摩擦学机敏材料中的相变控制润滑剂

探讨了摩擦学机敏材料的核心部件聚乙烯基复合导电自润滑材料的制备工艺与电性能，不同方法制得的复合材料的电阻率与导电组分炭黑含量的关系亦表现出很大的差别。与干法相比，湿法电阻率较低，而过渡区组分范围更宽。据此，确定出用作复合导电润滑材料的炭黑含量宜大于３５％（质量，不同），但经实验得出可以自加热发生熔融相变的合适的炭黑含 量为４０％，加入润滑剂后构成复合导电自润滑材料，通电加热，显示出快速、易控、热性     

相变可控的复合导电自润滑材料的加热特性

研制了相变可控的复合导电和自润滑材料，它是以低密度聚乙烯－炭黑为导电基材，加入固体润滑剂聚四氟乙烯、石墨和Ekonal（聚苯酯的商品名）构成。固体润滑剂的加入降低了材料的电阻率，以加入Ekonal降低幅度最大。该材料具有反复多次的加热性能，加热电压升高，升温速率加快，经历一个升温速率变化较小的平台期之后，升温速率又加快。台架实验表明，相变可控的复合导电自润滑材料可有效地减少表面的咬合。     

聚合物基PTC热敏导电材料的性能及机理研究

针对PTC材料体系，提出了“PTC强度可提高空间”与“体系提高PTC强度的能力”两个概念，以低密度聚乙烯(LDPE)、高密度聚乙烯（HDPE)和乙烯-醋酸乙烯共聚物(EVA)作为基体，以导电炭黑作为填充导电粒子，制备了聚合物基复合型PTC材料，详细分析了炭黑含量、EVA含量对PTC材料性能的影响．研究表明，所提出的有关概念可用于分析材料的PTC效应机理及各种因素的影响，有助于进一步对聚合物基PTC热敏导电材料作用机制的理解及研究；炭黑含量影响材料电阻率和PTC强度，炭黑含量取在逾渗区电阻率偏小处可得到较高的PTC强度；EVA含量不同时材料电阻率和PTC强度都有先减小后稍增大的现象。     

高电导率炭系复合高分子材料的研制

炭黑(CB)、石墨(C)、炭纤维(CF)炭系与基体树脂以特殊的工艺复合改性制得体积电阻率小于0.1Ω.cm的高导电高分子复合材料。研究了不同的复合体系(CB/PP)/SEBS、(PP/SEBS)/CB、(CB/SEBS)/PP及不同的配方与工艺获得的复合材料对导电性能的影响,结果表明,(PP/SEBS)/CB复合体系是最佳加工方式。采用扫描电镜(SEM)、力学性能测试等方法研究了炭系导电材料在PP/SEBS树脂中的分散机理及复合材料的力学性能。实验结果表明炭系复合组分含量为60%的PP/SEBS导电复合材料具有超高电导率、优良的力学性能和加工性能。     

导电炭黑填充PP-EAA复合材料的形态及电性能

以聚丙烯(PP) 和乙烯-丙烯酸共聚物( EAA) 的共混物为基体材料, 以导电炭黑为填料, 通过熔融共混的方法制备了导电复合材料。探讨了导电炭黑在两相基体中的分散情况以及聚丙烯结晶度对复合体系导电性能的影响。扫描电镜测试结果表明, 在共混物中炭黑粒子选择性分散在极性EAA 树脂中, 同时EAA 树脂在聚丙烯基体中形成连续网络结构, 从而显著降低了复合体系的渗滤阈值。电性能测试结果表明, 材料在相同导电炭黑含量下的体积电阻率相对于单基体体系有7～8 个数量级的降低, 并且结晶度较高的PP 更有利于降低复合体系的体积电阻率。此外, 炭黑/ PP-EAA 复合材料的拉伸强度相对于炭黑/ PP 体系有所下降, 而断裂伸长率有所提高。      

LDPE／炭黑复合导电材料PTC／NTC效应形成机理的探讨

本文从ＬＤＰＥ／炭黑复合导电材料的结晶性能出发，探讨了复合材料电阻率的正温度系数效应和负温度系数效应的形成机理，认为ＰＴＣ效应是由聚合物熔融时发生的晶相向非晶相的转变以及由此而产生的热膨胀共同引起，ＮＴＣ效应主要与炭黑粒子的附聚效应有关。     

