本文選題：PBT + 氧化鎂　； 參考：《北京化工大學》2015年碩士論文

【摘要】：導熱復合材料作為LED燈用外殼,具有質輕,易于加工成型,成本低等優(yōu)點。為了提高導熱復合材料的導熱性能及力學性能,以滿足LED燈用外殼的使用要求。本文以PBT為基體,以氧化鎂和氮化硼為導熱填料,使用雙螺桿擠出機制備了導熱復合材料。研究了導熱填料的種類、含量以及粒徑對復合材料導熱性能、力學性能、電性能、熱變形溫度以及加工性能等各項性能的影響。并通過加入EVA和玻璃纖維對其進行增強增韌處理。對于不同種類的無機填料,隨著無機填料添加量的增多,復合材料的導熱系數(shù)均逐漸增大。當氧化鎂的加入量為70%時,復合材料的導熱系數(shù)為1.854 W/m·K。無機填料添加量相同時,粒徑較大的高純氮化硼填充導熱塑料的導熱系數(shù)最高。無機填料添加量增加的過程中,導熱塑料的力學強度越來越差,其熱變形溫度和密度卻逐漸增大。填料填充量相同時,片狀的高純氮化硼填充復合材料的力學性能降低最多,球狀的氧化鎂填充復合材料的力學性能降低最少。相同添加量下,高純氮化硼填充復合材料的熱變形溫度最高,達到111.9℃。從密度角度考慮,氧化鎂填充復合材料密度的增幅大于氮化硼填充復合材料。無機填料的加入雖然導致復合材料電阻率的降低,但仍保持在較高的水平,符合絕緣的要求。復合材料的加工性能隨著無機填料的增多逐漸變差。為了提高復合材料的力學性能,加入不同含量的EVA和玻璃纖維對其進行增強增韌改性。聚乙烯-醋酸乙烯的含量越多,材料的沖擊性能越高,抗彎性能與拉伸性能越差,導熱性能基本不變。通過對比,選擇EVA含量為4%時,復合材料的綜合性能較為優(yōu)良。向氧化鎂填充PBT基復合材料中加入玻纖,復合材料的力學性能均在一定程度上有所提高。加入玻纖后,復合材料的表面電阻率和體積電阻率均降低了一個數(shù)量級,但仍保持在較高的水平�？偟膩碚f,添加EVA和玻纖,對復合材料的力學性能有明顯的提高。
[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，

本文編號：2081642