基于碳纳米管/聚合物芯鞘结构高导热纤维的制备

Preparation of highLY thermal conductivE fiber based on carbon nanotube / polymer CORE SHEATH structure

曾少博

11930432

硕士

材料工程

祝渊

2021-05-17

2021-06-07

南方科技大学

深圳

随着芯片集成度的提高，电子产品的功耗增加，芯片的发热量也与日俱增，诸如手机等电子产品需要能够实现有效散热的热界面材料。但是目前热界面材料已经无法满足现有的需求，如何有效解决电子元器件的热管理问题成为很多研究者关注的重点。热界面材料作为热管理技术中的关键技术，是解决电子元件散热的关键之所在。传统散热材料具有可变性能力小、弹性不佳等缺陷，而聚合物基导热材料具有密度小、可变形能力较大以及弹性好等特点，目前成为了新的研究热点。然而高分子本征材料的导热性能极差，热导率仅在0.1-0.2 W/(m·K)，不能满足现在电子器件的散热需求。为了提高聚合物材料的热导率，向其中添加高导热填料成为众多研究者的选择。制备具有高弹性及高导热聚合物基复合材料是解决目前电子元件面临难题的选择。本文将高分子链、微观填料等进行多层级逐级排列形成有序结构，从而得到具有高导热性能的聚合物基复合材料。本文选择采用静电纺丝的方式制备高导热的多壁碳纳米管/聚合物基取向结构复合纤维，并采用湿法纺丝技术大量制备具有高导热性能的多壁碳纳米管/聚乙烯醇芯鞘结构复合纤维。针对纺丝原液中高分子链缠结问题，本文采用了超声处理、机械搅拌处理、剪切挤出处理等方式解决高分子链缠结问题。通过测定纺丝原液的粘度、二维广角X射线衍射仪观察复合纤维的取向度以及红外偏振光测定复合纤维的取向，发现以上处理能够有效地对高分子进行解缠结。通过对多壁碳纳米管进行选型，并对多壁碳纳米管的添加量进行探究，本文筛选了适合的多壁碳纳米管型号以及添加量。对于复合纤维的取向研究，本文对比了整流挤出、空气拉伸、热拉伸三种不同方式对复合纤维取向的影响。发现通过以上方式对取向度有一定的提升，其中热拉伸能够有效提高复合纤维的取向度，同时在一定倍率的拉伸下，能够极大程度上提高复合纤维的热导率，然而当热拉伸的倍数过大时，虽然能够提高纤维的取向度，但是会将复合纤维内部的高导热通道破坏，从而降低复合纤维的热导率。经过对工艺的优化，本文采用静电纺丝制备的复合材料的热导率分别是：CNT/PVA(18.52 W/(m·K))、CNT/PAN(5.93 W/(m·K))、CNT/PET(5.90 W/(m·K));采用湿法纺丝制备得到的CNT/PVA复合纤维热导率为CNT/PVA(18.33 W/(m·K))。

With the increasing power consumption of electronic chips, the need for effective heat dissipation of electronic products is increasing. The existing heat dissipation materials cannot meet the requirements of the present electronic industry , therefore, the effective thermal management of electronic components becomes the key pint. The traditional heat dissipation materials, such as metal-based and ceramic-based heat dissipation materials, are usually suffering poor performance in thermal insulation, thermal deformation, etc. Thus, it is necessary to prepare polymer-based thermal conductive materials with light weight, low density, large deformability, good insulation properties and great elasticity.However, the thermal conductivity of polymer intrinsic materials is very low, giving only 0.1-0.2 W/(m·K), which is unacceptable for the applications of electronic devices. In order to improve the thermal conductivity of the polymer materials, adding high thermal conductive fillers is one of the best choices for now. With the inspiration from the ultra-high thermal conductive spider-silk with multi-stage sequence structure, this paper aims to adopt the design paradigm of multi-stage sequence structure material to arrange the polymer chain, micro-packing and so on into ordered structure step by step, so as to prepare polymer matrix composites with high heat conduction. In this paper, the multi-wall carbon nanotube / polymer oriented structure composite fiber with high thermal conductivity was prepared by electrospinning, and the multi-wall carbon nanotube / polyvinyl alcohol oriented structure composite fiber with high thermal conductivity was prepared by wet spinning technology.In order to solve the problem of polymer chain entanglement in spinning solution, ultrasonic treatment, mechanical stirring treatment and shearing extrusion treatment were used. By measuring the viscosity of the spinning solution, the orientation of the was observed by two-dimensional wide-angle X-ray diffraction and infrared polarized light, it was found that the above treatment can effectively untangle the polymer.Through the selection of multi walled carbon nanotubes, and the amount of multi walled carbon nanotubes to explore, this paper selects the appropriate multi walled carbon nanotubes model and amount.For the orientation study of composite fiber, the influence of different ways on the orientation was compared. It was found that the orientation degree of the composite fiber can be effectively increased by thermal stretching. It can greatly improve the of the composite fiber, but when the stretching ratio is too large, it can also improve the fiber orientation, but will break the internal high heat conduction channel, thus reducing the thermal conductance of composite fiber. After optimizing the process, the conductivity of the composite materials prepared by electrospinning are CNT/PVA (18.52 W/(m·K)), CNT/PAN (5.93 W/(m·K)), CNT/PET (5.90 W/(m·K)), and CNT/PVA composite fibers prepared by wet spinning are CNT/PVA (18.33 W/(m·K)).

高导热 芯鞘结构 多壁碳纳米管 复合材料 纺丝

high heat conduction Core sheath structure multi-walled carbon nanotubes composite spinning

中文

独立培养

南方科技大学

曾少博. 基于碳纳米管/聚合物芯鞘结构高导热纤维的制备[D]. 深圳. 南方科技大学,2021.