LED灯用导热塑料的研究

发布时间：2018-06-29 09:20

  本文选题：PBT + 氧化镁　； 参考：《北京化工大学》2015年硕士论文

【摘要】：导热复合材料作为LED灯用外壳,具有质轻,易于加工成型,成本低等优点。为了提高导热复合材料的导热性能及力学性能,以满足LED灯用外壳的使用要求。本文以PBT为基体,以氧化镁和氮化硼为导热填料,使用双螺杆挤出机制备了导热复合材料。研究了导热填料的种类、含量以及粒径对复合材料导热性能、力学性能、电性能、热变形温度以及加工性能等各项性能的影响。并通过加入EVA和玻璃纤维对其进行增强增韧处理。对于不同种类的无机填料,随着无机填料添加量的增多,复合材料的导热系数均逐渐增大。当氧化镁的加入量为70%时,复合材料的导热系数为1.854 W/m·K。无机填料添加量相同时,粒径较大的高纯氮化硼填充导热塑料的导热系数最高。无机填料添加量增加的过程中,导热塑料的力学强度越来越差,其热变形温度和密度却逐渐增大。填料填充量相同时,片状的高纯氮化硼填充复合材料的力学性能降低最多,球状的氧化镁填充复合材料的力学性能降低最少。相同添加量下,高纯氮化硼填充复合材料的热变形温度最高,达到111.9℃。从密度角度考虑,氧化镁填充复合材料密度的增幅大于氮化硼填充复合材料。无机填料的加入虽然导致复合材料电阻率的降低,但仍保持在较高的水平,符合绝缘的要求。复合材料的加工性能随着无机填料的增多逐渐变差。为了提高复合材料的力学性能,加入不同含量的EVA和玻璃纤维对其进行增强增韧改性。聚乙烯-醋酸乙烯的含量越多,材料的冲击性能越高,抗弯性能与拉伸性能越差,导热性能基本不变。通过对比,选择EVA含量为4%时,复合材料的综合性能较为优良。向氧化镁填充PBT基复合材料中加入玻纤,复合材料的力学性能均在一定程度上有所提高。加入玻纤后,复合材料的表面电阻率和体积电阻率均降低了一个数量级,但仍保持在较高的水平。总的来说,添加EVA和玻纤,对复合材料的力学性能有明显的提高。
[Abstract]:As the shell of LED lamp, thermal conductive composite has the advantages of light weight, easy processing and low cost. In order to improve the thermal conductivity and mechanical properties of thermal conductive composite materials, to meet the needs of LED lamp shell. In this paper, the thermal conductivity composites were prepared by using a twin-screw extruder with magnesium oxide and boron nitride as the thermal conductive fillers, PBT as the matrix and magnesium oxide and boron nitride as the thermal conductors. The effects of the type, content and particle size of the thermal conductive filler on the thermal conductivity, mechanical properties, electrical properties, thermal deformation temperature and processing properties of the composites were studied. EVA and glass fiber were added to strengthen and toughen it. For different kinds of inorganic fillers, the thermal conductivity of the composites increases with the increase of the amount of inorganic fillers. The thermal conductivity of the composite is 1.854 W / m K when the addition of magnesium oxide is 70. When the amount of inorganic filler is the same, the thermal conductivity of high purity boron nitride filled with larger particle size is the highest. With the increase of inorganic filler, the mechanical strength of thermal conductive plastics becomes worse and worse, but the thermal deformation temperature and density increase gradually. The mechanical properties of the high purity boron nitride filled composites with the same filler content decreased the most, while the mechanical properties of the spherical magnesium oxide filled composites decreased the least. The thermal deformation temperature of high purity boron nitride filled composites was the highest, reaching 111.9 鈩，

本文编号：2081642