The Preparation And Property Of Alumina Fiber/HDPE Thermal Conductive Polymer Composite

The types and preparation methods of the thermal conductive polymer composite are reviewed in the paper at first and then the development of the thermal conductive polymer composite is introduced on the base of the types of the fillers. At present, the major drawback of the thermal conductive polymer composite is the degradation increase with the enhancement of the thermal conductivity, which limiting its application greatly.In this dissertation, a thermal conductive polymer composite was prepared by two-roll mix blender, and using HDPE as the matrix and the alumina fiber as filler. In order to improve the interface between the filler and matrix, polyethylene grafted with acrylic acid (PE-AA) and polyethylene grafted with maleic anhydride(PE-MA) were used as compatibilizers during the polymer composite progressing. The mechanical and thermal conductive properties of the polymer composite are studied.The alumina fiber can strengthen the HDPE when the compatibilizer is added into the polymer composite. When the content of alumina is 50 (wt)%, the tensile strength and flexural strength of the sample with PE-AA is increased by 88% and 83% compared with the HDPE; the tensile strength and flexural strength of the sample without compatibilizer is increased by 35% and 42% compared with the HDPE. The SEM pictures showed that the interface between the alumina fiber and HDPE is improved by the use of the PE-AA.The test of thermal conductivity in the two directions: perpendicular(direction A) to and parallel to (direction B) the fluid flow direction was also conducted, respectively. The results showed that the thermal conductivity of two samples with PE-AA and without PE-AA have a similar change trend in two directions. The thermal conductivity of sample containing the PE-AA is smaller than another two samples without PE-AA in the direction A, while bigger than another two samples without PE-AA in the direction B. When the content of alumina is 50%(wt), the thermal conductivity of sample with PE-AA is increased by 40.4% in the direction A and 55% in the direction B. The thermal conductivity of sample without compatibilizer is increased by 48% and 51%.The result of XRD and DSC showed that the addition of PE-AA has little effect on the crystalline degree, however the SEM presented that the addition of PE-AA caused the alumina fiber oriented in the direction A. In the last, three types of alumina particles with different particle size(0.5 micron,4.7 micron and 10 micron),which was mixed with alumina fibers, respectively, were added into HDPE. The particles with 0.5 and 4.7 micron mixed with alumina fibers can't form thermal conductive network. The composite with particle with 10 micron mixed with alumina fibers can reach it's maximum thermal conductivity at particle:alumina fiber(m:m)=7:3, due to formation of conductive network.