Preparation and Properties of Temperature Resistant,Transparent and Flame Resistant Polyimide Dielectric Film
Dibenzocyclobutenyl phenylphosphine oxide(DBPPO)was prepared by the oxidation reaction of the product from the reaction of 4-bromobenzocyclobutene and phenyl dichlorophosphine.The DBPPO shows an excellent processing property with a melting temperature of 107℃.DBPPO can self-polymerize or copolymerize with bismaleimide(BMI-2B)to obtain phosphine oxide polyimide.A series of phosphine oxide polyimide were prepared by varying the molar ratios of DBPPO to BMI-2B.The dielectric properties,thermal stability,optical properties and fire resistance properties of phosphine oxide polyimide were investigated via a broadband dielectric impedance relaxation spectrometer,thermogravimetric analyzer,UV-visible spectrophotometer and micro combustion calorimeter.The results show that when the molar ratio of DBPPO to BMI-2B is 1 ∶1,the prepared phosphine oxygen polyimide(PI-11)has a dielectric constant of 3.53 and a tangent value of dielectric loss of 0.052(1 MHz).The temperature of 5%weight loss of PI-11 is 478℃.The transmittance of PI-11 is 94.5%at 800 nm.In addition,compared with BMI-2B,the total heat release of PI-11 during combustion is reduced by45.7%,indicating the good flame resistance of PI-11.
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