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
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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。
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.
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。
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.
引文
[1] 周宅忠，聚合物复合型PTC材料及应用，功能材料，1991，22(5)：298-302
[2] 汤浩，陈欣方，复合型导电高分子材料PTC效应的研究与应用，高分子材料科学与工程，1996，Vol．12，No．3：6-11
[3] 黄锐，刘劲松，导电塑料的进展，中国塑料，1992，Vol．6，No．，4：3-10
[4] 杨万辉，丁小斌，白限温电热带热稳定性的研究，中国科学技术大学学报，Vol．24，No．3：356-360
[5] 储九荣等，PTC陶瓷粉末掺杂高分子PTC材料的阻-温特性模拟分析，
绝缘材料通讯，2000年，第5期，43-45．
[6] 曾德平，刘光聪，何峰等．Tc≥400℃高温PTC陶瓷的研制．压电与声光，1996，18(6)：412-414
[7] Lux F., Percolation in electrical conductive polymer/filler systems. I: Density/filler curves according to a new thermodynamic percolation model, Polym.Eng.Sci., 1993,33:334-332.
[8] Lux F., Models proposed to explain the electrical conductivity of mixtures made of conductive and insulating materials, J. Mater. Sci., 1993, 28:285-301
[9] Kirkpatrick S., Percolation and conduction, Rev. Mod. Phys., 1973, 45:574-588
[10] Heaney M.B., Measurement and interpretation of nonuniversal critical exponents in disordered conductor-insulator composites, Phys. Rev. B, 1995, 52:12477-12480.
[11] Janzen J., On the critical conductive filler loading in antistatic composites, J. Appl. Phys., 1975, 46:966-969.
[12] Bueche F., Electrical resistivity of conducting particles in an insulating matrix, J. Appl. Phys., 1972, 43:4837-4838.
[13] Miyasaka K., Watanabe K., Jojima E., et al, Electrical conductivity of carbon-polymer composites as a function of carbon content, J. Mater. Sci.,1982, 17: 1610-1616.
[14] Sumita M., Sakata K., Asai S., et al, Dispersion of fillers and the electrical conductivity of polymer blends filled with carbon black, Polym.Bull., 1991, 25: 265-271.
[15] Rajagopal C., and Satyam M., Studies on electrical conductivity of insulator-conductor composites, J. Appl. Phys., 1978, 49: 5536-5542.
[16] Malliaris A., and Turner D. T., Influence of particle size on the electrical resistivity of compacted mixtures of polymeric and metallic powders, J. Appl. Phys., 1971, 42: 614-618.
[17] Bhattacharya S. K., and Chaklader A. C. D., Review on metal-filled plastics. Part 1. Electrical conductivity, Polym. Plast. Technol. Eng., 1982,
19: 21-51.
[18] Fowkes F. M., Attractive forces at interfaces, Ind. Eng. Chem., 1964, 56(12): 40-52.
[19] McLachlan D. S., An equation for the conductivity of binary mixtures with anisotropic grain structures, J. Phys. C: Solid State Phys., 1987, 20: 865-877.
[20] Blaszkicwicz M., McLachlan D. S., Newnham R. E., The volume fraction and temperature dependence of resistivity in carbon black and graphite polymer composites: An effective media-percolation approach, Polym. Eng. Sci., 1992, 32: 424-425.
[21] Yi Xiao-Su, Wu G., and Pan Y., Properties and applications of filled conductive polymer composites, Polym. Inter., 1997, 44:117-124.
[22] Polly M. H., and Boonstra B. B., Carbon blacks for highly conductive rubber, Rubber Chem. Technol., 1957, 30:170-179.
[23] Aneli D. N., and Topchishvili G. M., The conductivity mechanism of electrically conductive polymer composites, Inter. Polym. Sci. Technol., 1986, 13(9): T/91-92.
