| Bismaleimide?BMI?has high thermostability,outstanding processability and excellent insulativity.But the unmodified BMI has many disadvantages such as great brittleness,bad shock resistance and poor stress cracking resistance.Thermoplastic resin polyether sulfone?PES?and nano-Al2O3 were used to toughen BMI in this paper,in order to improve the toughness of BMI resin and avoid the damage of other properties meanwhile.And supercritical technology was used to modify nano-Al2O3 in order to improve the the consistency between the nano-Al2O3 and resin.4,4 '-diamino diphenyl methane bismaleimide?MBMI?,3,3 '-diallyl bisphenol A?BBA?and bisphenol-A diallyl ether?BBE?were used as the matrix?MABE?,polyether sulfone?PES?as the toughening agent and SCE-Al2O3 as modifier,SCE-Al2O3/PES-MBAE composite was prepared through situ sol-gel method.The mechanism and microstructure of nano-Al2O3 modified by supercutical fluid were studied by Fourier Transform Infrared Spectroscopy?FT-IR?,transmission electron microscope?TEM?,scanning electron microscope?SEM?and X-Ray Diffraction?XRD?methods.The results showed that the surface of nano-Al2O3 was coated with fluid molecules and the outline of nano-Al2O3 modified by supercrtical fluid was clear,the effect of dispersion was good.The effect of surface modification of nano-Al2O3 was the best when the nano-Al2O3 was modified by supercritical ethanol and the processing time was 5min,the temperature was 241 ?.The chemical structures and microstructures of PES-MBAE composites and SCE-Al2O3/PES-MBAE composites were investigated by FT-IR and SEM.The heat resistance,dielectric properties,impact strength and bending strength of composite were tested by Thermal gravimetric analysis?TGA?,dielectric spectrometer and universal electronic tensile machine,respectively.The test results of PES-MBAE samples showed that the PES resin dispersed in the MBAE matrix resin evenly and present as "Honeycomb".And the toughening effect was best when the content of PES resin was 5 wt%.The test results of 5 wt%PES-MBAE samples modified by SCE-Al2O3 showed that the thermal decomposition temperature of 3 wt%SCE-Al2O3/PES-MBAE composite was 441.23 ?,which was 17.34 ? higher than that of 5 wt%PES-MBAE.For electrical properties,the dielectric constant and dielectric loss decreased at first and increased then,while the conten of SCE-Al2O3 increased.The volume resistivity and breakdown strength increased at first and decreased then,at the same time.The mechanical properties of SCE-Al2O3/PES-MBAE composite were the best while the content of SCE-Al2O3 was 3 wt%,the the impact strength and bending strength were 141.21 MPa and 12.99 k J/mm2. |
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