LDPE/炭黑/多晶铁纤维/镍粉导电材料的性能

以多晶铁纤维、镍粉和炭黑作为导电填料填充LDPE，制备了一种导电复合材料。分析了多晶铁纤维和镍粉的加入对导电复合材料导电性、屏蔽效能和拉伸强度的影响。结果表明，随着多晶铁纤维和镍粉含量的增加，复合材料的拉伸强度呈下降趋势，导电性提高，当导电填料的含量达到渗滤阈值20％后，复合材料的表面电阻率从10^10Ω降低到10Ω；当炭黑、多晶铁纤维和镍粉的质量分数均为10％时．材料的屏蔽效能在10-30dB，优于LDPE／炭黑材料。     

助剂和工艺条件对导电性复合材料性能的影响及其分析

本文以低密度聚乙烯－镍粉为基础成分，引入各种助剂和改变工艺条件，研究了导电性复合材料的导电性和力学强度的变化规律，并考察了其作用机制。结果表明，导电性增加，伸长率和冲击强度就下降，这是由于填料的分散状态及其与聚合物基体的相互作用发生变化造成的。在实际使用中，必须良好地也能够适当地调节这两种性能。     

填料的形状对导电性复合材料性能的影响

以填料的形状和尺寸控制复合材料的性能是一个重要方法.选用了三种镍粉和不锈钢纤维,研究了它们对复合材料的导电性和力学强度的影响.结果表明,当填料的体积含量达到某临界值时,电阻率会发生突变,粒度愈小,形状愈不规则,该临界值愈小;同时,随着填料含量的增加,拉伸强度和冲击强度都是先升后降,转折变化时的体积含量都大于相同填料的材料电阻率陡峰时的临界值,这种变化规律都取决于材料的结构。     

不饱和聚酯树脂基复合材料的导电性能

以石墨、碳纤维、镍粉和不饱和聚酯树脂为原料通过模压成形固化制备导电复合材料,研究不同比例导电填料及用量、加工工艺对复合材料性能的影响.结果表明:导电填料比例和含量对复合材料的电导率与弯曲性能影响显著,一定含量下的镍粉和碳纤维,可以明显改善体系的强度,同时有助于降低材料的体积电阻率.加入适量丙酮溶剂作为稀释剂,提高了导电填料的分散和浸润,材料的导电性和弯曲性能明显提高.     

TiO2纳米粒子增强超高分子量聚乙烯和高密度聚乙烯复合材料的性能

利用硅烷偶联剂KH570对TiO₂纳米粒子进行表面改性,然后制备塑化超高分子量聚乙烯(PE-UHMW)/TiO₂复合材料,最后通过密炼-模压法制备不同含量和粒子尺寸的TiO₂纳米粒子增强PE-UHMW/高密度聚乙烯(PE-HD)复合材料。通过扫描电子显微镜、透射电子显微镜、差示热扫描量热仪、万能试验机、流变仪表征测试复合材料的微观结构、结晶、力学及流变性能。结果表明,低含量的Ti O₂纳米粒子(质量分数0.1%)能在聚合物基体中分散良好,使复合材料的力学性能、结晶度及流动性均有显著提升;随粒子尺寸增加,材料强度和刚度降低,断裂伸长率和熔体剪切黏度先增加后降低。然而,高含量粒子分散困难、易形成大的聚集体,导致复合材料性能下降。当TiO₂纳米粒子尺寸为5～10 nm、质量分数为0.1%时,复合材料展现出优异的力学性能和加工性能,拉伸强度和拉伸屈服强度分别高达58.21 MPa和44.53 MPa,且熔体剪切黏度下降19.7%。     

CB含量与混炼时间对CB/PP复合材料性能的影响

采用熔融共混-模压制备炭黑(CB)/聚丙烯(PP)导电复合材料,用扫描电镜(SEM)观察复合材料内部CB粒子的分布状态,探讨混炼时间、CB体积分数对导电性及力学性能的影响.研究表明,混炼时间对复合材料导电性的影响很大,较短或较长的混炼时间都对导电性不利,最佳混炼时间为15 min.复合材料的体积电阻率、断裂伸长率随着CB体积分数增加而减小,杨氏模量增大;拉伸强度随CB体积分数的增加先上升后下降.CB体积分数为5%～10%时,体积电阻率下降了近10个数量级.     

