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High Thermal Conductivity And Electrical Insulation Polymeric Conposites

Posted on:2011-08-10Degree:MasterType:Thesis
Country:ChinaCandidate:F RenFull Text:PDF
GTID:2121360305969884Subject:Food Science
Abstract/Summary:PDF Full Text Request
The electrically insulating and thermally conductivity polymer composite are increasingly important for high reliability and long life for micro-electronic devices because it can remain good performance simultaneously in electrically insulating and thermally conductivity. Linear low density polyethylene (LLDPE) was investigated to be used as matrix, and thermally conductive silicon carbide (SiC) and alumina (Al2O3) were used as main fillers by a powder mixing and hot press molding. The effects of fillers, content, particle sizes, surface treatment and processing technology on the thermal conductivity, mechanical properties, thermal stability, electrical properties and structures of composite plastics were discussed detailedly by many modern analytical apparatus, such as thermal tester, high insulation resistance meters, X-ray Diffraction (XRD), thermogravimetric analyzer (TGA), and scanning electron microscopy (SEM). The following conclusions can be obtained from the experiments:Firstly, single-component thermal conductivity of fillers on the properties of LLDPE was investigated. With addition of SiC or Al2O3 filler, thermal conductivity of the composite is promoted significantly. When the mass fraction was 50%, the thermal conductivity of SiC/LLDPE and Al2O3/LLDPE were 0.98W/m·k,0.88W/m·k. As filler loading increases, the thermal conductivity increase, and the electrical properties of composites, such as volume and surface resistivity, dielectric properties decline, but still remain quite high values. The mechanical properties decrease with increasing filler content. Using an appropriate amount of silane couping agent KH-550 dealing with the surface of SiC particles can improve the compatibility between filler and LLDPE matrix due to the reduced interfacial deflects and voids, and thus thermal conductivity is increased.Secondly, the effects of the hybrid particle size of SiC/LLDPE and SiC/Al2O3/LLDPE on the thermal conductivity, mechanical and electrical properties by adopting dual-component thermal conductivity fillers filling LLDPE matrix were studied and found that:using hybrid filler can significantly improve the thermal conductivity of the material, besides, changsing the ratio of hybrid fillers can obtain better combination property composites under the same filler content.Comparing some typical equation, such as Maxwell, and Cheng-Vochen, Agari.Y with experimental data of filled thermal conductive composites, Agari.Y was adaptable for SiC/LLDPE.
Keywords/Search Tags:linear low density polyethylene, silicon carbide, alumina, thermal property, mechanical property
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