【作者】 杨海涛；

【导师】 魏伯荣；

【作者基本信息】 西北工业大学 ， 材料学， 2006， 硕士

【摘要】 随着集成技术和组装技术的快速方展,电子元器件、逻辑电路的体积越来越小,迫切需要散热性好的高导热绝缘材料。而高导热性的高分子材料同时具有良好的导热性和优异的绝缘性,因此,研究高导热性能高分子材料有十分重要的意义。 本文采用非稳态法测试原理,设计和制造了测量热导率的简易装置,该装置具有测试快速、方便的特点。并在此基础上,设计了使用该装置测试热导率的流程和方法。通过与其它同类型先进热导率测试仪比较发现,本实验装置测试的结果误差小于10%,基本可以满足本研究的需要。另外,讨论了误差的产生原因和消除的方法。 基于此装置,对采用共混填充法制造的HDPE/LDPE、LDPE/导热填料、硅橡胶/导热填料三类材料的力学性能和导热性能进行了分析研究。 在HDPE/LDPE材料中,熔融峰温随HDPE含量的增大而逐渐增大;力学性能随HDPE含量的增加而有所提高。不同混合比的HDPE/LDPE材料之间的热导率变化不大,热导率均值都是呈现出先增大,到达最大值后减小,而后趋于定值的趋势。 在LDPE/导热填料中,由于无机导热填料的加入,熔融起始温度变大;填料含量的增加对熔融起始温度的影响不大。力学性能随导热填料的增加而降低,热导率随导热填料的增加而增加。 在硅橡胶/导热填料中,导热填料的加入引起拉伸强度和扯断伸长率呈增大趋势,而100%定伸应力和拉伸永久变形呈减小趋势,而使得材料导热性能提高。 本文进一步对高分子内部导热机理进行了探索,重点分析了导热填料种类和含量、温度、结晶度、比热容对橡塑材料导热性能的影响。研究发现,在LDPE和硅橡胶中加入导热填料,均能提高其导热性能,导热性能随导热填料含量的增大而提高,且与导热填料种类有关;LDPE/导热填料和硅橡胶/导热填料两类材料的热导率均值随着温度的升高,开始阶段急剧增大,而后缓慢增大,到最大值后又趋于下降;并对热导率的这种变化趋势做了理论解释;从分子角度讨论了结晶度对导热性能的影响,得出结论,若能提高聚合物材料的结晶度,即可有效提高材料导热性能。更多还原

【Abstract】 In recent years, with the development of integration and assembly technique, the volume of electronic components and logic circuit become smaller and smaller. So the materials which are insulated and with high thermal conductivity are needed. And that thermal conductive polymer materials are insulated and highly thermal conductive, therefore, the study on thermal conductive polymer materials become very important.In this paper, by means of unsteady state method, a simple new equipment used in measuring the thermal conductivity was designed. This equipment has its characteristics of being convenient and rapid. And a new method on measuring thermal conductivity based on this simple equipment was devised. Comparing with the advanced apparatus of measuring thermal conductivity, this equipment has its error less than 10%, which could satisfy the need of experiments. Furthermore, the reason of error and how to eliminate are discussed.Based on the new equipment and method, the mechanical performance and thermal conductive performance of the three kinds of materials: HDPE/LDPE, LDPE/thermal fills, silicon rubber/thermal fills, are analysed.In HDPE/LDPE, the melt temperature is increasing with the increasing of HDPE. The mechanical performance is improving with the increasing of HDPE. The thermal conductivities of HDPE/LDPE materials with different mixing proportion are approximate, all are increasing at the beginning, reaching the maximum, then reducing until to a certain value.In LDPE/thermal fills, because of the thermal fills, the temperatures of starting to melt are increasing, but approximately the same when the mixing proportions are different. The mechanical performance are reducing with the increasing of thermal fills, the thermal conductive performance are increasing with the increasing of thermal fills.In silicon rubber/thermal fills, the thermal fills make the tensile strength and failure elongation get improved, make the tensile permanence distortion definite elongation stress get worse, make the thermal conductive performance get improved.Furthermore, the internal mechanism of thermal conductibility was discussed. The main points are the effects of influence factors, such as kind and fills, proportion of fills, temperature, crystallinity, specific heat to the thermal conductivity. It is found that filling in either LDPE or silicon rubber with thermal fills can improve its thermal conductive performance. The thermal conductive performance are improving with the increasing of thermal fills, and it is also related to the kind of fills. With the temperature increasing, the thermal conductivities of LDPE/thermal fills and silicon rubber/thermal fills are increasing rapidly at the beginning, then increasing slower, reaching the top and reducing. The explanation of this change is given. The effects of crystallinity to the thermal conductive performance are discussed, the conclusion was made that if we could imcrease the crystallinity of polymer materials, the thermal conductive performance could be improved.更多还原