炭黑-聚酯复合型导电高分子材料的电热性能研究

研究了炭黑 -聚酯复合型导电高分子材料的电阻率随炭黑填充率及加工成型工艺变化的关系及其伏安特性和力学性能。实验结果表明 ,材料的电导率较高 ,具有非线性伏安特性和负温度系数效应 ,主要用作导电材料和电阻材料。     

炭黑复合导电材料的导电机理

讨论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,阐述了导电高分子材料的导电机理和影响因素,同时对导电复合材料未来的发展提出建议。     

炭黑填充聚丙烯复合材料的制备及性能

采用炭黑(CB)为导电组分填充聚丙烯制备复合型导电高分子材料。在分散剂作用下,炭黑可较好地分散在聚丙烯中,赋予材料导电性能,导电阚值为8％(质量)左右。采用差示扫描量热法(DSC)对该复合材料的热性能进行了分析。用扫描电子显微镜(SEM)和透射电子显微镜(TEM)研究了炭黑在复合材料中的分散形态,表明炭黑以葡萄状聚集体的形态存在是复合材料具有低导电阉值和良好导电性能的重要原因。     

SiO2纳米粉对炭黑／硅橡胶复合材料的压阻,阻温特性的影响

研究了添加导电炭黑和ＳｉＯ２纳米粉的硅橡胶复合材料的导电机理、压阻及阻温效应。发现：添加１５ｇ导电炭黑的硅橡胶（硅橡胶为１００ｇ，下同）的压阻效应，随着纳米Ｓｉ２量的增加显著提高。在一定压力范围内，电阻随压力增加而呈线性增加。只添加１５ｇ导电炭黑的硅橡胶材料的电阻率随温度升高而略为降低，而加入纳米级气相法生产的ＳｉＯ２的炭黑／硅橡胶复合材料的电阻随温度增加而增加。且其导电机制为欧姆导电。其电导率受     

导电混凝土的导电性能及影响因素研究进展

导电混凝土是具有导电、电热、电磁屏蔽等诸多特性或功能的复合材料,在道路融雪化冰、电气设备接地、结构健康监测以及电磁屏蔽等领域具有广阔的应用前景。导电混凝土应具有适宜的导电性能和电阻率稳定性,但是导电材料类型、形态和掺量以及导电混凝土含水率和环境温湿度等诸多因素都可能导致导电性能和电阻率稳定性降低,从而制约导电混凝土的工程应用。分类对比了常见导电材料的性能差异以及用不同导电材料制备的导电混凝土的导电性能差异,在此基础上,探讨了导电混凝土的导电性能和制备方法的研究现状,较为系统地分析了导电材料类型和掺量等因素对导电性能的影响,并提出了改善导电性能和电阻率稳定性的建议。     

碳黑/聚酯纤维非连续性导电行为研究

以熔体纺丝方法制备了碳黑/聚酯(CB/PET)导电纤维,分析了偶联剂对CB/PET纤维渗流阈值和T_g的影响,研究了碳黑含量与CB/PET纤维热性能和导电性能的关系。结果表明碳黑经偶联剂处理后,CB/PET纤维的渗流阈值和T_g均有所降低;碳黑含量对CB/PET纤维的性能影响显著,即随碳黑含量增加,CB/PET纤维的正效温度系数效应向高温移动;当碳黑含量为11%时,CB/PET纤维表现为较明显的正效拉力系数效应。     

The physical properties of polyurethane/graphite nanosheets/carbon black foaming conducting nanocomposites

Using polyester polyol and diphenylmethane diisocyanate (MDI) as basic component, and using graphite nanosheets (GN) and carbon black (CB) as conductive filler, polyurethane/graphite nanosheets/carbon black foaming conducting nanocomposites have been prepared by filling mold curing reaction. The morphology, electrical properties and mechanical properties of the prepared PU/GN foams have been investigated. It showed that the percolation threshold effect of PU/GN composite occurred at the content around 12 wt.% of the GN, which was lower than that of carbon black (CB) composite. Besides, PU/GN foams showed much better conductive properties and mechanical properties than that of CB system.     

