Recent Developments in Additive Manufacturing of Conductive Polymer Composites

Additive manufacturing, also named 3D printing, can be used to create objects from diverse polymers, metals, and other materials in diverse shapes and dimensions. If special physical or chemical properties are necessitated, using corresponding feedstock enables varying such properties in a broad range. Besides choosing a suitable base material, often composite materials are used for specific applications. Here, an overview of recent developments in 3D printing of polymer composites with conductive properties is given. After a definition of conductivity ranges and the respective potential applications, additive manufacturing methods applicable for these polymer composites as well as potential resistivity or resistance measurement methods are reported. An overview of the most recent reports of 3D printing polymer composites with different conductive fillers is followed by a summary of the applications found in the recent literature.     

结构型与复合型导电塑料研究进展

概述了导电塑料的重大发现,阐明了塑料的导电机理和导电渗滤阈值,分析了不同加工工艺、不同导电炭黑、不同聚合物体系对材料导电性能和力学性能的影响,介绍了纳米技术在导电聚合物中的应用,综述了国内外结构型与复合型导电塑料最新技术成果、应用领域和研究进展。     

石墨烯导热高分子复合材料的制备、性能与机理

石墨烯是一种具有超大的比表面积、良好的热和化学稳定性、超高的热导率以及易于化学修饰的蜂窝状单层碳材料,已作为填料广泛应用于导热高分子复合材料领域。近年来石墨烯导热高分子材料的研究重点是改善石墨烯在聚合物基体中的界面相容性和分散性能。阐述了近年来石墨烯导热高分子复合材料的制备方法及其热性能,并重点对石墨烯导热高分子复合材料的导热机理进行综述,同时结合研究现状对石墨烯导热高分子复合材料的研究方向进行展望。     

A review of vapor grown carbon nanofiber/polymer conductive composites

Vapor grown carbon nanofiber (VGCNF)/polymer conductive composites are elegant materials that exhibit superior electrical, electromagnetic interference (EMI) shielding effectiveness (SE) and thermal properties compared to conventional conductive polymer composites. This article reviews recent developments in VGCNF/polymer conductive composites. The article starts with a concise and general background about VGCNF production, applications, structure, dimension, and electrical, thermal and mechanical properties. Next composites of VGCNF/polymer are discussed. Composite electrical, EMI SE and thermal properties are elaborated in terms of nanofibers dispersion, distribution and aspect ratio. Special emphasis is paid to dispersion of nanofibers by melt mixing. Influence of other processing methods such as in-situ polymerization, spinning, and solution processing on final properties of VGCNF/polymer composite is also reviewed. We present properties of CNTs and CFs, which are competitive fillers to VGCNFs, and the most significant properties of their composites compared to those of VGCNF/polymer composites. At the conclusion of the article, we summarize the most significant achievements and address the future challenges and tasks in the area related to characterizing VGCNF aspect ratio and dispersion, determining the influence of processing methods and conditions on VGCNF/polymer composites and understanding the structure/property relationship in VGCNF/polymer composites.     

Thermal conductivity of polymer-based composites: Fundamentals and applications

Thermal management is critical to the performance, lifetime, and reliability of electronic devices. With the miniaturization, integration and functionalization of electronics and the emergence of new applications such as light emitting diodes, thermal dissipation becomes a challenging problem. Addressing this challenge requires the development of novel polymer-based composite materials with enhanced thermal conductivity. In this review, the fundamental design principles of highly thermally conductive composites were discussed. The key factors influencing the thermal conductivity of polymers, such as chain structure, crystallinity, crystal form, orientation of polymer chains, and orientation of ordered domains in both thermoplastics and thermosets were addressed. The properties of thermally conductive fillers (carbon nanotubes, metal particles, and ceramic particles such as boron nitride or aluminum oxide) are summarized at length. The dependence of thermal conductivity of composites on the filler loading, filler aggregate morphology and overall composite structure is also discussed. Special attention is paid to recent advances in controlling the microstructure of polymer composites to achieve high thermal conductivity (novel approaches to control filler orientation, special design of filler agglomerates, formation of continuous filler network by self-assembly process, double percolation approach, etc.). The review also summarizes some emerging applications of thermally conductive polymer composites. Finally, we outline the challenges and outlook for thermally conductive polymer composites.     

电磁屏蔽材料的发展现状及未来发展趋势

介绍了电磁屏蔽原理与导电聚合物复合材料（CPCs）特点,论述了不同应用场合下CPCs的物理特性（柔性、硬质、涂覆）,对近年来国内外电磁屏蔽材料中导电填料种类（金属、碳基、金属碳化物氮化物MXene）及其制备工艺进行了详细汇总分析,并对电磁屏蔽材料未来发展方向进行了展望。     

