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The time dependences of electrical conduction and self‐heating in high‐density polyethylene/acetylene carbon black composites crosslinked with electron beam irradiation at three different dosages are studied in relation to voltage and ambient temperature. The characteristic decay current constant (τi) and the exponential growth time constant for self‐heating (τg) are determined for the samples under voltages (U) above the onset voltage (Uc) of self‐heating. The influence of crosslinking on the current decay dynamics, self‐heating process, and amplitude of the resistance switching under field action are discussed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4418–4422, 2006 相似文献
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The time dependences of electrical conduction and self‐heating behaviors in high‐density polyethylene filled with acetylene carbon black of 0.082 in volume fraction are studied in relation to voltage and ambient temperature. The characteristic decay current constant τi, and the exponential growth time constant for self‐heating τg are determined for the samples under voltages U above the critical value Uc for the onset of self‐heating. The influences of voltage and ambient temperature on τi and τg as well as the amplitude of the low‐resistance to high‐resistance switching are discussed on the basis of the random resistor network (RRN) model and the relationship between Uc and the intrinsic resistivity. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1124–1131, 2006 相似文献
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高温热处理对HDPE/CB导电复合材料性能的影响 总被引：3，自引：0，他引：3
在高密度聚乙烯(HDPE)中加入适量的炭黑(CB)制备了HDPE/CB导电复合材料。通过对HDPE/CB导电复合材料热处理前后性能的研究,发现高温热处理可以消除成型加工对导电复合材料导电性的不利影响,显著改善未交联HDPE导电复合材料的导电性;并发现在热处理的温度上可以突破传统的将热处理温度限制在HDPE熔点之下的做法。而使材料的热处理温度超过熔点。 相似文献
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以炭黑(CB)为导电填料,高密度聚乙烯(PE–HD)为基体,有机蒙脱土(OMMT)为有机粒子,通过熔融共混法分别制备了PE–HD/CB与PE–HD/CB/OMMT导电复合材料,并研究了OMMT的加入对导电复合材料中CB分布的均一性及材料电性能的影响。研究发现,适当OMMT的加入可以改善CB在导电复合材料中的分布状态,在保持电性能的基础上降低导电复合材料的渗流阈值;当OMMT质量分数为3%时,PE–HD/CB/OMMT导电复合材料的渗流阈值为3.7%,与未添加OMMT的PE–HD/CB导电复合材料渗流阈值4.0%相比有所降低。在此基础上,选取PE–HD/CB导电复合材料(CB质量分数为5%)并测定其PTC强度为0.26;后加入质量分数为3%的OMMT,测得PE–HD/CB/OMMT导电复合材料(CB质量分数为5%)的PTC强度为0.79,后者有所提高。 相似文献
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炭黑/高密度聚乙烯导电纤维纺丝工艺探索 总被引：1，自引：0，他引：1
以高密度聚乙烯为基体,炭黑为导电介质共混得到导电母粒,通过熔融纺丝法制得炭黑/高密度聚乙烯共混导电纤维。考察了炭黑含量和粒径对可纺性的影响,发现炭黑含量为5%,粒径为40～50nm时,熔体可顺利纺丝,且所得纤维具有较好的导电性。通过多次试纺,确定了合适的纺丝工艺。 相似文献
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2种导电炭黑复合橡胶体系的导热性能研究 总被引：2，自引：0，他引：2
研究了2种导电炭黑复合天然橡胶材料的导热性能随着温度和填料用量的变化规律。结果表明,温度对于导电炭黑复合体系导热性能的影响不大。乙炔黑复合体系具有极高的导热性能,随着炭黑用量的增加,其导热性能优势越加明显。据透射电镜观察填料的微观形态,乙炔黑链枝状结构丰富,聚集体之间以面接触为主,这是其复合橡胶导热性能优异的原因,乙炔黑复合材料的热导率与炭黑体积分数呈线性关系。40B2复合体系的热导率与炭黑体积分数呈现逾渗规律,逾渗阈值在炭黑体积分数8.30%至13.63%之间。据扫描电镜观察复合材料的微观结构,逾渗现象与炭黑在基体内的分布密切相关。为更精确地描述填料用量与复合体系热导率的关系,对2种复合体系的热导率与炭黑的体积分数进行了回归。 相似文献
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The sensitive effect of weight ratio of the high‐density polyethylene (HDPE)/ethylene‐vinylacetate copolymer (EVA) on the electrical properties of HDPE/EVA/carbon black (CB) composites was investigated. With the EVA content increasing from 0 wt % to 100 wt %, an obvious change of positive temperature coefficient (PTC) curve was observed, and a U‐shaped insulator‐conductor‐insulator transition in HDPE/EVA/CB composites with a CB concentration nearby the percolation threshold was found. The selective location of CB particles in HDPE/EVA blend was analyzed by means of theoretical method and scanning electron micrograph (SEM) in order to explain the U‐shaped insulator‐conductor‐insulator transition, a phenomenon different from double percolation in this composite. The first significant change of the resistivity, an insulator‐conductor transition, occurred when the conductive networks diffused into the whole matrix due to the forming of the conductive networks and the continuous EVA phase. The second time significant change of the resistivity, a conductor‐insulator transition, appeared when the amorphous phase is too large for CB particles to form the conductive networks throughout the whole matrix. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献
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首次引入时温等效原理和松弛理论，在恒温条件下研究了材料电阻率与时间的关系，在此实验结果的基础上，对PTC／NTC的形成过程及机理提出了新的观点，使之更能全面地解释实验中的各种现象。 相似文献