炭黑/聚丙烯-聚(苯乙烯-乙烯/丁烯-苯乙烯)复合材料的介电性能和压阻性能

为了制备柔性较好的聚合物基压阻材料,利用熔融共混法制备了炭黑/聚丙烯-聚(苯乙烯-乙烯/丁烯-苯乙烯)(CB/PP-SEBS)复合材料,并研究了CB含量对CB/PP-SEBS复合材料介电性能和压阻性能的影响。结果表明:随着CB含量的增加,CB/PP-SEBS复合材料的介电常数、介电损耗及电导率均提高;CB/PP-SEBS复合材料发生导电逾渗时,CB的含量为12.2wt%;在CB/PP-SEBS复合材料发生弹性形变时,由于外力破坏了CB的导电网络,复合材料的电阻随着应变的增大而增大;循环压阻测试结果显示,在弹性变形区CB/PP-SEBS复合材料的电阻随着应变呈现周期性变化。研究结果可为制备具有稳定电阻变化的聚合物基压阻材料提供借鉴。     

Preparation and Thermodynamic Properties of Camphene/Stearic Acid Composites as Phase-Change Materials in Buildings

In this study, a series of shape-stabilized phase-change materials (PCMs) of camphene/stearic acid (CS) were prepared and their thermal properties were measured by differential scanning calorimetry. The results indicated that the mixture consisting of 60 mass% camphene and 40 mass% stearic acid is the most favorable as a PCM, in terms of the phase-change temperature and latent heat. Thereafter, the CS was absorbed in fly ash, pyroclastic, barite, and marble powder, which acts as a supporting material, to prepare four kinds of composite-based PCMs. DSC, FT-IR, and scanning electron microscopy measurements were made to investigate the structures and properties of the PCMs. DSC results showed that the latent heats of melting and freezing of the composite PCMs were sharply decreased. Morphology and structural characterization revealed that, in form-stable PCMs, the dispersion of the supporting materials in the camphene/stearic acid matrix is homogeneous and there is no chemical interaction between the CS and composites. The composite PCMs showed excellent thermal stabilities and reliabilities, when their phase-change temperatures were concerned. These indicate that the prepared composite-based PCMs are suitable for thermal energy storage because of their applicable temperature range, thermal reliability, and chemical stability.     

导电硅橡胶泡沫材料的制备与性能研究

在硅橡胶基体中添加碳系导电填料(CB、CNT),利用超临界CO2发泡技术,制备了CB/硅橡胶、CNT/硅橡胶以及CB/CNT/硅橡胶复合导电泡沫材料,研究了混料胶料的流变行为以及发泡前后复合材料电导率、电磁屏蔽效能的变化规律。结果表明,CB与CNT均会阻碍硅橡胶复合材料的初始交联,导电填料含量越多交联越迟缓。CB/CNT/硅橡胶复配体系中更容易形成导电通路,当CB/CNT(1∶1)总含量为8%(质量分数)时,硅橡胶复合材料的电导率可达10^-5 S/cm,其电磁屏蔽效能(EI)为14~26 dB。发泡后,硅橡胶复合材料的电导率及EI值均有所下降。     

Composite Yarns of Multiwalled Carbon Nanotubes with Metallic Electrical Conductivity

Unique macrostructures known as spun carbon‐nanotube fibers (CNT yarns) can be manufactured from vertically aligned forests of multiwalled carbon nanotubes (MWCNTs). These yarns behave as semiconductors with room‐temperature conductivities of about 5 × 10² S cm^?1. Their potential use as, for example, microelectrodes in medical implants, wires in microelectronics, or lightweight conductors in the aviation industry has hitherto been hampered by their insufficient electrical conductivity. In this Full Paper, the synthesis of metal–CNT composite yarns, which combine the unique properties of CNT yarns and nanocrystalline metals to obtain a new class of materials with enhanced electrical conductivity, is presented. The synthesis is achieved using a new technique, self‐fuelled electrodeposition (SFED), which combines a metal reducing agent and an external circuit for transfer of electrons to the CNT surface, where the deposition of metal nanoparticles takes place. In particular, the Cu–CNT and Au–CNT composite yarns prepared by this method have metal‐like electrical conductivities (2–3 × 10⁵ S cm^?1) and are mechanically robust against stringent tape tests. However, the tensile strengths of the composite yarns are 30–50% smaller than that of the unmodified CNT yarn. The SFED technique described here can also be used as a convenient means for the deposition of metal nanoparticles on solid electrode supports, such as conducting glass or carbon black, for catalytic applications.     

The thermoelectric performance of carbon black/poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) composite films

Carbon black/poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (CB/PEDOT:PSS) composite films have been prepared by a spin-coating method. The morphology of the composite films was investigated by field emission scanning electron microscopy and atomic force microscopy. The thermoelectric properties of CB/PEDOT:PSS composite films were measured at room temperature. As the content of CB increased from 0 to 11.16 wt%, the electrical conductivity of the composite films first increased sharply and then decreased, while the Seebeck coefficient increased slowly. A highest power factor of 0.96 μWm^?1 K^?2 was obtained.