超高分子量聚乙烯复合材料的制备与导热性能研究
发布时间：2018-08-31 19:24
【摘要】：聚合物材料因质量轻、价格低廉而应用广泛,然而热绝缘性限制了其在微电子领域的应用,如何提高聚合物材料导热性能已成为该领域的研究热点。提高聚合物导热性能较普遍的方案就是通过粉末共混法将导热粒子添加到聚合物基体中,导热粒子包覆聚合物形成隔离结构,这种导热网络结构方便声子传输,使其快速散热。但是,导热粒子和聚合物基体之间的界面张力大,难以有效结合,两相界面缺陷多,不利于提高聚合物热导率。填料的几何形态及其在基体中的分散状态对界面结构有显著影响,另外混合型导热粒子间存在协同效应,能够在聚合物基体中形成具有隔离结构的导热通路,可有效减小界面热阻。为此本文研究了不同形貌导热粒子、混杂型导热粒子、导热复合材料制备工艺等对UHMWPE导热性能、热稳定性影响。主要内容及研究结果如下:通过粉末共混-热压法成功制备了具有隔离结构的氮化硼/超高分子量聚乙烯(BN/UHMWPE)、氮化铝/超高分子量聚乙烯(AlN/UHMWPE)、(氮化硼+碳纳米管)/超高分子量聚乙烯((BN+MWCNT)/UHMWPE)三种复合材料。导热性能研究显示,复合材料热导率随着填料含量增加而增加,当填料含量为50wt%时,热导率(BN+MWCNT)/UHMWPEBN/UHMWPEAlN/UHMWPE,其中(BN+MWCNT)/UHMWPE 热导率可达1.505Wm~(-1)K~(-1),较单一填料BN/UHMWPE 热导率提高了 64%,表明 BN、MWCNT 二者间协同效应有助于提高UHMWPE导热性能。扫描电子电镜(SEM)、光学显微镜(OM)、原子粒显微镜(AFM)研究表明BN片与MWCNT纠缠一起,较纯BN、AlN复合材料内部导热网络更为致密,说明不同类型导热填料构成的导热网络以及其边界处界面不同,从而影响界面热阻,进而影响复合材料热导率。热失重(TGA)分析表明BN+MWCNT对复合材料的热稳定性影响并不明显,这是由于导热通路形成使基体内部所产生的热量可以快速散去。片状BN与管状MWCNT之间的协同作用能够有效提高复合材料的热导率。此外,对不同温度、压力模压成型工艺所制备的BN/UHMWPE、(BN+MWCNT)/UHMWPE的微观结构、导热性能进行了研究。OM、SEM研究表明不同工艺影响着填料在基体中分散状态,其中冷压-煅烧工艺所制备的复合材料内部导热网络最为密集,但是这种网络结构在高温高压的处理条件下会被破坏,所以高温高压工艺所制备的复合材料的导热性能发生下降。然而在(BN+MWCNT)/UHMWPE复合材料中,1D-MWCNT与2D-BN纠缠一起形成了 MWCNT-BN导热网络,这种网络结构因其特殊结构即使在高温高压工艺下也呈现了良好导热性能,50wt%(BN+MWCNT)混杂填料填充UHMWPE热导率可达1.761 Wm~(-1)K~(-1)。TGA分析表明填料在基体中分散状态对复合材料热稳定性有一定影响。
[Abstract]:Polymer materials are widely used because of their light weight and low price. However, thermal insulation has limited their application in the field of microelectronics. How to improve the thermal conductivity of polymer materials has become a research hotspot in this field. The common way to improve the thermal conductivity of polymer is to add the thermal conductive particles to the polymer matrix by powder blending method, and the thermal conductivity particles cover the polymer to form an isolated structure. This heat conduction network structure is convenient for phonon transmission and makes it rapidly dissipate heat. However, the interfacial tension between the thermal conductive particles and the polymer matrix is large, it is difficult to combine effectively, and there are many defects in the two-phase interface, which is not conducive to improving the thermal conductivity of the polymer. The geometry of fillers and their dispersion in the matrix have a significant effect on the interface structure. In addition, there is a synergistic effect among the mixed heat conduction particles, which can form a thermal conduction pathway with isolated structure in the polymer matrix. The interface thermal resistance can be reduced effectively. In this paper, the effects of different morphologies of thermal conductivity particles, hybrid thermal conductivity particles and preparation process of thermal conductive composites on the thermal conductivity and thermal stability of UHMWPE were studied. The main contents and results are as follows: boron nitride / ultra-high molecular weight polyethylene (BN/UHMWPE), aluminum nitride / ultra-high molecular weight polyethylene (AlN/UHMWPE), () / ultrahigh molecular weight polyethylene (AlN/UHMWPE), () were successfully prepared by powder blending and hot pressing method. High molecular weight polyethylene (BN MWCNT) / UHMWPE) three kinds of composite materials. The study of thermal conductivity shows that the thermal conductivity of the composites increases with the increase of the filler content, and when the filler content is 50 wt%, the thermal conductivity of the composite increases with the increase of the filler content. The thermal conductivity of (BN MWCNT) / UHMWPEBN / UHMWPEBN / UHMWPEAlN / UHMWPEPE1.The thermal conductivity of (BN MWCNT) / UHMWPE is 1.505Wm-1 K-1, which is 64% higher than that of single filler BN/UHMWPE, which indicates that the synergistic effect between BN,MWCNT and UHMWPEB / UHMWPEAlPE is helpful to improve the thermal conductivity of UHMWPE. Scanning electron microscopy (SEM), (SEM), optical microscope (OM), atomic particle microscopy (OM),) (AFM) study showed that the BN sheet was entangled with MWCNT, and the thermal conduction network was denser than that of the pure BN,AlN composite. The results show that the thermal network and the interface at the boundary of different types of thermal conductive fillers have different effects on the thermal resistance of the interface and then on the thermal conductivity of the composites. Thermogravimetric (TGA) analysis shows that BN MWCNT has no obvious effect on the thermal stability of the composites, which is due to the formation of heat conduction pathways which can rapidly dissipate the heat generated in the matrix. The synergistic effect between flake BN and tubular MWCNT can effectively improve the thermal conductivity of composites. In addition, the microstructure and thermal conductivity of BN/UHMWPE, (BN MWCNT) / UHMWPE prepared by different temperature and pressure molding process were studied. The inner heat conduction network of composite prepared by cold pressing and calcining process is the most dense, but this network structure will be destroyed under the condition of high temperature and high pressure. Therefore, the thermal conductivity of the composites prepared by high temperature and high pressure process decreased. However, in (BN MWCNT) / UHMWPE composites, 1D-MWCNT entangled with 2D-BN to form a MWCNT-BN thermal network. The thermal conductivity of the UHMWPE filled with 50 wt% (BN MWCNT) hybrid filler is 1.761 Wm~ (-1) K ~ (-1) .TGA analysis shows that the thermal stability of the composite is influenced by the dispersion state of the filler in the matrix.