[24] Verhelst W. F., Wolthuis K. G., Voet A., et al, The role of morphology and structure of carbon blacks in the electrical conductance of vulcanizates, Rubber Chem. Technol, 1977, 50: 735-746.
[25] Sichel E. K., Gittleman J. I., Sheng P., In Carbon Black-Polymer Composites: The Physics of Electrically Conducting Composites; Sichel E. K., Ed., New York: Marcel Dekker, 1982, 51-63.
[26] Zhang M. Q., Yu G., Zeng H. M., et al, Two-step percolation in polymer blends filled with carbon black, Macromolecules, 1998, 31: 6724-6726.
[27] Sheng P., Sichel E. K., and Gittleman J. I., Fluctuation-induced tunneling conduction in carbon-polyvinylchloride composites, Phys. Rev. Lett., 1978, 40: 1197-1200.
[28] Sichel E. K., Gittleman J. I., Sheng P., Transport properties of the composites material carbon-poly(vinyl chloride), Phys. Rev. B, 1978, 18: 5712-5716.
[29] Sherman R. D., Middleman L. M., and Jacobs S. M., Electrical transport processes in conductor-filled polymers, Polym. Eng. Sci., 1983, 23: 36-46.
[30] Klason C., Kubat J., Anomalous behavior of electrical conductivity and thermal noise in carbon black-containing polymers at T_g and T_m, J. Appl. Polym. Sci., 1975, 19: 831-845.
[31] Srumpler R., Polymer composite thermistors for temperature and current sensors, J. Appl. Phys., 1996, 80: 6091-6096.
[32] Heaney M. B., Resistance-expansion-temperature behavior of a disordered conductor-insulator composite, Appl. Phys. Lett., 1996, 69: 2602-2604.
[33] Jia W., Chen X., Effect of Polymer-filler interactions on PTC behaviors of LDPE/EPDM blends filled with carbon blacks, J. Appl. Polym. Sci., 1997, 66: 1885-1890.
[34] Foulger P. H., Electical properties of composites in the vicinity of the percolation threshold, J. Appl. Polym. Sci., 1999, 72: 1573-1582.
[35] Hindermann-Bischoff M., and Ehrburger-Dolle F., Electrical conductivity of carbon black-PE composites experimental evidence of the change of cluster connectivity in the PTC effect, Carbon, 2001, 39: 375-382.
[36] Yi X., Zhang X., Zheng Q., et al, Influence of irradiation conditions on the electrical behavior of PE-CB conductive composites, J. Appl. Polym. Sci., 2000, 77: 494-99.
[37] Mironi-harpaz I., and Narkis M., Thermoelectric behavior (PTC) of carbon black-containing TPX/UHMWPE and TPX/XL-UHMWPE blends, J. Polym. Sci.: Polym. Phys., 2001, 39: 1415-1428.
[38] Ohe K., and Naito Y. J., A new resistor having an anomalously large positive temperature coefficient, Jap. J. Appl. Phys., 1971, 10: 99-108.
[39] Matsushige K., Kobayashi K., Iwami N., et al, Nanoscopic analysis of the conduction mechanism in organic positive temperature coefficient composites materials, Thin Solid Films, 1996, 273:128-131.
[40] Meyer J., Glass transition temperature as a guide to selection of polymers
suitable for PTC materials, Polym. Eng. Sci., 1973, 13: 462-468.
[41] Miyoshi Y. and Chino K., Electrical properties of polyethylene single crystals, Jap. J. Appl. Phys., 1967, 6(2): 181-190.
[42] Van Roggen A., Electronic conduction of polymer single crystals, Phys. Rev. Lett., 1962, 9: 368-370.
