高导热复合材料研究进展

综述了高导热型聚合物基纳米复合材料的导热机理、填充型复合材料的导热模型、高导热型聚合物基复合材料及其导热填料的研究现状。最后,提出了高导热型聚合物基纳米复合材料存在的问题,并对其发展方向进行了展望。     

聚合物基导热复合材料的制备与性能研究进展

近年来,生活及工业上人们对聚合物基热管理材料的需求越来越大,因此对其导热系数或散热能力的提高引起了人们极大的研究兴趣。本文较为详细地介绍了本征型聚合物和填充型导热复合材料的导热机理及影响因素,在此基础上综述了几种不同类型的导热填料以及混合填料填充导热复合材料的制备方法和提高导热性能的途径。重点介绍了石墨烯在导热领域优异的物理性质以及多元填料复合材料中的双逾渗效应和协同效应,并从科学文献中给出了详细的实例,为高导热复合材料提供了指导。     

导热高分子复合材料研究进展

在介绍金属材料、无机非金属材料以及高分子材料导热机理的基础上,介绍了导热填料填充高分子复合材料的导热网链机理和热弹性组合机理2种导热机理,该理论可以解释导热高分子复合材料导热过程中不同的现象和规律;归纳了适用于粒子、纤维等填充的聚合物基复合材料的各种导热模型;讨论了树脂基体、导热填料和温度对于高分子复合材料热导率的影响...     

高导热网络聚合物基复合材料的研究进展

介绍了聚合物材料的导热机理;综述了国内外对聚合物基导热复合材料的研究现状;分析了导热聚合物的种类,包括本征型导热聚合物和填充型导热聚合物;其中填充型包括单一填料填充、混合填料填充以及双逾渗结构填充。最后,重点介绍了聚合物材料构建导热网络的种类及方法,并对高导热聚合物基复合材料未来的发展方向进行了展望。     

导热塑料及其加工研究进展

综述了结构型导热塑料和填充型导热塑料的导热机理,介绍了填充型导热复合材料的几种成型设备,包括双螺杆挤出、注塑机和模压机,并详细介绍了影响填充型导热塑料导热性能的几个因素,包括填料的填充量、形状尺寸、表面处理以及基体材料的粒径尺寸等。指出需要研究开发新型导热填料或改善加工工艺,在不影响材料力学性能且制备方法简单的情况下提高复合材料的导热系数,从而满足导热塑料在不同领域的应用要求。     

静电纺丝技术在导热复合材料领域的研究进展

静电纺丝技术可在导热复合材料成型过程直接构筑取向结构,提高复合材料的热传导能力。文章分析了静电纺丝技术在导热复合材料制备方面的研究现状,介绍了不同类型高导热复合材料的制备方法,包括石墨烯型、碳纳米纤维型、碳纳米管型和氮化硼型等,概述了不同类型导热复合材料的导热性能。指出静电纺丝技术可以实现导热填料特定的取向排列,也可以改善填料的分散度,从而增加复合材料的导热系数,提升复合材料的导热性能。     

高分子复合材料导热性能研究

以Al2O3、MgO和BN三种无机填料作为尼龙6(PA6)的导热填料,研究填料的种类、填充量、粒径大小和粒径配比等对复合材料热导率的影响。结果表明:PA6基复合材料的热导率随导热填料填充量的增加而增大,随导热系数大的填料填充量的增加增大较快;导热系数大的填料的粒径对复合材料的导热系数的影响比较明显;导热系数大的填料,不同粒径的复配可以显著提高复合材料的导热系。     

中国专利

一种具有核壳结构导热填料填充的聚丙烯复合材料本发明公开了一种具有核壳结构导热填料填充的聚丙烯复合材料。该聚丙烯复合材料中核壳结构导热填料的含量为35%~40%(w),导热系数为0.48~0.56 W/(m·K)。本发明将两种导热填料——氨基改性氮化硼和环氧基改性三氧化二铝通过化学键连接在一起,形成核壳结构的导热填料;导热系数较大的片状氨基改性氮化硼由于包覆在体积较大的球形环氧基改性三氧化二铝的表面,也更容易让具有较高导热系数的导热填料相互接触,从而形成导热网络,使核壳结构导热填料的导热系数提升0.1~0.2 W/(m·K)。该聚丙烯复合材料的制备中还添加了DMP?30型催化剂,有效地降低了化学反应的活化能,增加了核壳结构导热填料的数量,并且易于制备。     

