Preparation And Properties Of Thermal Conductive And Electrical Insulatingpolypropylene/boron Nitridecomposites

With the development of the electronics industry,the demand of thermal conductive insulating plastics is continuousincreasing.Polymer materials possess excellent properties except the property of heat conducing,while improving the property of heat conducting always brings about the performance weaken of its mechanical property.Polypropylene?PP?is a kind of general plastics with excellentPhysical and chemical properties,formability and low cost.Hexgonal boron nitride?hBN?is the most ideal thermal conductive fillerwith high thermal conductivity,chemical inertness and good electric insulation.In this paper,a series of PP/hBN composites were prepared by using PP as the matrix and hBN as the filler.The structure of the material characterized by SEM,XRD,TEM,AFM,the properties of composites were tested by thermal conductivity testerandelectronic universal material testing machine and the relationship between the structure and performance was studied.The main research contents and results of this paper are as follows:?1?Melt blending was used to prepare PP/hBN composites.The themeral conductivity of composites was improved and the electric insulation changed little.When the total loading volume fraction of BN was 20%,the thermal conductivity of the resultant composites was up to 0.64W/?m·K?and volume resistance was1×10¹⁵?·cmt.Howeverits mechanical properties remained to be improved.?2?Hexgonal boron nitride powder was Mechanical stirringed in ethylene glycol,the atomic force microscope image showed that the some boron nitride sheetswas exfoliated into BNNS withthickness of about 4nm.Melt blending preparation was used to prepare PP/BNNS composites,,the test of thermal conductivity showed that the thermal conductivity of composite became lager as hBN became thinner.The thermal conductivity of the resultant composites was up to 0.68W/?m·K?and volume resistance was 1.2×10¹⁵?·cm.However its mechanical properties still remained to be improved.?3?The composite was toughed by?nucleating agent and the notched impact test indicated that?nucleating agent only had slight influence on the toughness of composite when the matrix filled with high contents.The thermal conductivity of composites was measured and the results showed that thefluctuations of thermal conductivity of matrix almost had no influence on the resultant composites.Composite which had a good thermal conductivty was toughed by POE,as a result the toughness of resultant composite was improved meanwhile the processing fluidity also improved.Considering mechnical property and processing fluidity,when the total loading mass fraction of POE was 15%the composite had the best comprehensive performance.The thermal conductivity of the composites was about 0.68W/?m·K?and volume resistance,tensile strength,notched impact strength,melt index was1.2×10¹⁵?·cm,17.6MPa,4.39KJ·m^-2and1.6g/10min.