纳米碳管/高密度聚乙烯复合材料性能的研究

应用熔融共混法制备纳米碳管／高密度聚乙烯复合材料。考查了纳米碳管含量及制备工艺对材料电性能和力学性能的影响。结果表明加入纳米碳管可以显著提高高密度聚乙烯的导电性，电阻率变化呈现渗流现象。渗流阈值在20％～25％之间，其电阻率下降8个数量级。随纳米碳管含量的增加复合材料的模量提高，断裂伸长率下降。经过对纳米碳管进行溶液浸润预处理，复合材料的导电性和力学性能均得到改善。     

芦苇纤维增强低密度聚乙烯复合材料力学性能研究

以芦苇纤维作增强剂,制备了低密度聚乙烯(PE-LD)/芦苇纤维复合材料,研究了芦苇纤维、马来酸酐接枝低密度聚乙烯(PE-LD-g-MAH)及硅灰石的含量对PE-LD/芦苇纤维复合材料力学性能的影响.结果表明,未加入增容剂PE-LD-g-MAH时,随芦苇纤维含量的增加,复合材料的拉伸强度和弯曲强度先略有增加而后降低,冲击强度则呈下降趋势;PE-LD-g-MAH提高了复合材料的拉伸强度和弯曲强度,当PE-LD-g-MAH质量分数为10％时,复合材料的力学性能最好;硅灰石及芦苇纤维的质量分数分别为10％和20％时,复合材料具有较好的力学性能.     

镁合金水性镍系涂层的制备及导电防护性能研究

以双组分水性聚氨酯与镍粉为主要原料制备镁合金导电防护涂层。以提高涂层的导电性和对镁合金基体防腐蚀性为目的,通过电阻率测试、tafel极化曲线、扫描电镜(SEM)等检测方法,研究了镍粉含量、镍粉形状以及改性处理的镍粉对涂层导电性和防腐蚀性的影响。结果表明:随着镍粉含量的增加,涂层导电性越好,对镁合金基体防腐蚀性能越差;改性处理过的镍粉,含量为30%且球状与片状比为1∶2时,涂层具有较好的导电性和防腐蚀性能。     

HDPE／炭黑导电复合材料的改性

本文研究了导电炭黑的品种、含量及其对高密度聚乙烯（ＨＤＰＥ）性能的影响，以及动态硫化对改善ＨＤＰＥ／导电炭黑复合材料物性的贡献。结果表明，ＨＧ－４型导电炭黑填充ＨＤＰＥ具有很好的导电性，复合材料力学性能较差；ＡＣＥＴ炭黑导电性较差，复合材料力学性能最好。炭黑并用能有效地降低生产成本，而且保持了材料的性能。动态硫化法可以克服复合材料物性差的弱点，并能保持改性材料的高导电性。在ＨＧ－４型炭黑含量为７份时，材料的拉伸强度１３ＭＰａ，断裂伸长率３５０％，体积电阻率为２．１Ω·ｃｍ。     

Thermal and mechanical properties of aluminum powder-filled high-density polyethylene composites

Thermal conductivity and mechanical properties such as tensile strength, elongation at break, and modulus of elasticity of aluminum powder-filled high-density polyethylene composites are investigated experimentally in the range of filler content 0–33% by volume for thermal conductivity and 0–50% by volume for mechanical properties. Experimental results from thermal conductivity measurements show a region of low particle content, 0–12% by volume, where the particles are distributed homogeneously in the polymer matrix and are not interacting with each other; in this region most of the thermal conductivity models for two-phase systems are applicable. At higher particle content, the filler tends to form ag-glomerates and conductive chains resulting in a rapid increase in thermal conductivity. The model developed by Agari and Uno estimates the thermal conductivity in this region. Tensile strength and elongation at break decreased with increasing aluminum particles content, which is attributed to the introduction of discontinuities in the structure. Modulus of elasticity increased up to around 12% volume content of aluminum particles. Einstein's equation, which assumes perfect adhesion between the filler particles and the matrix, explains the experimental results in this region quite well. For particle content higher than 30%, a decrease in the modulus of elasticity is observed which may be attributed to the formation of cavities around filler particles during stretching in tensile tests. © 1996 John Wiley & Sons, Inc.     