填充型导热高分子复合材料的研究进展

针对不同种类导热填料在高分子中的应用,介绍了填充型导热高分子复合材料的研究进展。通过对复合材料导热性能影响因素的讨论,发现对填料进行表面改性以及采用适宜的制备工艺,进而改善有机-无机界面相容性、促进填料在基体中的良好分散性,是提高填充型导热复合材料热导率的关键。     

纳米Fe3O4/环氧树脂基复合材料制备及导热性研究

选用水热法制备Fe3O4纳米粒子为填料,通过直接混合分散法制备了纳米Fe3O4/环氧树脂基复合材料。测试分析了Fe3O4纳米粒子的形貌、结构和磁性能。并且复合材料的导热系数也被测定,结果表明,随着粒子填充体积增加,复合材料导热系数增大。当添加28.47%的纳米Fe3O4粒子时,复合材料导热系数达到0.409 W/（m.k）,是纯环氧树脂E-44的2.54倍。通过对Y.Agari导热模型分析计算,得到了能对该复合材料导热系数进行较好预测的方程。     

Thermal behavior of thermoplastic polymer nanocomposites containing graphene nanoplatelets

Polypropylene (PP), acrylonitrile butadiene styrene (ABS), and thermoplastic polyurethane (TPU) nanocomposites filled with 5 wt % of two different kinds of commercially available graphene nanoplatelets (GNPs) were prepared. Composites materials were characterized in terms of thermal properties (thermal conductivity and thermal stability) in order to study the effect of different fillers within different thermoplastic matrices. The exfoliation process and the mechanical properties were also investigated. We chose three different thermoplastic polymers (polyolefin, copolymer and elastomer) to cover a wide range of thermoplastic materials and identify a guideline in the use of GNPs for nanocomposite materials. No drastic differences were observed in terms of mechanical properties when the same matrices were filled with different GNPs. Concerning thermal conductivity, it was observed that the GNPs plane dimensions play a crucial role in the increase of conductive properties. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44814.     

Micro‐contact reconstruction of adjacent carbon nanotubes in polymer matrix through annealing‐Induced relaxation of interfacial residual stress and strain

Thermoplastic polyurethane (TPU)/multi‐walled carbon nanotubes (CNT) nanocomposites were prepared by twin‐screw extrusion and micro injection molding. The electrical conductivity of micro injection molded polymer nanocomposites exhibits a low value and uneven distribution in the micromolded samples. Real‐time tracing of electrical conductivity was conducted to investigate the post thermal treatment on the electrical conductivity of microinjection molded composites. The results show that postmolding thermal treatment leads to a significant increase in the electrical conductivity by over three orders of magnitude for 5 wt % CNT‐filled TPU composites. In‐situ Transmission electron microscopy confirms the conductive CNT network does not change at the micron/sub‐micron scale during thermal treatment. TEM image analysis by a statistical method was used to determine the spatial distribution of CNT in the sample and showed that the average distance between adjacent CNT reduced slightly at the nanometer scale after postmolding thermal treatment. A new conductive mechanism is proposed to explain the enhancement of electrical conductivity after thermal treatment, i.e. micro‐contact reconstruction of adjacent CNT in the polymer matrix through annealing‐induced relaxation of interfacial residual stress and strain. Raman spectra and small angle X‐ray scattering curve of annealed samples provide supporting evidence for the proposed new conductive mechanism. The electron tunneling model was used to understand the effect of inter‐particle distance on the conductivity of polymer composites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42416.     

