国外塑料专利

<正>专利名称:高性能聚合物基PTC材料专利号:US 8164414公开日:2012.04.24该发明提及了一种具有高性能的聚合物基PTC材料。这种材料包含以下成分:(A)一种导电填料;(B)一种聚合物材料;及(C)一种分布在聚合物PTC材料元件表面的金属材料。其中,导电填料是一种Ni合金填料,在高温及干燥的环境下,具有抗氧化功能。这种聚合物基PTC材料是一种热塑性结晶性聚合物。     

炭黑/聚烯烃导电复合材料PTC效应的研究

对炭黑/聚烯烃导电复合材料PTC效应做了较全面的论述,介绍了此类材料的导电机理和一些新的理论观点,总结了影响其PTC效应的主要因素及目前国内外研究这种新型功能材料的典型方法。文中详细讨论了工艺条件、基体与导电填料的性质、频率等方面对材料性能、PTC效应的影响,对研究、开发和应用高性能的PTC复合材料有重要的参考价值。     

环氧树脂基导电复合材料的PTC特性研究进展

介绍了聚合物基正温度系数（PTC）材料的导电机理;综述了国内外对环氧树脂基PTC复合材料的研究现状;分析了影响环氧树脂基导电复合材料PTC特性的因素,包括导电填料、环氧基体、第三基体组分、固化剂和固化温度、加工工艺等;并对该材料的应用和发展方向进行了讨论。     

尼龙12/炭黑高转变温度PTC材料的研究

研究了以尼龙12(PA12)为基体树脂,炭黑(CB)为导电填料的高转变温度正温度系数(PTC)材料.采用熔融共混方法制备了尼龙12/炭黑聚合物PTC复合材料,考查了炭黑含量,热循环等因素对材料PTC性能的影响.并采用示差扫描量热分析(DSC)、热机械曲线分析(TMA)研究了材料PTC效应与材料结构的关系.实验结果表明尼龙12/炭黑复合材料具有高转变温度的PTC特性,将复合材料进行多次热循环实验,此复合材料仍具有较强的PTC效应.     

导电填料/高密度聚乙烯(HDPE)导电复合材料的研究进展

综述了以炭黑、石墨、多壁碳纳米管为填料,以高密度聚乙烯为基体制备的复合材料电性能的研究进展。分析了不同填料对导电高分子材料的PTC、NTC效应等电性能的影响。     

PE-UHMW/GNPs导电复合材料的制备和表征

采用超声溶液分散法制备出超高分子量聚乙烯/石墨烯(PE-UHMW/GNPs)导电复合材料,研究了该材料的导电渗流行为和阻-温特性。研究发现,PE-UHMW/GNPs导电复合材料的导电渗流阈值为3.8%,即当导电填料在体系中的质量分数达到3.8%时,材料内部逐渐形成较为完善的导电网络,从而实现其导电特性。研究和探讨了PE-UHMW/GNPs导电复合材料的正温度系数(PTC)效应和负温度系数(NTC)效应。研究发现,PE-UHMW/GNPs导电复合材料的PTC效应会随着GNPs含量的增加逐渐增强,当导电填料GNPs的添加量达到3.8%时,通过阻-温曲线可以观察到,PE-UHMW/GNPs导电复合材料具有最大的PTC强度和相对较低的室温体积电阻率。场发射扫描电子显微镜分析结果表明,GNPs和PE-UHMW之间的相互作用会随着热循环次数的不同而发生变化,最终会影响到材料的PTC效应。     

HDPE/ PC/CB复合体系双逾渗行为的研究

以炭黑(CB)为导电填料,填充到2种不相容的高聚物高密度聚乙烯(HDPE)和聚碳酸酯(PC)基体中制备高分子基正温度效应(PTC)材料.研究表明,CB在HIRE中的逾渗阈值约为20%;HDPE/PC/CB三元复合体系形成了双逾渗行为,当HDPE/PC质量比为40/60时,三元复合体系具有较好的PTC及PTC重复性.     

