Preparation Of Organic/inorganic Double Layer Modified Carbon Nanotubes And Composites And Research On Dielectric Properties

Carbon nanotubes are widely used in the preparation of dielectric composites and microwave absorbing materials.Polymer high-dielectric composites with carbon nanotubes as fillers can be used as an energy storage material in capacitors.In order to obtain a low-loss,high-dielectric functional material,a double layers coaxial core-shell structure in which an organic and an inorganic material were constructed to coated carbon nanotubes.This special structure can effectively regulate the conductivity of carbon nanotubes,improve its dispersion in the polymer matrix and increase the dielectric constant of the composite by increasing the interface polarization effect.The specific work is as follows:?1?Preparation of inorganic/PANI@MWCNT hybrids:The first coating layer?PANI?were obtained using FeCl₃,K₂Cr₂O₇,(Ce?NH₄?₂?NO₃?₆ as the oxidants to initiate aniline polymerization by oxidation-reduction.and then,the metal ions in the reaction system were directly deposited on the surface of PANI@MWCNT and complete the second layer of the inorganic nanoparticles by normal precipitation method.?2?Preparation of inorganic/PANI@MWCNT-EP composites:We prepared new composites using modified carbon nanotubes as a filler and epoxy resin as a matrix material by blending and curing.when the filling amount was increased to 30%at I kHz.The dielectric constant of F e?OH?3/PANI@MWCNTs/Epoxy composites reached 202 and the dielectric loss was 0.69.The dielectric constant of Cr?OH?3/PANI@MWCNTs/Epoxy composites was 58.9 and the dielectric loss was 0.12.The dielectric constant of CeO₂/PANI@MWCNTs/EP composites is as high as 194.90 while the dielectric loss is only 0.10.?3?Preparation of Fe₃O₄/PANI@MWCNT absorbers:We prepared polyaniline coated carbon tube using ferric chloride as initiator by in-situ oxidation-reduction polymerization.We Prepared Fe₃O₄ particles by co-precipitation using and Fe³⁺ and Fe²⁺ in solution after reaction and achieved double-layer modification of Fe₃O₄ and PANI coated MWCNTs.The wave-absorbing test was conducted by blending hybrids with paraffin.When the thickness is 1.5mm,the corresponding max reflection loss was-15.65dB at 15.45GHz and the frequency range of effective reflection loss below-10dB was in the 14-17.5GHz.