Morphological and physical properties of a thermoplastic polyurethane reinforced with functionalized graphene sheet

BACKGROUND: Functionalized graphene sheet (FGS) was recently introduced as a new nano‐sized conductive filler, but little work has yet examined the possibility of using FGS as a nanofiller in the preparation of polymer nanocomposites. In particular, there are currently no published papers that evaluate polyurethane/FGS nanocomposites. The purpose of this study was to prepare a polyurethane/FGS nanocomposite and examine the morphological and physical properties of the material. RESULTS: A cast nanocomposite film was prepared from a mixture of thermoplastic polyurethane (TPU) solution and FGS suspended in methyl ethyl ketone. The FGS dispersed on the nanoscale throughout the TPU matrix and effectively enhanced the conductivity. A nanocomposite containing 2 parts of FGS per 100 parts of TPU had an electrical conductivity of 10^?4 S cm^?1, a 10⁷ times increase over that of pristine TPU. The dynamic mechanical properties showed that the FGS efficiently reinforced the TPU matrix, particularly in the temperature region above the soft segment melt. CONCLUSION: Our results show that FGS has a high affinity for TPU, and it could therefore be used effectively in the preparation of TPU/FGS nanocomposites without any further chemical surface treatment. This indicates that FGS is an effective and convenient new material that could be used for the modification of polyurethane. It could also be used in place of other nano‐sized conductive fillers, such as carbon nanotubes. Copyright © 2009 Society of Chemical Industry     

High-performance thermoplastic polyurethane nanocomposites induced by hybrid application of functionalized graphene and carbon nanotubes

A hybrid polymeric system containing carbon nanofillers with different geometrical dimensions is proposed for strategic applications, particularly for electrical properties. Two different carbon nanofillers including functionalized multiwalled carbon nanotubes (fCNTs) and functionalized graphene nanoplatelets (fGnPs) were added to thermoplastic polyurethane (TPU) to prepare single and hybrid nanofiller filled TPU through solution mixing. Sufficient exfoliation of the fGNPs in the single nanocomposites was confirmed by X-ray diffraction, while single filler and hybrid TPU nanocomposites containing fCNTs showed some re-aggregation of these nanofillers. Linear rheology together with scanning electron microscopy revealed a proper exfoliation and dispersion degree for fGnPs and fCNTs, respectively. We have shown that simultaneous addition of fCNTs–fGnPs in the form of a hybrid system into the TPU made a large surface area available and strong interfacial interactions were formed between the hybrid network and the TPU matrix. This in turn led to electrical, thermal and mechanical properties, which were superior to those predicted by the mixture law. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48520.     

Study on thermoplastic polyurethane/montmorillonite nanocomposites

The thermoplastic polyurethane/montmorillonite (TPU/MMT) nanocomposites were prepared by melt intercalation. The structure and property of the TPU/MMT nanocomposites were studied by XRD, TEM, TG, Molau test, and mechanical property measurement. The interlayer spacing between the MMT platelets in TPU/MMT nanocomposites blended for 10 and 15 min was the same. The silicate platelets were dispersed in TPU matrix on 5–15 nm scale for TPU/MMT nanocomposites. The interface interaction between the silicate layers and TPU matrix for TPU/MMT nanocomposites was strong. Compared to those of pure TPU, the tensile strength and tear strength of the TPU/MMT nanocomposites increased. The tensile strength and tear strength of the TPU/MMT nanocomposites decreased with increasing blending time because of the degradation of the TPU matrix. The thermal stability of the TPU/MMT nanocomposites was lower than that of the pure TPU in the first step, whereas in the second step, the TPU/MMT nanocomposites showed higher thermal stability. POLYM. COMPOS., 2008. © 2007 Society of Plastics Engineers     

高填充改性复合材料导热预测模型的建立及应用

在对高填充改性复合材料导热过程进行研究的基础上,建立了基于串并联/并串联模型并考虑了界面热阻作用的高填充改性复合材料导热预测模型。借助于双转子连续混炼机制备两种氧化铝粒径不同填充量的聚丙烯/氧化铝（PP/Al₂O₃）复合材料,运用激光导热仪对其导热性能进行了表征,并与模型预测结果进行了对比。结果表明,所建立的模型对高填充复合材料的导热性能的预测具有较高的准确性;当氧化铝填充量较低时,模型中的界面热阻因子最高;随着氧化铝填充量增加,界面热阻因子显著降低;当氧化铝填充量继续增加时,界面热阻因子逐渐降低并趋于稳定;高填充量下相同制备工艺下同种填充改性复合材料的界面热阻近似相同。     