Effect of nanosized reinforcement particles on mechanical properties of high density polyethylene–hydroxyapatite composites

Abstract

The effect of nanoscaled hydroxyapatite (HA) filler particles on the mechanical properties of the high density polyethylene–hydroxyapatite (HDPE–HA) composite samples has been investigated. Nanosized HA particles with an average size in the range of 40–50 nm were synthesised by mechanical milling method. The composite samples with various amounts of nanoscaled HA particles were produced by mixing the ceramic and high density polyethylene particles using a single screw extrusion system. The results of the mechanical testing on the composite samples showed an increase in the fracture strength and the young's modulus values with increasing volume fraction of HA content in the composite samples. At the same time, there were decreases in both the fracture strain and toughness values with increasing volume fraction of the ceramic filler particles. In addition the comparison of the results obtained in this study with the mechanical properties of the commercially available composite samples (HAPEX) shows that similar mechanical properties can be reached at a much lower ceramic content, if nanoscaled HA particles are used in the fabrication of these composite biomaterials.     

不同粒径氮化硼填充环氧树脂/玻璃纤维绝缘导热复合材料的研究

以聚砜改性环氧树脂为基体,通过高温模压制备了环氧树脂/玻璃纤维/氮化硼复合材料,研究了不同粒径及不同氮化硼导热粒子用量对复合材料导热性能、力学性能和电性能的影响。结果表明,大粒径粒子有利于复合材料力学性能的提高,小粒径有利于导热性能的提高;随着氮化硼用量的增加,复合材料的导热性能升高,力学性能呈现先增后降趋势,当氮化硼用量为10%(质量分数,下同)时,复合材料的冲击强度和弯曲强度均达到最佳,当氮化硼用量为20%时,复合材料仍保持较好的电性能。     

聚偏氟乙烯/鳞片石墨/碳纤维高导热复合材料的制备

以聚偏氟乙烯（PVDF）树脂为基体,天然鳞片石墨（FG）、碳纤维（CF）为填料,采用熔融共混法制备了PVDF/FG/CF复合导热材料,并研究了FG、CF含量及其改性对复合材料导热性能和力学性能的影响。结果表明,复合材料的热导率随FG含量的增加而增大,力学性能随着FG含量的增加而降低;CF的加入提高了复合材料的力学性能,但热导率略有降低;对CF进行表面氧化处理将使得复合材料的热导率以及力学性能有所提高,当CF含量为5 %、FG含量为50 %时,复合材料的热导率为11.4 W/(m·K),拉伸强度为48 MPa,断裂伸长率为11 %。     

集成电路封装用GNPs/CNTs/HDPE导热高分子复合材料的研究

本文以高密度聚乙烯(HDPE)为基体,以自制的h-G-C-2/1体系杂化填料为导热填料,制备了GNPs/CNTs/HDPE导热高分子复合材料,重点对比了杂化填料和复配填料对GNPs/CNTs/HDPE复合材料在导热、导电及力学性能方面的影响。结果表明,GNPs/CNTs/HDPE导热高分子复合材料的拉伸强度为31.9 MPa,冲击强度为22.1 kJ/m^2,体积电阻率为690 MΩ·cm,热导率为0.759 W/(m·K),满足集成电路封装用技术参数要求。杂化填料的分散性优于复配填料,杂化填料在提高复合材料的拉伸性能方面优于复配填料,复配填料在提高复合材料的热导率方面优于杂化填料。本文所获得的研究成果为制备新型综合性能优异的集成电路封装用导热高分子复合材料提供了一条新的思路。     