【学位授予单位】：西安理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O632.12;TB332
本文编号：2215933
[Abstract]:Polymer materials are widely used because of their light weight and low price. However, thermal insulation has limited their application in the field of microelectronics. How to improve the thermal conductivity of polymer materials has become a research hotspot in this field. The common way to improve the thermal conductivity of polymer is to add the thermal conductive particles to the polymer matrix by powder blending method, and the thermal conductivity particles cover the polymer to form an isolated structure. This heat conduction network structure is convenient for phonon transmission and makes it rapidly dissipate heat. However, the interfacial tension between the thermal conductive particles and the polymer matrix is large, it is difficult to combine effectively, and there are many defects in the two-phase interface, which is not conducive to improving the thermal conductivity of the polymer. The geometry of fillers and their dispersion in the matrix have a significant effect on the interface structure. In addition, there is a synergistic effect among the mixed heat conduction particles, which can form a thermal conduction pathway with isolated structure in the polymer matrix. The interface thermal resistance can be reduced effectively. In this paper, the effects of different morphologies of thermal conductivity particles, hybrid thermal conductivity particles and preparation process of thermal conductive composites on the thermal conductivity and thermal stability of UHMWPE were studied. The main contents and results are as follows: boron nitride / ultra-high molecular weight polyethylene (BN/UHMWPE), aluminum nitride / ultra-high molecular weight polyethylene (AlN/UHMWPE), () / ultrahigh molecular weight polyethylene (AlN/UHMWPE), () were successfully prepared by powder blending and hot pressing method. High molecular weight polyethylene (BN MWCNT) / UHMWPE) three kinds of composite materials. The study of thermal conductivity shows that the thermal conductivity of the composites increases with the increase of the filler content, and when the filler content is 50 wt%, the thermal conductivity of the composite increases with the increase of the filler content. The thermal conductivity of (BN MWCNT) / UHMWPEBN / UHMWPEBN / UHMWPEAlN / UHMWPEPE1.The thermal conductivity of (BN MWCNT) / UHMWPE is 1.505Wm-1 K-1, which is 64% higher than that of single filler BN/UHMWPE, which indicates that the synergistic effect between BN,MWCNT and UHMWPEB / UHMWPEAlPE is helpful to improve the thermal conductivity of UHMWPE. Scanning electron microscopy (SEM), (SEM), optical microscope (OM), atomic particle microscopy (OM),) (AFM) study showed that the BN sheet was entangled with MWCNT, and the thermal conduction network was denser than that of the pure BN,AlN composite. The results show that the thermal network and the interface at the boundary of different types of thermal conductive fillers have different effects on the thermal resistance of the interface and then on the thermal conductivity of the composites. Thermogravimetric (TGA) analysis shows that BN MWCNT has no obvious effect on the thermal stability of the composites, which is due to the formation of heat conduction pathways which can rapidly dissipate the heat generated in the matrix. The synergistic effect between flake BN and tubular MWCNT can effectively improve the thermal conductivity of composites. In addition, the microstructure and thermal conductivity of BN/UHMWPE, (BN MWCNT) / UHMWPE prepared by different temperature and pressure molding process were studied. The inner heat conduction network of composite prepared by cold pressing and calcining process is the most dense, but this network structure will be destroyed under the condition of high temperature and high pressure. Therefore, the thermal conductivity of the composites prepared by high temperature and high pressure process decreased. However, in (BN MWCNT) / UHMWPE composites, 1D-MWCNT entangled with 2D-BN to form a MWCNT-BN thermal network. The thermal conductivity of the UHMWPE filled with 50 wt% (BN MWCNT) hybrid filler is 1.761 Wm~ (-1) K ~ (-1) .TGA analysis shows that the thermal stability of the composite is influenced by the dispersion state of the filler in the matrix.
【学位授予单位】：西安理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O632.12;TB332
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