高导热填充型环氧树脂复合材料研究进展

对填充型环氧树脂基高导热材料的最新研究进展进行了总结,从导热机理、新型导热填料、构建完善有效的导热网络以及填料与环氧基体间界面层结构设计等方面进行了分析,提出了该研究领域的技术关键点和发展趋势。     

Fabrication of electrical and thermal conductive thermoplastic polyurethanes-based nanocomposite with azide polyurethane as interfacial compatibilizer

Electrical and thermal conductive polymers have aroused extensive interest in research recently due to their hi-tech applications in the fields of novel electronics. A novel electrical and thermal conductive nanocomposite (MWCNTs@PU/TPU) made with multiwall carbon nanotubes (MWNTs) and thermoplastic polyurethanes (TPU) by using azide polyurethane (PU) as interfacial compatibilizer. The MWNTs could form well-developed electrical and thermal conductive networks in the TPU matrix. The developed nanocomposite inherited advantageous properties from its constituents, namely the high conductivity and diathermancy from MWNTs, and the high mechanical properties from the TPU. Conductivity tests showed that, compared with neat MWCNTs/TPU, the electrical conductivity of MWCNTs@PU/TPU was significantly enhanced (up to 3.4 × 10⁻⁶ S/cm), with incorporating only 3.0 wt% MWCNTs@PU. And most importantly, the thermal conductivity was greatly improved by about 46.4% when the MWCNTs@PU loading was 6.0 wt%.     

Dynamic mechanical properties of nanoclay filled TPU/PP blends with compatibiliser

Abstract

Blends of thermoplastic polyurethane (TPU) and polypropylene (PP) are highly incompatible because of large differences in polarities and high interfacial tensions. On one hand, PP is added to TPU to improve TPU's thermal stability, chemical properties, mechanical properties (modulus, strength and hardness) and processing performance and to reduce TPU's cost. On the other hand, TPU is blended with PP to improve PP's properties (e.g. abrasion, flexibility, tear strength, shock absorbing capabilities, impact strength, adhesion and paintability/printability). Earlier works in polyurethane/organoclay nanocomposites, PP/organoclay nanocomposites and TPU/PP blends were studied. In our experimental work, both ester and ether based TPU nanocomposites were prepared by melt blending using 3?wt-% Cloisite 10A (organically modified montmorillonite clay) as the nanoscale reinforcement and blended with PP with/without PP-graft-maleic anhydride as the compatibiliser. Blends of nanoclay filled TPU/PP were evaluated for dynamic mechanical properties such as storage modulus E′, loss modulus E″ and dissipation factor tanδ.     

Montmorillonite–multiwalled carbon nanotube nanoarchitecture reinforced thermoplastic polyurethane

Montmorillonite (MMT)–multiwalled carbon nanotube (MWCNT) hybrids were prepared in different weight ratios by simple dry grinding method and characterized. Subsequently, MMT–MWCNT (1:1) hybrid was used as reinforcing filler in developing thermoplastic polyurethane (TPU) nanocomposites by solution blending method. Thermogravimetric analysis showed that 0.25 wt% hybrid‐loaded TPU nanocomposite exhibited maximum enhancement of 31°C corresponding to 50 wt% loss in thermal stability when compared with neat TPU. Differential scanning calorimetry of this composite also indicated that its crystallization and melting temperatures are enhanced by 37 and 13°C, respectively. Mechanical data showed that tensile strength and Young's modulus of 0.50 wt% filled TPU were maximum improved by 57 and 87.5%, respectively. Dynamic mechanical analysis (DMA) measurements indicated 174% (50°C) improvement in storage modulus of 0.50 wt% hybrid‐loaded TPU. Such improvements in thermal and mechanical properties have been attributed to homogeneous dispersion, strong interfacial interaction, and synergistic effect. POLYM. COMPOS., 37:1775–1785, 2016. © 2014 Society of Plastics Engineers