PTC热敏电阻的开发应用现状

介绍了正温度系数(PTC)效应,PTC材料的分类、发展历史及现状,分析其电阻温度、电压电流和电流时间三大特性,通过对PTC材料三大特性的研究概述了陶瓷基PTC热敏电阻作为恒温加热元件和自动开关元件,高分子基PTC热敏电阻作为自控温加热元件和过电流保护元件等领域的应用状况及产业化发展情况,展望了今后PTC材料及生产工艺的技术发展动向。     

高分子基PTC材料PTC强度的影响因素

本文探讨了影响高分子基PTC材料PTC强度的几种因素,得出高分子基PTC材料要想获得高PTC强度,需综合考虑基体树脂、导电粒子、加工工艺的影响的结论。     

GF/PVDF导电复合材料的PTC行为

以石墨纤维(GF)、乙炔炭黑(CB)为导电填料,聚偏氟乙烯(PVDF)为基体,通过熔融共混方法分别制备GF/PVDF、CB/PVDF导电复合材料。讨论了导电填料形状、含量对复合材料正温度系数效应(PTC)的影响。并通过实验现象分析认为具有长径比结构的GF是导电复合材料负温度系数效应(NTC)减弱的原因,结合差示扫描量热分析(DSC)证明PTC效应与聚合物结晶熔融有直接关系。     

Designs of conductive polymer composites with exceptional reproducibility of positive temperature coefficient effect: A review

Conductive polymer composites with positive temperature coefficient (PTC) effect have gained intensive attention for the potential application in the smart heating field. The PTC reproducibility is significantly essential to guarantee the security and utility of PTC composites. Regrettably, during the repeated temperature cycles, the irreversible self-aggregation of conductive filler and the random reconstruction of conductive network lead to unsatisfactory performance of PTC reproducibility. Extensive efforts have been conducted to address this issue by strategies, including modification of fillers, cross-linking of a polymer matrix, hybrids of fillers, and application of binary polymer matrix. Nevertheless, there are very limited reviews about this issue. In this review, the recent advances in fabricating PTC composites with the enhanced PTC reproducibility have been systematically summarized. Meanwhile, the current challenges and future prospects of PTC composite are also presented. We hope that this review will provide some inspirations for designing PTC materials of long-term performance for commercial applications.     

Thermally induced performance decay in conductive polymer composites

In the course of long-term service, electrically conductive polymer composites acting as positive temperature coefficient (PTC) materials are faced with performance decay characterized by gradually increased room temperature resistivity and decreased PTC intensity. To reveal the influencing factors and to find appropriate ways for solving the problems, thermal-cold cycling experiments (which simulate the extreme operating conditions of PTC type materials in a laboratory environment) and electrification tests are carried out in the current work. The results demonstrate that irreversible damage of partial conductive networks and, in particular, oxidation degradation induced crystallizability deterioration of the matrix polymer are responsible for the electrical performance decay. Additionally, an increase in the contact resistance formed at the metallic electrode/composite contacts exerts a negative influence on the service life of the composites. Polym. Compos. 25:270–279, 2004. © 2004 Society of Plastics Engineers.     

有机PTC材料稳定性研究进展

介绍了导电粒子填充有机PTC材料稳定性的主要影响因素,指出要提高有机PTC材料的稳定性,在本质上必须控制导电粒子的分散程度与分布状态。综述了近年来国内外通过基体选择、导电粒子处理及交联等多种方法来提高有机PTC材料稳定性方面的工作及其最新进展,为PTC材料提高稳定性及实现产业化提供了指导。     

金属及其化合物填充聚合物PTC材料的研究进展

某些有机高分了聚全物可与导电材料形成PTC复合材料。评述了用金属系分散体作导电材料填充聚合物形成聚合物基PTC复合材料时所用金属系物质的种类、用量等对复合材料PTC强度的影响及其导电机理。认为在聚合物／碳系分散体构成的二元体系中添加合适的金属系分散体组成三元复合材料时,可望得到性能优良的PTC复合材料。     