[43] 席保锋等，聚合物／碳黑复合材料PTC特性的理论研究进展，高分子材料科学与工程，Vol．15，No．6
[44] 杜仕国．聚合物抗静电材料的研究与发展[J]．工程塑料应用，1998，(10)：31
[45] 李丽，谭洪生，迟丽萍，自限温发热材料、元件分类及应用[J]．工程塑料应用，1999，(10)：34．
[2] 汤浩，陈欣方，复合型导电高分子材料PTC效应的研究与应用，高分子材料科学与工程，1996，Vol．12，No．3：6-11
[3] 黄锐，刘劲松，导电塑料的进展，中国塑料，1992，Vol．6，No．，4：3-10
[4] 杨万辉，丁小斌，白限温电热带热稳定性的研究，中国科学技术大学学报，Vol．24，No．3：356-360
[5] 储九荣等，PTC陶瓷粉末掺杂高分子PTC材料的阻-温特性模拟分析，
绝缘材料通讯，2000年，第5期，43-45．
[6] 曾德平，刘光聪，何峰等．Tc≥400℃高温PTC陶瓷的研制．压电与声光，1996，18(6)：412-414
[7] Lux F., Percolation in electrical conductive polymer/filler systems. I: Density/filler curves according to a new thermodynamic percolation model, Polym.Eng.Sci., 1993,33:334-332.
[8] Lux F., Models proposed to explain the electrical conductivity of mixtures made of conductive and insulating materials, J. Mater. Sci., 1993, 28:285-301
[9] Kirkpatrick S., Percolation and conduction, Rev. Mod. Phys., 1973, 45:574-588
[10] Heaney M.B., Measurement and interpretation of nonuniversal critical exponents in disordered conductor-insulator composites, Phys. Rev. B, 1995, 52:12477-12480.
[11] Janzen J., On the critical conductive filler loading in antistatic composites, J. Appl. Phys., 1975, 46:966-969.
[12] Bueche F., Electrical resistivity of conducting particles in an insulating matrix, J. Appl. Phys., 1972, 43:4837-4838.
[13] Miyasaka K., Watanabe K., Jojima E., et al, Electrical conductivity of carbon-polymer composites as a function of carbon content, J. Mater. Sci.,1982, 17: 1610-1616.
[14] Sumita M., Sakata K., Asai S., et al, Dispersion of fillers and the electrical conductivity of polymer blends filled with carbon black, Polym.Bull., 1991, 25: 265-271.
[15] Rajagopal C., and Satyam M., Studies on electrical conductivity of insulator-conductor composites, J. Appl. Phys., 1978, 49: 5536-5542.
[16] Malliaris A., and Turner D. T., Influence of particle size on the electrical resistivity of compacted mixtures of polymeric and metallic powders, J. Appl. Phys., 1971, 42: 614-618.
[17] Bhattacharya S. K., and Chaklader A. C. D., Review on metal-filled plastics. Part 1. Electrical conductivity, Polym. Plast. Technol. Eng., 1982,
19: 21-51.
[18] Fowkes F. M., Attractive forces at interfaces, Ind. Eng. Chem., 1964, 56(12): 40-52.
[19] McLachlan D. S., An equation for the conductivity of binary mixtures with anisotropic grain structures, J. Phys. C: Solid State Phys., 1987, 20: 865-877.
[20] Blaszkicwicz M., McLachlan D. S., Newnham R. E., The volume fraction and temperature dependence of resistivity in carbon black and graphite polymer composites: An effective media-percolation approach, Polym. Eng. Sci., 1992, 32: 424-425.
[21] Yi Xiao-Su, Wu G., and Pan Y., Properties and applications of filled conductive polymer composites, Polym. Inter., 1997, 44:117-124.
[22] Polly M. H., and Boonstra B. B., Carbon blacks for highly conductive rubber, Rubber Chem. Technol., 1957, 30:170-179.
[23] Aneli D. N., and Topchishvili G. M., The conductivity mechanism of electrically conductive polymer composites, Inter. Polym. Sci. Technol., 1986, 13(9): T/91-92.
[24] Verhelst W. F., Wolthuis K. G., Voet A., et al, The role of morphology and structure of carbon blacks in the electrical conductance of vulcanizates, Rubber Chem. Technol, 1977, 50: 735-746.