Thermal conductivity augmentation of composite polymer materials with artificially controlled filler shapes

Plastics or polymers of high thermal conductivity are highly desired in various industries. Adding fillers of high thermal conductivity to the base materials is a solution to make composite plastics of high thermal conductivity. Previous researches were focused on increasing the thermal conductivity of the composite materials by increasing the filler content and the thermal conductivity of the fillers. Relatively little attention was paid to the optimization of filler shapes. In this study, the effects of the filler shapes on the thermal conductivity of the composite materials are investigated, where the filler shapes are artificially designed. Heat conduction between the base materials and the artificially designed fillers is modeled. It is found that the filler shapes have great impacts on the effective thermal conductivity of the composite materials. Of the various shapes, the double Y shaped fillers are found to be the best choice for composite materials in which the fillers are distributed randomly. In future industrial applications, new filler shapes, such as double Y, Y, quad Y shaped, I and T shapes should be specially produced to replace the traditional fillers shapes: particles, fibers or slices. At last, composite materials made of paraffin wax and steel fillers of ten shapes are fabricated to simulate and validate the results. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39550.     

Electrical and thermal phenomena in low-density polyethylene/carbon black composites near the percolation threshold

Low-density polyethylene (LDPE)/carbon black (CB) composites were fabricated via melt-compounding technique. The percolation threshold was found to be around 20 wt % CB, and an electrical network formed by conductive CB was proven by scanning electron microscopy investigation. Dielectric responses depicted an interfacial relaxation peak at 20 wt % CB content. LDPE/CB composites showed an electric field-dependent conductivity as and a hysteresis behavior around the percolation threshold region. The CB particles with high thermal conductivity increased the heat conductance of the LDPE/CB20 up to 56%. The dynamic mechanical analysis of the LDPE/CB composites exhibited a noticeable contribution of CB throughout the composites, increasing the storage and loss modulus. The physical interactions between CB particles in the filler network enhanced the thermal degradation of the LDPE/CB25 composite for more than 76°C. The maximum breakdown strength of the LDPE/CB composites appeared with an approximately 10% improvement for LDPE/CB5 than pure LDPE. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47043.     

Thermal conductivity of polymer filled with carbon materials: Effect of conductive particle chains on thermal conductivity

Thermal and electric conductivities of polyethylene and poly(vinyl chloride) filled with carbon materials over a wide range are measured in order to study the effect of formed conductive particle chains on thermal conductivities of the composites. With increase of content of carbon particles, the amount of formed conductive chains exponentially increases and the conductive chains tend largely to increase thermal conductivity of a composite. Some models proposed to predict thermal conductivity of a composite in a two-phase system could not be applied to the system with high volume content of particles. In this study, a new thermal conduction model is proposed to correctly predict thermal conductivity of a composite which contains various amounts of particles ranging from a small content, to the region in which conductive chains largely effect a thermal conductivity of a composite. Thermal conductivity of a polymer filled with high volume content of particles largely decreased with a rise in temperature. This phenomenon can be referred to as a PTC phenomenon in thermal resistance.     

Evaluation of different conductive nanostructured particles as filler in smart piezoresistive composites

ABSTRACT: This work presents a comparison between three piezoresistive composite materials based on nanostructured conductive fillers in a polydimethylsiloxane insulating elastomeric matrix for sensing applications. Without any mechanical deformation upon an applied bias, the prepared composites present an insulating electric behavior, while, when subjected to mechanical load, the electric resistance is reduced exponentially. Three different metal fillers were tested: commercial nickel and copper spiky-particles and synthesized highly-pointed gold nanostars. These particles were chosen because of their high electrical conductivity and especially for the presence of nanosized sharp tips on their surface. These features generate an enhancement of the local electric field increasing the tunneling probability between the particles. Different figures of merit concerning the morphology of the fillers were evaluated and correlated with the corresponding functional response of the composite.