氮化铝微球的制备及其在高导热复合材料中的应用

发布时间：2018-06-13 08:50

本文选题：氮化铝 + 导热绝缘　；参考：《浙江大学》2017年硕士论文

【摘要】：目前,电气、电子产品都朝着质轻、体积小、集成度高和功率大等方向发展,这对其封装材料提出了更高的要求,它不再止于导热系数这一单一性能。导热绝缘材料由于有耐腐蚀、价廉、质轻、易加工、成型能耗低、电绝缘性能好等无可比拟的优异性能而受到越来越广泛的重视。本论文主要研究了氮化铝微球的可控制备以及利用氮化铝微球为填料研究了表面改性、填料含量、多壁碳纳米管共掺和聚合物基体对高导热绝缘复合材料性能的影响。采用溶胶凝胶法与氮化还原法相结合的模式制备了氮化铝微球,研究凝胶促进剂PO和表面添加剂(十六烷基三甲基溴化铵(CTAB)、硫酸铵、氯化铵、蔗糖、柠檬酸、PEO-PPO-PEO和聚乙二醇)对氮化铝前驱体形貌和球粒径的影响。结果表明PO会加速凝胶反应过程,添加量在7-9 ml的范围内能得到球形前驱体。表面添加剂(硫酸铵、氯化铵、蔗糖、柠檬酸、PEO-PPO-PEO和聚乙二醇)的加入均会使氮化铝前驱体的粒径变大,而十六烷基三甲基溴化铵(CTAB)的加入则会使氮化铝前驱体的粒径变小。以超高分子量聚乙烯(UHMWPE)作为聚合物基体,改性过的氮化铝(KH550-AlN)微球作为填料,通过溶液混合和热压成型的方法制备了 KH550-AlN/UHMWPE复合材料,比较了自制氮化铝微球和商业氮化铝颗粒对复合材料导热性能的影响,同时研究了填料含量对KH550-AlN/UHMWPE复合材料的热稳定性、导热性能、力学性能和电绝缘性的影响。热分析表明氮化铝的添加使复合材料的熔融温度和热分解温度提高,结晶度稍减少;导热结果表明自制氮化铝微球填充的复合材料具有更高的导热系数,随着氮化铝含量的提高,KH550-AlN/UHMWPE复合材料的导热系数增加,当填充量高于30 wt%,复合材料的导热系数由于导热网链的形成而出现明显的上升。力学分析表明复合材料拉伸强度和断裂伸长率都随氮化铝填充量的增加而降低。电绝缘性能测试表明在整个KH550-AlN的添加范围内,复合材料的介电常数小于7,介电损耗在10-2的数量级内,表面和体积电阻率在1014数量级上,这说明复合材料的电绝缘性能满足绝缘材料的要求。采用多巴胺(DA)对多壁碳纳米管(MWCNT)进行表面化学修饰得到聚多巴铵(PDA)包覆的多壁碳纳米管(PDA-MWCNT),然后在40wt%KH550-AlN填充的UHMWPE复合材料中添加1 wt%的PDA-MWCNT制备PDA-MWCNT/KH550-AlN/UHMWPE 复合材料。采用 SEM、TEM、FTIR、TG 和 XPS 对 PDA-MWCNT进行表征,同时测量PDA-MWCNT/KH550-AIN/UHMWPE的导热系数和拉伸性能。SEM、TEM、FTIR、TG和XPS结果都说明据多巴胺成功包覆在MWCNT表面,且改性过的MWCNT与KH550-AIN/UHMWPE复合材料之间具有很好的界面相容性。热导和力学测试结果表明在PDA-MWCNT/KH550-AIN/UHMWPE复合材料具有比KH550-AIN/UHMWPE更高的导热系数和拉伸强度。讨论了聚苯乙烯(PS)、高密度聚乙烯(HDPE)、聚苯硫醚(PPS)和聚酰胺6(PA6)四种聚合物基体中分别添加60 wt%KH550-AIN和60 wt%PDA-A12O3后的导热系数,研究聚合物基体在高导热材料中的作用。结果表明聚合物基体在制备高导热复合材料中起着非常重要的作用,复合材料导热系数从大到小顺序为PA6HDPEPPSPS,相对应的导热系数分别是 1.85、1.41、0.95 和 0.84 W·m-1·K-1。
[Abstract]:At present, electrical and electronic products are developing in the direction of light quality, small size, high integration and high power, which put forward higher requirements for its packaging materials. It no longer stops at the single performance of thermal conductivity. The heat conduction insulation material has no comparison because of corrosion resistance, low price, light quality, easy processing, low molding energy consumption and good electrical insulation performance. In this paper, the controllable preparation of aluminum nitride microspheres and the effect of aluminum nitride microspheres as filler on the surface modification, filler content, multi wall carbon nanotube co admixture and polymer matrix on the properties of high thermal insulation composites were studied in this paper. The sol-gel method and nitriding reduction method were used. The effect of PO and surface additives (sixteen alkyl three methyl ammonium bromide (CTAB), ammonium sulfate, ammonium chloride, sucrose, citric acid, PEO-PPO-PEO and PEG) on the morphology of aluminum nitride precursor and the spherulite diameter were investigated. The results showed that PO would accelerate the gel reaction process and add the amount of 7-9 ml. The addition of the surface additives (ammonium sulfate, ammonium chloride, sucrose, citric acid, PEO-PPO-PEO and PEG) will increase the particle size of the aluminum nitride precursor, and the addition of sixteen alkyl three methammonium bromide (CTAB) will make the particle size of the aluminum nitride precursor smaller. As an ultra high molecular weight polyethylene (UHMWPE) Polymer matrix and modified aluminum nitride (KH550-AlN) microspheres were used as filler to prepare KH550-AlN/UHMWPE composites by solution mixing and hot pressing. The effect of aluminum nitride microspheres and commercial aluminum nitride particles on the thermal conductivity of the composites was compared. The filler content was studied for KH550-AlN/UHMWPE composites at the same time. Thermal stability, thermal conductivity, mechanical properties and electrical insulation. The thermal analysis shows that the addition of aluminum nitride makes the melting temperature and thermal decomposition temperature of the composites increase, and the crystallinity is slightly reduced; the thermal conductivity shows that the composites filled with aluminum nitride microspheres have higher thermal conductivity, and with the increase of aluminum nitride content, KH550-A The thermal conductivity of lN/UHMWPE composites increases, when the filling amount is higher than 30 wt%, the thermal conductivity of the composite increases obviously due to the formation of the heat conduction network chain. The mechanical analysis shows that the tensile strength and elongation at break of the composite decrease with the increase of the amount of aluminum nitride. The electrical insulation performance test shows that the whole KH550-AlN is in the whole. In the addition range, the dielectric constant of the composite is less than 7, the dielectric loss is within the magnitude of 10-2, the surface and the volume resistivity are at the 1014 order of magnitude, which indicates that the electrical insulation performance of the composite satisfies the requirements of the insulating material. The surface chemical modification of the multi wall carbon nanotube (MWCNT) with dopamine (DA) is coated with polydopamine (PDA). The multi wall carbon nanotube (PDA-MWCNT) is then added to the 40wt%KH550-AlN filled UHMWPE composite material with 1 wt% PDA-MWCNT to prepare the PDA-MWCNT/KH550-AlN/UHMWPE composite. SEM, TEM, FTIR, TG and XPS are used to characterize the PDA-MWCNT, and the thermal conductivity and tensile properties are measured. XPS results show that it is clear that dopamine is successfully coated on the surface of MWCNT, and the modified MWCNT and KH550-AIN/UHMWPE composites have good interfacial compatibility. The thermal conductivity and mechanical test results show that the PDA-MWCNT/KH550-AIN/UHMWPE composites have higher thermal conductivity and tensile strength than KH550-AIN/UHMWPE. The polyphenylene B is discussed. The thermal conductivity of PS, high density polyethylene (HDPE), polyphenylene sulfide (PPS) and polyamide 6 (PA6) four polymer matrix was added to 60 wt%KH550-AIN and 60 wt%PDA-A12O3 respectively. The effect of polymer matrix in high thermal conductivity materials was studied. The results showed that polymer matrix played a very important role in the preparation of high thermal conductivity composite. The thermal conductivity of the composites is PA6HDPEPPSPS from large to small, and the corresponding thermal conductivity is 1.85,1.41,0.95 and 0.84 W. M-1. K-1., respectively.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB332;TQ133.1

【参考文献】