[25] Sichel E. K., Gittleman J. I., Sheng P., In Carbon Black-Polymer Composites: The Physics of Electrically Conducting Composites; Sichel E. K., Ed., New York: Marcel Dekker, 1982, 51-63.
[26] Zhang M. Q., Yu G., Zeng H. M., et al, Two-step percolation in polymer blends filled with carbon black, Macromolecules, 1998, 31: 6724-6726.
[27] Sheng P., Sichel E. K., and Gittleman J. I., Fluctuation-induced tunneling conduction in carbon-polyvinylchloride composites, Phys. Rev. Lett., 1978, 40: 1197-1200.
[28] Sichel E. K., Gittleman J. I., Sheng P., Transport properties of the composites material carbon-poly(vinyl chloride), Phys. Rev. B, 1978, 18: 5712-5716.
[29] Sherman R. D., Middleman L. M., and Jacobs S. M., Electrical transport processes in conductor-filled polymers, Polym. Eng. Sci., 1983, 23: 36-46.
[30] Klason C., Kubat J., Anomalous behavior of electrical conductivity and thermal noise in carbon black-containing polymers at T_g and T_m, J. Appl. Polym. Sci., 1975, 19: 831-845.
[31] Srumpler R., Polymer composite thermistors for temperature and current sensors, J. Appl. Phys., 1996, 80: 6091-6096.
[32] Heaney M. B., Resistance-expansion-temperature behavior of a disordered conductor-insulator composite, Appl. Phys. Lett., 1996, 69: 2602-2604.
[33] Jia W., Chen X., Effect of Polymer-filler interactions on PTC behaviors of LDPE/EPDM blends filled with carbon blacks, J. Appl. Polym. Sci., 1997, 66: 1885-1890.
[34] Foulger P. H., Electical properties of composites in the vicinity of the percolation threshold, J. Appl. Polym. Sci., 1999, 72: 1573-1582.
[35] Hindermann-Bischoff M., and Ehrburger-Dolle F., Electrical conductivity of carbon black-PE composites experimental evidence of the change of cluster connectivity in the PTC effect, Carbon, 2001, 39: 375-382.
[36] Yi X., Zhang X., Zheng Q., et al, Influence of irradiation conditions on the electrical behavior of PE-CB conductive composites, J. Appl. Polym. Sci., 2000, 77: 494-99.
[37] Mironi-harpaz I., and Narkis M., Thermoelectric behavior (PTC) of carbon black-containing TPX/UHMWPE and TPX/XL-UHMWPE blends, J. Polym. Sci.: Polym. Phys., 2001, 39: 1415-1428.
[38] Ohe K., and Naito Y. J., A new resistor having an anomalously large positive temperature coefficient, Jap. J. Appl. Phys., 1971, 10: 99-108.
[39] Matsushige K., Kobayashi K., Iwami N., et al, Nanoscopic analysis of the conduction mechanism in organic positive temperature coefficient composites materials, Thin Solid Films, 1996, 273:128-131.
[40] Meyer J., Glass transition temperature as a guide to selection of polymers
suitable for PTC materials, Polym. Eng. Sci., 1973, 13: 462-468.
[41] Miyoshi Y. and Chino K., Electrical properties of polyethylene single crystals, Jap. J. Appl. Phys., 1967, 6(2): 181-190.
[42] Van Roggen A., Electronic conduction of polymer single crystals, Phys. Rev. Lett., 1962, 9: 368-370.
[43] 席保锋等，聚合物／碳黑复合材料PTC特性的理论研究进展，高分子材料科学与工程，Vol．15，No．6
[44] 杜仕国．聚合物抗静电材料的研究与发展[J]．工程塑料应用，1998，(10)：31
[45] 李丽，谭洪生，迟丽萍，自限温发热材料、元件分类及应用[J]．工程塑料应用，1999，(10)：34．