原位缩聚合成含聚芳酰胺/酯的分子复合材料Ⅰ分子复合材料的研究进展

高分子复合材料是指两种或两种以上物理和化学性质不同的高分子所组成的多相固体材料,是能够将各组分的优点有机结合起来,并表现某些新的有用特性的材料体系。近年来有关刚性棒状高分子与柔性基体聚合物的复合与研究非常活跃,但是,由于刚性棒状高分子与柔性基体存在着在热力学上的不相容性,使两组分达到分子水平的分散相当困难;而且由于刚性棒状高分子难溶难熔,因此更难于用溶液共混或螺杆挤出共混的方法制备分子复合材料。因此改进刚性高分子与柔性链聚合物基体的混溶性是多相高分子体系的一个重要课题。文章综述并讨论了分子复合材料的研究进展以及各种合成技术。     

Evolution of supramolecular healable composites: a minireview

Efforts to further extend the range of applications of polymer based materials have resulted in the recent production of healable polymers that can regain their strength after damage. Within this field of healable materials, supramolecular polymers have been subject to extensive investigation. By virtue of their reversible non‐covalent interactions, cracks and fractures in such polymers can be readily and repeatedly healed in order to regain key physical properties. However, many supramolecular polymers are relatively weak and elastomeric in nature, which renders them unsuitable for high strength structural applications. To overcome these deficiencies, preliminary studies have shown that it is possible to reinforce supramolecular polymers with microscale and nanoscale fillers to afford composites that are not only stronger and stiffer compared with the polymers alone but also retain their healing abilities. In this minireview we discuss the evolution of these supramolecular composites and their advantages over more conventional, covalent polymeric materials. © 2014 Society of Chemical Industry     

Melt spinning of conducting polymeric composites containing carbonaceous fillers

Fibers produced by melt spinning of conductive polymer composites are attractive for several applications; the main drawback is however reduced processability at high filler concentrations. Carbon nanotubes (CNTs) are considered suitable fillers for conductive polymer composites, replacing conductive grades of carbon black (CB). In this study, the fiber‐forming properties of conductive polymer composites based on a conductive grade of CB and two masterbatches with CNT in a polyethylene matrix were investigated. The CB was also used in a polypropylene matrix for comparison. The rheological properties of the filler‐containing melts in shear and their extensional behavior were evaluated. A piston‐driven device was used to extrude the molten materials through a capillary; different capillary geometries were tested. Fibers were produced at various draw ratios, and their conductivity was determined. To assess the ultimate extensibility, a modified Rheotens method was used. The results showed that a conductive CB grade can have a lower percolation threshold and higher conductivity than a material with CNT. Conductivity decreased with increasing melt draw ratio for both types of fillers. The spinnability of the materials decreased with increasing concentration of filler material and correlations were found between spinnability and melt elasticity. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Recent Progress on Fabrication and Performance of Polymer Composites with Highly Thermal Conductivity

The rise of miniaturized, integrated, and functional electronic devices has intensified the need for heat dissipation. To address this challenge, it is necessary to develop novel thermally conductive polymer composites as packaging materials. In this paper, a number of factors for the construction and design of thermally conductive polymers are concluded. Special attention is focused on the analysis and comparison of the thermally conductive composites prepared by various fillers or strategies to provide guidelines and references for future design of composite materials. The current commonly used preparation strategies of thermally conductive polymer are summarized, such as using a variety of fillers, vacuum filtration, template method, and so on. The challenges of thermally conductive polymer composites are finally sketched. This review can inspire the design of polymer composites with brilliant thermal conductivity.     

可加工导电高分子材料的研究进展

综述了可加工导电高分子的研究进展，着重叙述了制备可溶导电高分子及导电高分子复合材料的方法，并介绍了加工工艺对结构和性能的影响。     

Preparation，properties and applications of hydroxyapatite/synthetic polymer composites

随着生物医用材料的需求量日趋增大,磷灰石与人工合成高分子的复合材料成为组织修复和替代材料的研究热点。以不同单体分类,综述了磷灰石与合成的非降解高分子、可降解高分子复合材料的研究进展;对羟基磷灰石/合成高分子复合材料的制备方法、性能及其应用等方面进行研究,并对此复合材料存在的问题和发展前景进行讨论。说明从分子水平设计出具有良好力学性能、生物活性和生物相容性的医学材料,具有十分重要的意义。     

Biodegradable and electrically conducting polymers for biomedical applications

Conducting polymers have been widely used in biomedical applications such as biosensors and tissue engineering but their non-degradability still poses a limitation. Therefore, great attention has been directed toward the recently developed degradable and electrically conductive polymers (DECPs). The different strategies for synthesis of degradable and conducting polymers containing conducting oligomers are summarized and discussed here as well as the influence of different macromolecular architectures such as linear, star-shaped, hyperbranched and cross-linked DECPs. Blends and composites of biodegradable and conductive polymers are also discussed. The developing trends and challenges with the design of DECPs are also presented.     

