导热绝缘尼龙6复合材料的性能研究

发布时间：2018-06-26 20:35

本文选题：PA6 + Al_2O_3　；参考：《合肥工业大学》2015年硕士论文

【摘要】：导热绝缘高分子复合材料的开发是解决当前电子电器和LED灯具散热的重要课题。基于很多文献报道的导热绝缘复合材料的力学性能或者热导率不能满足某些高要求场合的使用,本文以PA6为基体,Al2O3为导热填料,采用双螺杆挤出机制备了导热绝缘复合材料。研究了Al2O3添加量和粒径对复合材料的性能影响。结果表明：复合材料热导率均随着Al2O3添加量的增加而增大,但力学性能下降；Al2O3的填充量相同时,Al2O3粒径越大,PA6/Al2O3导热绝缘复合材料热导率越高,力学性能越差。当Al2O3添加量为70 wt%时,4μm、6μm、15μm和40μm Al2O3填充PA6复合材料的热导率分别为1.213 W/(m·K), 1.268 W/(m·K),1.289 W/(m·K)和1.455 W/(m·K),而拉伸强度分别只有57.37MPa、53.77 Npa、52.12 MPa和49.5 MPa。为了改善复合材料的力学性能,本文以甲乙酮肟和异氰酸酯为原料,制备了一种封闭异氰酸酯硅烷,该物质用作偶联剂对Al2O3进行表面改性,研究了该偶联剂对PA6/Al2O3复合材料的性能影响。SEM结果表明该封闭异氰酸酯硅烷可以改善Al2O3在基体中分散,增强与基体的连接性;平衡扭矩和力学性能结果表明该封闭异氰酸酯硅烷在复合材料熔融加工过程中解封,与PA6链端氨基或羧基发生原位反应,起到扩链剂的作用,改善了复合材料的力学性能；封闭异氰酸酯硅烷改性Al2O3/PA6复合材料的热导率也较未改性有所提升。当Al2O3的添加量增加到70 wt%时,拉伸强度达到85.16 MPa,超过纯PA6的拉伸强度；热导率达到1.18 W/m·K,是PA6热导率的3.83倍。综合考虑复合材料的力学性能、热导率和加工性能,将导热填料的填充量确定为60 wt%,但该填充量下复合材料的热导率较低。为了提高热导率,本文采用大小粒径Al2O3按不同的比例复配对PA6进行填充,结果表明6μm和40μm Al2O3按质量比1：1复配时复合材料的性能最佳。为了进一步提高热导率,我们采用上述最佳复配A1203再分别与AlN、BN和SiC三种高导热填料制成复配填料填充PA6,研究高导热填料的种类和添加量对复合材料性能的影响。最终得到力学性能和热导率俱佳的导热绝缘尼龙复合材料。
[Abstract]:The development of thermal insulating polymer composites is an important problem to solve the heat dissipation of electronic appliances and LED lamps. Based on the fact that the mechanical properties or thermal conductivity of thermal insulating composites reported in many literatures can not meet some high requirements, the thermal insulating composites were prepared by twin-screw extruder with PA6 as the matrix and Al _ 2O _ 3 as the thermal conductive filler. The effects of Al _ 2O _ 3 addition and particle size on the properties of composites were studied. The results show that the thermal conductivity of the composites increases with the increase of Al _ 2O _ 3 content, but the lower the mechanical properties are, the larger the particle size of Al _ 2O _ 3 is and the higher the thermal conductivity of PA6 / Al _ 2O _ 3 thermal insulation composites is, the worse the mechanical properties are. The thermal conductivity of PA6 composites filled with 40 渭 m Al _ 2O _ 3 is 1.213 W / (m K), 1.268 W / (m K) 1.289 W / (m K) and 1.455 W / (m K), respectively, while the tensile strength is 57.37 MPA, 53.77 nm, 52.12 MPA and 49.5 MPA, respectively, when the content of Al _ 2O _ 3 is 70 wt%, and 40 渭 m Al _ 2O _ 3-filled PA6 composites are 1.213 W / (m K), 1.268 W / (m K) and 1.455 W / (m K), respectively. In order to improve the mechanical properties of the composites, a sealed isocyanate silane was prepared from methyl ethyl ketone oxime and isocyanate, which was used as coupling agent for surface modification of Al _ 2O _ 3. The effect of the coupling agent on the properties of PA6 / Al _ 2O _ 3 composite was studied. SEM results showed that the sealing isocyanate silane could improve the dispersion of Al _ 2O _ 3 in the matrix and enhance the connectivity with the matrix. The results of equilibrium torque and mechanical properties show that the sealing isocyanate silane is unsealed during the melt processing of the composite, and then reacts in situ with the amino or carboxyl groups of the PA6 chain, which acts as a chain extender and improves the mechanical properties of the composite. The thermal conductivity of Al _ 2O _ 3 / PA _ 6 composite modified by blocked isocyanate silane was also improved. When the amount of Al _ 2O _ 3 was increased to 70 wt%, the tensile strength reached 85.16 MPA, which was higher than that of pure PA6, and the thermal conductivity reached 1.18 W / m K, 3.83 times of that of PA6. Considering the mechanical properties, thermal conductivity and processing properties of the composites, the filling amount of the thermal conductive fillers is determined to be 60 wts, but the thermal conductivity of the composites is relatively low. In order to improve the thermal conductivity, PA6 was filled with Al _ 2O _ 3 in different proportions. The results showed that the composite with 6 渭 m and 40 渭 m Al _ 2O _ 3 had the best properties when the mass ratio of 6 渭 m and 40 渭 m was 1:1. In order to further improve the thermal conductivity, the best composite A1203 was used to make PA6 filled with AlNNBNBN and sic respectively. The effects of the type and amount of high thermal conductivity fillers on the properties of composites were studied. Finally, thermal insulating nylon composites with good mechanical properties and thermal conductivity were obtained.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB332

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