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The bisphenol A dicyanate ester resin (BADCy) is currently the most widely used commercial cyanate ester resin in China. It has a higher glass transition temperature (Tg=288℃), thermal stability (T5%=434℃) and mechanical properties due to the low steric hindrance of isopropylene group and high crosslinking density. However, the dielectric and water resistance of BADCy resin is relatively poor. Therefore, it has a great potential to modify for BADCy resin as a structural material. Based on this, the research of this paper is as follows.1. The 1,4-bis (3,5-dimethyl-4-cyanatobenzyl)benzene (BBZCy) was synthesized and used to copolymerize with BADCy. The cure kinetics of copolymer was studied by nonisothermal DSC and kinetics parameters were determined by Kissinger and Crane method. The water absorption, thermal, hydrothermal, dielectric and mechanical properties of modified cyanate ester resins immersed in the boiling water and the relative humidity environment (RH96%,50℃) were investigated by the methods of the weight measurement, DMA, dielectric analysis and three-point bending test. The results showed that the water absorption, dielectric constant and dissipation factor decreased gradually with the increase of the content of BBZCy. Meanwhile, the hydrothermal properties of modified cyanate ester resins were improved a lot. The modified system with 30wt% BBZCy showed the best performance overall, the water absorption at RH96% and 50℃was 0.87%, and the flexural strength, glass transition temperature (Tg), dielectric constant and dissipation factor were respectively 125MPa,275℃,2.90 and 3.9x10"3 in dry state at 25℃.2. The tetramethyl bisphenol F cyanate ester resin (TBFCy) was synthesized and used to copolymerize with BADCy. The chemical structures of TBF and TBFCy were characterized by FTIR,!H NMR, EI-MS and EA. The water absorption, thermal, hydrothermal, dielectric and mechanical properties of modified cyanate ester resins immersed in the boiling water and the relative humidity environment (RH96%,50℃) were investigated by the methods of the weight measurement, TGA, DMA, dielectric analysis and three-point bending test. The results showed that the water absorption, dielectric constant and dissipation factor decreased gradually with the increase of the content of TBFCy. Meanwhile, the hydrothermal properties of modified cyanate ester resins were improved a lot. The modified system with 50wt% TBFCy showed the best performance overall, the water absorption in the boiling water for 100 hour was 1.585%, and the flexural strength, Tg, dielectric constant and dissipation factor were respectively 135MPa,274℃,2.92 and 3.17x10-3 in dry state at 25℃.
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