Thermal conductivity of carbon nanotubes and their polymer nanocomposites: A review

Thermally conductive polymer composites offer new possibilities for replacing metal parts in several applications, including power electronics, electric motors and generators, heat exchangers, etc., thanks to the polymer advantages such as light weight, corrosion resistance and ease of processing. Current interest to improve the thermal conductivity of polymers is focused on the selective addition of nanofillers with high thermal conductivity. Unusually high thermal conductivity makes carbon nanotube (CNT) the best promising candidate material for thermally conductive composites. However, the thermal conductivities of polymer/CNT nanocomposites are relatively low compared with expectations from the intrinsic thermal conductivity of CNTs. The challenge primarily comes from the large interfacial thermal resistance between the CNT and the surrounding polymer matrix, which hinders the transfer of phonon dominating heat conduction in polymer and CNT.This article reviews the status of worldwide research in the thermal conductivity of CNTs and their polymer nanocomposites. The dependence of thermal conductivity of nanotubes on the atomic structure, the tube size, the morphology, the defect and the purification is reviewed. The roles of particle/polymer and particle/particle interfaces on the thermal conductivity of polymer/CNT nanocomposites are discussed in detail, as well as the relationship between the thermal conductivity and the micro- and nano-structure of the composites.     

Graphite/Polyaniline (GP) composites: Synthesis and characterization

Ever since the discovery of inherently conducting polymers (ICPs), research dealing with the applications of these unique materials continues to grow. The use of ICPs, especially polyaniline (PANi) and polypyrrole (PPy), and carbon black (CB) as conductive additives in the thermoplastics industry have been limited due to undesirable properties of each at high temperatures. Carbon black-ICP composites, however, have shown improved properties at higher temperatures. The applications of these composites are still limited because the conductivities are below that of carbon black alone and about the same order of magnitude as PANi. Graphite/ICP composites have also been touted as possible electrode materials in rechargeable batteries and have numerous other applications. The exploration of graphite/PANi composites in our research lab has yielded conducting composites which exhibit conductivities greater than the graphite or PANi alone. In addition to higher conductivities, these graphite/PANi composites exhibit controllable conductivities as a function of pH.     

导电复合橡胶用导电填料的应用研究进展

对导电复合橡胶用导电填料如炭系、金属系、颗粒表面镀金属等的种类、性质等因素对复合橡胶材料导电率的影响及应用进行了综述。也对采用新型的填料即本征导电聚合物主要是聚苯胺填充制备导电复合橡胶的研究进展进行了综述。炭系是目前制备导电复合橡胶主要的导电填料,但有污染,不适合制备有颜色要求的导电材料,金属系、颗粒表面镀金属的比重大,在聚合物中分散较困难,也不太适合于有比重要求的制品。本征导电聚合物导电填充填料是制备导电复合橡胶发展的一个重要方向,可以解决不熔难溶造成的在聚合物中分散性差的问题。     

聚合物基导电复合材料几种导电理论的评述

近年来,有关聚合物基导电复合材料的研究已受到普遍的重视,但对导电复合材料导电机理研究的不足制约了其应用和发展。导电复合材料的导电机理相当复杂,通常可分为导电通路如何形成和材料形成导电通路后如何导电这两个方面来研究。人们提出了许多导电机理模型,详细介绍了渗滤理论、有效介质理论、量子力学隧道效应理论等几种具有代表性的导电理论,对其适用范围、优缺点等进行了评述。通过对这些导电机理的探讨,有助于加深对复合型导电塑料以及其它导电复合材料导电行为的了解。     

导电高分子材料制备及应用研究进展

在介绍导电高分子材料导电机理的基础上,对目前最常见的两种导电高分子材料的制备方法进行综述;重点讨论了含大型离域π键导电高分子材料、化学掺杂型共轭结构导电高分子材料和新型本征导电高分子材料等本征型导电高分子材料的制备方法,并研究了金属及其氧化物、碳系纳米材料、有机组分以及新型导电填料等对填充型导电高分子材料导电性能的影响...     

Influence of Distinct Environment on the Mechanical Characteristics of Arhar Fiber Polymer Composites

Over the past decades the need for eco-friendly, non-toxic and biodegradable material is growing significantly. Natural fiber polymer composites have become the prior choice for many applications, as the natural fiber polymer composites are economical and eco-friendly materials in contrast with synthetic fiber reinforced composites. In the current study arhar fiber is used as a reinforcing material. Arhar fiber epoxy composites are fabricated using the hand lay-up technique. The materials were tested for weight gain in different environments (saline water, mineral water and subzero temperature condition). The composite samples immersed in the different environments were tested for tensile strength. It is observed that weight gain is more in mineral water and saline water, minimum weight gain is observed in subzero condition. Maximum tensile strength is observed in 10%fiber content samples. Strength depreciation ismore in samples immersed in the saline water environment.     

Electroactive polymer blends

The rapid development of two new classes of electrically active polymer materials, electronically conducting and electroactive polymers and ion-conducting polymers respectively, offers new possibilities for application of both classes of material, especially in combination with each other. While some of these combinations have been attempted before, they all met serious problems due to poor interpenetration of the two polymers. The recent availability of solubilized and soluble electroactive and conductive polymers has greatly advanced the possibilities of reducing the interpenetration problem. Some experimental studies using the combination of solubilized electroactive polypyrrole with poly(ethylene oxide) in an electroactive polymer blend electrode for solid-state polymer batteries are discussed. The opportunities for using polymer blends for solid-state electrochemical polymeric devices, and avenues for the development of materials for such devices, are also reviewed.