Study On The Preparation And Properties Of Flame Retardant And Conductive Expandable Graphite

In order to prepare for the expandable graphite of expandable flame retardant system and Nano graphite sheet of conductive corrosion protection system, in this article, the preparation technology of flame retardant expandable graphite by using H₂SO₄/H₃PO₄ and HClO₄/H₃PO₄ mixed acid oxidation intercalation method was studied. The effects of various factors on the properties of expandable graphite were discussed and the optimum preparation technology of expandable graphite was optimized by the orthogonal experiment method. The preparation technology of conductive Nano graphite sheet was studied by HClO₄/H₃PO₄ mixed acid oxidation intercalation and ultrasonic stripping method. The influence of the factors on the organization structure and electrical conductivity was studied. By means of scanning electron microscope, X-ray diffraction, laser particle size analyzer and atomic force microscope, the structure and morphology of expandable graphite and Nano graphite sheet prepared by the optimized process were characterized. Experiments show that:First, the expansion volume of flame retardant expandable graphite up to 223 mL/g under the conditions of the reaction temperature is 35 degrees, reaction time is 60 min and C（g）:H₂SO₄（mL）:H₃PO₄（mL）:K₂Cr₂O₇（g）=1:2:2:0.12. The addition of five gram expandable graphite can make the oxygen index of EPS increase from 18% to 26.3%.Second, the expansion volume of flame retardant expandable graphite up to 235 mL/g under the conditions of the reaction temperature is 35 degrees, reaction time is 60 min and C（g）:HClO₄（mL）:H₃PO₄（mL）:KMnO₄（g）=1:3:2:0.1. The addition of five gram expandable graphite can make the oxygen index of EPS increase from 18% to 22.7%.Third, the expansion volume of expandable graphite up to 360 mL/g by microwave expansion method and its power is 350 W, time is 15 s. Compared with the high temperature method, the expansion volume is large and the aperture is more dense and uniform.Four, the best stripping conditions of Nano graphite sheet is that ethanol（g）:expanded graphite（g）=150:1, ultrasonic power is 400 W and ultrasonic time from 4 hours to 6hours, Which can get Nano graphite sheet average particle size in the range of 17 microns to 10 microns, thickness in the range of 50 nanometer to 150 nanometer. The addition of 20% Nano graphite sheet can make the volume resistivity of E51 reach 320 Ω·cm.