BLACK PARTICLE COMPOSITE BY POSITRON ANNIHILATION LIFETIME SPECTROSCOPY  

作　　者：Yang-mei Fan Xian-feng Zhang Bang-jiao Ye Xian-yi Zhou Hui-min Weng Jiang-feng Du Rong-dian Han Shao-jin Jia Zhi-cheng Zhang Department of Modern Physics, University of Science and Technology of China, Hefei 230027, China Department of Polymer Science and Engineering University of Science and Technology of China, Hefei 230027 China 

出　　处：《Chinese Journal of Polymer Science》2002年第3期243-252,共10页高分子科学（英文版）

基　　金：This work was supported by the National Natural Science Foundation of China (Grant No: 19875050, 10075041, 10075044).

摘　　要：The microstructure and conductive mechanism of high density polyethylene/carbon black (HDPE/CB) composite were investigated by positron annihilation lifetime spectroscopy (PALS). The PALS were measured in two series of samples, one with various CB contents in the composites and the other with various gamma-irradiation doses in HDPE/CB composite containing 20 wt% CB. It was found that CB particles distribute in the amorphous regions, the CB critical content value in HDPE/CB composite is about 16.7 wt% and the suitable gamma-irradiation dose for improving the conductive behavior of HDPE/CB composite is about 20 Mrad. The result observed for the second set of samples suggests that gamma-irradiation causes not only cross-linking in amorphous regions but also destruction of the partial crystalline structure. Therefore, a suitable irradiation dose, about 20 Mrad, can induce sufficient cross-linking in the amorphous regions without enhancing the decomposition of crystalline structure, so that the positive temperature coefficient (PTC) effect remains while the negative temperature coefficient (NTC) effect is suppressed. A new interpretation of the conductive mechanism, which might provide a more detailed explanation of the PTC effect and the NTC effect has been proposed.The microstructure and conductive mechanism of high density polyethylene/carbon black (HDPE/CB) composite were investigated by positron annihilation lifetime spectroscopy (PALS). The PALS were measured in two series of samples, one with various CB contents in the composites and the other with various gamma-irradiation doses in HDPE/CB composite containing 20 wt% CB. It was found that CB particles distribute in the amorphous regions, the CB critical content value in HDPE/CB composite is about 16.7 wt% and the suitable gamma-irradiation dose for improving the conductive behavior of HDPE/CB composite is about 20 Mrad. The result observed for the second set of samples suggests that gamma-irradiation causes not only cross-linking in amorphous regions but also destruction of the partial crystalline structure. Therefore, a suitable irradiation dose, about 20 Mrad, can induce sufficient cross-linking in the amorphous regions without enhancing the decomposition of crystalline structure, so that the positive temperature coefficient (PTC) effect remains while the negative temperature coefficient (NTC) effect is suppressed. A new interpretation of the conductive mechanism, which might provide a more detailed explanation of the PTC effect and the NTC effect has been proposed.

关 键 词：conductive mechanism PALS free volume HDPE/CB 

分 类 号：TQ325.12[化学工程—合成树脂塑料工业]