| Polyimide (PI) and epoxy resin (EP) have their respective advantages, inthis paper, polyamide acid (PAA) was synthesized by3,3’-diethyl-4,4’-diaminodiphenyl methane (DEDADPM) and3,3’,4,4’-benzophenone tetracarb-oxylicdianhydride (BTDA) in the solvent which was N, N’-dimethylacetamide(DMAc), then the prepolymer were prepared through adding epoxy resion (E-51)into PAA. The surface of nano-SiO2and nano-Al2O3was modified by silanecoupling agent (KH550). Nanoparticles were doped into the prepolymer throughin situ polymerization, the PI-EP nanocomposites was prepared through thesystem cured in gradient temperature.Chemical structure of PAA-EP solution and PI-EP were studied by FT-IR,the heat-resistant and shear strength were tested by Thermal gravimetric analysis(TGA) and universal electronic tensile machine. Epoxy group could reactefficiently with carboxyl group and polyamine of PAA. The test results showedthat with increase of EP content, thermostability decreased and shear strengthincreased.Chemical structure and microstructure of PI-EP nanocomposites werestudied by FT-IR, X-ray diffractometer (XRD), SEM, the heat-resistant, dielectricproperties, shear strength and adhesion level were tested by Thermal gravimetricanalysis (TGA), precision impedance analyzer, universal electronic tensilemachine and adhesion tester, respectively. Modified particle and matrix producedchemical bonding through KH550, which improved the compatibility of twophase and reunion phenomenon was abated, dispersed more uniformity. The heatresistance of material were increased, and the influence of SiO2was the mostobvious, the Onset temperature increased to23.39℃, when the content ofinorganic component was5wt%. When the shear strength of5wt%Al2O3composite achieved maximum11.9MPa, which was74.4%of PI-EP (6.82MPa). The adhesive forces of all materials were at one or two level. The dielectricconstant and dielectric loss factor of composite rise, Volume resistivity showeddownward trend compared to PI-EP. When the mass ratio of SiO2/Al2O3was3:1and total content of inorganic components reached5wt%, its breakdown strengthwas the most outstanding and attained208.94MV/mm which increased32%thanthat of polymer matrix. |
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