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Polymeric materials are widely used as insulation and jacketing materials in wire and cable. When such materials are used for long‐term applications, they undergo thermal oxidation aging in the environment. It is necessary to develop an in situ and nondestructive condition monitoring (CM) method to follow the aging of cable materials. The main objective of this work was to investigate low‐density polyethylene/carbon black (LDPE/CB) conductive polymer composites as potential sensor materials for this purpose. LDPE/CB composites with a carbon black loading below the percolation threshold underwent accelerated thermal oxidation aging experiments. The results indicated that the substantial resistivity decreases of the LDPE/CB composites could be directly related to the increases in volume fraction of the conductive carbon black, which was mainly caused by the mass loss of polymer matrix and sample shrinkage during the thermal oxidation aging process. Compared to existing CM method based on density change, the electrical resistivity is more explicit regarding its absolute changes throughout the thermal oxidation aging. The change in resistivity spanned over four orders of magnitude, whereas the composite density only increased 10%. The results offer strong evidence that resistivity measurements, which reflect property changes under thermal aging conditions, could represent a very useful and nondestructive CM approach as well as a more sensitive method than density CM approach. Crystallinity changes in materials investigated by modulated DSC and TGA measurements indicated deterioration of crystalline regions in polymer during the thermal oxidation aging. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 513–520, 2004 相似文献
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李博;季铁正;李佳;莫祥友 《中国塑料》2011,25(2):60-64
采用溶液法制备了高密度聚乙烯/多壁碳纳米管（PE-HD/MWCNTs）和PE-HD/炭黑(CB)导电复合材料,并研究了该复合材料的阻温特性。结果表明,与PE-HD/CB复合材料相比,PE-HD/MWCNTs复合材料的室温电阻率更低,并且可以具有较高的正温度系数（PTC）强度和较小的负温度系数（NTC）效应,因而具有更加广泛的应用前景。同时通过对PE-HD/MWCNTs复合材料阻温全过程进行分析,发现PTC效应由碳纳米管向晶区扩散及基体体积膨胀效应共同导致,而NTC效应则是由于碳纳米管的热运动形成的相互接触所致,而并非粒子附聚。 相似文献
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聚合物PTC材料的老化失效规律研究 总被引：1，自引：0，他引：1
聚合物PTC材料在很多领域都有广泛应用，但材料稳定性一直制约着各种产品的进一步发展，以聚乙烯－醋酸乙烯酯共聚物／炭墨体系为研究对象，采用熔融共混挤出成型的方法进行制样，研究了聚合物PTC材料老化失效规律及老化失效过程预测，提出了相应的经验公式。 相似文献
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A study on the contribution of thermal volume expansion to electrical properties is carried out for high‐density polyethylene (HDPE)/carbon black (CB) composites irradiated by an electron beam. The results show that the volume expansion obviously generates the positive temperature coefficient (PTC) characteristic of resistivity for unirradiated HDPE/CB composites, but the contribution of volume expansion is decreased for crosslinked HDPE in the composites by electron beam irradiation. A higher degree of crosslinking produced by irradiation in the molten state limits the movability of HDPE chains and CB particles so effectively that it decreases the PTC intensity, which is compared with that irradiated at room temperature. It is suggested that the differences in the resistivity–temperature behavior are not explained satisfactorily on only the basis of the thermal volume expansion, and the decreased movability of HDPE chains and CB particles are believed to be the most fatal factors in lowering the PTC effect. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 3117–3122, 2002; DOI 10.1002/app.10050 相似文献
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炭黑填充复合导电高分子材料研究和应用 总被引：4，自引：0，他引：4
概述了目前国内外炭黑填充复合导电高分子材料的研究现状、进展及应用，主要对炭黑性质，用量，基体树脂性能以及导电复合材料的特性进行了讨论。 相似文献
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LDPE/石墨导电复合材料的研究 总被引：3，自引：0，他引：3
为了制备具有低渗滤阈值的导电复合材料,通过溶液插层法,选用三种不同的导电填料（石墨,膨胀石墨,膨化石墨）,引入马来酸酐接枝聚乙烯。制备低密度聚乙烯/石墨导电复合材料,导电填料的结构对复合材料的电性能和力学性能有很大的影响,其中膨化石墨可使复合体系具有较低的导电渗滤阈值,但复合材料的力学性能较差。 相似文献
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炭黑预处理对炭黑／HDPE导电复合材料性能的影响 总被引：5，自引：0，他引：5
通过用四种有代表性的处理剂对炭黑进行预处理，研究了处理后炭黑填充的HDPE复合材料的电性能、力学性能和流变性能。发现四种处理剂对复合材料的性能均有一定的改善。但也表现出各自的差异，在导电性能上表现的差异更为明显，如经钛酸酯偶联剂和硬脂酸处理的炭黑，在炭黑含量为15%时，可使复合材料的电阻率降低1-2个数量级。为此笔者分析了上述结果的原因。 相似文献
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The resistivity and volume expansion of carbon black (CB)/high‐density polyethylene (HDPE) composite with different CB volume fractions at different temperatures were measured simultaneously. A model based on Meyer's theory is proposed to explain the positive temperature coefficient resistance (PTCR) effect. The relationship between resistivity and volume expansion was determined. It was found that the phase change is the main cause of the PTC effect in the crystalline polymer PTC materials. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 53–58, 2000 相似文献
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炭黑复合导电高分子材料成型加工研究进展 总被引：12，自引：1，他引：12
概述了导电高分子材料的分类和性能特点,以及炭黑复合导电高分子材料的导电特性与机理。介绍了炭黑预处理。炭黑与基体混合,高分子材料加工方法及工艺条件等对炭黑复合导电高分子材料性能影响的国内外研究进展,总结了材料加工现有的技术难点。 相似文献