聚合物基PTC热敏材料的研究

综述了聚合物基PTC热敏材料的PTC效应机理、PTC效应影响因素以及PTC效应稳定化的途径。     

具有PTC效应的聚合物基复合材料发展概况

本文对具有PTC效应的聚合物基复合材料的导电机理进行概述,并对该类材料的发展概况及研究展望作详细论述。     

Electrical behavior of carbon black-filled polymer composites: Effect of interaction between filler and matrix

The effect of interaction between carbon black and polymer on electrical behavior was studied using the ESR method. The polymer matrices used were HDPE, LDPE, and ethylene/vinyl acetate (EVA). Two kinds of carbon blacks (CB), high structure CSF-III and low structure FEF, were used as a conductive filler. Compared to that of the HDPE/FEF compound, the positive temperature coefficient (PTC) intensity is lower and electrical reproducibility is worse for the HDPE/CSF-III compound; however, it can be improved significantly by radiation cross-linking. On the other hand, the cross-linking has no practical effect on the PTC intensity of the LDPE/CSF-III compound while it can be achieved by mixing the compound for a longer time. The great PTC intensity was obtained in the HDPE/EVA/CSF-III compound, and it is greater than that of HDPE/CSF-III or EVA/CSF-III. We explain these results using the concept of interaction between the filler and matrix. The absorption of the polymer on the carbon black surface may be physical or chemical; the latter is caused by the free-radical reaction between the polymer and carbon black, and it can occur during the radiation or preparation process of the compound. These “bound polymers” are essentially important for materials to have a great PTC intensity and good reproducibility. © 1994 John Wiley & Sons, Inc.     

Positive temperature coefficient effect and mechanism of compatible LLDPE/HDPE composites doping conductive graphite powders

Linear low density polyethylene (LLDPE)/high density polyethylene (HDPE) blends doped conductive graphite powders were constructed by the traditional melt‐blending method to acquire the conductive compatible polymer composites, and corresponding positive temperature coefficient (PTC) effect of electrical resistivity was investigated. The results indicated that the room‐temperature resistivity gradually decreased and PTC effects were remarkably enhanced by regulating the graphite contents or LLDPE/HDPE ratios. Especially, with increasing graphite contents, the polymer‐fixed composites showed the notable double PTC effects, originating from the volume expansion of the co‐crystallization or their fraction. Whereas, with increasing the LLDPE/HDPE ratio, the PTC effects of the graphite‐fixed composites occurred at the lower temperature, even far below the melting points of the co‐crystallization. Therefore, the regulation of co‐crystallization morphology of compatible polymer matrices was a new idea in the improvement of PTC materials. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46453.     

炭黑/聚合物基PTC复合材料研究新进展

对聚合物基PTC材料的研究现状及导电机理进行概述,对最近提出的新理论,应力模型和双临界物理模型作详细介绍,并对该类材料的研究展望作详细论述.     

Electrical properties of polymer composites prepared by sintering a mixture of carbon black and ultra-high molecular weight polyethylene powder

Conductive polymer composites were prepared by sintering a mixture of ultrahigh molecular weight polyethylene (UHMWPE) powder and carbon black. Two processing parameters—time and temperature—were shown to have a notable effect on the resistivity of the composites. The relationships between the processing parameters and morphology were studied using optical microscopy and transmission electron microscopy (TEM). The results of the optical microscopy studies indicate that the carbon black is distributed in the interfacial regions between the UHMWPE particles. The dimension of the carbon black channels increases with the carbon black concentration. TEM micrographs show that a high degree of intermixing between the carbon black and the polymer occurs at higher temperatures and longer processing times, resulting in higher resistivities. A positive temperature coefficient (PTC) effect was observed for these materials. A mechanism for the PTC effect in this system is proposed. The magnitude of the PTC effect is found to be inversely proportional to the dimension of the carbon black channels in the composites. The dimension is directly related to the carbon black concentration. The PTC effect is a result of the polymer volume expansion caused by melting of the crystallites. A large PTC effect is observed for the composites with a low carbon black concentration and vice versa. No negative temperature effect (NTC) is observed at temperatures substantially above the melting point of the polymer.